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PREVENTIVE  MEDICINE 
AND  HYGIENE 


BY 


MILTON  J.  ROSENAU 

PROFESSOR   OF   PREVENTIVE    MEDICINE   AND   HYGIENE,    HARVARD;     FORMERLY    DIRECTOR 
OF   THE   HYGIENIC   LABORATORY,    U.  S.  PUBLIC   HEALTH   SERVICE 


WITH    CHAPTERS    UPON 

SEWAGE    AND   GARBAGE,  BY   GEORGE  C.  WHIPPLE,  PROFESSOR   OF   SANITARY   ENGINEERING, 

HARVARD 

VITAL   STATISTICS,    BY    CRESSY    L.   WILBUR,  CHIEF    STATISTICIAN,    BUREAU    OF    THE    CENSUS, 
DEPARTMENT    OF    COMMERCE    AND   LABOR 

THE    PREVENTION    OF    MENT.\L    DISEASES,    BY    THOMAS    W.    SALMON,    DIRECTOR    OF    SPECIAL 
STUDIES,    NATIONAL    COMJHTTEE    FOR    MENTAL    HYGIENE,    ETC. 


NEW  YORK    AND    LONDON 

D.    APPLETON    AND     COMPANY 

1913 


Copyright,  1913,  by 
D.  APPLETOX  AND   COMPANY 


Printed  in  the  United  States  of  America 


TO 

MY   WIFE 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 

Open  Knowledge  Commons 


http://www.archive.org/details/preventivemedici1913rose 


PREFACE 

This  book  has  been  written  in  response  to  a  demand  for  a  treatise 
based  upon  modern  progress  in  hygiene  and  sanitation.  The  work  is 
planned  to  include  those  fields  of  the  medical  and  related  sciences 
which  form  the  foundation  of  public  health  work.  So  far  as  I  know, 
no  other  book  on  the  subject  covers  the  broad  field  considered  in  this 
volume.  The  progress  in  hygiene  and  sanitation  has  been  so  rapid  that 
the  subject  of  preventive  medicine  has  become  a  specialty,  and  its  scope 
has  become  so  broad  that  the  question  throughout  the  making  of  this 
book  has  been  rather  what  to  leave  out  than  what  to  include.  The  facts 
here  brought  together  are  widely  scattered  in  the  literature  and  many  of 
them  are  difficult  of  access;  they  have  been  collected  for  the  convenience 
of  the  student  of  medicine  and  the  physician,  as  well  as  those  engaged 
in  sanitary  engineering  or  public  health  work. 

During  twenty-three  years  of  varied  experience  in  public  health 
work  it  has  been  my  good  fortune  to  have  served  as  quarantine  officer, 
in  epidemic  campaigns,  in  epidemiological  investigations,  and  in  public 
health  laboratories,  at  home,  on  the  Continent,  and  in  the  tropics.  The 
fruits  of  these  experiences  are  reflected  in  this  book,  which  may  be 
taken  as  representing  my  personal  views  gained  in  the  field,  in  the 
laboratory,  in  the  classroom,  and  in  administrative  offices. 

It  is  wellnigh  impossible  to  prevent  or  suppress  a  communicable 
disease  without  a  knowledge  of  its  mode  of  transmission.  This  is 
the  most  important  single  fact  for  successful  personal  prophylaxis,  as 
well  as  in  the  general  warfare  against  infection;  therefore,  the  com- 
municable diseases  have  been  grouped  in  accordance  with  their  modes  of 
transference.  Each  one  of  the  important  communicable  diseases  is  dis- 
cussed separately  in  order  to  bring  out  the  salient  points  upon  which 
prevention  is  based.  The  classification  adopted  is  believed  to  be  unique 
and  should  prove  helpful  to  those  who  are  especially  concerned  in  the 

prevention  of  infection. 

vii 


viii  PEEFACE 

The  book  may  be  considered  in  two  parts,  namely,  that  which  deals 
with  the  person  (liygiene)  and  tliat  which  deals  with  the  environ- 
ment (sanitation).  The  first  part  includes  the  prevention  of  the 
coninumicablo  diseases,  venereal  prophylaxis,  heredity,  ininninity,  eu- 
genics, and  similar  subjects.  The  second  part  deals  with  our  environ- 
ment in  its  relation  to  liealth  and  disease  and  includes  a  discussion  of 
food,  water,  air,  soil,  disposal  of  wastes,  vital  statistics,  diseases  of  occu- 
pation, industrial  hygiene,  school  hygiene,  disinfection,  quarantine,  isola- 
tion, and  otlier  topics  of  sanitary  importance,  as  well  as  subjects  of 
interest  to  health  ofhcers.  All  the  important  methods  used  in  public 
health  laboratories  are  described. 

To  have  made  this  book  in  monographic  style  with  references  to 
authorities  for  every  statement  would  have  resulted  in  an  unwieldy 
work  of  impractical  size  and  form.  The  textbook  style  has  therefore  been 
adopted  and  citation  of  authorities  for  facts  that  are  now  well  estab- 
lished has  been  regarded  as  unnecessary.  In  this  respect  it  may  seem 
that  I  have  given  scant  credit  to  many  workers  from  whose  writings 
I  have  borrowed  results,  thoughts,  and  sometimes  words  or  even  sen- 
tences. At  the  end  of  each  chapter  will  be  found  a  list  of  references 
to  articles  or  books  that  I  have  especially  drawn  upon,  and  I  desire  to 
acknowledge  my  obligations  to  these  sources  as  well  as  to  refer  the  reader 
to  them  for  further  study  of  particular  subjects.  I  have  also  drawn 
freely  upon  my  own  previous  writings  and  those  of  my  co-workers  in 
compiling  tliis  book.  The  chapter  on  "Disinfection"  is  based  upon  my 
book  entitled :  "Disinfection  and  Disinfectants,"  published  by  P.  Blaki- 
ston's  Sons  &  Co.,  Philadelphia,  1902. 

I  have  received  generous  help  from  a  number  of  friends  and  it  is  a 
pleasure  here  to  acknowledge  especially  my  obligation  to  Dr.  David  L. 
Edsall  for  reading  and  correcting  the  chapter  on  "Diseases  of  Occupa- 
tion," to  Dr.  John  F.  Anderson  and  Dr.  Joseph  Goldberger  for  re- 
vising the  chapters  upon  "Measles"  and  "Typhus  Fever,"  to  Prof.  George 
C.  Whipple  for  reading  and  improving  the  chapter  upon  "Water,"  to 
Charles  T.  Brues  for  many  suggestions  in  the  section  upon  insect-borne 
diseases,  and  to  Prof.  W.  E.  Castle  for  a  similar  service  with  the  section 
on  "Heredity."  Dr.  Charles  Wardell  Stiles  has  kindly  furnished  infor- 
mation concerning  the  relation  of  parasites  to  soil.  I  also  desire  to 
express  my  obligations  to  Prof.  Arthur  I.  Kendall,  Dr.  Harold  L.  Amoss, 


PEEFACE  ix 

Dr.  LeT\as  W.  Hackett,  Prof.   William  D.   Frost,   and  Miss  Emily  G. 
Philpotts. 

It  has  been  my  object  to  give  in  this  volume  the  scientific  basis 
ujDon  wliich  the  j)revention  of  disease  and  the  maintenance  of  health 
must  rest.  Exact  knowledge  has  taken  the  place  of  fads  and  fancies 
in  hygiene  and  sanitation;  the  capable  health  officer  now  possesses  facts 
concerning  infections  which  permit  their  ■  prevention  and  even  their 
suppression  in  some  instances.  Many  of  these  problems  are  complicated 
with  economic  and  social  difficulties,  which  are  given  due  consideration, 
for  preventive  medicine  has  become  a  basic  factor  in  sociolog}^ 


CO]SI  TENTS 

SECTION   I 
PREVENTION    OF    THE    COMJMUNICABLE   DISEASES 

PAGE 

I. — Diseases  HA\^N■G  Specific  or  Special  Prophylactic  Measures        1 

Smallpox  and  Vaccination  :  Historical  Note,  1 ;  Vaccination,  3 ; 
Vaccine  Virus,  3;  Methods  of  Vaccination,  8;  Indices  of  a  Suc- 
cessful Vaccination,  11;  The  Immimity,  14;  Revaecination,  15; 
Claims  for  Vaccination,  17;  Vaccination  of  Exposed  Persons,  17; 
Dangers  and  Complications,  19;  Government  Control  of  Vaccine 
Virus,  21;  The  Unity  of  Cowpox  and  Smallpox,  21;  Compulsory 
Vaccination,  22 ;  Inoculation  or  Variola  Inoculata,  23 ;  Prevalence 
of  SmaUpox,  25;  Epidemiology,  27;  Modes  of  Infection,  27;  Re- 
sistance of  the  Virus,  28;  Smallpox  in  the  Vaccinated  and  Un- 
vaccinated,  29;  Result  of  Vaccination  in  Germany,  33;  Isolation 
and  Disinfection,  33. 

Rabies:  General  Considerations,  36;  Period  of  Incubation,  38; 
Entrance  and  Exit  of  the  Virus,  38;  Relative  Danger  of  Bites, 
38;  Viability,  39;  Prophylaxis,  39;  Local  Treatment  of  the 
Wound,  40;  Pasteur  Prophylactic  Treatment,  41. 
The  Venereal  Diseases  :  Syphilis,  50 ;  Gonorrhea,  53. 
Venereal  Prophylaxis  and  Hygiene  of  Sex:  Attitude,  55; 
Education,  55;  Registration  of  Cases,  57;  Continence,  57;  Per- 
sonal Hygiene,  58;  Prostitution,  58;  Medical  Prophylaxis,  58; 
Segregation,  59. 

Preventable  Blindness:  Ophthalmia  Neonatorum,  61;  Preva- 
lence, 62;  Prevention,  63. 

Tetanus:  Etiology,  66;  Incubation,  70;  Resistance,  70;  Prophy- 
laxis, 72. 

n. — Diseases   Spread  Largely   Through  the  Al\^ne   Discharges      74 

Typhoid  Fe\t:r:  General  Considerations,  74;  Prevalence,  75; 
Channels  of  Entrance  and  Exit,  80 ;  Diagnosis,  80 ;  Bacillus  Car- 
riers, 83;  Resistance  of  the  Virus,  83;  Typhoid  Bacillus  in  Na- 
ture, 84;  Modes  of  Spread,  86;  Preventive  Typhoid  Inoculations, 
94;  Management  of  a  Case  so  as  to  Prevent  Spread,  98;  Sum- 
mary— Personal  Prophylaxis,  100. 

xi 


xii  CONTENTS 

PAGE 

Cholera:  General  Considerations,  101;  Cause  and  Contributinc: 
Causes  of  Cholera,  102;  Diagnosis,  103;  Modes  of  Transmission, 
104;  Imnumity  and  Prophylactic  Inoculations,  108;  Quarantine, 
109;  Pei-sonal  Prophylaxis,  110;  Summary — Prevention,  110. 
Dysentery:  Classification,  111;  Modes  of  Transmission,  112; 
Resistance,  113;  Immunity,  113;  Pei-sonal  Prophylaxis,  113. 
HooK^voRM  Disease:  Distribution,  114;  Varieties  of  Hookworm, 
115;  Modes  of  Transmission,  115;  The  Parasite,  116;  Immunity, 
118;  Resistance  of  the  Parasite,  118;  Prevention,  119;  Collateral 
Benefits,  121. 

III. — Diseases    Spread    Largely    Through    Discharges    from    the 

Mouth  and  Nose 122 

Tuberculosis:  General  Considerations,  122;  Difference  between 
the  Human  and  the  Bovine  Tubercle  Bacilli,  123;  Bovine  Tuber- 
culosis in  Man,  124;  Modes  of  Infection,  129;  Immunity,  135; 
Resistance  of  the  Virus,  137;  Prevention,  138. 
Diphtheria:  General  Considerations,  143;  Modes  of  Transmis- 
sion, 144;  Resistance,  149;  Immunity,  149;  Prevention,  149;  Pre- 
vention of  Post -diphtheritic  Paralysis,  151;  Prevention  of  Sen;m 
Sickness,  152;  Historical  Note,  153. 

Measles:  General  Considerations,  154;  Immunity,  155;  Resis- 
tance of  the  Virus,  156;  Modes  of  Transmission,  156;  Preven- 
tion, 158. 

Scarlet  Fever:  Modes  of  Transmission,  160;  Immunity,  163; 
Prophylaxis,  163. 

Whooping  Cough:   Mode  of  Transmission,  166;  Immimity,  166; 
Prevention,  167;  Mortality,  167. 
Mumps,  168. 

Lobar  Pneumonia  :  General  Considerations,  168 ;  Modes  of 
Transmission,  169;  Resistance  of  the  A^irus,  169;  Immunity,  170; 
Prevention,  170. 

Influenza:  Immunity,  172;  Modes  of  Transmission,  172;  Pro- 
phylaxis, 173. 

Common  Colds:  General  Considerations,  173;  Prevention,  175. 
Cerebrospinal  Fever:  General  Considerations,  176;  Preven- 
tion, 179. 

IV. — Insect-borne  Diseases 181 

General  Considerations,  181. 

Insecticides:  Preparation  of  the  Room  for  Fumigation,  187; 
The  Relative  Efficiency  of  Insecticides,  188;  Sulphur,  190;  For- 
maldehyde, 191;  Pyrethrum,  192;  Phenol-eamphor,  193;  Hydro- 


CONTENTS  xiii 

PAGE 

cyanic  Acid  Gas,  194;  Bisulphid  of  Carbon,  195;  Petroleum,  196; 
Arsenic,  197. 

Mosquitoes  :  Life  History  and  Habits,  200 ;  Destruction  of  Mos- 
quitoes, 202;  Malaria,  207;  Yellow  Fever,  212;  Dengue,  220; 
Filaiiasis,  222. 

FiiiES:  General  Considerations,  223;  Life  Histoiy  of  the  Musca 
Domestica,  224;  Life  History  of  Stomoxys  Calcitrans,  226;  Flies 
as  Mechanical  Carriers  of  Infection,  226;  Suppression,  230; 
Sleeping  Sickness,  232;  Pappataci  Fever,  237. 
Fleas:  General  Considerations,  237;  Pulicides,  240;  Relation  of 
Plague  to  Rats  and  Fleas,  240. 

Rats  and  Other  Rodexts  :  General  Considerations,  242 ;  Breed- 
ing and  Prevalence,  243;  Migration,  244;  On  Vessels,  245;  Food, 
245;  Habits,  245;  Plague  in  Rats,  246;  Rat  Leprosy,  248;  Trichi- 
nosis, 248 ;  Other  Parasites,  248 ;  Economic  Importance,  248 ; 
Suppression,  249 ;  Squirrels,  253 ;  Plague,  254. 
Ticks:  General  Considerations,  261;  Texas  Fever,  263;  Rocky 
Mountain  Spotted  Fever,  263;  Relapsing  Fever,  266;  South 
African  Tick  Fever,  267. 

Lice:    General  Considerations,  268;  Typhus  Fever,  269. 

Bedbugs  :  General  Considerations,  272 ;  Suppression  of  Bedbugs, 
273;  Kala-azar,  274. 

References,  274. 

V. — Miscellaneous  Diseases 275 

Infantile  Paralysis  :  General  Considerations,  275 ;  Resistance  of 
the  Virus,  277;  Immunity,  277;  Modes  of  Transmission,  277. 

Chickenpox,  280.  . 

Glanders:   Diagnosis,  281;  Prevention,  284. 

Anthrax:    Resistance,  285;  Immunity,  285. 

FoOT-AND-MoUTH  DISEASE,  286. 

Malta  Fever:    Modes  of  Transmission,  288;   Goats'  Milk  and 
Malta  Fever,  290;  Resistance,  291;  Prevention,  291. 
Leprosy  :     General    Considerations,    292 ;    Immunity,    293 ;    Rat 
Leprosy,   293 ;    Modes    of    Transmission,    294 ;    Prevention,    296 ; 
Specific  Prevention,  297. 

Mental  Diseases  (By  Thomas  W.  Salmon,  M.  D.)  :  General 
Considerations,  298;  Infectious  Diseases  Which  Cause  Insanity, 
299;  Acute  and  Chronic  Poisonings  Which  Cause  Insanity,  301; 
Head  Injuries  and  Insanity,  304;  Heredity  and  Insanity,  304; 
Psychical  Causes,  306 ;  Economic  Factors,  306 ;  Immigration,  ■ 
307;  Agencies  Available  for  the  Application  of  Preventive 
Measures,  308. 


xiv  CONTENTS 

PAQB 

VI. — Some  General  Considerations 313 

Sources  of  Infection,  313;  Modes  of  Transference,  314;  Carriers, 
315;  Missed  Cases,  316;  Channels  of  Infection,  316 ;  "Contagious" 
and  "Infectious,"  317;  Epidemic,  Endemic,  Pandemic,  and  Proso- 
demic,  317;  The  Management  of  an  Epidemic  Campaign,  319. 
Quarantine:  General  Considerations,  321;  Maritime  Quaran- 
tine, 322;  Quarantine  Procedures,  326;  The  Bill  of  Health,  327; 
Equipment  of  a  Quarantine  Station,  328;  Qualifications  of  a 
Quarantine  Officer,  328;  Disinfection  of  Ships,  329;  Cargo,  332; 
Ballast,  332;  Foreign  Inspection  Service,  333;  National  versus 
State  Quarantine,  333 ;  Interstate  Quarantine,  334. 
ISOIiATION,  334. 


SECTION   II 
IMMUNITY,    HEREDITY    AND    EUGENICS 

I. — Immunity 337 

General  Considerations,  337;  Mechanism  of  Immunity — Theories 
of  Immunity,  338;  Natural  Immunity,  341;  Acquired  Immunity, 
343;  Mixed  Immunity,  343;  How  Immunity  May  Be  Acquired, 
343;  Specificity,  346;  Local  and  General  Immunity,  347;  Bacillus 
Carriers  or  Immunitas  Non  Sterilans,  348 ;  Latency,  350 ;  Lowered 
Resistance,  351;  Ehrlieh's  Side-chain  Theory  of  Immunity,  355; 
Antitoxic  Immunity,  360. 

ToxiNES,  360. 

Antitoxins:    General  Considerations,  365;  Gibson's  Method  of 
Concentrating  Diphtheria  Antitoxin,  370;  Dried  Antitoxin,  370; 
Mode  of  Action,  371. 
Endotoxins,  372. 

Tetanus  Toxine:  General  Considerations,  373;  Mode  of  Ac- 
tion, 376. 

Tetanus  Antitoxin,  377. 

Standardization  of  Antitoxic  Sera:  Standardization  of  Diph- 
theria Antitoxin,  378;  Standardization  of  Tetanus  Antitoxin,  380, 

Phagocytosis,  384. 
Opsonins:    The  Opsonic  Index,  388. 

Lysins:   General  Considerations,  388;  Pfeiffer's  Phenomenon,  389. 
Hemolysis,  392. 
Cytotoxins,  393. 

The  Bordet-Gengou  Phenomenon  —  Fixation  of  Comple- 
ment^ 394. 


CONTENTS  XV 


PAGE 


The  Neisser-Wechsbeeg  Phenomenon  or  Deviation  op  the 
Complement^  395. 

Isohemolysins,  396. 

Precipitins  :    General  Considerations,  396 ;  Tests  for  Blood,  399. 
Agglutinins,  400. 

Anaphylaxis  :  General  Considerations,  403 ;  Examples  of  Ana- 
phylaxis, 404;  Experimental  Sernm  Anaphylaxis,  404;  Specificity, 
406;  Sensitization  by  Feeding,  408;  Maternal  Transmission,  408; 
Serum  Anaphylaxis  in  Man,  or  Serima  Sickness,  408;  Hypersus- 
ceptibility  and  Immunity  Produced  by  Bacterial  Proteins,  411; 
Relation  of  Anaphylaxis  to  Protein  Metabolism,  411;  Relation  of 
Anaphylaxis  to  Endotoxins,  412 ;  Relation  of  Anaphylaxis  to 
Tuberculosis,  412;  Relation  of  Anaphylaxis  to  Vaccination,  413; 
Other  Practical  Relations  of  Anaphylaxis,  413. 
References^  414. 


II. — Heredity  and  Eugenics 415 

General  Considerations,  415 ;  Prevention  of  Propagation  of  Defec- 
tives, 416 ;  Statistics  of  Defectives,  418 ;  Degenerate  Families,  419. 
Eugenics,  423. 

Principles  of  Heredity  :   Variation,  425 ;  Darwin's  Theoi-y,  425 ; 
Mutation,  426;  De  Vries — Discontinuous  Evolution,  427;   Weis- 
mann's  Views,  427;  Mendel's  Law,  428;  Atavism  and  Reversion, 
432;  Galton's  Law  of  Filial  Regression,  433. 
The  Cell  in  Heredity^  434. 
Biometry,  436. 

Heredity  versus  Environment,  440. 
Immunity  Gained  Through  Inheritance,  440. 


III. — The  Hereditary   Transmission   of  Disease       .        .        .        .    442 

General  Considerations,  442;  The  Mierobie  Diseases,  445;  Hered- 
itary Transmission  of  a  Tendency  to  a  Disease,  445;  Tubercu- 
losis, 446;  Syphilis,  446;  Cancer,  448;  Leprosy,  448;  Deaf- 
mutism,  448;  Albinism,  448;  Color-blindness  or  Daltonism,  449; 
Hemophilia,  450;  Gout,  451;  Brachydactylism,  451;  Polydac- 
tylism,  451;  Myopia,  451;  Cataract,  451;  Retinitis  Pig-mentosa, 
451;  Diabetes  Mellitus,  452;  Orthostatic  Albuminuria,  453;  Al- 
eohoUsm,  453;  Epilepsy,  453;  Huntington's  Chorea,  454;  Fried- 
reich's Disease — Hereditary  Ataxia,  455;  Imbecility,  Defectives 
and  Delinquents,  455;  Insanity,  455. 
References,  457. 


xvi  CONTENTS 

SECTION  III 

FOODS 

I. — General  Considerations 

The  Uses  of  Food,  400. 

Classification  of  Foods,  461. 

Amount  op  Food:    Excessive  Amounts,  462;  Insufficient   Food, 

463;  Unbalanced  Diets,  464. 

Adulteration  of  Food,  465. 

Decomposed  Foods:    General  Considerations,  468;  Fermentation 

and   Putrefaction,   469;    "Ptomaine"   Poisoning,  469. 

Preservation  op  Foods  :   General  Considerations,  473 ;  Cold,  474 ; 

Drying,  477;   Salting  and  Pickling,  479;  Jellies  and  Preserves, 

480;  Smoking,  481;  Canning,  481;  Chemical  Preservatives,  483. 

Preparation  op  Food:    Cooking,  491;  Methods  of  Cooking,  492. 

II. — Animal  Foods  :    Milk     ........ 

General  Considerations,  494;  Composition,  495;  Milk  Standards, 
499 ;  Ferments  or  "Life"  in  Milk,  500 ;  "Leukocytes"  in  Milk,  502 ; 
Excretion  of  Drugs  in  Milk,  503 ;  Differences  between  Cow's  Milk 
and  Woman's  Milk,  503;  Classification  of  Milk,  504;  Decomi^osi- 
tion  of  Milk,  506;  Bitter  Milk,  508;  Colored  Milk,  508;  Adul- 
terations of  Milk,  509 ;  Dirty  Milk— The  Dirt  Test,  509 ;  Bacteria 
in  Milk,  509 ;  Germicidal  Property  of  Milk,  511 ;  Diseases  Spread 
by  Milk,  512;  Character  of  Milk-borne  Epidemics,  516;  Fresh 
Milk  Products,  517;  Inspection,  518;  Pasteurization,  518;  Effect 
of  Heat  Upon  Milk,  522. 

Bacteriological  Examination  op  Milk:  Number  of  Bacteria, 
523 ;  Kinds  of  Bacteria,  524. 

Microscopic  Examination:  The  Stewart-Slack  Method,  525; 
The  Doane-Buckley  Method,  526;  The  Prescott-Breed  Method,  526. 
Chemical  Analysis  of  Milk  :  Total  Solids,  527 ;  Determination 
of  Total  Solids,  527;  Determinalion  of  Fats,  528;  Determination 
of  Milk  Sugar,  531;  Determination  of  Proteins,  532;  Water,  532; 
Reaction,  533;  Specific  Gravity,  534;  Heated  Milk,  535;  Tests 
for  Enzymes  and  Their  Significance,  535. 
References,  537. 

TIL — Animal  Foods:  Meat,  Fish,  Eggs,  Etc. 

Meat:  Structure  and  Composition  of  Meats,  538;  Nutritive 
Value  of  Meat,  539;  Sources  of  Meat,  540;  Recognition  of  Spoiled 
Meat,  540;  Prevention,  541;  Meat  Presen-atives,  541;  Meat  In- 
spection, 542;  Meat  Poisoning,  552. 


CONTENTS  xvii 


PAGE 


Fish:  Physiological  Fish  Poisoning,  564;  Bacterial  Poisons,  564; 
Fish  Tapeworm,  565. 

Shellfish:    General  Considerations,  565;  Mussel  Poisoning,  567; 
Miscellaneous,  567. 
Bob  Veal,  567. 
Eggs,  568. 

IV. — Plant  Foods .        .571 

Poisoning  feom  Plant  Foods:  Ergotism,  571;  Lathyrism,  572; 
Mushroom  Poisoning,  572;  Potato  Poisoning,  573;  Beri-beri,  574; 
Pellagra,  577. 

SECTION    IV 

AIE 

I. — Composition  of  the  Air 582 

General  Considerations,  582;  Oxygen,  584;  Nitrogen,  585;  Argon, 
585;  Ozone,  585;  Hydrogen  Peroxid,  586;  Ammonia,  586;  Min- 
eral Acids,  587;  Carbon  Dioxid,  587;  CO2  as  an  Index  of  Vitia- 
tion, 588;  Methods  for  Determining  Carbon  Dioxid,  590. 

II. — Pressure,  Temperature,  and  Humidity 598 

Pressure:  Normal  Atmospheric  Pressure,  598;  Diminished  At- 
mospheric Pressure,  598 ;  Increased  Atmospheric  Pressure,  600 ; 
Barometers,  601. 

Movements  op  the  Atmosphere,  602. 

Temperature  of  the  Air:  Generar Considerations,  603;  Methods 
of  Recording  Temperature,  604. 

Humidity:  Aqueous  Vapor,  605;  Methods  of  Detennining  Hu- 
midity in  the  Air,  610;  Relation  of  Humidity  and  Temperature 
to  Health,  613;  Effects  of  Warm,  Moist  Air,  616;  Effects  of  Cold, 
Damp  Air,  616 ;  Effects  of  Warm,  Dry  Air,  617. 

III. — Miscellaneous 619 

Odors,  619;  Light,  620;  Electricity,  621;  Radioactivity,  622; 
Smoke,  622;  Fog,  625;  Dust,  625;  Dust  and  Disease,  627;  Meth- 
ods for  Examining  Dust,  628. 

IV. — Bacteria  and  Poisonous  Gases  in  the  Air        ....     630 

Bacteria  in  the  Air:    General  Considerations,  630;  Method  for 
Determining  Bacteria  in  the  Air,  631;  Air  and  Infection,  632. 
Poisonous  Gases  in  the  Air:    Carbon  Monoxid,  635;  Illumi- 
nating Gas,  636;  Other  Gases  in  the  Air,  638. 
Sewer  Gas  :   General  Considerations,  638 ;  Bacteria  in  Sewer  Air, 
639;  Ventilation  of   Sewers,  640. 


xviii  CONTENTS 

PA.OE 

V. — Fresh  and  Vitiated  Air 6il 

Benefits  of  Fresh  Air,  641. 

Effects  of  Vitiated  Air:    General    Considerations,   641;    The 

Effects  of  Increased  Carbon  Dioxid  and  Diminished  Oxygen,  643; 

Poisons  in   the   Expired  Breath,   644;   Physical   Changes  in   the 

Air,  647. 

Summary,  649. 

VI. — Ventilation  and  Heating 651 

Ventilation  :  General  Considerations,  651 ;  Vitiation  by  Respira- 
tion, 653 ;  The  Amount  of  Air  Required,  654 ;  Standards  of  Purity 
— Efficiency  of  Ventilation,  656;  The  Size  and  Shai^e  of  the 
Room,  657;  Inlets  and  Outlets,  659;  External  Ventilation,  661; 
Natural  Ventilation,  661 ;  Mechanical  Ventilation,  665. 
Heating:  General  Considerations,  665;  Open  Fires,  666;  Frank- 
lin Stoves,  667;  Open  Gas  Heaters,  667;  Hot-air  Furnaces,  667; 
Hot-water  and  Steam  Pipes,  668;  Electric  Heating,  668;  Cooling 
of  Rooms,  668. 

SECTION  V 

SOIL 

I. — General  Considerations 670 

Classification  of  Soils,  671;  Surface  Configuration,  671;  Compo- 
sition of  the  Soil,  672;  Soil  Air,  674;  Soil  Water,  675;  The 
Nitrogen  Cycle,  676 ;  The  Carbon  Cycle,  680. 

II. — The  Soil  and  Its  Relation  to  Disease 681 

Bacteria  in  Soil,  681;  Pollution  of  the  Soil,  682;  Dirt,  683; 
Cleanliness,  684;  Influence  of  Soil  Upon  Health,  684;  Diseases 
Associated  with  the  Soil,  685. 

SECTION    VI 
WATER 
I. — General  Considerations 691 

Composition,   692;   Classification   of  Water,   692;    Properties  of 
Water,  693;  Uses  of  Water  in  the  Body,  693;  Amount  of  Water 
Used  and  Wasted,  694;  Double  Water  Supplies,  697. 
Sources  of  Water:    Rain  Water,  698;   Surface  Waters,  702; 
Ground  Water,  708. 

Sources  and  Nature  of  Water  Pollution  and  Infection: 
General  Considerations,  717;  Simple  Tests  to  Determine  Sources 
of  Pollution,  718;  Interstate  Pollution  of  Streams,  719;  Care 
of  Catchment  Areas,  720. 


CONTENTS  xix 

PAGE 

II. — Sanitary  Analysis  of  Water      .        .        .        .        .        .        .    722 

Standard  Methods^,  722. 

Odors  and  Tastes:  General  Considerations,  723;  Method  of 
Determining  Odor,  726;  Prevention  and  Removal  of  Tastes  and 
Odors,  727. 

Color:  General  Considerations,  728;  Method  for  Estimating 
Color,  729. 

Turbidity  :   General  Considerations,  729 ;  Methods  for  Estimating 
Turbidity,  731. 
Reaction,  731. 

Total  Solids:  General  Considerations,  732;  Methods  for  Esti- 
mating Total  Solids,  733. 

Hardness  :  General  Considerations,  733 ;  Methods  for  Determin- 
ing Hardness,  735. 

Organic  Matter:  Free  Ammonia,  736;  Albuminoid  Ammonia, 
739;  Nitrites,  741;  Nitrates,  742. 

Chlorin  :  General  Considerations,  744 ;  Determination  of  Chlo- 
rin,  745. 

Oxygen:    Oxygen  Consumed,  746;  Dissolved  Oxygen,  748. 
Iron:    General  Considerations,  749;  Iron  Pipes,  750. 
Lead:    Tests,  751. 
Expression  of  Chemical  Results,  751. 


III. — Microscopical  Examination  of  Water 753 

Methods  of  Microscopical  Examination,  753;  Significance  of  the 
Examination,  754. 

Bacteriological  Examination  :  General  Considerations,  754 ; 
Number  of  Bacteria  in  Water,  755;  Kinds  of  Bacteria  in  Water, 
758;  Colon  Bacillus,  759;  Sewage  Streptococci,  761;  Typhoid 
Bacillus,  761;  Cholera,  761. 

IV. — Interpretation  of  Sanitary  Water  Analysis    ....    763 

General  Considerations,  763;  Allowable  Limits,  764;  Illustrative 
Analyses  Interpreted,  765. 

V. — The  Purification  of  Water 776 

Nature's  Method  op  Purifying  Water  :  General  Considerations, 
776;  Evaporation  and  Condensation,  777;  Self-purification  of 
Streams,  777 ;  Storage  in  Lakes  and  Ponds,  779 ;  Sunlight,  779. 


XX  CONTENTS 

Distilled  Water,  780. 
Boiled  Water.  7S0. 

Filters:     Slow    Sand    Filters,    781;    Mechanical    Filters,    788; 
Household    Filteis,    792;    Serubbiuii    or   Roughing   Filters,   793; 
Screening,  793. 
Storage,  793. 
Sedimentation,  794. 

Chemical  Methods  of  Purifying  Water:    Ozone,  794;  Chlo- 
rinated Lime  Bleaching  Powder,  797;  Perniangaiuite  of  Potash, 
798;  Alum  or  Sulphate  of  Alununum,  799;   Metallic   Iron:   The 
Anderson  Process,  800;  Co^^per  Sulphate,  800. 
Ultra-violet  Rays,  801. 

VI. — Water  and  Its  Relation  to  Disease  

General  Considerations,  803. 
The  Mills- Reincke  Phenomenon,  804. 

Non-specific  Diseases  Due  to  Water:    General  Considerations, 
806;  Goiter,  807;  Lead  Poisoning,  810. 

Specific  Diseases  Due  to  Water:   General  Considerations,  813; 
Cholera,  815;   Typhoid   Fever,   822;    Dysentery,   834;    Diarrhea, 
835;  Malaria,  83G;  Yellow  Fever,  837;  Animal  Parasites,  837. 
Ice:    General  Considerations,  837;  Natural  Ice,   838;   Manufac- 
tured Ice,  839;  Properties  of  Ice,  840;  Ice  and  Disease,  840. 
References,  842. 


SECTION   VII 

SEWAGE  DISPOSAL 

By  George  C.  Whipple 

General  Considerations:  Importance  of  Speedy  Removal  of 
Fecal  Matter,  843;  Dry  Earth  System,  844;  Water  Carriage  Sys- 
tem, 844;  Separate  and  Combined  Systems,  845;  Quantity  of 
Sewage,  846;  Composition  of  Sewage,  846;  Ventilation  and 
Flushing  of  Sewers,  848. 

Stream  Pollution:   Sewage  Disposal  by  Dilution,  848;  Hygienic 
Aspects  of  Stream  Pollution,  850;  Protection  Against  Pollution, 
851 ;  Water  Filtration.  851 ;  Treatment  of  Sewage,  851. 
Cooperative  Sanitation,  863. 
The  Rural  Problem  of  Sewage  Disposal,  864. 
References,  868. 


CONTENTS 

SECTION  VIII 

REFUSE  DISPOSAL 

By  George  C.  Whipple 

General  Considerations,  870;  Incineration  Plants,  872;  Reduction 
Plants,  872;  Feeding  Garbage  to  Hogs,  873;  Collection  of  Gar- 
bage, 873;  References,  873. 

SECTION   IX 

VITAL   STATISTICS 

By  Cressy  L.  Wilbur,  M.  D. 

General  Considerations,  874;  Necessity  of  Vital  Statistics  in 
Public  Health  Work,  875 ;  Neglected  Condition  of  Vital  Statistics 
in  the  United  States,  876;  Collection  of  Vital  Statistics,  878; 
Population,  8S8;  Vital  Rates,  888;  Specific  and  Corrected  Death 
Rates,  901 ;  Classification  of  Causes  of  Death,  905 ;  References  to 
Sources  and  General  Precautions  in  Use  of  Statistical  Data,  908. 


SECTION  X 
INDUSTRIAL  HYGIENE  AND  DISEASES  OF  OCCUPATION 

General  Considerations,  911. 

Some  Fundamental  Considerations  in  Prevention  :  General 
Considerations,  915;  Hours  of  Work,  916;  Fatigue,  916; 
Children,  917:  Women,  918;  Factory  Inspection,  919;  Pre- 
ventable Accidents,  920;  Sedentary  Occupations,  921. 
Diseases  of  Occupation:  Classification  of  the  Occupational 
Diseases,  921;  Lead,  922;  Phosphorus,  930;  Arsenic,  934;  Mer- 
cury, 935 ;  Carbon  Monoxid,  936 ;  Hydrogen  Sulphid,  937 ;  Dusty 
Trades,  938 ;  The  Textile  Industries,  939 ;  Wood  Dust,  941 ;  Min- 
ing, 941;  Effects  of  Heat,  942;  Parasites,  943;  Caisson 
Disease,  944. 

REFERENCES;    944. 

SECTION   XI 

SCHOOLS 

General  Considerations,  945;  School  Building,  947;  The  School- 
room, 948;  School  Furniture,  949;  Posture,  952;  Lighting,  953; 


xxii  CONTENTS 

Ventilation  and  Heatinsr,  954;  Water-closets  and  Urinals,  955; 
Cloak-rooms,  955;  Cleanliness,  956;  Medical  Inspection  of 
Schools,  956;  The  Conimuuicable  Diseases  of  Childhood,  959; 
The  Eyes,  959 ;  The  Eai-s,  961 ;  The  Teeth,  961 ;  Nose  and  Throat, 
961 ;  Diseases  of  the  Skin,  962 ;  Nervous  Diseases  and  Mental 
Defects,  963 ;  Vaccination,  964 ;  References,  964. 


SECTION  xn 

DISINFECTION 

I. — General  Considerations 966 

Definitions,  966 ;  Nature's  Disinfecting  Agencies,  967 ;  Cleanliness, 
968;  Symbiosis,  968;  When  and  Where  to  Disinfect,  969;  Qualifi- 
cations of  the  Disinfeetor,  969;  Controls,  969;  Disinfection  Must 
Be  in  Excess  of  Requirements,  970;  The  Ideal  Disinfectant,  970; 
Terminal  Disinfection,  970 ;  Standardization  of  Disinfectants,  971. 

II. — Physical  Agents  op  Disinfection 979 

Sunlight,  979;  Ultra-violet  Rays,  979;  Electricity,  980;  Burning, 
980;  Dry  Heat,  980;  Boiling,  981;  Steam,  982. 

III. — Chemical  Agents  op  Disinfection 992 

Gaseous  Disinfectants:    Preparation  of  the  Room,  992;  For- 
maldehyd   Gas,   993;    Sulphur   Dioxid,   997;    Hydrocyanic   Acid 
Gas,  1004;  Chlorin,  1004;  Oxygen,  1005;  Ozone,  1005. 
Liquid  Disinfectants  :  General  Considerations,  1006 ;  Methods  of 
Using   Chemical   Solutions,   1008 ;   Bichlorid   of   Mercury,   1009 ; 
Carbolic  Acid,  1011;  The  Cresols,  1013;  Formalin,  1014;  Potas- 
sium Permanganate,  1015;  Lime,  1016;  The  Hypochlorites,  1019; 
Antiformin,  1020;  Bromin  and   lodin,  1021;   Ferrous   Sulphate, 
1021 ;  Sulphate  of  Copper,  1021 ;  Clilorid  of  Zinc,  1021. 
Acros,  1021. 
Soaps,  1022. 

Convenient  Formula  for  Disinfecting  Solutions:  Bichlorid 
of  Mercury — Con-osive  Sublimate,  1023;  Formalin,  1023;  Milk 
of  Lime,  1024;  Carbolic  Acid,  1024;  Chlorinated  Lime,  1024. 

IV. — Methods  of  Disinfection     .        .        .        .    '     .        .        .        .  1025 

Air,  1025;  Rooms,  1026;  Stables,  1027;  Railroad  Cars,  1028; 
Feces,  1030;  Bed  and  Body  Linen,  1032;  Books,  1033;  Cadavers, 
1034;  Thermometers,  1034;  Wells  and  Cisterns,  1034. 


LIST   OF   ILLUSTRATIONS 

PIGUKE  PAGE 

1. — Vaccinia.     Course  of  the  eruption  from  the  fourth  to  the 

ninth  day  ........       12 

2. — Vaccinia.    Course  of  the  eruption  from  the  tenth  day       .       13 
3. — Course  of  vaccination  and  revaccination         ...       16 
4. — Eatio  of  mortality  of  variola  for  10,000  of  the  population, 

in  Boston,  from  1841  to  1911,  inclusive         ...       26 
5. — Smallpox  mortality  per  100,000  of  population  in  Breslau       30 
6. — Smallpox  mortality  per  100,000  of  population  in  Vienna       31 
7. — Smallpox  mortality  per  100,000  of  population  in  Prussia       34 
8. — Smallpox  mortality  per  100,000  of  population  in  Austria       35 
9. — Chart  showing  relation  of  enforcement  of  muzzling  law 

to  prevalence  of  rabies  in  Great  Britain     ...       40 
10. — Curve  showing  death  rate  from  typhoid  fever  in  Albany 

before  and  after  filtration  of  water     ....       79 

11. — Influence  of  public  water  supplies  on  the  typhoid  fever 

death  rate         ........       85 

12. — Immediate  and  striking  effect  of  purifying  a  badly  infected 

water  supply  upon  the  typhoid  situation     ...       87 
13. — Abrupt  reduction  in  death  rates  from  typhoid  fever  inci- 
dent to  water  purification  in  four  American  cities       .       89 
14. — Hookworms,  natural  size         ......     115 

15. — Hookworm  embryo         .......     115 

16. — Chart  computed  from  the  United  States  census  report  to 
show  how  the  opening  of  schools  in  autumn  increases 

diphtheria 144 

17. — A  South  African  blood-sucking  fly  (Pangonia),  illustrat- 
ing   long    proboscis   to  pierce    heavy    fur   of    certain 
animals    .........     183 

188 
209 
214 
215 
216 
216 
217 


18. — Example  of  sealing  doors  for  purpose  of  fumigation 
19. — Anopheles  punctipenis  ...... 

20. — Stegomyia  calopus  (female)   ..... 

21. — Head  of  stegomyia  calopus   (male) 

22. — Eggs  of  stegomyia  calopus    ..... 

28. — Larva  of  stegomyia  calopus  .  .  .  . 

24. — Pupa  of  stegomyia  calopus   ..... 

xxiii 


xxiv  LIST    OF    ILLUSTRATIONS 

FIGURE  PAGE 

25. — House  fly,  showing  proboscis  in  the  act  of  eating  sugar     .  224 

26. — Eggs  of  house  fly,  as  laid  in  a  mass   ....  224 

27.— Eggs  of  house   fly 225 

28. — Larva?  of  house  fly 225 

29. — Puparium  of  house  fly  .          .          .          .          .          .          .  226 

30.— Stable  fly 226 

31. — Head,  showing  proboscis,  stomoxys  calcitrans         .  227 

32.— Wing  of  stable  fly 227 

33.— The  "little  house  fly" 228 

34. — ^Wing  of  house  fly,  showing  how  it  carries  dust  particles  229 

35. — The  Hodge  fly  trap  on  a  garbage  can           .          .          .  231 

36.— Tsetse  fly 233 

37. — Various  gnats       ........  235 

38.— The  Indian  rat  flea 238 

39. — The  common  rat  flea  of  Europe  and  North  America         .  239 

40.— The  human  flea 239 

41. — A  squin-el  flea     ........  241 

42. — General  scheme  for  testing  plague  rat  infection,  city  of 

Manila 259 

43. — Isolated  plague-infested  center,  Manila,  P.  I.  .          .          .  260 

44._The  Texas  fever  tick 263 

45. — Roclrv^  ^Mountain  spotted  fever  tick           ....  264 

46.— The  bedbug 272 

47. — A  device  for  preventing  rats  traveling  along  hawsers     .  325 
48. — The  cell  with  its  various  combining  groups,  or  side  chains, 

known  as  receptors  .......  357 

49. — The  toxin  molecule,  showing  the  haptaphore  (combining) 

group,  and  the  toxaphore  (poison)  group  .          .          .  357 
50. — The  first  stage  of  antitoxin  formation :  a  toxin  molecule  an- 
chored to  a  receptor  .......  357 

51. — The  second  stage:  continued  stimulation  causes  a  repro- 
duction of  receptors  .......  358 

52. — Third  stage :  the  receptors  beginning  to  leave  the  cell     .  358 
53. — Fourth  stage:  the  receptors  have  left  the  cell  and  float 

free  in  the  blood — antitoxin       .....  358 

54. — The  neutralization  of  a  toxin  by  antitoxin:    the  free  re- 
ceptors in  the  blood  have  united  with  the  toxin  =  anti- 
toxic immunity         .......  359 

55. — The    second    order    of    immunity,    showing    complement 

and  immune  body     .......  359 

56. — The  third  order  of  immunity,  showing  an  immune  body 

having  two  affinities           ......  359 

•  57. — History  of  the  family  Zero    ......  420 


LIST    OF    ILLUSTRATIONS  xxv 

FIGUKE  PAGE 

58. — History   (condensed  and  incomplete)    of  three  markedh^ 

able  families     ........  423 

59. — Wilson's  theory  of  inheritance  modified  by  Locke     .          .  428 
60.- — Diagram   showing  the   course    of    color   heredity   in   the 
Andalusian   fowl,   in  which   one   color   does  not    com- 
pletely dominate  another            .....  430 

61. — Diagram   showing   the    course    of   color   heredity   in    the 
guinea-pig,  in  which  one    color    completely    dominates 

another    .........  431 

62. — Model  to  illustrate  the  law  of  probability  or  "chance"     .  437 

63. — Normal  heredity  curve  .          .          .          .          .          .  '        .  438 

64. — Family  history  showing  deaf-mutism     ....  448 

65. — Family  history  showing  polydactylism  ....  452 

66. — Family  history  sho^^^ng  Huntington 's  chorea  .          .          .  454 

67. — Family  history  showing  feeble-mindedness       .          .          .  456 

68. — L'nsanitary  surroundings  of  a  cow-bam  ....  506 

69. — Conditions  under  which  it  is  difficult  to  cleanse  and  disin- 
fect milk  bottles  and  milk  pails  .....  510 

70. — A  dark,  poorly  ventilated  cow  shed,  difficult  to  keep  clean  517 

71. — Automatic  temperature  recorder  for  pasteurizers     .          .  520 

72. — Straus  home  pasteurizer         ......  521 

73. — Trichinella  spiralis        .......  560 

74. — Tenia  solium,  the  pork  or  measly  tapeworm           .          .  563 

75. — Beef  tapeworm     ........  563 

76. — Dibothriocephalus  latus,  the  fish  tapeworm     .          .          .  565 
77. — Portable  Haldane  apparatus  for  small  percentages  of  car- 
bon dioxid        ........  591 

78. — Petterson-Palmquist  apparatus       .          .          .          .          .  594 

79. — Fitz  air-tester       . 596 

80.— Wolpert's  air-tester       .  .  .  .  .  .  .596 

81. — Dewing  Co.  apparatus  .......  596 

82. — ^Diagram  showing  absolute  humidity  in  grains  at  dilferent 

temperatures     .          .          .          .          .          .          .          .  607 

83. — Sling  psychrometer        .......  610 

84. — Relative  humidity  table           ......  611 

85. — Dew-point  apparatus     .          .          .          .          .          .          .  612 

86. — Table  showing  the  density  of  smoke,  in  accordance  with 
the  Ringelmann  chart,  which  may  be  emitted  from  the 
various  classes  of  stacks  in  Boston,  ]Mass.,  and  the  dura- 
tion of  such  emission        ......  624 

87. — Magnus  aspirator           .......  632 

88. — Double  aspirator  ,,.....•  632 


xxvi  LIST    OF    ILLUSTRATIONS 

FIGURE  PAGE 

89. — The  position  of  inlets  and  outlets,  and  their  relation  to 

the  air  currents  in  a  room  .....  660 

90. — "Window    ventilator        .......  663 

91. — Diagrammatic  sketch  of   various   provisions   for  ventila- 
tion .........  664 

92. — The  nitrogen  cycle        .......  677 

93. — The  nitrogen  cycle  in   diagrammatic  vertical  section     .  678 

94.— Ground  water 708 

95. — Usual  method  of  pollution  and   even  infection  of  wells  712 

96. — Proper  construction  of  a  well         .....  713 

97. — Popular  idea  of  how  wells  become  infected  from  surface 

pollution  ........  714 

98. — Depression  of  the  ground  water  level  by  pumping  and  ten- 
dency to  draw  nearby  pollution  from  the  soil  or  cesspool  715 
99. — In  a  limestone  formation  it  is  difficult  to  tell  anything 

about  the  source  of  water  obtained  from  a  well         .  715 
100. — Spring  exposed  to  contamination  from  surface  washings 
from  the  hill  above.     Spring  protected  from  surface 
washings,  and  with  bucket  which  can  be  filled  without 

contaminating   the    flow    ......  717 

101. — Algae:  uroglena ;  spirogyra;  resting  spores  of  spirogyra: 
chlamydomonas  showing  resting  condition  and  repro- 
ductive bodies  ........  724 

102. — Algse:    clathrocystis ;  anabasna;  oscillatoria ;  asterionella ; 

navicula  showing  structure  of  diatom         .         .         .  725 

103.— The  oil  droplets  in  a  diatom 726 

104. — Diagram  illustrating  the  character  of  the  ground  water  in 
relation  to  soil  pollution,  to  assist  the  interpretation  of 

a  sanitary  analysis  .......  765 

105. — Diagram  showing  the  location  of  samples        .         .         .  775 

106.— Section  of  an  English  filter  bed 782 

107. — The  arrangement  of  a  slow  sand  filter  ....  783 

108.— Diagram  illustrating  "loss  of  head"       .  .  .     •    .  786 

109. — Asiatic  cholera  and  the  Broad  Street  pump,  London,  1854  816 

110. — Asiatic  cholera  and  the  Broad  Street  well,  London,  1854  819 

111. — Map  showing  Hamburg  water  supply   ....  821 

112. — Change  in  water  supply       ......  824 

113. — Mean  death  rates  from  typhoid  fever,  1902  to  1906,  in 

66  American  cities  and  7  foreign  cities       .  .  .  825 

114.— Map  of  Plymouth,  Penn.,  in  1885 828 

115. — Map  showing  water  supply  of  Ashland,  Wis.         .         .  830 

116. — Typical  section  of  an  Imhoff  tank         ....  853 


LIST    OF    ILLUSTRATIONS  xxvii 

FIGURE  PAGE 

117. — Imhoff  tanks  and  sludge  drying    beds,    Emscher    District, 

Germany            ........  851 

118. — Chemical  precipitation  plant  at  Worcester,  Mass.,  inlet      .  855 

119. — Chemical  precipitation  plant  at  "Worcester,  Mass.,  outlet  855 

120. — Triple  contact  beds  at  Hampton,  England       .          .          .  856 
121. — Inclined  screen,  operated  by  water  wheel,  Birmingham, 

England 857 

122. — Trickling   filters   and   final   settling  basin   and   roughing 

filter  at  Hj'de,  England   ......  858 

123. — Trickling  filter  at  Birmingham,  England         .          .          .  859 
124. — Removing    sludge    from    a    septic    tank    at    Manchester, 

England            ........  861 

125. — Septic  tank  and  chemical  precipitation  tanks  at  Rochdale, 

England 862 

126. — Bur^'ing  sludge  from  hydrolytic  tank  at  Hampton,  Eng- 
land        .         .         . 863 

127. — Chemical  precipitation  tanks  at  Glasgow,  Scotland.  Lower 

end 865 

128. — Chemical  precipitation  tanks  at  Glasgow,  Scotland.  Upper 

end           .........  865 

129. — Intermittent  sand  filtration  bed    at    Brockton,    Mass.      .  866 
130. — Filter   bed   with   sand   ridged   for   winter    operation    at 

Brockton,    Mass.        .......  867 

181. — Discharge  of  sewage  upon  a  filter  bed  at  Brockton,  Mass.  868 
132. — Red  oxid  of  lead  and  litharge,  being  mixed  in  the  manu- 
facture of  storage  batteries         .....  913 

133. — An  effective  dust-removing  system  in  the  boot  and  shoe 

industry  .........  917 

134. — System  of  hoods  and  ventilators  to  carry  off  the  fumes 

from  the  furnaces  in  a  foundry  .....  921 

135. — A  worker  with  lead  oxid,  showing  respirator  to  protect 

himself  against  the  poisonous  dust     ....  925 

136.— The  stone  industry 929 

137. — Workman  exposed  to  zinc  fumes  in  brass  casting,  causing 

a  condition  known  as  "brass-founders'   ague"            .  933 
138. — Drum  with  nails   which  combs   out   the   small  pieces   of 

broom  corn       ........  938 

139.— Faulty  posture 950 

140. — The  Heusinger  desk     .......  951 

141. — Boston  school-desk  and  chair  .          .      •   .          .          .          .  952 

142. — Device  for  determining  carbolic  coefficients     .          .          .  973 

143. — Hot  air  sterilizer 981 

144. — Section  through  Arnold  steam  sterilizer  ....  983 


xxviii  LIST    OF    ILLUSTRATIONS 

FIGURE  PAGE 


145. — Section  through  autoclave     .... 

146. — Brarawell-Deane  steam  sterilizer     . 

147. — Cross  section  through  steam  disinfecting  chamber 


148. — Longitudinal  section  through  steam  disinfecting  chamber     986 


149. — Kiuyoun-Francis  steam  disinfecting  chamber  . 

150. — Automatic  thermometer  ..... 

151. — Plan  showing  the  method  of  installing  the  double-ended 

steam  chambers  at  a  national  quarantine  station  . 
152. — Chart  showing  application  of  steam  under  pressure 
153. — Flaring  top  tin  bucket  for  generating  formaldehyd  by  the 

permanganate  method  .      .  .  .  .  . 

154. — The  pot  method  of  burning  sulphur 

155. — Large  stack  burner  for  sulphur,  with  15  of  the  18  pans 

removed  to  show  construction     .... 
156. — Liquefied  sulphur  dioxid  in  tin  can 
157. — Section  through  sulphur  furnace   .... 


984 

984 
985 


988 
989 

990 
991 

996 
999 

1000 
1001 
1003 


PREVENTIVE   MEDICINE 

SECTION    I 
PREVENTION    OF    THE    COMMUNICABLE    DISEASES 

CHAPTER  I 

DISEASES  HA^^NG  SPECIFIC  OR  SPECIAL  PROPHYLACTIC 

MEASURES 

SMALLPOX   AND   VACCINATION 

The  prevention  of  smallpox  depends  primarily  upon  vaccination^  sec- 
ondarily ujDon  isolation  and  disinfection.  Yaccination  was  the  first 
specific  prophjdactic  measure  given  to  man;  it  produces  an  active  im- 
munity to  smallpox  (variola).  On  account  of  its  importance  and  great 
practical  value  this  subject  Tvill  be  considered  in  some  detail^  for  much 
of  the  antivaccination  sentiment  is  due  to  ignorance  or  misconstruction 
of  the  facts. 

Historical  Note.' — The  credit  of  giving  vaccination  to  the  world  is 
due  to  Jenner,  who  proved  through  carefully  planned  experiments  that 
cowpox  protects  against  smallpox.  This  fact  had  been  familiar  to  the 
farmers  and  folk  of  England  as  a  vague  tradition  for  a  long  time.  A 
young  girl  who  sought  medical  advice  of  Jenner,  when  a  student  at 
Sudbury,  said,  "I  cannot  take  smallpox  because  I  have  had  cowpox" ;  this 
remark  made  a  strong  impression  upon  the  young  medical  student. 

Benjamin  Jesty,  a  Dorchestershire  farmer,  in  1774  successfully  vac- 
cinated his  wife  and  two  sons.  Plett,  in  Holstein,  in  1791  also  success- 
fully vaccinated  three  children.  It  was  Jenner,  however,  who  through 
logical  and  scientific  methods  proved  that  a  person  who  has  had  the 
mild  disease,  cowpox,  enjoys  jirotection  against  the  serious  and  often 
fatal  disease,  smallpox.  Waterhouse  and  others  soon  repeated  and  cor- 
roborated Jenner's  experiments  and  helped  to  establish  the  soundness 
of  his  conclusions. 

Jenner  made  his  crucial  experiments  in  1796,  when  he  transferred 
the  vaccine  matter  from  the  hand  of  a  dairy  maid  (Sarah  Xelms)  to 
the  arm  of  a  boy  about  8  3'ears  old — name  not  given.     Sarah  Xelms 

1 


2  SPECIFIC    PROPHYLACTIC    MEASURES 

scratched  her  hand  with  a  thoru  and  "was  infected  with  the  cowpox 
from  hor  master's  cows,  in  May,  179G."  Jenncr  transferred  the  vaccine 
virus  from  the  eruption  upon  the  hand  of  Sarah  Nelms  to  the  arm  of 
the  8-year-old  boy  on  May  14,  179G.  A  typical  take  followed.  "In 
order  to  ascertain  whether  the  boy,  after  feeling  so  slight  an  affection 
of  the  system  from  the  cowpox  virus,  was  secure  from  the  contagion  of 
the  smallpox,  he  was  inoculated  the  first  of  July  following  with  variolous 
matter,  immediately  taken  from  a  pustule.  Several  slight  punctures 
and  incisions  were  made  on  both  arms,  and  the  matter  was  carefully  in- 
serted, but  no  disease  followed.  The  same  appearances  were  observable 
on  the  arm  as  we  commonly  see  when  a  patient  has  had  variolous  mat- 
ter applied,  after  having  either  the  cowpox  or  the  smallpox.  Several 
months  afterward  he  was  again  inoculated  with  variolous  matter,  but  no 
sensible  effect  was  produced  on  the  constitution." 

In  addition  to  such  direct  experimental  proof,  Jenner  inoculated 
smallpox  matter  into  ten  persons  who  had  at  some  previous  time  con- 
tracted cowpox. 


Date  of  Inoculation 

Ascertained  to 

with  Smallpox 

1.  1778 

2.  1791 

3.  1792 

t  \  1 '  95 

Name 
Mrs.  H. 
Mary  Barge 
Sarah  Portlock 
{  Joseph  Merret 
{  William  Smith 

Have  Had  Cowpox 
When  very  young 
31  years  previously 
27  years  previously 
25  years  previously 
1,  5,  15  years  previously 

7.  (  1797 

8.S 

9.     After  1782 

r  Elizabeth  Wynne 
)  Sarah  Wynne 
(  William  Rodway 
Simon  Nichols 

10  months  previously 
9  months  previously 
38  years  previously 
Some   years   previously 

10.     Not  stated 

John  Phillips 

53  years  previously 

In  justification  of  such  human  experimentation  it  should  be  re- 
membered that  at  that  time  the  inoculation  of  smallpox  matter  into 
healthy  individuals  was  an  acknowledged  method  of  preventing  that 
disease.  Jenner  himself  was  inoculated  when  a  boy.  The  question  of 
"inoculation"  (with  smallpox)  as  contrasted  with  "vaccination"  (with 
cowpox)   will  be  discussed  presently. 

With  such  proof  as  this  Jenner  put  a  popular  belief  upon  a  scien- 
tific basis.  He  demonstrated  that  cowpox  is  a  local  and  trivial  disease 
in  man,  that  it  may  be  readily  transferred  from  man  to  man,  and  that 
it  protects  against  smallpox.  The  chain  of  evidence  was  complete,  but 
he  first  proved  his  thesis  to  his  own  satisfaction  before  he  gave  it  to 
the  world.  He  said  himself:  "I  placed  it  on  a  rock  where  I  knew  it 
would  be  immovable  before  I  invited  the  public  to  take  a  look  at  it." 
Jenner  presented  the  results  of  his  observations  to  the  Royal  Society,  of 
which  he  was  a  Fellow,  but  the  paper  was  refused.     He  then  published 


SMALLPOX    AND    VACCIXATIOX  3 

it  in  1798  as  a  book,  modestly  entitled,  "An  Inquiry  Into  the  Causes 
and  Effects  of  the  Tariolse  Yaccinge^  a  Disease  Discovered  in  Some  of  the 
Western  Counties  of  England,  Particularly  Gloucestershire,  and  Known 
by  the  Xame  of  the  Cowpox."  Every  student  of  preventive  medicine 
should  read  this  brief  '"inquir}'"  in  the  original.  It  may  be  taken  as  a 
model  of  accurate  observation  and  logical  presentation,  showing  great 
self-restraint  and  moderation  of  an  observant,  imaginative,  and  judicial 
mind. 

Dr.  Benjamin  "Waterhouse,  the  first  professor  of  Theory  and  Prac- 
tice of  Physic  in  the  Harvard  Medical  School,  early  became  convinced 
of  the  value  of  Jenner's  demonstration  and  obtained  some  vaccine  virus 
from  abroad.  On  July  8,  1800,  he  vaccinated  his  son,  Daniel  Oliver 
Waterhouse,  then  five  years  old.  This  was  the  first  person  vaccinated 
in  America,  so  far  as  existing  records  show.  Thomas  Jefferson  helped 
materially  to  spread  the  new  doctrine  in  this  country,  and,  in  1806,  in 
writing  to  Jenner,  said:  "Future  nations  will  know  by  history  only 
that  the  loathsome  smallpox  has  existed  and  by  you  has  been  extir- 
pated." This  prophecy  has  not  yet  been  fulfilled — though  eminently 
possible. 

VACCINATION 

Yaccination  may  be  defined  as  the  transference  of  the  virus  from 
the  skin  eruption  of  an  animal  having  vaccinia  or  cowpox  into  the  skin 
of  another  animal.  For  over  one  hundred  years  vaccination  (from 
vaccn — a  cow)  was  a  specific  term  limited  to  the  introduction  of  the 
virus  of  cowpox  into  the  skin,  in  order  to  induce  vaccinia  and  prevent 
variola.  In  recent  years,  however,  the  term  has  been  used  in  a  generic 
sense  to  include  the  introduction  of  many  different  substances  in  many 
different  ways  and  for  many  different  purposes.  Thus  we  speak  of 
attenuated  or  killed  bacterial  cultures  as  bacterial  vaccines;  and  the 
subcutaneous  inoculation  of  organic  substances  of  diverse  origin  and 
nature  is  often  spoken  of  as  vaccination.  TVe  hear  of  typhoid  vaccines, 
anthrax  vaccines,  staphylococcus  vaccines,  and  we  read  in  the  litera- 
ture of  animals  "vaccinated"'  with  extracts  of  cancer  and  other  organic 
substances.    For  distinction  between  a  vaccine  and  a  virus,  see  page  344. 

YACCIKE    ^TEUS 

Yaccine  virus  is  the  specific  principle  in  the  matter  obtained  from 
the  skin  eruption  of  animals  having  a  disease  known  as  "vaccinia'''  or 
"cowpox."  Yaccine  virus  is  obtained  from  calves,  man,  the  buffalo, 
sometimes  the  camel,  and  other  animals. 

Cowpox,  or  vaccinia,  is  an  acute  specific  disease  to  which  many 
animals  are  susceptible,  namely,  man,  cattle,  camels,  rabbits,  monkeys, 


4  SPECIFIC    PROPHYLACTIC    MEASURES 

guinea-pi gS;,  rats,  etc.  The  disease  runs  practically  the  same  clinical 
course  in  all  susceptible  species.  The  eruption  is  always  ^  local  and 
confined  to  the  site  of  the  vaccinated  area;  the  constitutional  symptoms 
are  always  benijin  and  usually  sli<f]it.  Vaccinia  or  cowpox  is  a  l)onign 
disease;  when  uncomplicated,  it  has  never  been  known  to  cause  death  or 
leave  any  unpleasant  sequela\ 

After  an  incubation  ])eriod  of  from  three  to  four  days  the  local 
eruption  begins  as  a  ])apule  which  soon  develops  into  a  vesicle,  and 
later  into  an  umbilicated  pustule.  Surrounding  the  vesicle  is  a  red- 
dened, inflamed,  and  tender  areola.  The  neighboring  lymph  glands 
are  swollen  ami  tender,  and  there  is  slight  fever  lasting  several  days. 
The  pustule  dries,  leaving  a  crust  or  scab,  which  comes  away,  disclosing 
a  typical  foveated  or  pitted  scar. 

Human  and  Bovine  Vaccine  Virus. — Vaccine  virus  may  be  obtained 
cithrr  fi'om  bovine  or  human  sources. 

Human  virus  is  now  seldom  used,  for  the  reason  that  the  supply 
would  not  be  sufficient.  Upon  the  appearance  of  a  smallpox  outbreak 
it  is  sometimes  necessary  to  have  enough  virus  to  vaccinate  from  one 
hundred  tliousand  to  a  million  people.  Such  large  quantities  evidently 
could  not  be  obtained  from  man  at  any  desired  time.  Another  ol)jec- 
tion  to  the  use  of  human  virus  is  the  possibility,  although  snuill,  of 
transmitting  syphilis,  and  perhaps  other  diseases.  When  Ininian  seed 
is  used  the  virus  may  be  transferred  directly  from  arm  to  arm ;  or  the 
virus  may  be  preserved  dry  in  the  scab;  or  the  contents  of  the  vesicle 
may  be  kej)t  in  either  a  dried  or  moist  state,  as  described  below  for 
bovine  virus.  Arm  to  arm  vaccination  is  still  practiced  in  several  parts 
of  the  world,  particularly  in  Mexico,  where  it  is  claimed  that  it  has 
the  advantage  of  prodi;cing  a  better  take;  that  the  results  are  surer  in 
that  there  are  fewer  unsuccessful  vaccinations;  and,  finally,  it  is  stated 
that  the  human  virus  affords  a  better  immunity,  but  as  to  this  there 
is  no  proof  and  some  doubt. 

Bovine  virus  has  been  used  more  or  less  since  the  time  of  Jenner, 
but  especially  since  Copeman  showed  in  1891  how  to  purify  it  with 
glycerin.  It  has  the  great  advantage  of  being  readily  obtained  in  any 
amount  and  when  desired.  It  further  totally  eliminates  the  danger 
of  conveying  syphilis  and  other  diseases  peculiar  to  man. 

Forms  of  Vaccine  Virus. — Vaccine  virus  may  be  used  in  one  of 
three  forms:   (1)   fresh,  (2)  dry,   (3)  glycerinated. 

The  fresh  virus  may  be  taken  from  the  eruption  of  the  calf  or  man 
and  transferred  directly.  Thus  the  Institut  Vaccinale  at  Paris  still 
prefers  to  use  the  fresh  virus.  The  vesicle  is  squeezed  at  its  base  1)e- 
tween  the  blades  of  forceps,  and  some  of  the  contents  are  transferred 

^Eare  exceptions  to  this  statement  will  be  noted  later. 


SMALLPOX   AND   VACCINATION  S 

directly  from  the  calf  to  the  skin  of  the  arm  by  means  of  a  thumb 
lancet  or  an}^  similar  instrument. 

The  vaccinal  matter  may  be  dried,  and  the  virus  remains  potent  in 
this  state  a  very  long  time,  especially  if  kept  cold  and  protected  from 
the  light.  The  virus  may  be  dried  upon  a  splinter  of  ivory  or  other 
substance.  Formerly  physicians  preserved  the  dried  crust  from  a  typi- 
cal take.  Small  portions  of  this  crust  were  ground,  moistened,  and  then 
inserted  into  the  skin. 

Glycerinated  virus  consists  of  vaccine  pulp  treated  with  60  per  cent, 
pure  glycerin.  This  purifies  it  and  hence  is  preferable.  Before  taking 
up  the  question  of  gh'cerination,  we  must '  understand  the  difference  be- 
tween vaccine  lymph  and  vaccine  pulp. 

Vaccine  Pulp  and  Vaccine  Lymph. — A  distinction  is  drawn  between 
the  pulp  and  the  lymph.  The  pulp  consists  of  the  entire  vesicle. with 
its  contents,  which  is  scraped  from  the  skin,  and  is  composed  of  epi- 
thelium, leukocytes,  bacteria,  products  of  inflammatory  reaction,  the 
fluid  content  of  the  vesicle,  debris,  etc.  The  lymph  is  the  serous  fluid 
contained  in  the  vesicle  or  which  often  exudes  from  the  broken  vesicle. 
When  the  eruption  is  produced  on  the  skin  of  a  calf  in  a  large  con- 
fluent area,  the  surface  of  the  eruption  is  scraped  away  and  the  exuding 
lymph  is  placed  upon  points  by  dipping  or  brushing.  Most  of  the  active 
principle  of  vaccine  virus  is  contained  in  the  epithelial  cells,  and  this 
portion  i^  largely  lost  when  only  the  lymph  is  used.  The  pulp,  which 
includes  the  lymph,  therefore  contains  the  virus  in  greater  concentration, 
and  is  almost  exclusively  used  in  this  country  at  the  present  time. 

Dry  Points  Versus  Glycerinated  Vaccine  Virus. — The  old-fashioned 
dry  points  were  prepared  by  dipping  splinters  of  ivory  into  the  vaccine 
lymph.  Later  the  lymph  was  collected  upon  a  brush  and  thus  trans- 
ferred to  the  ivory  point.  Bone  or  glass  may  be  sul^stituted  for  ivory. 
Bone  is  undesirable  because  it  is  exceedingly  difficult  to  sterilize.  The 
only  advantage  of  the  dry  point  is  its  convenience  in  vaccinating.  Its 
disadvantage  is  that  the  virus  dried  upon  such  points  cannot  be  purified 
as  is  the  case  with  glycerinated  pulp.  Further,  the  points  are  used  as 
scarifiers  and  the  method  of  scarification  favors  irritation  and  infection 
of  the  wound.  The  dry  points  practically  always  contain  more  bacteria 
than  the  glycerinated  virus.  For  these  reasons  dry  points  are  no  longer 
permitted  in  interstate  traffic  in  accordance  with  the  federal  regulations. 

The  superiority  of  the  glycerinated  virus  will  be  evident  from  a 
study  of  the  ripening  or  purification  of  vaccine  virus  with  glycerin  (see 
below) . 

The  old-fashioned  dry  points  must  not  be  confused  with  the  points 
now  placed  on  the  market  by  manufacturers  containing  a  drop  of  glycer- 
inated lymph.     There  is  no  special  objection  to  these,  except  that  it 

encourages  vaccination  by  the  method  of  scarification.     Some  manufac- 
3 


6  SPECIFIC    PEOPHYLACTIC    MEASUPES 

turers  imitate  the  old-fashioned  dn'  point  by  reniovintr  most  of  the 
glycerin  from  the  rijiened  pulp  bv  pressing  it  between  l)lotting  papers. 
The  remaining  pulp  is  then  attached  to  the  points  with  sterile  dextrose, 
blood  serum,  or  some  other  gummy  substance. 

The  Process  of  Ripening. — When  the  vaccine  virus  is  fresh  it  is  said 
to  be  "green."  Glycerin  is  added  to  the  green  pulp,  and  after  it  has 
acted  a  certain  period  of  time  the  virus  is  said  to  be  "ripe."  The  use 
of  glycerin  for  this  purpose  was  introduced  by  Moncton  Copeman  in 
1891  for  the  purpose  of  preserving  and  purifying  the  virus.  The  glycer- 
in acts  as  a  differential  germicide,  that  is,  it  preserves  ^  the  active 
principle  in  the  vaccine  virus,  but  destroys  the  frail  non-spore-bearing 
bacteria.  In  time  the  virus  itself  succumbs.  Vaccine  virus  must,  there- 
fore, not  be  used  while  green  nor  when  too  old.  Manufacturers  usually 
date  their  products  as  "not  reliable  after"  or  "return  after"  4  to  6 
weeks  in  the  summer  time  and  3  months  during  the  cold  season. 

Sixty  per  cent,  glycerin  of  the  best  quality  is  used.  I  have  shown 
that  no  growth  of  bacteria,  yeasts,  or  molds  takes  place  in  this  percen- 
tage. Two  to  four  parts  of  60  per  cent,  glycerin  are  added  to  1  part  of 
the  pulp  by  weight.  The  mixture  is  then  thoroughly  ground  with  a 
mortar  and  pestle  by  hand,  or  between  glass  rollers  in  a  special  mill 
driven  by  machinery.  The  pulp  should  be  thoroughly  broken  up  and  a 
uniform  suspension  obtained.  The  amount  of  glycerin  added  depends 
upon  the  consistency  and  character  of  the  pulp.  The  only  objection 
to  adding  more  glycerin  would  be  the  greater  dilution  of  the  virus,  and, 
therefore,  a  larger  proportion  of  negatire  takes.  A  higher  percentage 
than  GO  per  cent,  of  glycerin  soon  renders  the  virus  inert.  The  glycerin 
probably  destroys  the  bacteria  Ijy  virtue  of  its  dehydrating  action.  The 
time  required  for  the  virus  to  ripen  depends  upon  the  temperature. 
Most  of  the  non-spore-bearing  bacteria  perish  in  30  days  at  15°  to 
20°  C.  Approximately  the  same  effect  may  be  obtained  at  37°  C.  in 
from  24  to  48  hours.  At  low  temperatures  the  glycerin  has  practically 
no  bactericidal  effect.  The  process  must  always  be  controlled  bacterio- 
logically. 

Substances  other  than  glycerin  are  used  for  the  purpose  of  purifying 
vaccine  virus.  Carbolic  acid  (0.5  to  1.0  per  cent.)  is  used  with  success" 
in  Japan,  and  to  some  extent  in  this  country.  Potassium  c}anid,  chloro- 
form, elilorobiitanol.  etc..  liave  been  tried,  with  less  success  in  practice. 

Bacteria  in  Vaccine  Virus.- — Vaccine  virus  always  contains  bacteria. 
There  is  no  such  thing  as  asej^tic  vaccine  virus.  The  active  principle 
has  not  been  grown  in  pure  cultures.  However,  the  bacteria  which  con- 
taminate vaccine  virus  are,  for  the  most  part,  harmless  to  man.  They 
are  commonly  those  that  are  found  on  and  in  the  skin  of  the  calf.    The 

'  Glycerin  also  serves  as  a  preser\-ative  for  other  filterable  viruses,  as  foot 
and  mouth  disease,  anterior  poliomyelitis,  rabies,  etc. 


SMALLPOX    AND    VACCINATION  7 

non-spore-bearing  varieties  are  largely  eliminated  by  the  process  of 
ripening.  There  are  fewer  bacteria  in  the  typical  unbroken  vesicle  than 
in  a  broken,  crusty,  inflamed  eruption.  Green  virus  may  contain  from 
a  few  thousand  to  over  a  million  bacteria  per  cubic  centimeter.  The 
ripened,  glycerinated  virus  contains  comparatively  much  fewer,  and  these 
mostly  spores  of  the  hay  bacillus,  common  molds,  and  other  harmless 
saprophytes.  The  number  of  such  bacteria  in  the  ripened  virus  may 
be  taken  as  an  indication  of  the  care  and  cleanliness  with  which  the 
virus  has  been  prepared.  Staphylococci,  streptococci,  members  of  the 
hemorrhagic  septicemic  group,  and,  in  a  few  instances,  tetanus  spores 
and  the  gas  bacillus  have  been  found  in  vaccine  virus. 

Seed  Vaccine. —The.  seed  virus  may  be  obtained  (1)  from  cowpox, 
(2)  from  smallpox,  (3)  by  retrovaccination. 

Spontaneous  or  casual  cowpox  occasionally  occurs,  that  is  to  say,  the 
disease  appears  to  arise  spontaneously  because  its  origin  cannot  be  traced. 
Casual  cowjDox  comes  either  from  another  case  of  cowpox  or  from  a 
case  of  smallpox.  Cattle  are  not  subject  to  smallpox,  but,  when  small- 
pox virus  is  introduced  into  the  skin  of  a  calf,  it  produces  cowpox. 
When  smallpox  is  thus  converted  into  cowpox,  it  remains  fixed  as  such, 
and  never  reverts  to  smallpox.^  In  several  instances  in  England,  Ger- 
many, and  this  country  the  seed  virus  has  been  obtained  by  starting 
cowpox  through  the  inoculation  of  smallpox  virus.  Such  virus  should 
not  be  used  until  several  transfers  from  calf  to  calf  have  been  made, 
for  the  reason  that  some  of  the  smallpox  virus  may  be  carried  over 
unaltered,  during  the  first  few  transfers.  Eetrovaccination  consists  in 
carrying  the  vaccine  virus  back  from  child  to  calf.  By  this  method  its 
virulence  is  maintained.  Instead  of  calves,  monkeys  or  rabbits  may  be 
used  for  the  purposes  of  retrovaccination. 

Propagation. — In  the  propagation  of  bovine  virus  young  calves  are 
preferred,  because  they  are  more  manageable,  the  skin  is  more  tender, 
and  the  eruption  is  therefore  more  abundant  and  typical.  With  young 
animals  a  milk  diet  may  be  used,  which  simplifies  the  problem  of  dust 
contamination  from  dry  feed.  If  hay  or  fodder  is  used,  it  must  first 
be  autoclaved.  Either  heifers  or  bull  calves  are  suitable. 

The  animals  are  held  in  quarantine  for  seveiL  days,  under  observa- 
tion, to  determine  the  absence  of  infections  such  as  tuberculosis,  glan- 
ders, foot-and-mouth  disease,  tetanus,  and  skin  eruptions  of  any  kind. 

Before  vaccinating  the  calf  it  is  carefully  cleaned,  and  the  site 
of  the  inoculation  is  shaved  and  prepared  surgically,  but  without  the 
use  of  germicidal  solutions.  Germicides  are  not  suitable  for  the  reason 
that  they  are  apt  to  destroy  the  vaccine  virus.  Cleanliness  and  asepsis 
are  the  watchwords.     The  area  selected  is  usually  the  abdominal  wall  be- 

"^  It  is  highly  significant  that  casual  cowpox  was  formerly  much  more  com- 
mon when  smallpox  was  much  more  prevalent. 


8  SPECIFIC    PROPHYLACTIC   MEASURES 

tween  the  tip  of  the  sternum  and  the  groin,  sometimes  including  the 
inner  side  of  the  thigli.  The  usual  method  is  to  make  long,  superficial 
incisions  in  the  skin  ahout  one  inch  apart,  and  the  seed  virus  is  gently 
rul)bed  into  these  incisions.  The  calves  must  then  be  kept  rigidly  iso- 
lated in  a  special  room,  moderately  lighted,  free  from  dust,  and  screened 
to  keep  out  insects.  The  temperature  of  the  animal  is  taken  several 
times  daily,  and  the  eruption  at  each  stage  of  the  disease  is  closely 
watched  and  recorded. 

The  virus  is  usually  taken  from  the  animal  between  the  fifth  and 
the  eighth  day.  It  is  an  advantage  to  take  the  virus  as  early  as  prac- 
ticable, in  order  to  avoid  contaminating  infections  which  may  occur 
when  the  vesicles  supjmrate.  Only  typical  and  entirely  characteristic 
vesicles  should  be  removed.  Before  the  virus  is  removed,  the  animal  is 
killed  to  avoid  pain,  and  an  autojjsy  is  done  as  soon  as  the  virus  is  re- 
moved. If  the  autopsy  shows  any  lesions  indicating  infection?  other 
than  vaccinia,  the  virus  is  discarded. 

It  is  not  wise  in  propagating  vaccine  virus  to  vaccinate  too  large 
an  area.  This  favors  infections  by  lowering  resistance;  less  typical 
eruptions  are  obtained  than  when  the  area  vaccinated  is  moderate  in 
extent.  A  yield  of  from  twenty  to  forty  grams  of  pulp  from  one  calf 
should  satisfy  the  propagator. 

Before  the  virus  is  taken  the  animal  is  placed  upon  a  special  taljle, 
the  site  of  the  vaccination  exposed  and  given  a  very  thorough  washing 
and  prolonged  scrubl)ing  with  soap,  and  an  abundant  flushing  with 
sterile  water.  The  pulp  is  usually  obtained  by  scraping  the  vesicles 
with  a  sharp  spoon  curette. 

Glycerin  (GO  per  cent.)  in  proper  proportion  is  added  at  once  to 
the  pulp,  and  this  is  ground  to  a  state  of  fine  and  uniform  sulidivision 
in  a  Doring  lymph  mill,  or  simply  by  hand  with  a  mortar  and  pestle. 
This  glyccrinated  pulp  is  then  allowed  to  ripen,  and  when  ripe  it  is 
hermetically  sealed  in  capillary  tubes,  or  placed  in  small  vials,  or  upon 
glass  or  ivory  points,  for  the  market. 

METHODS    OF    VACCINATION 

Vaccination  consists  in  transferring  the  virus  from  one  animal  to 
the  skin  of  another  animal.  The  operation  may  be  compared  to  the 
transfer  of  a  culture  in  a  bacteriologic  lal)oratory.  Precisely  similar 
precautions  to  prevent  contamination  must  he  used  in  both  cases.  Vac- 
cination must  be  regarded  as  a  surgical  operation.  No  person  unfamiliar 
with  surgical  cleanliness  should  be  permitted  to  perform  this  "little" 
operation. 

The  vaccine  virus  may  be  introduced  in  one  of  three  ways:  (1)  by 
puncture,  (2)  by  incision,  or  (3)  by  scarification. 


SMALLPOX    AND    VACCINATION  9 

Jenner  used  punctures  or  short  incisions.  Later  blisters  were  raised 
upon  the  skin  and  the  virus  placed  upon  the  abraded  surface.  The 
incisions  were  then  increased  in  number,  and  finally  cross  scratchings 
were  made. 

Puncture.— The  simplest  and  best  method  is  puncture  with  a  needle, 
for  there  is  least  chance  of  contamination  and  the  eruption  is  typical. 
The  disadvantage  is  that  the  virus  now  used  is  diluted  with  glycerin, 
and  therefore  somewhat  attenuated,  so  that  a  few  simple  punctures  are 
less  apt  to  take. 

Incision. — The  method  advised  and  recommended  is  that  of  incision. 
Incision  is  the  only  method  of  vaccination  permitted  by  the  laws  of 
Germany,  and  recommended  by  the  Local  Government  Board  of  Eng- 
land. Incision,  if  not  too  deep,  consists  really  of  a  series  of  punctures, 
and  serves  the  same  purpose.  Incisions  may  be  made  with  the  point  of 
a  scalpel.  I  prefer  to  use  a  needle.  The  incision. or  scratch  should  not 
be  deep  enough  to  draw  blood,  but  a  few  drops  do  no  harm.  It  is 
rather  difficult  to  control  the  depth  of  the  incision  with  a  scalpel,  espe- 
cially if  it  is  sharp.  Scratching  with  a  needle  is  much  more  easily 
controlled.  •  The  incisions  should  be  about  three-quarters  of  an  inch 
long  and  about  an  inch  apart.  The  vaccine  virus  is  then  placed  upon 
the  abraded  surface,  and  gently  rubbed,  not  ground,  in.  It  is  impor- 
tant not  to  cause  any  unnecessary  irritation  so  as  to  avoid  attracting 
infections. 

Scarification. — Scarification  or  cross-scratching  is  prohibited  in  Ger- 
many by  ministerial  decree  of  March  31,  1897,  which  was  incorporated 
into  the  revised  rules  of  the  Bundesrath,  July  28,  1898.  The  objec- 
tion to  scarification  is  that  this  method  produces  an  abraded  surface  . 
which  is  soon  covered  by  a  crust  of  serum  and  blood,  through  which  the 
eruption  cannot  pierce.  The  vesicles  form  a  ring  around  the  scarified 
area,  leaving  a  central  irritated  wound,  inviting  infection.  It  is  be- 
lieved that  most  of  the  cases  of  tetanus  complicating  vaccination  oc- 
curred in  cases  in  which  scarification  was  used.  In  this  method  fa- 
vorable anaerobic  conditions  are  produced  under  the  crust  or  scab  which 
forms  over  the  abraded  surface. 

The  Point  of  Election.— The  outer  surface  of  the  left  arm  at  about 
the  insertion  of  the  deltoid  is  the  most  convenient  for  the  operator  and 
the  patient.  This  is  the  original  site  selected  by  Jenner,  and  is  less 
liable  to  severe  glandular  complications  than  other  points. 

Flachs  recommends  the  side  of  the  chest  at  about  the  level  of  the 
sixth  rib,  in  the  axilla.  Here  the  scar  is  not  visible;  there  is  little  mo- 
tion, and  it  is  easily  bandaged,  but  this  site  is  open  to  ihe  disadvantage 
of  greater  heat  and  moisture  and  there  is,  therefore,  greater  danger  of 
complications. 

The  leg  is  sometimes  selected  to  avoid  disfigurement,     The  vaccina- 


10  SPECIFIC    PKOrilY LACTIC    MEASUEES 

tion  sear  should  not  be  regarded  as  a  deformity.  To  tlie  sanitarian  a 
typical  vaccine  scar  is  a  sanitary  dinii)lc.  'J'he  leg  is  more  exposed 
than  the  arm  to  traumatism,  and,  therefore,  to  complications.  Dock 
refuses  to  vaccinate  on  the  leg  unless  the  patient  will  stay  in  bed  until 
the  vesicle  heals.  With  babies  in  diapers  and  with  young  children  it  is 
exceedingly  difficult  to  keep  these  parts  clean.  If  the  leg  is  selected,  the 
vaccination  should  be  done  on  the  calf  below  the  head  of  the  fibula, 
and  not  on  the  outer  surface  of  the  thigh. 

Number  of  Incisions.— This  has  an  important  bearing  upon  the 
probability  of  the  take,  as  well  as  the  ])rotection.  It  is  not  wise  to  de- 
pend upon  one.  The  relation  of  the  number  of  vesicles  and  the  amount 
of  reaction  to  the  degree  and  length  of  the  immunity  has  not  been 
worked  out.  The  German  regulations  of  1891)  require  at  least  four  in- 
cisions, each  one  centimeter  long,  and  two  centimeters  apart.  The 
Local  Government  Board  of  England  directs  that  four  vesicles  should 
be  produced,  and  that  the  total  area  of  the  vesicle  formation  shall  not 
be  less  than  one-half  a  square  inch.  My  own  practice  follows  that  of 
Dock,  who  makes  not  less  than  two  incisions  about  an  inch  long  and 
an  inch  apart;  but  in  case  of  exposure  to  smallpox  three  or  four  such 
incisions  are  advisable. 

The  Operation. — The  skin  at  the  site  of  the  operation  must  be  sur- 
gically clean,  but  need  not  necessarily  be  treated  with  antiseptics.  If 
such  are  used,  they  must  be  carefully  washed  away  in  order  not  to 
destroy  the  activity  of  the  virus.  A  thorough  scrubbing  with  soap  and 
water  is  necessary  for  a  dirty  skin.  Washing  with  warm  water  followed 
by  alcohol  is  usually  enough.  The  alcohol  should  be  permitted  to  evap- 
orate before  the  incision  is  made.  In  general,  the  less  the  skin  is  irri- 
tated the  less  is  the  danger  of  complications.  Needles  are  particularly 
handy,  as  they  may  be  flamed  just  before  the  operation,  and  are  con- 
venient in  saving  time  when  many  people  are  to  be  vaccinated.  The 
vaccine  virus  is  gently  rubbed  into  the  incision,  not  ground  in,  and  then 
allowed  to  dry.  No  dressing  is  necessary  at  the  beginning,  but  several 
layers  of  dry  sterile  gauze  held  in  place  by  adhesive  plaster  do  no 
harm,  and  serve  as  a  protection.  Pads,  plasters,  and  shields  of  any  sort 
are  unwise,  because  by  retaining  heat  and  moisture  they  cause  a  soften- 
ing and  breaking  down ;  in  other  words,  they  act  like  a  poultice.  Bath- 
ing need  not  be  omitted,  nor  any  of  the  ordinary  occupations,  but  un- 
necessary use  of  the  arm  must  be  guarded  against,  as  this  increases  the 
congestion,  inflammation,  and  the  chances  of  infection. 

Schamberg  and  Kolmer  ^  have  recently  advised  the  use  of  a  4  per 

cent,  alcoholic  solution  of  picric  acid  on  the  vaccinated  area  48  hours 

after  the  insertion  of  the  lymph.     This  apparently  does  not  interfere 

with  the  success  of  the  vaccination.     Schamberg  and   Kolmer  believe 

1  Lancet,  Nov.  8,  1911,  CLXXXI,  No.  4603. 


SMALLPOX    AND    VACCINATION^  11 

that  the  picric  acid  lessens  the  degree  of  the  local  inflammatory  reaction 
and  that  the  patients  are  not  so  apt  to  exhibit  constitutional  disturb- 
ances.   It  also  decreases  the  liability  of  extraneous  bacterial  infection. 

INDICES    OF    A    SUCCESSFUL   VACCINATION 

The  take  must  be  typical  and  the  clinical  course  characteristic,  other- 
wise we  have  no  assurance  that  the  individual  is  protected  against  small- 
pox. The  best  indices  of  a  successful  take  are :  ( 1 )  the  course  of  the 
eruption,   (2)  the  general  symptoms,  and  (3)   the  scar. 

The  importance  of  knowing  the  skin  lesions  of  vaccinia  were  in- 
sisted upon  by  Jenner.  Every  vesicle,  scab,  ulcer,  or  irritated  wound  is 
not  vaccinia.  No  confidence  should  be  placed  in  doubtful  or  atypical 
takes.  The  typical  features  of  vaccination  are  singularly  alike.  The 
clinical  course  of  a  primary  vaccination  is  as  follows : 

Course  of  the  Eruption. — The  primary  wound  soon  heals.  Appar- 
ently nothing  occurs  for  3  to  4  days,  which  is  the  period  of  incubation. 
Then  one  or  more  small  papules  appear  upon  the  skin  where  the  vac- 
cine virus  was  introduced.  The  papule  is  small,  round,  flat,  bright 
red,  hard,  but  superficial.  About  the  fifth  day  the  summit  of  the 
papule  becomes  vesicular.  The  vesicle  is  at  first  clear  and  pearl-like. 
Umbilication  soon  develops  as  the  vesicle  enlarges.  A  deep,  red,  and 
swollen  areola  surrounds  the  vesicle  and  grows  wider  as  the  lesion  ad- 
vances. This  gives  the  picture  of  the  "pearl  upon  the  rose  leaf"  which 
constitutes  the  true  Jennerian  vesicle.  By  the  seventh  day  the  vesicle 
is  full  size,  round  or  oval,  flat  on  top,  umbilicated,  and  contents  clear. 
It  is  multilocular ;  if  pricked  with  a  pin  or  accidentally  opened  only 
that  portion  of  the  lymph  contained  in  the  compartment  opened  will 
exude.  By  the  eighth  day  it  turns  yellowish,  the  middle  is  fuller,  fol- 
lowing which  the  so-called  second  umbilication  develops.  Meanwhile 
the  areola  deepens,  widens,  and  may  be  swollen.  The  skin  feels  hot, 
is  painful,  and  the  axillary  glands  become  enlarged  and  tender.  About 
the  ninth  day  the  areola  begins  to  fade  and  the  swelling  subsides.  By 
the  eleventh  or  twelfth  day  the  vesicle  rapidly  dries,  leaving  a  brown, 
wrinkled  scab,  which  finally  drops  ofi^.  It  should  never  be  removed,  as 
it  forms  the  best  bandage. 

The  scar  is  at  first  red,  finally  turns  white,  with  the  pits  or  fovea- 
tions  so  characteristic  of  true  cowpox. 

General  Symptoms. — The  general  symptoms  vary.  There  are  malaise, 
loss  of  appetite,  sometimes  nausea  and  vomiting,  headache,  pain  in  the 
muscles  of  the  back,  and  other  indications  of  a  mild  febrile  reaction. 
The  temperature  may  go  to  38°  or  38.5°  C.  between  the  third  and 
seventh  days.  The  febrile  reaction  bears  no  special  relation  to  the  size 
^nd  number  of  the  vesicles  or  to  the  areola,     The  nitrogen  eliiriina,tion 


Eighth  Day 


Ninth  Day 


Fig.  1. — Vaccinia.    Course  of  the  Eruption  from  the  Fourth  to  the  Ninth  Dat. 

12 


Twelftli  Day 


Fourteenth  Day 


Tliirteeiitli  Day 


Scar— Sixth  Week 


Fig.  2. — Vaccinia.    Course  of  the  Eruption  from  the  Tenth  Day. 

13 


14  SPECIFIC    PROPHYLACTIC    MEASURES 

increases  about  the  tenth  day  for  a  sliort  time.  The  blood  changes  re- 
semble those  of  smallpox,  an  early  leukopenia  and  secondary  leukocy- 
tosis. 

Secondary  vaccinations  often  run  an  accelerated,  milder,  or  modified 
course. with  shortened  jieriod.s  of  incubation  (see  re  vaccination). 

THE    IMMUNITY 

The  immunity  appears  about  the  eighth  day  of  the  vaccination. 
Layet  puts  the  ])oint  of  safety  at  the  ninth  day,  Burckhard  at  the  elev- 
enth. These  data  are  based  ujion  the  early  work  with  variolation,  when 
persons  were  inoculated  with  smallpox  at  various  ])eriods  following  vac- 
cination. Sacco  got  only  local  eruption  by  inoculating  smallpox  on  the 
eighth  to  the  eleventh  days,  and  none  after  that. 

Vaccination  protects  not  only  against  smallpox,  but  also  against 
vaccinia.  Curiously  enough,  the  degree  and  length  of  immunity  ap- 
pear to  l)e  greater  against  smallpox  than  against  itself.  It  is  irra- 
tional to  attempt  to  fix  a  definite  time  for  the  duration  of  the  immu- 
nity. This  varies  as  in  other  infectious  processes.  It  is  known  through 
experiment  and  experience  that  the  immunity  gradually  wears  off.  Defi- 
nite protection  on  the  average  lasts  about  seven  years.  The  degree  of 
protection  is  usually  al)Solute  for  some  years,  and  then  gradually  fades. 
In  this,  as  in  other  diseases,  immunity  is  a  relative  term.  Smallpox 
itself  does  not  always  protect  against  smallpox.  Some  people  have  two 
and  even  three  attacks  of  smallpox.  Such  cases,  however,  are  excep- 
tional, and  it  is  also  exceptional  to  have  smallpox  occur  in  an  individual 
who  has  been  ])roperly  vaccinated. 

Careful  statistics  collected  in  Japan  since  1879  show  quite  definitely 
the  gradual  diminution  of  the  immunity,  beginning  with  the  second  year 
after  vaccination.     Kitasato's  table,'  based  on  951  cases,  is  as  follows: 


SUCCESSFUL  REVACCINATION  AFTER: 

1  year 13.6  per  cent. 

2  years 32.9 

3  years 46.6 

4  years 57.3 

5  years 51.1 

6  years 63.8 

"Weil,  in  1899,  reported  72.5  per  cent,  of  successful  revaccinations 
after  seven  years,  80  jier  cent,  after  eight  years,  85  per  cent,  after  nine 
3'ears,  and  88.0  per  cent,  after  ten  years. 

It  is  a  fallacy  to  state  that,  if  a  revaccination  takes,  the  subject  was 
therefore  suscejitible.    While  this  is  usually  true,  it  does  not  necessarily 

Wqurnal  A.  M.  A.,  March  25,  1911,  p.  889. 


SMALLPOX    AND    VACCINATION  15 

follow.  It  is  a  still  greater  fallacy  to  state  that,  if  a  vaccination  fails, 
the  subject  is  therefore  immune.  This  view  may  result  in  real  harm. 
Vaccination  may  fail  for  many  reasons — the  operation  may  not  have 
been  properly  done,  or  the  virus  may  have  been  inert.  Sometimes  per- 
sons are  unsuccessfully  vaccinated  three,  four,  or  more  times  before  a 
typical  take  is  obtained. 

The  nature  of  the  changes  in  the  body  which  produce  the  immunity 
are  not  understood.  In  this  sense  vaccination  is  still  an  empiric  pro- 
cedure. We  now  know  of  many  analogous  instances,  however,  where 
an  active  acquired  immunity  is  induced  by  means  of  an  attenuated  virus. 
The  immunity  produced  by  vaccine  virus  does  not  depend  upon  an  anti- 
toxin. The  blood,  however,  contains  specific  antibodies,  shown  by  the 
fact  that  equal  parts  of  blood  serum  from  a  calf  two  weeks  after  suc- 
cessful vaccination  mixed  with  vaccine  virus  destroy  its  activity. 

EEVACCINATION 

The  fact  that  the  immunity  wears  off  after  a  number  of  years  makes 
it  necessary  to  practice  revaccination  in  order  to  afford  a  continuous 
protection.  There  is  some  difference  of  opinion  as  to  just  when  it  is 
best  to  vaccinate  the  second  time.  Ten  years  is  too  long  a  period,  prob- 
ably, to  depend  upon  in  individual  cases.  One  year — advised  by  some — 
is  shorter  than  necessary  in  most  cases.  The  five-year  interval  of  Japan 
is  good  in  many  respects,  but  probably  not  better  than  revaccination  in 
the  twelfth  year  obligatory  in  Germany. 

The  best  time  to  vaccinate  is  in  the  first  year  before  the  second  sum- 
mer, again  at  from  ten  to  thirteen  years.  After  this  it  is  usually  un- 
necessary to  vaccinate  again,  unless  there  is  particular  danger  of  expo- 
sure to  smallpox. 

All  persons  exposed  directly  or  indirectly  to  smallpox  should  at  once 
be  vaccinated — imless  they  have  had  the  disease  or  have  recently  been 
successfully  vaccinated.  There  are  no  contraindications  to  vaccinating 
babies  immediately  after  birth. 

The  clinical  picture  of  secondary  vaccinations  may  be  quite  different 
from  the  typical  take  following  a  primary  vaccination.  These  altered 
reactions  were  known  in  the  time  of  Jenner,  but  were  lost  sight  of  until 
recently  rediscovered,  and  their  significance  realized  from  studies  in 
anaphylaxis. 

Eevaccinations  may  be  divided  into  three  groups:  (1)  they  may  run 
an  unaltered  course  resembling  prim.ary  takes  in  all  respects,  showing 
that  immunity  to  cowpox  has  disappeared;  (2)  they  may  run  a  slightly 
more  rapid  course  in  which  the  period  of  incubation  is  shortened  and 
in  which  the  height  of  the  pustular  stage  occurs  about  the  sixth  day 
(this  is  known  as  the  accelerated  reaction) ;  or   (3)   they  may  run  a 


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16 


SMALLPOX    AND    YACCINATIOK  1^ 

very  much  shortened,  milder,  and  rapid  course.  The  eruption  may  be 
only  a  small  papule  or  an  almost  imperceptible  erythema  which  soon 
disappears;  the  period  of  incubation  is  less  than  24  hours.  This  is 
known  as  the  immediate  reaction  and  resembles  a  cutaneous  tuberculin 
reaction  in  many  respects.  These  altered  reactions  have  been  studied 
especially  by  Von  Pirquet  and  are  shown  graphically  in  Fig.  3. 

The  immediate  reaction  may  be  put  to  practical  use  in  order  to  dis- 
tinguish smallpox  from  chickenpox.  Thus,  Tieche  has  shown  that  small- 
pox virus  introduced  into  the  skin  of  a  person  immunized  by  vaccination 
will  show  the  typical  immediate  reaction;  whereas  the  virus  of  chicken- 
pox  is  invariably  negative.  This  test  can  be  freed  of  all  possible  danger 
by  heating  the  virus  to  60°  C.  for  30  minutes,  which  does  not  seem  to 
affect  the  reaction. 

CLAIMvS    FOR    VACCINATION 

1.  If  successful,  it  protects  the  individual  against  smallpox  for  a 
period  which  has  not  been  determined  mathematically  for  the  individual, 
but  which  averages  about  seven  years. 

2.  The  protection  may  be  renewed  by  a  second  vaccination. 

3.  Persons  successfully  vaccinated  on  two  occasions  are  usually 
immune  against  smallpox  for  life. 

4.  Vaccination  and  revaccination  systematically  and  generally  car- 
ried out  confer  complete  protection  to  a  community  or  a  nation.     In, 
other  words,  while  the  individual  protection  is  not  always  perfect,  the 
communal  protection  is  absolute. 

5.  A  person  vaccinated  once  and  at  a  later  time  contracting  small- 
pox as  a  rule  has  the  disease  in  a  less  serious  form  than  unvaccinated 
persons  (varioloid).^  The  degree  of  favorable  modification  of  smallpox 
is  in  inverse  jjroportion  to  the  period  of  time  elapsing  between  the  vac- 
cination and  the  attack  of  smallpox. 

6.  The  beneficial  effects  of  vaccination  are  most  pronounced  in  those 
in  whom  the  vaccine  affection  has  run  its  most  typical  and  perfect 
course. 

VACCINATION    OF    EXPOSED    PERSONS   . 

The  question  frequently  arises  whether  persons  exposed  to  smallpox 
should  be  vaccinated.  The  effect  of  vaccination  during  the  period  of 
incubation  of  smallpox  is  very  interesting,  and  may  be  summed  up  as 
follows : 

The  term  varioloid  was  introduced  by  Thompson  in  1820  to  describe  the 
mild  and  modified  form  of  smallpox  occurring  after  vaccination.  The  eruption 
in  varioloid  disappears  more  rapidly  than  in  variola.  Yolfert,  Dornbleuth,  and 
Harden  showed  that  one  vaccination  was  not  sufficient  protection  against  small- 
pox for  a  lifetime,  that  revaccination  was  necessary  and  that  the  clinical  mani- 
festations of  this  vaccination  are  as  different  from  those  of  the  first  vaccination 
as  varioloid  is  from  variola. 


18 


SPECIFIC    PKOPHYLACTIC    MEASURES 


1.  Vaccination  just  l)e('()i'e  or  diirinij  tlio  priniai-y  fever  of  small- 
pox does  not  inihu'nce  the  disease,  nor  does  the  vaeeinalion  take. 

2.  If  the  vaccination  is  done  during  the  last  stage  of  the  period  of 
incubation  of  smallpox,  the  two  infections  run  their  course  side  by  side 
without  influencing  cacb  other. 

3.  If  it  is  done  about  the  sixth  or  eighth  day  of  the  period  of  in- 
cubation the  vaccination  takes  and  may  modify  the  severity  of  the 
smallpox. 

4.  Vaccination  done  at  the  beginning  of  the  incubation  period  in 
time  to  have  the  vaccine  eruption  reach  maturity  before  the  smallpox 
begins  will  prevent  or  abort  tlie  disease.  This  is  shown  in  tlie  follow- 
ing diagram : 

THE  EFFECT  OF  VACCINATION  DURING  THE  PERIOD  OF  INCUBATION  OF  SMALLPOX 


Toward  the 

During  the 

Early  in  the 

Middle  of  the 

end  of  the 

Primary 

On  the 

Incubation 

Incubation 

Incubation 

Fever,  or 

First 

Period 

Period 

Period 

Preeruption 

Day 

2nd  to  6th  days 

Gth  to  8th  days 

9th  to  14  th  days 

Stage 

.    Variola 

Prevent 

Smallpox  is 

Varioloid  or 

Smallpox  not 

Smallpox  not 

smallpox 

aborted 

mild  case 

influenced 

influenced 

1 

1 

1        1        1        1        1        1       1         1          1         1          1          1 
J      3      4      5      6      7      8      9      10      11       12       13      14 

1      2      3 

1 

Period  of  Incubation  of  Smallpox — in  Days 

1        1        1        1    .1        1       1          1          1         1          1          1 

Primary  Fever       Eruption 

The    vaccina- 

The    vaccination 

The      vaccina- 

The vaccination 

The     vaccination 

tion  takes. 

takes. 

tion  takes  2  or 
4  days  before 
primary  fever. 

takes  and  both  af- 
fections   run    side 
by  side. 

does  not  take  (?) 

To  produce  the  best  results  the  vac- 

- Vaccinia 

cination  should  precede  this  period, 

so  as  to  reach  maturity  before  the 

onset  of  the  primary  fever.     The 

vaccine     vesicle  reaches    maturity 

about  the  8th 

day. 

As  we  can  never  be  quite  sure  just  what  stage  in  the  period  of  in- 
cubation a  given  case  may  be  in,  it  is  always  advisable  to  vaccinate 
exposed  persons.  Furthermore,  little  harm  will  be  done  if  it  is  too 
late  and  the  vaccine  eruption  is  added  to  the  smallpox.  Indeed,  Hanna,  ^ 
presents  claims  to  the  effect  that  there  is  abundant  evidence  in  mitigat- 
ing the  severity  of  smallpox  when  vaccination  is  performed  at  any  time 
after  infection  up  to  the  day  of  onset  and  even  afterward. 


^Public  Bealih.,  July,  1910,  XXIIT,  No.  10,  p.  351. 


SMALLPOX    AND    VACCINATION  19 


DANGERS    AND    COMPLICATIONS 

The  alleged  danger  from  vaccination  has  been  greatly  magnified  by 
the  antivaccinationists.  However,  vaccination  is  not  always  a  harmless 
procedure;  it  must  be  looked  upon  as  the  production  of  an  acute  infec- 
tious disease,  and,  although  the  disease  is  always  mild  and  trivial,  it 
must  not  be  treated  as  trifling.  The  chief  danger  lies  in  the  fact  that 
we  have  produced  an  open  wound,  which  is  subject  to  the  complications 
of  any  wound.  Even  a  pin  prick  or  a  razor  scratch  may  result  in  death. 
While  the  aggregate  number  of  deaths  resulting  from  the  complications 
of  vaccination  may  be  considerable,  the  aggregate  of  the  individual  risk 
is  so  small  as  to  be  disregarded,  especially  when  proper  precautions  are 
taken.  Many  of  the  infections  after  vaccination  occur  in  those  in  whom 
the  regard  for  cleanliness  is  slight,  and  who  neglect  the  site  of  the  wound. 
In  recent  years,  owing  to  the  improved  quality  of  the  vaccine  virus  and 
the  introduction  of  aseptic  methods,  a  bad  sore  arm  is  a  rare  occurrence, 
and  serious  complications  still  rarer.  In  any  case,  the  danger  connected 
with  vaccination  is  infinitesimal  when  compared  with  the  benefit  con- 
ferred.    The  important  complications  are : 

Auto  Vaccination. — This  is  usually  due  to  scratching  the  virus  into 
the  finger,  the  nose,  the  mouth,  the  mucous  membranes,  or  any  part  of 
the  skin.  When  carried  into  the  eye  it  may  cause  blindness.  Physicians 
sometimes  vaccinate  their  lips  by  blowing  into  vaccine  tubes.  In  vac- 
cine establishments  accidental  vaccination  of  the  hand  is  common. 

Generalized  Vaccination. — This  is  sometimes  reported,  but  is  usu- 
ally a  mistaken  diagnosis.  A  generalized  eruption  of  cowpox  is  ex- 
ceedingly rare,  if  it  ever  occurs.  I  have  seen  it  in  the  calf  after  intra- 
venous injection  of  a  large  amount  of  the  virus,  in  which  case  there  is 
a  prolonged  period  of  incubation. 

Wound  infections,  such  as  ulcers,  gangrene,  erysipelas,  abscesses, 
lymphangitis,  suppuration  of  the  axillary  glands,  and  other  septic  infec- 
tions are  now  exceedingly  rare,  and  should  be  treated  with  the  usual 
measures  to  prevent  their  occurrence. 

Impetigo  contagiosa  occasionally  occurs  and  may  be  a  serious  com- 
plication of  vaccination,  especially  the  bullous  impetigo  or  pemphigoid 
forms,  which  presumably  have  their  origin  in  cattle. 

Syphilis,  tuberculosis,  and  leprosy  are  sometimes  feared,  but  these 
are  practically  impossible  with  the  use  of  bovine  virus.  In  any  case  it 
is  doubtful  whether  tuberculosis  or  leprosy  could  be  so  transferred. 

Tetanus  deserves  a  special  word.  Several  outbreaks  have  been  re- 
ported in  this  country  after  the  use  of  certain  viruses.  Willson  in  1902 
found  tetanus  spores  in  the  vaccine  virus  used  in  a  New  Jersey  out- 
break.    Glycerin  does  not  destroy  the  tetanus  spore.     Many  hundreds  of 


20  SPECIFIC    PROniYLACTIC    MEASURES 

examinations  made  in  tlie  Hygienic  Laboratory  at  Washington  have 
failed  to  discover  a  tetanus  spore  in  a  single  vaccine  point  or  tube.  The 
occasional  danger  cannot  be  denied.  It  is  probable,  however,  that  the 
infection  in  some  of  these  cases  comes  from  outside  sources. 

The  occurrence  of  occasional  stray  spores  in  vaccine  virus  was  demon- 
strated by  Carini.^  Such  vaccine,  however,  had  proved  entirely  harm- 
less in  thousands  of  cases.  It  is  more  than  probable  that  the  actual 
danger  would  begin  if  such  occasional  stray  spores  were  allowed  to  ger- 
minate in  the  vaccine  pulp  through  some  serious  fault  in  manipulation. 
It  is  conceivable  that  the  vaccine  pulp  after  removal  from  the  calf  or 
heifer,  if  not  at  once  chilled,  or  if  not  at  once  mixed  with  glycerin,  may 
form  a  very  rich  medium  for  anaerobic  bacteria.  Some  carelessness  or 
neglect  just  at  this  stage  might  prove  disastrous  if  tetanus  spores  ac- 
cidentally present  should  multiply.  The  epidemic  in  this  country  in 
1902  reported  by  Willson  ^  and  MacFarland  ^  may  have  been  the  result 
of  some  such  occurrence.  On  the  other  hand,  neglected  vaccination 
wounds  or  those  in  Avhicli  proper  bandages  or  shields  favor  anaerobiosis 
may  stimulate  the  germination  of  spores  coming  from  without  and  lead 
to  the   occasional   reported   sporadic  cases  following  vaccination. 

To  prevent  tetanus  complications  it  is  important  to  avoid  scarification 
and  irritation,  also  to  avoid  the  use  of  shields  and  bandages  which  favor 
anaerobic  conditions;  to  practice  strict  cleanliness,  and  to  use  vaccine 
virus  that  has  been  properly  prepared  and  tested.  Special  tests  for 
tetanus  are  now  required  by  federal  regulations  of  every  lot  of  vaccine 
virus  before  it  is  placed  upon  the  market. 

Foot  and  Mouth  Disease. — The  infection  of  foot  and  mouth  disease 
has  in  one  instance  been  demonstrated  as  a  contamination  of  vaccine 
virus.*  It  is,  however,  impossible  to  convey  foot  and  mouth  disease  to 
man  through  cutaneous  inoculation.  While  no  harm  has  been  done  to 
man,  the  contamination  is  undesirable,  and  special  federal  regulations 
now  require  vaccine  virus  to  be  tested  from  time  to  time  to  assure  its 
freedom  from  this  infection. 

As  an  illustration  of  how  seldom  complications  are  caused  by  vac- 
cination we  have  the  results  of  Germany,  where  in  thirteen  years  (1885- 
1893)  32,166,619  children  were  vaccinated.  Of  these  115  died  within 
a  few  weeks  or  months  after  the  operation,  presumably  of  injuries  in- 
cidental thereto.  Of  these  at  least  48  probably  did  not  die  as  a  direct 
result  of  the  vaccination. 

The  figures  of  recent  years  are  still  better,  for  it  is  now  exceedingly 
rare  for  a  death  to  be  recorded  as  directly  due  to  vaccination.     For 

^CentraJbl.  f.  Bait.,  Orig.  1904,  XXXVII,  p.   1147. 
'Jour.  A.  M.  A.,  1902,  XXXYIII,  p.  1147. 
^  Jour.  Med.  Besearch,  1902,  n.  s.  II,  p.  474. 

*  yUMer  and  Rosenau,  U.  S.  Dept.  of  Agriculture,  B.  A.  T.  Circular  147,  June 
16,  1909. 


SMALLPOX    AND   VACCINATION  21 

example,  in  the  PhilijDpine  Islands  in  the  past  few  years  the  United 
States  authorities  Yacciiiated  3,515,000  persons  without  a  single  death 
or  any  serious  post-vaeeinal  complications. 

THE    GOVEENMENT    COXTEOL    OF    A^ACCINE    VIEUS 

By  the  law  of  July  1,  1902,  the  vaccine  virus  sold  in  interstate  traf- 
fic in  the  United  States  must  come  from  a  licensed  manufacturer. 
These  licenses  are  issued  by  the  Secretary  of  the  Treasury  only  after  a 
careful  inspection  of  the  plant,  personnel,  and  product  by  a  competent 
government  officer.  The  licenses  are  good  for  one  year  only,  and  are 
reissued  only  after  reinspection.  The  government  regulations  require 
each  lot  of  vaccine  virus  to  be  examined  carefully  by  modern  bacterio- 
logical methods  to  determine  the  number  of  bacteria,  and  special  tests 
must  be  made  to  determine  the  absence  of  pathogenic  microorganisms. 
These  tests  include  animal  inoculations,  as  well  as  cultural  methods. 
Special  tests  for  each  lot  of  vaccine  must  be  made  to  determine  the 
presence  or  absence  of  streptococci,  tetanus  spores,  foot  and  mouth  infec- 
tions, etc.  The  government  does  not  guarantee  the  purity  and  potency  of 
each  package  of  vaccine  virus,  but  through  its  inspections  and  frequent 
examinations  of  the  virus  on  the  market  every  confidence  may  now  be  had 
in  the  vaccine  virus  propagated  by  licensed  manufacturers  in  this  country. 

THE  UNITY  OF  COWPOX  AND  SMALLPOX 

The  unity  or  duality  of  these  two  diseases  has  been  the  subject  of 
much  contention.  Jenner  originally  considered  cowpox  to  he  a  modified 
smallpox.  The  successful  experiments  in  Germam^,  England,  and  this 
country,  in  which  smallpox  has  actually  been  modified  by  passing 
variolous  matter  through  calves  has  proved  positively  that  we  are  dealing 
with  two  forms  of  one  disease.  Much  of  the  vaccine  virus  used  during 
the  past  hundred  years  was  originally  obtained  from  cases  of  casual 
cowpox.  This  virus  has  been  shown  by  experience  and  experiments  to 
protect  against  smallpox,  which  makes  it  highly  probable  that  we  are 
dealing  with  one  disease.  The  parasite  Cytorrliyctes  variolce,  discovered 
by  Councilman,  Brinckerholf,  and  Tyzzer,  gives  a  probable  explanation 
of  how  smallpox  may,  under  certain  circumstances,  become  attenuated. 
The  life  cycle  of  this  parasite  interpreted  by  Calkins  indicates  that  the 
mild  disease,  cowpox  or  vaccinia,  is  due  to  the  asexual  phase  in  the  life 
cycle  of  the  parasite  which  lives  and  multiplies  in  the  c}i;oplasm  of  the 
epithelial  cell;  smallpox  is  caused  by  the  combined  asexual  and  sexual 
cycle  of  the  same  parasite,  the  latter  phase  occurring  in  the  nucleus  of 
the  epithelial  cell.  When  the  Cytorrliyctes  varioIcB  loses  its  power  to  gen- 
erate by  sexual  division  it  never  again  regains  it;  that  is,  while  small- 
4 


22  SPECIFIC    PKOPHYLACTIC    MEASURES 

pox  may  be  modified  into  cowpox,  cowpox  has  never  been  returned  to 
smallpox. 

It  seems  plain  that  much  of  the  so-called  casual  cowpox  probably 
has  its  origin  from  smallpox  through  accidental  inoculation  in  milking 
or  handling  these  animals  by  persons  having  or  recovering  from  variola. 
Once  started,  the  propagation  of  the  modified  virus  from  cow  to  cow 
would  be  comparatively  simple. 

COMPULSORY    VACCINATION 

Vaccination  affords  a  high  degree  of  immunity  to  the  individual,  and 
a  well-nigh  perfect  protection  to  the  community.  To  remain  unvac- 
cinated  is  selfish  in  that  such  persons  steal  a  certain  measure  of  pro- 
tection from  the  community  on  account  of  the  barrier  of  vaccinated 
persons  around  them. 

The  laws  ^  and  regulations  relating  to  vaccination  in  the  several 
states  of  the  United  States  show  marked  lack  of  uniformity.  Compulsory 
general  vaccination  can  be  said  to  exist  by  law  only  in  Kentucky,  Rhode 
Island,  and  Porto  Rico.-  Arizona,  Hawaii,  Maryland,  New  Mexico, 
North  Dakota  have  laws  requiring  vaccination  of  children.  In  recent 
years  smallpox  has  been  so  mild  in  the  United  States  that  the  case 
death  rate  has  been  as  low  as  0.2  per  cent.,  or  1  death  in  500  cases. 

Decisions  in  the  various  courts  in  the  United  States  have  held  com- 
pulsory vaccination  to  be  legal.  A  decision  of  the  Supreme  Court  of 
the  United  States  (Henning  Jacobson  vs.  The  Commonwealth  of  Massa- 
chusetts, April  1,  1905)  upheld  in  every  respect  the  statute,  the  validity 
of  which  was  questioned  vmder  the  Constitution. 

The  liberty  secured  by  the  Constitution  of  the  United  States  .... 
does  not  impart  an  absohite  right  in  each  person  to  be,  at  all  times,  and  in 
all  circumstances,  wholly  freed  fi'om  restraint.  Real  liberty  for  all  could 
not  exist  under  the  opei'ation  of  a  principle  which  recognizes  the  right  of 
each  individual  person  to  use  his  own,  whether  in  respect  to  his  person  or 
his  property,  regardless  of  the  injuiy  that  may  be  done  to  others. 

Theoretically  it  would  be  ideal  if  all  persons  submitted  to  vaccina- 
tion and  revaccination  voluntarily.  But  experience  has  shown  that  this  is 
impractical,  and.  wherever  tried,  has  failed.  The  best  results  have  always 
been  obtained  where  vaccination  has  been  compulsory,  and,  in  my  judg- 
ment, this  is  the  only  present  means  by  which  smallpox  may  bo  eliminated. 

The  world  may  learn  a  valuable  lesson  from  the  splendid  results 
obtained   in   Germany  through   compulsory  vaccination  and   revaccina- 

^  Kerr,  J.  W.,  "Vaccination,  and  Analysis  of  the  Laws  and  Eegiilations  Re 
lating  Thereto  in  Force  in  the  United  States,"  Public  Health  Bull.   52. 

^  Massachusetts,  in  1809,  was  the  first  state  to  enact  legislation  relative  to 
vaccination. 


SMALLPOX    AXD    TACCIXATIOX 


23 


tion.  In  England  the  ^'conscience  clause'"  allows  man}-  persons  to  re- 
main unvaccinated  and  thereby  seriously  diminishes  the  effects  of  the 
vaccination  laws  of  that  land.  In  Minnesota  the  state  health  authori- 
ties became  weary  of  the  clamor  against  compulsory  vaccination  and 
assisted  in  having  "the  law  repealed.  They  said,  in  substance,  to  the 
people  of  the  state:  "Take  your  choice.  Be  vaccinated  and  protect 
yourself,  or  run  the  risk  of  contracting  smallpox;  if  you  get  it,  it 
is  your  own  fault."" 

TABLE  1.— DEATHS  FROM  SMALLPOX  IX  COUXTRIES  WITH  CO^IPULSORY  VACCIXA- 
TIOX  AXD  THOSE  WITHOUT  COMPULSORY  VACCIXATIOX 


Population 


1886 


-Smallpox  Deaths- 
1SS7  18S8 


Average 

of 
Deaths 


Average  per 
Million  of 
Population 


S-vreden* 4,746,465 

Ireland* 4,S0S,72S 

Scotland* 4,013,029 

Germany* 47,923,735 

England* 28,247,151 

Switzerland 2,922,430 

Belgium 5,940,365 

Russia 92,822,470 

Austria 23,000,000 

Italy 29,717,982 

Spain 11,564,000 


24 
197 
275 

182 

1,213 

16,938 

8,794 


14 

17 

168 

505 

14 

610 

25,884 

9,591 

16,249 


9 

3 

0 

112 

1,026 

17 
865 

14,138 
18,110 
14,378 


6 

200 

23 

3 
1,212 
? 

12,358 
13,416 

8,472 


12 
169 
458 

54 
975 
21,411 
11,220 
15,925 
11,425 


1 
1 
3 

3.5 
16 

18.5 
164 
231 
510 
536 
963 


*Compulsor\'  vaccination. 


IKOCULATIOX    OB    VAEIOLA   LYOCULATA 


The  practice  of  inoculation  must  be  carefully  distinguished  from 
that  of  vaccination.  By  inoculation  we  mean  the  introduction  of  small- 
pox matter  into  the  skin  of  man.  The  disease  thus  produced  is  usually 
very  mild,  but  is  nevertheless  true  smallpox,  and  just  as  contagious  as 
smallpox. 

This  phase  of  the  subject  may  be  made  clearer  by  considering  small- 
pox as  existing  in  three  forms:  (1)  variola  vera  or  true  smallpox;  (2) 
variola  inoculata  or  inoculated  smallpox;  (3)  vaccinia,  c•o^vpox.  or 
modified  smallpox.  The  differences  between  these  affections  are  shown 
in  the  table  on  the  following  page. 

Emphasis  must  be  placed  on  the  fact  that  variola  inoculata,  while 
usually  a  mild  disease,  is  just  as  communicable  as  true  smallpox,  and 
those  who  contract  the  disease  in  this  way  get  true  smallpox,  often  in 
serious  or  fatal  form.  Inoculation,  therefore,  protects  the  individual 
hut  endangers  the  community. 


24 


SPECIFIC    PEOPHYLACTIC    MEASURES 


\'ariola  Vera 

Variola  Inoculata 

Vaccinia  or  Cowpox 

True  smallpox. 

Inoculated  amallpos. 

Modified  and  attenuated  small- 
pox. 

Only  occurs  in  man. 

Occurs  in  man  and  monkeys. 

Man,  monkeys,  cattle,  guinea- 
pigs,  rabbits,  rats,  camels,  and 
many  other  mammals. 

High  mortality. 

Milder;  rarely  fatal;  about  1  in 
500. 

Verj-  mild ;  never  fatal. 

A  general  eruption,    often 
confluent  or  hemorrhagic. 

A  general  eruption,  fewer  pus- 
tules (rarely  over  200) ;  seldom 
confluent  or  hemorrhagic. 

Always  local  and  confined  to  the 
site  of  the  vaccination. 

Highly  contagious 

Equally  highly  contagious. 

Not  contagious  —  contracted 
only  by  mechanical  transfer 
of  vaccine   virus. 

Period  of  incubation  12-14 
days. 

S  days. 

3-1  days. 

Inoculation  is  a  ven'  old  custom.  It  was  practiced  by  the  Chinese 
from  time  immemorial.  The  method  was  introduced  into  western  civili- 
zation through  Lady  !Mary  Wortly  Montagu,  who  learned  of  the  method  at 
Constantinople  and  had  her  own  bo}'  "engrafted"  with  successful  result. 
In  1717  Lady  ^lontagii  wrote  her  now  famous  letter  to  her  friend 
Sarah  Chiswell.  and  the  practice  soon  became  popular  in  England 
(1721)  and  spread  to  America  and  the  Continent.  It  was  introduced 
into  this  country  by  Dr.  Zabdiel  Boylston  at  Boston.  But  the  dangers 
were  early  realized  and  inoculation  was  soon  replaced  by  vaccination. 
According  to  Plehn.  inoculation  is  still  practiced  in  central  Africa. 

The  method  of  inoculation  is  precisely  similar  to  that  of  vaccina- 
tion. The  matter  is  obtained  from  the  vesicle  or  pustule  of  a  case  of 
smallpox.  This  material  is  then  introduced  into  the  skin  by  means  of 
a  pimcture,  an  incision,  or  tlirough  an  al)raded  surface.  The  Chinese, 
it  is  said,  practice  inoculation  by  blowing  the  dried  smallpox  crusts 
into  the  nostrils. 

While  inoculation  has  properly  fallen  into  disuse,  there  are  con- 
ceivable emergencies  in  which  the  practice  would  be  justified.  For 
example,  on  board  ship  or  on  an  island  or  isolated  place,  in  the  absence 
of  vaccine  virus.  Under  such  circumstances  it  would  be  essential  to 
inoculate  everybody  at  the  same  time. 

The  inoculation  of  smallpox  will  always  remain  for  the  student  of 
preventive  medicine  one  of  the  most  interesting  episodes  in  the  develop- 


SMALLPOX    AND    VACCINATION  25 

ment  of  the  sanitary  sciences.  It  illustrates  in  the  clearest  manner 
some  of  the  fundamental  phenomena  of  infection,  susceptibility,  and 
immunity.  It  was  animal  experimentation  on  a  huge  scale,  the  like  of 
which  we  shall  never  see  repeated  on  man  as  the  subject  (Sedgwick). 
It  is  now  a  matter  of  regret  that  for  the  sake  of  science  better  advan- 
tage was  not  taken  of  the  data. 

PREVALENCE    OF  SMALLPOX 

It  is  very  difficult  for  us  now  to  realize  that  smallpox  was  once  much 
more  common  than  measles  and  much  more  fatal.  Many  of  those  who 
recovered  were  disfigured  for  life,  left  blind,  or  with  some  other  serious 
consequence  of  the  disease.  For  centuries  smallpox  was  one  of  the 
greatest  scourges.  It  depopulated  cities  and  exterminated  nations.  In 
Europe  alone,  where  its  ravages  were  comparatively  slight,  it  killed 
hundreds  of  thousands  yearly.  In  the  18th  century,  of  which  we  have 
the  best  records,  almost  everybody  had  it  before  he  grew  up.  Parents 
sometimes  exposed  their  children  to  the  disease  in  order  to  be  through 
with  it,  just  as  they  now  sometimes  do  with  the  minor  contagious 
diseases. 

Smallpox  was  formerly  a  disease  of  children.  It  was  called  "kinder- 
hldttern."  Since  vaccination  protects  the  child,  smallpox  has  now  be- 
come more  prevalent  among  adults. 

The  distinguished  mathematician,  Bernouille,.  estimated  that  15,000,- 
000  people  died  of  smallpox  in  25  years  in  the  18th  century.  It  has 
been  estimated  that  60  million  people  died  of  smallpox  during  that 
century.  Haygarth  gives  an  account  of  a  smallpox  epidemic  in  Chester, 
England,  population  14,713.  At  the  termination  of  the  epidemic  there 
were  but  1,060  persons,  or  7  per  cent,  of  the  population,  who  had  never 
had  smallpox.  Many  similar  instances  are  cited  in  the  literature. 
The  French  physician  de  la  Condamine  (1754)  said  that  "every  tenth 
death  was  due  to  smallpox  and  that  one-fourth  of  mankind  was  either 
killed  by  it  or  crippled  or  disfigured  for  life."  Sarcone  (1782)  esti- 
mated the  number  of  persons  in  Italy  who  suffered  from  smallpox  as 
90  per  cent,  of  the  population. 

Smallpox  was  introduced  into  the  western  hemisphere  by  the  Span- 
iards about  15  years  after  the  discovery  of  America.  In  Mexico  within 
a  short  period  three  and  one-half  million  persons  are  said  to  have  died 
of  the  disease  (Chapman).  Catlin  (1841)  states  that  of  12,000,000 
American  Indians  6,000,000  fell  victims  to  smallpox.  In  Iceland,  in 
1707,  18,000  perished  out  of  a  population  of  50,000,  that  is,  smallpox 
killed  36  per  cent,  of  the  total  population  in  one  year. 

A  good  example  is  that  of  Boston  in  1752,  population  at  that  time 
15,684.  Of  this  number  5,998  had  previously  had  smallpox.  During 
the  epidemic  5^545  persons  contracted  the  disease  in  the  usual  manner. 


26 


SPECIFIC    rKOPHYLACTIC    MEASUKES 


and  '^M"?-!  tdok  it  by  inoculation.  1,843  persons  escaped  from  the  town 
to  avoid  the  infection.  Tlicro  were,  therefore,  left  in  the  city  but  174 
persons  who  had  never  had  >niallpox. 


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Smallpox  is  still  as  serious  as  it  was  in  former  times.     Thus,  in 
five  vears,  from  1893-1897,  346,520  persons  died  of  smallpox  in  sixteen 


SMALLPOX    AXD    A\1CCIXATI0X  27 

countries.  Of  this  number  Eussia  alone  lost  275,502.  Tliese  figures  are 
the  more  terrible  when  it  is  realized  that  these  lives  might  have  been 
saved  by  the  use  of  a  simple  2:)rophylactic  measure  within  reach  of  all. 

EPIDEMIOLOGY 

Few  of  the  acute  infectious  diseases  show  such  a  complete  inde- 
pendence of  conditions  such  as  race,  climate,  soil,  age,  sex,  and  occu- 
pation, sanitary  surroundings,  etc.,  as  does  smallpox.  •  It  thrives  wher- 
ever the  contagion  is  carried,  and  wherever  it  finds  susceptible  people. 
Probably  no  one  is  naturally  immune.  The  susceptibility  of  the  popu- 
lation varies,  because  a  smallpox  outbreak  leaves  so  many  immune.  This 
is  one  reason  why  the  disease  recurs  in  waves.  The  mortality  varies 
greatly  in  different  epidemics.  At  times  it  is  less  than  one  per  cent. ; 
it  frequently  reaches  thirty  per  cent,  and  over. 

In  1901-1903  the  mortality  in  the  United  States  was  as  low  as  2  per 
cent,  and  following  that  0.5  per  cent.  These  differences  occurred  in 
the  prevaccination  era  as  well  as  now. 

The  epidemiolog}'  of  smallpox  bears  no  relation  to  improved  sanita- 
tion, which  has  diminished  the  prevalence  of  tuberculosis,  typhoid, 
cholera,  and  has  practically  subdued  typhus  and  relapsing  fever.  It  is 
evident  that  general  sanitation  could  not  affect  contagious  diseases  like 
smallpox  and  measles.  Smallpox  spares  neither  high  nor  low,  the 
rich  or  poor;  before  the  days  of  vaccination  it  counted  many  kings, 
queens,  and  princes  among  its  victims. 

MODES    OF   INFECTION 

"We  are  still  ignorant  of  the  precise  mode  by  which  smallpox  is 
conveyed.  The  view  generally  held  is  that  the  infection  is  air-borne 
and  enters  the  system  through  the  respiratory  mucous  membrane.  It 
has  been  surmised  that  a  local  lesion  may  be  produced  in  this  favor- 
able soil,  the  so-called  "'"propustule,"  from  which  general  infection 
through  the  blood  takes  place.  The  blood  infection  is  marked  by  a 
sharp  onset  (the  initial  symptoms),  and  the  skin  eruption  is  embolic  in 
character.  The  objection  to  this  view  is  that  a  careful  search  of  54 
cases  in  Boston  by  Coimcilman  and  his  colleagues  failed  to  find  such 
a  propustule. 

It  is  known  that  the  Chinese  inoculated  the  disease  by  placing  a 
crust  from  the  eruption  in  the  nostrils,  but  whether  the  disease  so 
produced  was  variola  vera  or  variola  inoculata  is  not  known. 

The  virus  of  smallpox  is  always  contained  in  the  skin  lesions.  Of 
this  we  have  experimental  evidence.  It  is  also  supposed  to  be  in  the 
expired  air.  This,  however,  has  never  been  experimentally  proven. 
The  disease  is  contagious  before  the  eruption  appears.  It  is  even  be- 
lieved to  be  communicable  during  the  period  of  incubation.     Smallpox 


28  SPECIFIC    PROPHYLACTIC    MEASURES 

has  always  been  taken  as  the  type  of  the  contagious  diseases;  the  con- 
tagion is  the  most  "volatile"  of  any  of  the  diseases  of  man.  This 
volatility,  however,  has  been  overestimated,  and,  while  probably  an  air- 
borne infection,  the  radius  of  danger  is  contracted.  English  observers 
have  long  taken  the  view  that  smallpox  may  be  blown  for  great  distances, 
and  they  attribute  the  prevalence  of  smallpox  to  the  windward  of  hos- 
pitals as  an  indication  that  the  virus  may  be  carried  down  the  wind. 
My  experience  with  the  disease  teaches  me  that  the  danger  from  such 
a  source  is  practically  nil.  One  may  safely  live  next  door  to  a  smallpox 
hospital  that  is  well  screened  and  properly  managed.  The  influence  of 
flies  and  other  insects,  or  surreptitious  visiting,  may  account  for  the 
spread  of  this  disease  outside  of  hospital  w^alls. 

In  addition  to  more  or  less  direct  contact  smallpox  may  be  spread 
indirectly  in  a  great  variety  of  ways.  The  secretions  from  the  mouth 
and  nose  doubtless  contain  the  infection,  and,  while  suspicion  has  not 
particularly  fallen  upon  the  feces  and  urine,  it  is  probable  that  all  the 
secretions  and  excretions  from  the  body  may  be  infective  at  some  time 
throughout  the  disease,  or  during  convalescence.  Toys,  pencils,  books, 
letters,  spoons,  cups,  towels,  handkerchiefs,  bedding,  and  objects  of  the 
greatest  variety  that  have  in  any  way  come  in  contact  with  the  patient 
may  carry  the  infection.  Under  favorable  circumstances  the  active 
principle  may  probably  live  for  a  considerable  time  upon  fomites. 

Smallpox  is  not  usually  considered  an  insect-borne  disease,  but  it  is 
highly  prol)al)le  that  a  fly  lighting  upon  a  smallpox  patient  and  get- 
ting its  proboscis,  feet,  and  other  portions  of  its  body  smeared  with  the 
variolous  matter,  and  then  flying  to  a  susceptible  person,  could  thus 
readily  transmit  the  infection.  Other  insects  may  by  such  mechanical 
transfer  play  a  similar  role. 

RESISTANCE    OF    THE    VIRUS 

It  is  generally,  and  doubtless  correctly,  assumed  that  the  active 
principle  of  variola  has  approximately  the  same  resistance  to  external 
conditions  as  vaccine  virus.  This  assumj^tion  is  confirmed  by  experi- 
mental evidence,  which  shows  that  the  virus  of  smallpox  is  even  more 
readily  destroyed  than  the  virus  of  cow-pox.  Scientific  data  concerning 
the  viability  of  variolous  matter  is  meager,  owing  to  the  fact  that  this 
question  can  only  be  settled  by  prolonged  and  repeated  experiments 
upon  monkeys.  Brinckerhoff  and  Tyzzer  ^  found  that  variolous  virus 
is  less  resistant  to  desiccation  than  vaccine  virus;  that  variolous  virus 
does  not  pass  a  Berkefeld  filter  and  is  attenuated  by  long  exposure  to 
60  per  cent,  glycerin. 

In  general  it  may  be  said  that  variolous  virus  is  killed  by  exposure 

to    ordinary    germicidal    substances,   both    liquid    and   gaseous,    in    the 

^"Studies  upon  Experimental  Variola  and  Vaccinia  in  Quadrumana, " 
Jour.  Med.  Eesearch,  Vol.  XIV,  No.  2,  Jan.,  1906,  pp.  223-359. 


SMALLPOX    AXD    A^ACCIXATION" 


29 


strengths  and  time  commonly  employed.     It  succumbs  in  fact  before 
the  average  non-spore-bearing  bacteria. 

There  is  a  probable  exception  to  this  statement  in  the  case  of  car- 
bolic acid  and  the  coal-tar  disinfectants.  McClintock  and  Ferry  ^  have 
shown  that  such  germicides  as  carbolic  acid,  cresols,  and  the  like  do  not 
destroy  the  virulence  of  vaccine  virus  in  0.5  per  cent,  solutions  in  five 
hours'  exposure.  In  this  strength  and  time  almost  all  non-spore-bearing 
bacteria  would  be  destroyed.  The  inference  is  allowable  that  this  class  of 
disinfectants  cannot  be  relied  upon  to  prevent  the  spread  of  smallpox. 

SMALLPOX  IN  THE  VACCINATED  AND  UNVACCINATED 
The  experience  of  over  one  hundred  years  offers  convincing  proof 
of  the  pronounced  difference  in  the  mortality  and  morbidity  from  small- 
pox in  the  vaccinated  and  the  unvaccinated.  The  following  table  from 
Schamberg  shows  that,  among  thousands  of  cases  of  smallpox  occurring 
in  cities  all  over  the  world,  the  death  rate  from  smallpox  has  been  from 
five  to  sixteen  times  greater  among  the  unvaccinated  than  among  the 
vaccinated : 

TABLE    2— DEATH-RATE     FROM     SMALLPOX    AMONG    VACCINATED    AND    UNVAC- 
CINATED IN  VARIOUS  COUNTRIES^ 


Places  and  Time  of  Obsei^'ation 


France,  1816-1S41 

Quebec,  1819-1820 

Philadelphia,  1825 

Canton  Vaud,  1825-1829 

Verona,  1828-1829 

Milan,  1830-1851 

Breslau,  1831-1833 

Wurttemberg,  1831-1835 

Camiola,  1834-1835 

Vienna  Hospital,  1834 

Carinthia,  1834-1835 

Adriatic,  1835 

Lower  Austria,  1835 

Bohemia,  1835-1855 

Galicia,  1836 

Dalmatia,  1836 

London  Smallpox  Hospital,  1836-1856  . 

Vienna  Hospital,  1837-1856 

Kiel,  1852-1853 

Wurttemberg  (no  date) 

Malta  (no  date) 


Epidemiological  Society  Returns  (no  date) 


Total  No. 
of  Cases 
Observed 


Death  Rate  per  100 

Cases 


16,397 
? 

140 
5,838 

909 
10,240 

220 
1,442 

442 

360 
1,626 
1,002 
2,287 
15,640 
1,059 

723 
9,000 
6,213 

218 
6,258 
7,570 
4,624 


AiEong 
the  Unvac- 
cinated 


16.L25 

27 

60 

24 

46.66 

38.33 

53.8 

27.33 

16.25 

51.25 

14.5 

15.2 

25.8 

29.8 

23.5 

19.66 

35 

30 

32 

38.9 

21.07 

23 


Among 
the  Vac- 
cinated 

1 

1.66 

0 


.16 

.66 

.66 

.11 

.1 

.4 

.5 

.5 


2. 

5. 

7. 

2. 

7. 

4. 
12. 

0. 

2.8 
11.5 

5.16 

5.14 

8.25 

7 

5 

6 

4.2 
2.9 


^Jour.  of  the  Amer.  Public  Health  Assn.,  June,  1911  (Vol.  I,  No.  6),  p.  418. 

-  Extract  from  papers  prepared  in  1857  by  Sir  John  Simon,  Medical  Officer 
of  the  General  Board  of  Health  of  England,  and  at  that  time  laid  before  Parlia- 
ment with  reference  to  the  History  and  Practice  of  Vaccination.  Published  in 
first  Eeport  of  the  Eoyal  Commission  on  Vaccination,  1889,  Appendix  1,  p.  74. 

^  Jour,  of  the  Amer,  Fiiblic  Health  Assn.,  June,  1911   (Vol.  1,  No.  6),  p.  418. 


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SPECIFIC    riJurilYLACTlC    MEASURES 


TABLE   3— ANNUAL  SMALLPOX   DEATHS    IN    SWEDEN   BEFORE   AND   AFTER   THE 
INTRODUCTION  OF  VACCINATION' 


Before  Vaccination 

1749-    4,453 

1750      C.ISO 


After  Vaccination 


1751 
1752 
1753 
1754 
1755 
1750 


5,546 
10,302 
8,000 
6,862 
4,705 
7,858 


1757   10,241 

1758   7,104 

1759   3.910 

1760   3,568 

1701   5,731 

1762   9,389 

1763   11,662 

1764   4,562 

1765   4,697 

1766   4,092 

1767   4,189 

1768  10,650 

1709   10,215 

1770   5,215 

1771   4,362 

1772   5,435 

1773   12,130 


1774 
1775 
1776 

1777 
1778 


2,065 
1,275 
1,503 
1,943 
6,007 


1779   15,102 

1780   3,374 

1781   1,485 

1782   2,482 

1783   3,915 

1784   12,456 

1785   5,077 

1786   071 

1787   1,771 

1788   5,402 

1789   0,704 

1790   5,893 

1791   3,101 

1792   1,939 

1793   2,103 

1794   3,964 

1795   6,740 

1796   4,503 

1797   1,733 

1798   1,357 

1799   3,750 

1800   12,032 

1801   6,057 


Total  (53  years) 125,130 


1802 
1803 
1804 
1805 
1806 
1807 
1808 


1,533 
1.464 
1,400 
1,090 
1,482 
2,129 
1,814 


1809   2,404 


1810* 

1811 

1812 

1813 

1814 

1815 

1816 


1817 
1818 
1819 
1820 
1S21 


Compulsory  Vaccination 
in  Infancy 


824 
089 
404 
547 
308 
472 
690 


242 
305 
161 
143 
37 


Total  (20  years) 18,217 

1822      11 

1823 39 

1824      618 

1825      1,243 

1826      625 

1827      600 

1828      257 

1829      53 

1830      104 

1831      612 

1832      022 

1833      1,145 

1834      1,049 

1835      445 

1836      138 

1837      361 

1838      1,805 

1839      1,934 

1840      650 

1841      237 

1842      58 

1843      9 

1844      6 

1845      6 

1846      2 

1847      13 

1848     71 

1849      341 

1850      1,376 

1851      2,488 

1852      1,534 

1853     279 

1854     204 

1855     41 


'^The  population  in  1751  was  1,785,727:  in  1855  it  was  3,639,332. 
2  From  1749  to  1773,  inclusive,  deaths  from  measles  are  included. 
'  First  successful  vaccination  in  Stockholm. 


SMALLPOX    AIs^D    VACCIXATIOX  33 

In  countries  like  Germany,  Sweden,  Ireland,  Scotland,  and  England, 
where  vaccination  is  more  or  less  compulsory,  there  is  comparatively  little 
smallpox.  In  countries  like  Belgium,  Eussia,  Austria,  and  Spain,  which 
have  no  compulsory  vaccination  laws,  smallpox  yearly  claims  many 
victims.     See  table  1,  page  23. 

THE   EESULT    OF    VACCINATION   IN    GERMANY 

April  8tli,  1874,  Germany  passed  a  general  compulsory  vaccination 
and  revaccination  law.  The  law  requires  the  vaccination  of  all  infants 
before  the  expiration  of  the  first  year  of  life,  and  a  second  vaccination 
at  the  age  of  twelve.  Since  this  law  went  into  effect  there  have  been 
no  epidemics  of  smallpox  in  Germany,  despite  the  fact  that  the  disease 
has  been  frequently  introduced  from  without.  In  1897  there  were  but 
8  deaths  from  smallpox  in  the  entire  German  empire — population  54,- 
000,000.  Since  then  long  periods  have  passed  without  a  single  death 
from  smallpox.  From  1901  to  1910  there  were  only  380  deaths  from 
smallpox  in  Germany;  during  the  same  period  there  were  4,286  deaths 
from  smallpox  in  England  and  Wales,  with  only  about  half  the  popula- 
tion of  Germany;  furthermore,  many  of  the  deaths  in  Germany  were 
in  foreigners :  Thus  in  1909,  out  of  26  deaths  from  smallpox,  13  were 
foreigners,  11  of  whom  were  Eussians.  In  the  huge  German  army  there 
have  been  only  two  deaths  from  smallpox  since  1874.  One  of  these  was 
a  reservist  who  had  not  been  successfully  vaccinated.  Germany  has 
taught  the  world  how  to  utilize  Jenner's  great  demonstration. 

ISOLATION   AND    DISINFECTION 

Isolation  and  disinfection  are  only  secondary  measures  in  prevent- 
ing smallpox.     They  cannot  be  regarded  as  substitutes  for  vaccination. 

Isolation  should  be  carried  out  with  strictness  for  the  reason  that 
smallpox  is  one  of  the  most  contagious  of  the  communicable  infections. 
While  the  patient  should  be  isolated,  it  is  not  necessary  to  isolate  the 
hospital  by  banishing  it  to  an  inconvenient  or  undesirable  location. 
There  is,  in  fact,  no  good  reason  why  a  smallpox  hospital  should  not 
be  one  of  the  units  of  the  general  hospital  for  communicable  diseases. 
In  any  event,  there  is  no  danger  from  a  smallpox  hospital  situated  upon 
a  high  road  or  near  other  habitations,  provided  always  proper  precau- 
tions are  taken  to  prevent  the  spread  of  the  disease. 

The  smallpox  hospital  should  not  be  a  pest  house,  but  should  be 
as  inviting  and  attractive  as  economic  conditions  justify.  Smallpox 
should  not  be  treated  in  the  home.  From"  the  standpoint  of  prophylaxis 
the  hospital  is  the  logical  and  best  place  to  care  for  this  and  other  com- 
municable infections.     If  smallpox  is  treated  in  the  home,  this  should 


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36  SPECIFIC    PKOriiYLACTIC    MEASURES 

only  be  permitted  if  skilled  nursing  and  trained  attendants  can  be  pro- 
vided. 

The  room  in  which  the  smallpox  patient  is  isolated  should  be  simply 
furnished  to  facilitate  cleanliness  and  to  permit  purification.  It  must 
be  well  screened  and  free  from  insects  and  vermin  of  all  kinds.  The 
room  should  be  well  ventilated.  This  may  be  accomplished  by  an  open 
firci)lace,  in  which  case  the  contagium,  if  contained  in  the  outgoing  air, 
is  burned  in  exit. 

The  nurse  attending  a  case  of  smallpox  should  also  be  segregated, 
and  all  visiting  should  be  strictly  interdicted.  A  separate  kitchen  should 
be  provided  and  care  should  be  taken  that  the  dishes  be  scalded  and 
remnants  of  food  burned. 

Bedding,  underwear,  towels,  and  other  objects  should  not  leave  the 
sick  room  unless  they  are  first  boiled,  steamed,  or  immersed  in  a  suitable 
germicidal  solution,  such  as  bichlorid  of  mercury,  1-1,000,  or  formalin, 
10  per  cent.     Carbolic  acid  should  not  be  trusted. 

For  terminal  disinfection  either  sulphur  dioxid  or  formaldehyde 
may  be  used.  Objects  particularly  contaminated  or  soon  to  be  used 
by  others  should  be  given  a  separate  and  special  disinfection.  Finally, 
the  room  should  be  thoroughly  cleansed,  aired,  and  sunned. 

The  patient  must  be  regarded  as  the  source  and  fountainhead  of 
the  infection,  and  measures  should  be  used  at  the  bedside  to  prevent 
the  surroundings  from  becoming  contaminated.  Cloths,  cotton,  and 
other  dressings  that  become  soiled  Avith  the  contents  of  the  vesicles  and 
pustules  after  they  break  should  be  burned.  The  urine  and  feces  may 
be  disinfected  with  chlorinated  lime.  The  sputum  and  discharges  from 
abscesses  must  be  carefully  disinfected  by  an  approved  method  (see 
Section  XII).  As  a  rule,  smallpox  patients  are  not  dismissed  from 
quarantine  until  desquamation  has  ceased.  This  may  be  favored  by 
the  use  of  warm  baths  and  a  generous  use  of  soap,  also  by  anointing 
the  skin  with  vaselin  or  a  bland  oil.  Special  attention  should  be  given 
to  the  hair,  which  should  be  well  shampooed,  to  the  interdigital  spaces, 
and  the  fingernails,  as  well  as  to  all  folds  of  the  skin,  before  the  patient 
is  released. 

The  management  of  smallpox  epidemics  is  discussed  on  page  319. 

RABIES 

Synokyms. — Jlyclroph  oh  la  ;  Wasserscheu,  Wu  tJi ,  To Uicu  th  ( Ger- 
man) ;  Lyssa  (Greek)  ;  La  liage  (French). 

Eabies  is  an  acute,  specific,  rapidly  fatal  infection  commimicated 
from  a  rabid  animal  to  a  susceptible  animal,  usually  through  a  wound 

^Collateral  reading:  "Facts  and  Problems  of  Eabies, "  Stimson,  Hyg.  Lab. 
Bull.  No.  65,  U.  S.  P.  H.  &  M.  H.  S. 


RABIES  37 

produced  by  biting.  Man  always  contracts  the  disease  from  some  lower 
animal,  usually  the  dog.  The  infective  agent  must  be  inoculated  into 
the  tissues;  the  virus  is  harmless  when  ingested.  Eabies  may  be  re- 
garded as  a  wound  infection.  The  specific  principle  is  contained  in 
the  saliva  of  animals  suffering  with  the  disease.  The  infection,  there- 
fore, may  be  conveyed  by  licking  provided  there  are  fissures  or  open 
wounds  in  the  skin.  It  is  also  possible  to  introduce  the  virus  through 
autopsy  accidents  and  other  unusual  ways,  but  commonly  it  is  intro- 
duced through  wounds  produced  by  the  teeth  of  a  rabid  animal. 

Every  mammalian  animal  is  susceptible.  Even  birds  may  contract 
the  disease.  It  is  most  common  in  dogs,  but  it  also  occurs  frequently 
in  wolves,  Jackals,  foxes,  and  hyenas.  Eabies  in  cats  is  comparatively 
rare.  Cattle,  sheep,  and  goats  are  infected  relatively  in  about  the  same 
degree.  It  is  less  common  in  horses.  Swine  contract  the  disease  less 
frequently  than  other  domestic  animals.  Skunks  have  the  disease  and 
sometimes  transmit  it  to  man. 

Although  all  mammals  are  susceptible  to  rabies,  it  is  perpetuated  in 
nature  almost  exclusively  by  the  domestic  dog,  only  to  a  small  extent 
by  wild  animals  of  the  dog  family,  and  occasionally  by  skunks,  cats,  etc. 
Outbreaks  have  been  reported  under  unusual  circumstances.  Thus 
Carini  ^  reports  an  epizootic  causing  the  death  of  about  4,000  cattle  and 
1,000  horses  in  Sao  Paulo,  Brazil.  There  was  no  unusual  prevalence 
of  rabies  in  dogs  at  the  time  but  it  was  noticed  that  bats,  in  broad 
daylight,  attacked  and  bit  the  cattle,  and  Carini  suggests  that  bats 
may  have  been  the  source  of  the  extensive  epizootic.  The  animals 
affected  all  died  after  a  few  days  and  the  meat  and  hides  were  utilized 
but  no  mishaps  have  been  known  to  follow. 

Eabies  exists  practically  all  over  the  world,  except  in  Australia,  and 
recently  in  England.  It  is  most  common  in  France,  Beligum,  and  Eussia. 
In  the  United  States  111  human  deaths  were  reported  in  1908.  In 
the  same  year  there  were  535  localities  in  which  rabid  animals  were 
reported;  in  1911  there  were  1,381  localities,  and  98  deaths  in  man. 
In  1890  the  United  States  census  reported  143  deaths  in  30  states,  and 
in  1900  but  23  deaths. 

Eabies  is  remarkable  in  that  the  mortality  is  100  per  cent.  After 
symptoms  begin  recovery  never  occurs  in  man  or  other  animals.  Jo- 
seph Koch  (1910),  however,  describes  an  abortive  rabies.  The  disease 
is  peculiar  in  several  other  particulars,  especially  the  period  of  incuba- 
tion, which  is  more  variable  and  more  prolonged  than  that  of  any  other 
acute  infection. 

Eabies  is  commonly  supposed  to  prevail  only  during  the  hot  months, 

but  it  may  be  just  as  bad  in  cold  weather.     In  fact,  exposure  to  cold 

seems  to  increase  its  virulence.     More  cases  occur  from  April  to  Sep- 

^  Ann.  de  I' Inst.  Pasteur,  Paris,  Nov.,  XXV,  11,  p.  785. 
5 


38  SPECIFIC    PROPHYLACTIC    MEASURES 

tember  than  from  October  to  March  in  tliis  climate,  because  dogs  run 
abroad  more  freely  at  this  season  of  the  year.  It  is  this  fact,  and  not 
the  temperature,  that  influences  the  prevalence  of  tlie  disease. 

Period  of  Incubation. — From  the  standpoint  of  prevention  it  is  for- 
tunate that  the  period  of  incubation  of  this  disease  is  prolonged.  This 
period  varies  from  14  days  to  a  year  or  more.  The  average  period  is 
as  follows:  Man,  40  days;  dogs,  21-40  days;  hors^es,  28-56  days;  cows, 
28-56  days;  pigs,  14-21  days;  goats  and  sheep,  21-28  days;  birds,  14-40 
days. 

The  period  of  incubation  depends  largely  upon  the  site  of  the  wound, 
the  relation  to  the  nerve,  the  amount  and  virulence  of  the  virus.  It 
requires  about  15  days  to  induce  an  active  immunity  to  the  disease  by 
means  of  the  Pasteur  preventive  treatment.  There  is,  therefore,  usu- 
ally plenty  of  time,  if  the  case  is  seen  early,  to  prevent  the  development 
of  symptoms. 

It  is  probable  that  tlie  prolonged  period  of  incubation  is  due  in  part 
to  the  fact  that  the  living  principle  reaches  the  central  nervous  system, 
but  remains  dormant  until  favorable  conditions  permit  multiplication 
and  the  production  of  toxic  effects  (Joseph  Kocli). 

Entrance  and  Exit  of  the  Virus. — The  active  principle  of  rabies 
occurs  principally  in  the  saliva  and  in  the  central  nervous  system.  It 
may  be  in  the  saliva  at  least  three  days  (possibly  eight)  before  the  ani- 
mal shows  symptoms  (Roux  and  Nocard).  It  is,  therefore,  sufficient  to 
watch  a  dog  that  has  bitten  a  person  or  another  animal  for  ten  days. 
If  no  symptoms  of  rabies  appear  during  this  time  there  is  no  danger 
of  conveying  the  disease,  and  the  Pasteur  treatment  is  unnecessary. 

The  virus  may  also  be  found  in  the  adrenals,  the  tear  glands,  the 
vitreous  humor,  the  spermatic  fluid,  the  urine,  the  lymph,  the  milk,  as 
well  as  all  parts  of  the  central  nervous  system  and  the  peripheral  nerves. 
It  is  also  found  in  the  spinal  and  ventricular  fluids.  It  has  not  been 
demonstrated  in  the  liver,  spleen,  blood,  or  muscles. 

The  virus  enters  the  system  through  the  broken  skin  and  follows 
the  nerve  trunks  from  the  seat  of  injury  to  the  spinal  cord,  thence  to 
the  medulla  and  brain.  The  route  corresponds  to  that  of  tetanus  toxin. 
The  mode  of  invasion  of  the  virus  may  explain  why  pain,  throbbing, 
tingling,  numbness  and  other  nervous  disturbances  are  the  first  symp- 
toms to  occur  in  parts  of  the  body  that  have  received  the  virus.  It 
also  partly  explains  the  variable  period  of  incubation,  which  is  shorter  in 
wounds  of  the  face  than  in  wounds  of  the  extremities.  It  also  explains 
why  the  disease  is  more  serious  when  the  wounds  are  in  parts  of  the 
body  where  there  is  an  abundant  nerve  supplv. 

The  Relative  Danger  of  Bites. — Wolf  bites  are  most  dangerous  on 
account  of  the  savage  character  of  the  wound,  and  the  virulence  of  the 
virus.     Cat  bites  come  next,  and  then  dog  bites.     The  relative  danger 


RABIES  39 

of  bites  of  other  animals  is  as  follows :  foxes,  jackals,  horses,  asses,  cattle, 
sheep,  pigs.  There  is  no  authentic  instance  of  the  transmission  of  the 
disease  by  the  bite  of  man,  though  this  may  be  possible.  The  bites  of 
horses  and  other  herbivora  are  less  dangerous  because  their  blunt  teeth 
usually  cause  contused  wounds  without  breaking  the  skin. 

Bites  on  exposed  surfaces  are  more  dangerous  than  through  the 
clothing,  because  the  saliva  is  wiped  from  the  teeth  and  little  or  none 
enters  the  wound.  Long-haired  dogs  and  sheep  often  escape  infection 
for  the  same  reason.  Bites  upon  the  face  are  most  apt  to  be  followed 
by  rabies. 

ISTot  every  person  bitten  by  a  mad  animal  develops  rabies.  Leblanc's 
figures  are  16.6  per  cent.  The  statistics  are  difficult  to  analyze,  and  it 
is  almost  impossible  now  to  collect  sufficient  data.  According  to  the 
most  reliable  data,  it  would  seem  that  rabies  develops  in  not  less  than 
one  person  in  ten  bitten  by  mad  dogs,  and  not  receiving  the  Pasteur 
treatment.     Paltauf  places  the  figures  at  6  to  9  per  cent. 

Viability.- — The  virus  of  rabies  in  the  spinal  cord  of  rabbits  dies  in 
about  14  days  when  dried  at  20° -22°  C,  if  protected  from  putrefaction 
and  light.  Spread  in  thin  layers,  it  dies  in  4  or  5  daj^s,  and  exposed 
to  the  sunlight  in  40  hours.  It  is  quite  resistant  to  putrefaction.  In 
a  decomposed  carcass  it  may  be  recovered  by  placing  some  of  the  cen- 
tral nervous  system  in  glycerin.  The  glycerin  destroys  most  of  the  con- 
taminating bacteria,  but  j^reserves  the  virus.  Eabies  virus  is  completely 
destroyed  at  50°  C.  in  one  hour,  and  at  60°  C.  in  30  minutes.  It  is 
not  injured  by  extreme  cold.  Five  per  cent,  carbolic  acid  for  one  hour, 
1-1,000  bichlorid  of  mercury  for  one  hour,  or  a  saturated  solution  of 
iodin  in  water  completely  destroys  its  virulence. 

PROPHYLAXIS 

The  prevention  of  rabies  is  considered  under  three  heads:  (1) 
Treatment  of  the  wounds;  (2)  the  Pasteur  prophylactic  treatment,  and 
(3)  the  control  of  the  disease  in  dogs  by  muzzling  and  quarantine. 

The  cauterization  of  the  wound  and  the  Pasteur  prophylactic  treat- 
ment are  efficient  preventive  measures  for  the  individual,  but  they  are 
not  the  true  and  best  methods  of  controlling  and  preventing  rabies. 
The  disease  may  be  avoided,  even  exterminated,  by  an  intelligent  system 
of  muzzling  and  quarantining  of  dogs.  A  high  tax  on  dogs  and  leash- 
ing are  only  restrictive  measures.  In  England,  wdien  the  dogs  were 
muzzled,  rabies  diminished.  The  law  was  repealed,  owing  to  misplaced 
sympathy  for  the  dog,  and  rabies  promptly  increased.  The  law  was 
again  enforced,  and  in  about  two  years  the  disease  disappeared  (see  the 
accompanying  chart).  Now  a  strict  quarantine  of  six  months  is  main- 
tained against  dogs  entering  England.     It  is  no  longer  necessary  to 


40 


SPECIFIC    PROPHYLACTIC    MEASURES 


muzzle  dogs  in  England,  but  muzzles  will  again  be  required  should  the 
disease  reappear.  Consistent  muzzling  of  all  dogs  for  two  years  will 
practically  exterminate  rabies.  In  Australia  there  are  few  carnivorous 
animals,  mostly  marsupials;  there  rabies  does  not  exist,  for  it  has 
been  kept  out  owing  to  early  and  effective  quarantine  measures. 


Fig.  9. — Chart  Showing  Relation  of 
LENCE  OF  Rabies  in  Great  Britain. 
number  of  persons  who  died  of  rabies 
sent  cases  in  dogs.   (Frothingham.) 


Enforcement  of  Muzzling  Law  to  Preva- 
The  figures  in  the  cross-hatching  indicate  the 
in  England  and  Wales.     The  ordinates  repre- 


Prophylactic  measures  necessar}'  to  control  the  dog  question  are: 
the  destruction  of  ownerless  dogs;  license  fee  and  tag  for  all  dogs; 
owners  to  be  legally  responsible  for  damage  inflicted  by  their  dogs; 
education  of  the  dog-owning  public  concerning  the  spread  of  commun- 
icable diseases,  especially  rabies;  compulsory  reporting  of  all  cases  or 
suspected  cases  of  rabies.  Further  special  and  temporary  measures 
advocated  are:  muzzling;  restraint  with  chains,  leash,  etc.;  observation 
in  quarantine,  or  killing  of  all  animals  bitten  by  dogs;  disinfection,  etc. 


THE    LOCAL    TREATMENT    OF    THE    WOUND 

Wounds  produced  by  the  bite  of  an  animal  in  which  there  is  any 
suspicion  of  rabies  should  at  once  be  cauterized  with  fuming  nitric 
acid.  The  acid  is  best  applied  with  a  glass  rod  very  thoroughly  to  all 
the  parts  of  the  wound,  care  being  taken  that  pockets  and  recesses  do 
not  escape.    Thorough  cauterization  at  once  reduces  the  danger  of  wound 


RABIES  41 

complications,  and  experience  demonstrates  that  wounds  so  treated  at 
once,  are  practically  never  followed  by  rabies.  Marie  obtained  conflicting 
results  with  local  treatment  in  experimental  rabies;  Cabot  obtained  the 
best  results  in  a  series  of  extensive  experiments  with  nitric  acid.  Poor  ^ 
was  able  to  save  the  lives  of  45  per  cent,  of  guinea-pigs  by  cauterization 
with  nitric  acid  at  the  end  of  24  hours.  In  the  absence  of  nitric  acid 
the  actual  cautery  may  be  used.  Strong  antiseptics,  such  as  carbolic 
acid  and  formalin,  are  less  reliable.  Nitrate  of  silver  is  valueless.  In 
any  wound  produced  by  the  bite  of  an  animal  the  rule  is  to  cauterize 
unless  sure  that  the  animal  is  not  mad. 

It  has  been  shown  that  the  virus  may  remain  alive  and  virulent  in 
the  scar  for  a  long  time,  and  it  has  become  a  question  whether  patients 
seen  after  the  wound  has  healed  should  not  have  the  scar  excised;  this, 
however,  is  not  the  present  practice. 

THE    PASTEUR    PROPHYLACTIC    TREATMENT 

This  method  of  prophylaxis  was  announced  December  6,  1883,  by 
Pasteur,  at  the  International  Congress  at  Copenhagen,  and  on  February 
24,  1884,  he  laid  before  the  French  Academy  the  details  of  his  experi- 
ments and  results.  The  next  year  Pasteur,  with  the  help  of  Eoux  and 
Chamberland,  worked  out  the  details  of  the  method  now  used. 

The  principle  of  the  treatment  consists  in  producing  an  active  im- 
munity by  means  of  an  attenuated  virus.  The  virus  is  attenuated  by 
drying.  The  fixed  virus  contained  in  the  spinal  cord  of  rabbits  dead  of 
hydrophobia  is  the  material  used,  for  subcutaneous  injection. 

Street  Virus  and  Fixed  Virus. — The  distinction  between  fixed  and 
street  virus  is  of  fundamental  importance  in  reference  to  the  question 
of  immunity.  Street  virus  refers  to  the  virus  obtained  from  mad 
dogs  naturally  infected.  When  this  virus  is  inoculated  into  a  rabbit,  it 
reproduces  the  disease  after  a  period  of  incubation  of  from  14  to  21 
days  or  more.  This  street  virus  may  then  be  conveyed  from  rabbit  to 
rabbit  through  a  number  of  transfers.  In  the  passage  from  rabbit  to 
rabbit  the  virus  becomes  more  virulent  for  rabbits,  but  less  so  for  dogs 
and  other  animals.  The  period  of  incubation  is  progressively  shortened, 
until  finally  the  rabbits  invariably  sicken  on  the  sixth  or  seventh  day  and 
die  on  the  ninth  or  tenth.  When  the  virus  has  reached  this  degree  of 
virulence  for  rabbits,  it  is  said  to  be  "fixed,"  for  the  reason  that  its 
potency  remains  constant.  In  its  passage  through  rabbits  the  modifica- 
tion from  street  virus  to  fixed  virus  is  gradual.  It  is  important  to  note 
that  fixed  virus,  which  has  attained  a  high  degree  of  virulence  for  rab- 

^  Collected   Studies,   Research   Lab.,    Dept.    of    Health,    City    of   N.    Y.,    VI, 
1911,  p.  25. 


42  SPECIFIC    PROPHYLACTIC    MEASURES 

bits,  has  lost  imicli  of  its  virulence  for  dogs,  and  is  probably  entirely 
avirulent  for  man. 

Proesclier  ^  injected  into  himself  the  entire  brain  and  medulla  of 
a  rahl)it  (fixed  virus),  and  anotlier  entire  brain  into  a  volunteer.  No 
ill  eil'ects  of  any  kind  were  noted  in  either  case.  A  control  rabbit  in- 
jected willi  a  <>.(f-^  dilution  of  the  same  emulsion  died  in  seven  days 
with  experimental  rabies. 

Marx  tested  the  fresh  fixed  virus  upon  monkeys  in  large  doses,  with 
negative  results.  Ferran  in  Barcelona  in  1887  inoculated  85  persons 
with  the  fresh  fixed  virus  as  a  pro])hylactic  treatment  for  dog  bites 
with  good  results,  which  have  been  further  confirmed  by  Wysokowiez 
and  Nitsch.  The  evidence  points  clearly  to  the  fact  that  the  fixed  virus 
of  rabbits  does  not  pi'oduce  rabies  in  man  when  introduced  into  the  sub- 
cutaneous tissue. 

Preparation  of  the  Virus. — Rabbits  are  injected  under  the  dura 
mater  with  a  few  drops  of  an  emulsion  of  fresh  fixed  virus  obtained 
from  the  pons  or  medulla  of  another  rabbit  dead  of  hydrophobia.  Strict 
aseptic  precautions  are  necessary  in  order  to  keep  out  other  infections. 
The  rabbit  should  begin  to  show  symptoms  on  the  sixth  or  seventh  day, 
and  die  on  the  ninth  or  tenth.  Usually  the  rabbit  is  not  allowed  to 
die,  l)ut  is  chloroformed  on  the  last  day  in  order  to  avoid  terminal  in- 
fections and  unnecessary  suffering.  The  spinal  cord  is  removed  and 
hung  in  a  bottle  containing  potassium  hydroxid.  These  bottles  are 
kept  in  the  dark  at  a  temperature  of  20°-22°  C.  Under  these  conditions 
the  cord  gradually  desiccates,  and  at  the  same  time  the  virulence  of 
the  virus  diminishes.  Tintil  the  fourteenth  day,  when  it  is  no  longer 
infective.  This  is  why  Pasteur  started  the  treatment  with  a  cord  four- 
teen days  old. 

One  half  a  cubic  centimeter  of  the  cord  constitutes  a  dose.  This  is 
ground  in  sterile  salt  solution  so  as  to  produce  a  uniform  emulsion,  which 
is  injected  into  the  subcutaneous  tissue  of  the  abdominal  wall.  In  many 
institutes  the  small  segments  cut  each  day  from  the  drying  cord  are 
placed  in  pure  glycerin.  The  virulence  of  the  cord  in  glycerin  is  not 
altered  for  at  least  30  days,  if  kept  in  the  dark  and  at  15°  C.  This 
method,  introduced  by  Calmette,  is  very  convenient,  especially  where 
comparatively  few  ])atients  are  treated.  Glycerin  has  the  added  advan- 
tage of  destroying  infections  due  to  non-spore-bearing  bacteria  that 
may  be  present.  As  a  further  precaution,  bacteriological  examinations 
are  made  of  parts  of  the  spinal  cord  in  order  to  insure  the  absence  of 
bacteria,  and  the  rabbit  is  carefully  autopsicd  as  a  guarantee  that  no 
other  disease  is  present. 

The   scheme  of   treatment   advocated   by    Pasteur  and    still   used   at 

I'Institut  Pasteur  in  Paris  and  many  other  places  is  as  follows: 

^N.  Y.  Med.  Jour.,  Oct.  9,  1909,  also  Arch,  of  hit.  Med.,  Sept.,  1911,  VIII, 
3,  p.  353. 


EABIES 


43 


PASTEUR  PROPHYLACTIC  TREATMENT— RECOMMENDED  BY  PASTEUR 


Mild  Treatment 

Intensive  Treatment 

Day 

of 

Treatment 

Age  of 

the  Dried 

Cord 

Amount  of 

Injected 

Emulsion 

1  cm.  to  5  c.  c. 

Day 
of                 th 
Treatment 

Age  of 
e  Dried 
Cord 

Amount  of 

Injected 

Emulsion 

1  cm.  to  5  c.  c. 

14  Days 

3  c.  c. 

1 

/  14  Days 

3  c.  c. 

1 

13 

3 

113 

3 

12 

3 

>^^ 

3 

^0 

3 

2 

fl2 

3 

2 

9 

3 

ill 

3 

8 

3 

7 

3 

3 

/  10 

3 
3 

3                  ■ 

'    6 
I    6 

2 
2 

4 

3 
3 

4 

5 

2 

5 

2 
2 

5 

5 

2 

6 

5 

2 

6 

4 

2 

7 

5 

2 

7 

3 

1 

8 

4 

2 

8 

4 

2 

9 

3 

1 

9 

3 

1 

10 

5 

2 

10 

5 

2 

11 

5 

2 

11 

5 

2 

12 

4 

2 

12 

4 

2 

13 

4 

2 

13 

4 

2 

14 

3 

2 

14 

3 

2 

15 

3 

2 

15 

3 

2 

16 

5 

2 

16 

5 

2 

17 

4 

2 

17 

4 

2 

18 

3 

2 

18 

3 

2 

19 

5 

2 

20 

4 

2 

21 

3 

2 

Many  Pasteur  institutes  now  use  a  modified  treatment,  starting  with 
an  8-day  instead  of  a  14-day-old  cord,  which  is  exemplified  in  the  scheme 
on  next  page,  used  at  the  Hygienic  Laboratory,  Public  Health  Service. 

The  Pasteur  scheme  has  been  further  modified  in  various  ways. 
Bujwid  and  Babes  use  stronger  treatment  than  that  advocated  by  Pas- 
teur. Puscariu  in  Jessy  uses  a  method  based  upon  the  experiments  of 
Babes,  which  show  that  an  emulsion  of  fixed  virus  when  heated  to  50°- 
58°  C.  is  attenuated  in  virulence.  Tizzoni  and  Cattani  attenuate  the 
virus  in  gastric  juice,  and  Hoyges  simply  dilutes  the  fresh  virus.  The 
original  dilution  is  1-100,  and  the  first  dose  is  one  ten-thousandth  of 
this.  Ferran  in  Barcelona,  Proescher  in  Pittsburgh,  and  others  in- 
ject patients  with  the  unaltered,  fresh,  fixed  virus.  •  The  advantages 
of  using  the  virus  as  fresh  and  strong  as  possible  are  that  an  active  im- 
munity is  produced  more  quickly,  and  this  is  of  considerable  importance 
in  wounds  of  the  face;  also  in  wolf  and  cat  bites,  which  frequently 
have  a  short  period  of  incubation.     Further,  only  one  or  two  injection^s. 


44 


SPECIFIC    rROPIIYLACTIC    MEASURES 


PASTEUR  PROPHYLACTIC  TREATMENT— HYGIENIC  LABORATORY,   WASHINGTON. 

D.  C. 


1 

Age  of  the  Dried 

Amount 

Day 

Cord 

Adult                       5  to  10  Years 

1 
1 

1  to  5  Years 

Scheme  for  Mild  Treatment 

1                  i 

S-7-6 

2.5  c.  c. 

2.5  c.  c. 

2.0  c.  c. 

2                  1 

5-4 

2.5 

2.5 

1.5 

3                 ' 

4-3 

2.5 

2.5 

2.0 

4 

5 

2.5 

2.5 

2.5 

5 

4 

2.5 

2.5 

2.5 

6 

3 

2.5 

2.5 

2.0 

7 

3 

2.5 

2.5 

2.0 

8 

2 

2.5 

1.5 

1.0 

9 

2 

2.5 

2.0 

1.5 

10 

5 

2.5 

2.5 

2.5 

11 

5 

2.5 

2.5 

2.5 

12 

4 

2.5 

2.5 

2.5 

13 

4 

2.5 

2.5 

2.5 

14 

3 

2.5 

2.5 

2.0 

15 

3 

2.5 

2.5 

2.0 

16 

2 

2.5 

2.0 

1.5 

17 

2 

2.5 

2.0 

1.5 

18 

4 

2.5 

2.5 

2.5 

19 

3 

2.5 

2.5 

2.5 

20 

2 

2.5 

2.5 

2.0 

21 

2 

2.5 

2.5 

2.0 

Scheme  for  Intensive  Treatment 

1 

8-7-6 

2.5  c.c. 

2.5  c.c. 

2.5  c.c. 

2 

4-3 

2.5 

2.5 

2.0 

3 

5-4 

2.5 

2.5 

2.5 

4 

3 

2.5 

2.5 

2.0 

5 

3 

2.5 

2.5 

2.0 

6 

2 

2.5 

2.0 

1.5 

7 

2 

2.5 

2.5 

2.0 

8 

1 

2.5 

1.5 

1.0 

9 

5 

2.5 

2.5 

2.5 

10 

4 

2.5 

2.5 

2.5 

11 

4 

2.5 

2.5 

2.5 

12 

3 

2.5 

2.5 

2.0 

13 

3 

2.5 

2  5 

2.0 

14 

2 

2.5 

2.5 

2.0 

15 

2 

2.5 

2.5 

2.0 

16 

4 

2.5 

2.5 

2.5 

17 

3 

2.5 

2.5 

2.5 

18 

2 

2.5 

2.5 

2.0 

19 

2 

2.5 

2.5 

2.0 

20 

3 

2.5 

2.5 

2.5 

21 

2 

2.5 

2.5 

2.0 

of  the   fresh   vims   are   necessary   to   produce   an   immunity,    and   this 
shortens  and  simplifies  the  treatment  very  much. 


RABIES  45 

Harris  ^  has  shown  that  rabic  material  may  be  completely  desiccated 
without  destruction  of  virulence,  provided  the  dehydration  takes  place 
at  a  low  temperature.  The  lower  the  temperature  the  greater  will  be 
the  amount  of  virulence  preserved.  Virus  so  desiccated  contains  per 
weight  as  much  infectivity  as  the  fresh  virus.  The  loss  of  virulence 
of  the  dried  virus  is  so  slow  that  it  may  be  standardized,  permitting  an 
accuracy  of  dosage  hitherto  impossible.  The  unit  is  the  smallest  amount 
which,  when  injected  intracerebrally  into  a  full-grown  rabbit,  will  pro- 
duce paresis  on  the  seventh  day.  The  use  of  this  desiccated  virus  in  the 
prophylactic  immunization  of  anim:.]s  and  persons  offers  many  ad- 
vantages over  other  methods. 

Treatment  at  a  distance  from  a  Pasteur  institute  is  now  possible 
by  sending  a  piece  of  cord,  or  the  emulsion  in  glycerin. 

Care  During  the  Treatment. — During  the  treatment  the  patient 
may  go  about  his  usual  business.  It  is  not  necessary  to  stay  in  bed. 
The  patient  should,  however,  avoid  fatigue,  cold,  and  alcohol.  It  has 
been  shown  that  these  are  important  predisposing  factors  to  the  disease. 
It  was  found  that  customs'  officers  returning  to  the  Siberian  borders 
after  prophylactic  treatment  for  wolf  bites  showed  an  unusual  mortal- 
ity, which  seemed  to  be  due  to  exposure  to  cold.  The  disease  has  been 
observed  to  be  brought  on  after  a  cold  bath,  falling  into  the  water, 
and  similar  depressing  influences. 

Complications  of  the  Treatment.- — The  Pasteur  prophylactic  treat- 
ment may  be  complicated  by  (1)  local  reactions  or  (2)  paralysis. 

Local  reactions  at  the  site  of  the  wound  are  usually  trivial.  Ab- 
scesses almost  never  occur.  The  local  reactions  consist  of  redness  and 
induration.  Their  occurrence  increases  with  the  progress  of  the  treat- 
ment; they  are  most  frequent  in  the  second  week.  As  the  treatment  in- 
volves the  introduction  of  a  large  quantity  of  foreign  proteins  into 
the  body,  it  is  probable  that  these  reactions  represent  a  phase  of  hyper- 
susceptibility.      (See  Anaphylaxis.) 

Paralysis. — Paralysis  occasionally  occurs  and  may  be  fatal.  There 
is  doubt  concerning  the  cause  of  this  paralysis,  and  a  question  whether 
it  may  be  a  mild  or  modified  type  of  rabies,  or  a  form  of  anaphylaxis. 
In  a  case  treated  at  the  Hygienic  Laboratory  the  paralysis  came  on  18 
days  after  treatment,  and  was  transient.  The  New  York  Pasteur  In- 
stitute reports  a  death  from  "ascending  paralysis,"  which  came  on  four 
days  after  the  treatment.  W.  A.  Jones  -  reported  two  cases  with  re- 
covery. In  1905  Eemlinger,  head  of  the  Constantinople  Institute  for 
Eabies,  reported  40  cases  of  paralysis ;  Mliller  found  16  cases  in  the  liter- 
ature, and  had  two  of  his  own;  Panpoukis,  three  cases;  Jones,  2;  mak- 
ing a  total  of  63,  2  of  whom  died. 

''Jour,   of  Infect.  Bis.,   May,    1912,   X,   3,   pp.   369-377, 
?/pwr,  4.  M.  A.,  Nov.  13,  1909,  p.  1626, 


46  SPECIFIC    riJOPIIYLACTIC    MP]ASURES 

The  Immunity. — Dukation. — The  immunity  appears  two  weeks  af- 
ter tlie  treatment  and  lasts  a  varying  period  of  time,  depending  upon 
the  individual — at  least  for  several  years.  In  this  respect  it  does  not 
differ  from  other  instances  of  acquired  imnnmity.  The  fact  that  the 
immunity  appears  on  about  the  fifteenth  day  after  the  end  of  the  treat- 
ment was  discovered  by  Pasteur  as  a  result  of  animal  experimentation. 
The  statistics  of  the  Pasteur  Institute,  giving  the  mortality  from  rabies 
in  persons  following  the  prophylactic  treatment,  exclude  instances  in 
which  the  disease  develops  within  fifteen  days  after  the  end  of  the 
treatment. 

Nature. — The  nature  of  the  immunity  is  not  clear.  It  certainly 
is  not  due  to  an  antitoxin.  Immune  bodies  are  demonstrable  in  the 
blood  twenty  days  after  the  last  injection.  This  is  determined  by  mixing 
in  vitro  the  active  virus  with  the  blood  serum,  which  neutralizes  its 
activity.  Tliis  neutralization  is  generally  considered  to  be  microbicidal 
or  lytic  in  nature. 

Degree. — The  degree  of  the  immunity  also  varies,  as  is  evidenced 
by  the  fact  that  a  certain  small  percentage  of  the  persons  treated  die 
of  rabies. 

The  Results  of  the  Treatment. — Statistics  giving  the  results  of  the 
treatment  are  somewhat  difficult  to  analyze,  as  many  factors  are  unob- 
tainable. Patients  should  l)e  kept  under  observation  at  least  a  year. 
Exceptional  cases  occur  one  year  following  the  treatment.  Cases  that 
occur  witliin  fifteen  days  after  the  treatment  are  excluded  from  the 
French  statistics,  for  reasons  that  have  already  been  stated.  The  fig- 
ures on  this  basis  show  a  mortality  which  averages  about  0.5  per  cent. 
Better  results  arc  being  obtained  from  year  to  year. 

The  table  on  the  following  page  gives  the  general  results  at  Tlnstitut 
Pasteur,  Paris,  since  beginning  the  treatment. 

When  we  compare  these  figures  with  the  fact  that  from  (5  to  10  per 
cent,  and  sometimes  16.6  per  cent,  of  all  persons  bitten  by  rabid 
dogs  die  of  rabies,  the  prophylactic  value  of  the  Pasteur  treatment  is 
evident. 

Some  series  of  cases  give  a  much  higher  mortality.  Thus,  of  855 
cases  collected  by  Tordieu,  Thamehayn,  and  Bouley,  399  ended  in  death, 
or  46.6  per  cent.  In  another  series  of  cases  given  by  Bouley,  out  of 
266  persons  bitten  by  mad  dogs,  152  died  of  hydrophobia.  But  of 
these  120  were  bitten  on  the  face  and  hands^  the  greater  danger  of 
which  has  been  mentioned.  The  mortality  of  bites  from  wolves  is  placed 
at  from  GO  to  80  per  cent. 

Contraindications. — There  are  no  particular  contraindications  to  the 
treatment.  All  ages  and  conditions  should  be  treated  if  exposed.  Ap- 
parently no  harm  is  done  pregnant  women.  I  have  injected  patients 
having  malaria  without  trouble  following.     The  treatment  may  be  con- 


RABIES 

RESULTS  OF  TREATMENT  AT   L'INSTITUT   PASTEUR,   PARIS. 


47 


Year 

Persons 

Deaths 

Mortality 

1886 

2,671 

25 

0.94% 

1887 

1,770 

14 

0.79 

1888 

1,622 

9 

0.55 

1889 

1,830 

7 

0.38 

1890 

1,540 

5 

0.32 

1891 

1,559 

4 

0.25 

1892 

1,790 

4 

0.22 

1893 

1,648 

6 

0.36 

1894 

1,387 

7 

0.50 

1895 

1,520 

5 

0.38 

1896 

1,308 

4 

0.30 

1897 

1,521 

6 

0.39 

1898 

1,465 

3 

0.20 

1899 

1,614 

4 

0.25 

1900 

1,420 

4 

0.28 

1901 

1,321 

5 

0.38 

1902 

1,005 

2 

0.18 

1903 

628 

2 

0.32 

1904 

755 

3 

0.39 

1905 

727 

3 

0.41 

1906 

772 

1 

0.13 

1907 

786 

3 

0.38 

1908 

524 

1 

0.19 

1909  ■ 

467 

1 

0.21 

tinned  in  patients  having  colds,  fevers,  and  other  ailments  without  no- 
ticeable harm. 

When  to  Give  the  Pasteur  Treatment. — It  is  sometimes  dilhcult  to 
decide  whether  the  Pasteur  ^prophylactic  treatment  should  or  should 
not  be  given.  The  treatment  causes  sufficient  personal  inconvenience, 
not  to  speak  of  the  danger  (however  slight)  of  paralysis,  to  avoid  ad- 
vising it  if  unnecessary.  In  many  cases  it  is  impossible  to  discover 
whether  the  dog  which  inflicted  the  bite  is  mad  or  not.  The  rule  in 
cases  of  doubtful  exposure  is  to  advise  the  treatment. 

Persons  not  infrequently  apply  for  advice  giving  the  following  his- 
tory": They  have  not  been  bitten,  but  they  have  been  licked  on  the 
hands  and  face  by  a  dog  which  subsequently  developed  the  disease. 
Persons  are  sometimes  similarly  exposed  by  washing  the  mouth  of  a 
rabid  horse.  In  these  cases  the  important  question  is  whether  there 
were  fissures  or  abrasions  in  the  skin  at  the  time.  There  may  be  little 
wounds  in  the  skin  not  evident  to  the  naked  eye.  In  such  cases  the 
danger  is  slight,  but  in  apprehensive  subjects  the  assurance  of  protection 
which  the  treatment  affords  is  an  important  element  in  arriving  at  a 
decision. 

In  all  cases  it  is  important  to  know  whether  the  dog  is  mad  or  not. 
If  the  dog  can  be  found  and  kept  under  observation  for  10  days  and 
no  symptoms  appear,  the  Pasteur  treatment  is  not  necessary.  Animals 
killed  early  in  the  course  of  rabies  may  fail  to  show  the  miscroscopic 


48  SPECIFIC    PlJUrilY LACTIC    MEASURES 

evidence  of  the  disease,  thus  causing  an  indefinite  delay  in  diagnosis 
awaiting  inoculation  tests.  Should  symptoms  develop,  the  question  of 
diagnosis  is  all-important. 

Diagnosis  of  Rabies  in  Dogs. — The  diagnosis  of  rabies  in  dogs  may 
be  made  in  three  ways:  (1)  from  the  symptoms;  (2)  from  the  presence 
of  Negri  bodies  in  the  central  nervous  system,  and  (3)  by  animal 
inoculations. 

1.  The  syiiiptouis  may  be  very  suggestive,  but  a  diagnosis  must 
always  rest  upon  the  pathological  lesions  and  the  inoculation  tests. 
The  course  of  the  disease  may  be  divided  into  three  stages:  a  pre- 
monitory stage,  a  stage  of  excitement,  and  a  paralytic  stage.  The 
first  two  stages  may  be  absent  or  transient.  All  rabid  animals  invariably 
become  paralyzed  before  they  die.  In  dogs  the  first  symptom  consists 
solely  in  a  change  in  the  disposition  of  the  animal.  He  is  easily  ex- 
cited, but  docs  not  show  a  disposition  to  bite.  Soon  the  restlessness 
becomes  more  marked,  and  the  animal  may  become  furious  and  even 
show  signs  of  delirium.  The  animal  does  not  fear  water,  as  is  com- 
monly supposed,  but  rushes  about  attacking  every  object  in  his  way. 
Dogs  sufl'ering  from  furious  rabies  have  a  tendency  to  run  long  dis- 
tances (35  miles  or  more)  often  biting  and  inoculating  large  numbers 
of  other  animals  and  persons  en  route.  Very  soon  paralysis  sets  in, 
commencing  in  the  hind  legs,  and  finally  becomes  general.  The  course 
of  the  disease  is  always  rapid,  averaging  from  4  to  5  days,  rarely  exceed- 
ing 10  days.  When  the  stage  of  excitement  is  brief  or  absent,  the  disease 
is  known  as  dumb  rabies.  This  is  the  prevailing  type  in  Turkey.  This 
explains  the  relative  rarity  of  rabies  in  man  in  Turkey,  where  dogs 
abound. 

2.  There  is  a  difference  of  opinion  concerning  the  significance  of 
the  Negri  bodies  {Neuroryctes  hydrophohioe) ,  which,  however,  are  very 
constant  in  rabies  and  peculiar  to  it.  If  Negri  bodies  are  found  in 
the  dog,  the  Pasteur  treatment  should  be  started  at  once.  The  absence 
of  Negri  bodies,  however,  does  not  necessarily  mean  the  absence  of 
rabies.  These  bodies  are  sometimes  difficult  to  find,  or  may  not  be 
present  in  the  parts  of  the  central  nervous  system  which  are  examined. 
Negri  bodies  for  diagnostic  purposes  may  best  be  demonstrated  by  im- 
pression preparations  stained  according  to  Van  Gieson,  as  recommended 
by  L.  Frothingham;  or  smears  stained  by  the  Mallory  eosin-metliylene- 
blue  method  recommended  by  Williams  and  Lowden.  Smears  are 
prepared  by  crushing  a  small  portion  of  the  brain  matter  between  two 
slides;  portions  are  selected  from  Ammon's  horn  and  also  from  the 
cerebellum,  cerebral  cortex,  and  medulla.  These  smears  are  then  fixed 
and  stained  as  follows: 

(a)  Zenker's  solution  for  15  minutes. 

(b)  Wash  in  tap  water. 


THE   VENEEEAL   DISEASES  49 

(c)  Ninety-five  per  cent,  alcohol  tinted  with  iodin. 

(d)  Absolute  alcohol  five  minutes. 

(e)  Five  to  ten  per  cent,  watery  solution  of  eosin  (Griibler  W.  g.) 
five  minutes. 

(f)  Stain  in  Unna's  polychrome  methylene  blue  two  to  three  min- 
utes. 

(g)  Wash  in  water. 

(h)   Differentiate  in  ninety-five  per  cent,  alcohol. 

(i)   Blot  off,   dry,  and  examine  with  oil   immersion  lens. 

The  lesions  of  Van  Gehuchten  and  Nelis,  described  in  1900,  are  the 
most  characteristic  anatomical  changes.  These  lesions  are  found  in  the 
peripheral  ganglia  of  the  cerebrospinal  and  sympathetic  systems,  espe- 
cially in  the  plexiform  ganglia  of  the  pneumogastric  nerve,  and  also  the 
Gasserian  ganglia.  The  normal  nerve  cells  of  these  ganglia  lie  in  a 
capsule  lined  with  a  single  layer  of  endothelial  cells.  In  rabies  these 
endothelial  cells  proliferate  and  the  nerve  cells  are  pushed  aside  and 
even  destroyed.     The  ganglion  may  finally  contain  only  round  cells. 

3.  The  final  diagnosis  of  rabies  rests  upon  animal  experimenta- 
tion. A  small  quantity  of  the  suspected  material  is  placed  under  the 
dura  mater  of  a  rabbit  or  guinea-pig.  The  diagnosis  by  this  method, 
however,  requires  so  much  time  (on  acco^mt  of  the  long  period  of  in- 
cubation of  the  disease)  that  it  is  of  no  practical  value  in  deciding 
whether  or  not  the  Pasteur  prophylactic  treatment  should  be  given,  but 
in  any  critical  case  the  positive  evidence  furnished  by  animal  experi- 
mentation is  incontrovertible. 


THE    VENEREAL    DISEASES 

As  a  danger  to  the  public  health,  as  a  peril  to  the  family,  and  as  a 
menace  to  the  vitality,  health,  and  physical  progress  of  the  race,  the 
venereal  diseases  are  justly  regarded  as  the  greatest  of  modern  plagues, 
and  their  prophylaxis  the  most  pressing  problem  of  preventive  medicine 
that  confronts  us  at  the  present  day. 

There  are  three  venereal  diseases :  syphilis,  gonorrhea,  and  chancroid. 
In  order  to  have  a  clear  understanding  of  the  problems  of  venereal 
prophylaxis  it  is  necessary  to  have  a  knowledge  of  the  essential  features 
of  these  preventable  infections.  Two  of  them,  syphilis  and  gonorrhea, 
are  of  great  importance,  because  they  are  very  prevalent  and  because 
they  are  very  serious  infections  with  grave  consequences. 


50  SPECIAL    PROPHYLACTIC    MEASURES 


SYPHILIS 

Thero  are  many  ptrikiiif;  tilings  almiit  syphilis,  but  nothing  so  strik- 
ing as  its  persistence  in  spite  of  knowledge  complete  enough  to  stamp 
it  out  and  in  view  of  the  popular  dread  in  which  the  disease  is  held. 
It  is  prevental)le,  even  cural)lc — yet  scarcely  another  disease  equals  it 
in  the  extent  and  intensity  of  its  ravages. 

Syphilis  is  a  good  illustration  of  the  fact  that  it  is  much  more  diffi- 
cult to  control  a  disease  transmitted  directly  from  man  to  man  than  a 
disease  transmitted  hy  an  intermediate  host,  or  one  in  which  the  infective 
principle  is  transferred  through  our  environment.  We  have  a  certain 
amount  of  control  over  our  surroundings,  and  we  have  dominion  over 
the  lower  ani nulls,  but  the  control  of  num  requires  the  consent  of  the 
governed. 

Civilization  and  syphilization  have  been  close  companions,  hut  syph- 
ilis is  now  less  prevalent  among  civilized  than  uncivilized  peoples — this 
is  promising.  Civilization,  however,  should  not  be  content  until  it  has 
controlled  syphilis  as  effectively  as  it  has  a  few  other  preventable  in- 
fections.    The  effort  to  do  so,  at  least,  must  be  persistent  and  sincere. 

From  the  economic  side,  syphilis  is  not  a  serious  disease  in  its  pri- 
mary and  secondary  stages;  that  is,  persons  with  syphilis  during  the 
early  stages  are  usually  not  ill  enough  to  cease  work.  Acutely  fatal 
cases,  such  as  frequently  occurred  in  the  sixteenth  century,  are  now 
rare;  in  other  words,  the  disease  has  lost  much  of  its  early  virulence. 
It  is  the  late  numifestations,  the  sequelae  and  the  so-called  parasyph- 
ilitic  lesions,  as  well  as  the  inherited  consequences  of  the  disease,  that 
cause  great  economic  loss.  About  one-fifth  of  all  the  insane  in  our 
asylums  are  eases  of  general  paresis ;  90  per  cent,  of  these  give  the 
Wassermann  reaction.  Syphilis,  alcohol,  and  heredity  fill  our  insane 
asylums. 

The  consequences  of  syphilis  are  often  more  severe  upon  the  off- 
spring than  upon  the  syphilitic  parent.  The  infection  itself,  or  various 
defects,  especially  of  the  nervous  system,  resulting  from  the  consequences 
of  syi)hilis,  may  l)e  transmitted  from  parent  to  child,  often  with  fatal 
results.    When  death  does  not  ensue  the  results  may  be  still  more  tragic. 

Syphilis  is  an  infection  caused  by  the  Treponema  pallidum  (formerly 
known  as  the  SpirocJiceta  pallida).  It  is  a  communicable  disease  ac- 
quired by  direct  contact  with  infected  persons  or  things.  It  runs  a 
chronic  course  with  local  and  general  manifestations,  usually  divided 
into  three  stages,  which  are  not  always  well  defined.  The  primary 
stage  consists  of  the  chancre  which  forms  at  the  site  of  the  initial  in- 
fection. The  chancre  is  a  hard  indurated  ulcer  in  the  skin  or  mucous 
membrane,   and  appears  about  three  weeks   (not  less  than  ten   days) 


THE    VENEEEAL   DISEASES  51 

after  the  receipt  of  the  infection.  The  secondary  stage  is  characterized 
by  a  general  invasion  of  the  spirochete  throughout  the  system,  as  in- 
dicated by  a  general  involvement  of  the  lymph  nodes,  eruptions  upon  the 
skin  and  mucous  membranes,  fever,  anemia,  and  other  indications  of 
a  generalized  infection.  The  third  stage  is  characterized  by  a  localized 
granulomatous  growth  known  as  a  gumma.  Gummata  may  appear  in 
almost  any  tissue  or  organ  of  the  body.  A  fourth  stage  is  sometimes 
added  to  the  picture,  consisting  of  the  sequela  or  parasyphilitic  phe- 
nomena, such  as  general  paresis,  arteriosclerosis,  locomotor  ataxia,  an- 
eurysm, etc. 

The  health  officer  should  regard  syphilis  just  as  he  does  the  acute 
febrile  exanthematous  diseases.  Because  syphilis  runs  a  slow  and  often 
chronic  course  witli  mild  constitutional  symptoms  during  its  early 
stages,  it  is  often  placed  in  a  class  by  itself.  This  is  a  mistake.  Syph- 
ilis has  its  period  of  incubation,  eruption,  and  decline,  just  as  measles 
and  smallpox  have. 

There  is  no  natural  immunity  to  syphilis ;  all  are  susceptible,  hut  the 
severity  of  individual  cases  varies  greatly.  This  is  due  either  to  the 
virulence  of  the  strain,  the  amount  of  the  infection,  or  to  variation  in 
individual  resistance.  The  disease  is  now  much  less  severe  than  it  was 
following  the  pandemic  which  spread  over  the  civilized  world  after  1494, 
when  the  army  of  Charles  VIII,  32,000  strong,  started  out  to  conquer 
the  Italian  peninsula. 

One  attack  of  sj^philis  confers  an  immunity,  in  that  reinfections  do 
not  produce  another  chancre.  ,  That  is,  the  virus  cannot  be  inoculated 
upon  a  person  who  has  or  has  had  the  disease.  The  immunity  is  pe- 
culiar in  that,  while  the  person  cannot  have  a  second  chancre,  this  fact 
has  no  influence  upon  the  development  of  the  secondary  and  tertiary 
lesions  resulting  from  the  first  infection.  For  CoUes'  and  Profeta's 
laws  of  syphilitic  immunity  and  the  transmission  of  syphilis  see 
page  447. 

In  a  large  majority  of  all  cases  of  syphilis  the  infection  is  trans- 
mitted during  sexual  approach.  It  is,  therefore,  spoken  of  as  a  venereal 
disease;  many  cases,  however,  are  contracted  out  of  venery.  These  ac- 
cidental infections  are  more  common  than  is  ordinarily  supposed. 
Metchnikoff  reports  that  a  great  number  of  cases  of  non-venereal  syph- 
ilis occur  among  children  in  Eussia,  where  the  peasants  live  huddled 
together  and  in  ignorance.  Syphilis  may  be  passed  from  one  person  to 
another  by  kissing,  and  the  danger  is  greater  when  there  are  mucous 
patches  or  other  open  lesions  upon  the  mouth.  The  disease  may  also 
be  transmitted  in  wounds  inflicted  by  the  teeth  of  syphilitics.  In  sur- 
gery and  midwifery  practice  physicians  are  not  infrequently  infected 
through  minute  abrasions — a  pin  prick  or  a  scratch  from  a  scalpel  is 
sufficient  to  introduce  the  virus.     Midwifery  chancres  are  usually  upon 


52  SPECIAL    PROPHYLACTIC    MEASURES 

the  fingers.  Chancre  of  the  lip  is  the  most  common  of  the  erratic  or 
extragenital  forms,  and  may  be  acquired  in  many  ways  apart  from  direct 
infection,  such  as  the  use  of  spoons,  glasses,  pipes,  etc.,  which  have 
recently  been  mouthed  by  a  syphilitic.  The  virus  may  also  be  trans- 
mitted by  towels,  clothing,  razors,  handkerchiefs,  surgical  and  dental 
instruments,  human  vaccine  virus,  etc.  The  list  of  articles  that  have 
conveyed  the  contagium  is  comprehensive.  The  Treponema  pallidum  is 
a  fragile  organism  and  soon  dies  upon  fomites,  but  the  infection  is  suffi- 
ciently prevalent  and  the  danger  sufficiently  real  to  demand  care. 
Chancres  of  the  mouth  and  on  the  tonsils  result,  as  a  rule,  from  per- 
verted practices.  Wet  nurses  are  sometimes  infected  on  the  nipple,  and 
it  occasionally  happens  that  the  relatives  of  a  syphilitic  child  are  acci- 
dentally infected.  The  hereditary  and  congenital  transmission  of  syph- 
ilis is  discussed  on  page  446. 

Syphilis  lowers  the  standard  of  health  and  paves  the  way  for  other 
diseases.  Wliatever  the  etiological  relationsliip  may  be,  it  is  definitely 
known  that  syphilitics  are  prone  to  die  early  from  affections  of  the  heart 
and  vessels,  general  paresis,  diseases  of  the  central  nervous  system  (loco- 
motor ataxia),  chronic  nephritis,  arteriosclerosis,  aneurysm,  etc.  The 
actuaries  of  all  life  insurance  companies  know  that  the  morbidity  and 
mortality  rates  among  syphilitics  are  very  much  higher  than  that  of  any 
other  class  of  individuals  of  the  community  who  enjoy  apparent  good 
health  at  the  time  of  examination. 

ilost  insurance  companies  refuse  to  accept  syphilitics  at  all.  Some 
companies  require  extra  premiums  to  compensate  for  the  extra  risks;  a 
few  companies  will  accept  exceptionally  favorable  cases  who  have  had 
a  thorough  course  of  treatment,  and  who  have  shown  no  symptoms  for 
3  to  5  years,  but  under  these  circumstances  only  special  policies  are 
contracted  for  which  do  not  keep  the  applicant  on  the  companies'  books 
after  55  years  of  age. 

Syphilis  was  regarded  as  an  infection  peculiar  to  man  until  Xicolle 
and  Hamonic  in  1902,  and  Metchnikoff  and  Roux  in  1903,  transmitted 
the  disease  to  the  higher  apes.  As  a  result  of  these  experiments  cer- 
tain important  facts  in  reference  to  prophylaxis  were  discovered.  ^Metch- 
nikoff  and  Roux  found  that  bichlorid  of  mercury,  1-2.000,  applied  one 
hour  after  inoculation,  does  not  prevent  the  development  of  the  pri- 
mary lesion  in  the  monkey.  This  is  probably  due  to  the  fact  that  the 
action  of  the  bichlorid  is  limited  to  the  surface;  it  lacks  penetration 
owing  to  its  well-known  property  of  coagulating  albumin.  Other  anti- 
septics were  tested,  but  in  a  long  series  of  experiments,  carried  out  on 
chimpanzees,  baboons,  and  Macacus  monkeys,  Metchnikoff  and  Roux 
showed  that  mercurial  inunctions  are  most  successful  in  preventing  the 
development  of  the  chancre.  The  mercurial  inunctions  may  be  made 
with   metallic  mercury,  calomel,   white   precipitate    (aramoniated   mer- 


THE    VENEEEAL    DISEASES  53 

cur}^),  or  salicyl-arsenite  of  mercury.  Calomel  ointment  appears  to  be 
the  best,  and  is  the  one  now  generally  used.  It  is  rubbed  up  in  lanolin 
in  the  proportions  of  1  to  3  or  1  to  4.  The  ointment  should  be  rubbed 
upon  the  place  for  4  to  5  minutes  and  not  later  than  20  hours  after 
the  receipt  of  the  infection.  This  will  usually  prevent  the  development 
of  the  disease.  Excision,  or  destruction  of  the  chancre  with  the  actual 
cautery  or  with  corrosive  antiseptics  does  not  influence  the  development 
of  the  disease. 

GONOBRHEA 

Gonorrhea  is  much  more  prevalent  than  syphilis,  and  common  opin- 
ion regards  it  as  a  comparatively  trivial  infection,  that  is,  "no  worse 
than  an  ordinary  cold."  As  a  matter  of  fact,  gonorrhea  is  one  of  the 
serious  infectious  diseases,  and  the  gonococcus  occupies  a  position  of 
high  rank  among  the  virulent  pathogenic  microorganisms.  From  an 
economic  and  public  health  standpoint,  gonorrhea  does  not  fall  very 
far  short  of  syphilis  in  importance;  in  fact,  some  give  it  first  place. 

The  serious  consequences  of  gonorrhea  are:  complications  such  as 
periurethral  abscess,  gonorrheal  prostatitis  in  the  male,  and  vaginitis, 
endocervicitis,  and  inflammation  of  the  glands  of  Bartholini  in  the  fe- 
male. Perhaps  the  most  serious  of  all  the  sequelse  of  gonorrhea  are 
those  which  result  from  the  spread  by  direct  continuity  of  tissues,  such 
as  inflammation  of  the  Fallopian  tube,  and  sometimes  of  the  endomet- 
rium, the  ovar}',  or  even  the  peritoneum.  The  gonococcus  has  been 
found  in  pure  culture  in  cases  of  acute  general  peritonitis.  Other  in- 
flammations caused  by  the  spread  of  the  infection  are  cystitis,  which 
sometimes  extends  upward  through  the  ureters  to  the  kidneys. 

The  gonococcus  sometimes  invades  the  blood  and  produces  a  general 
septicemia  and  pyemia ;  death  may  occur  from  acute  endocarditis.  Gon- 
orrheal arthritis  is,  in  many  respects,  the  most  damaging,  disabling, 
and  serious  of  all  the  complications  of  gonorrhea.  It  may  even  follow 
ophthalmia  neonatorum.  It  is  more  frequent  in  males  than  in  females, 
but  a  gonorrheal  arthritis  of  great  intensity  may  occur  in  a  newly  mar- 
ried woman  infected  by  an  old  gleet  in  her  husband  (Osier).  The 
serious  nature  of  gonorrheal  complications  in  the  eye  will  be  considered 
separately  under  Ophthalmia  Xeonatorum.  Gynecologists  tell  us  that 
the  greater  part  of  their  practice  is  made  up  of  the  consequences  of 
gonorrhea. 

Sterility  is  one  of  the  serious  consecjuences  of  gonorrhea.  This 
may  be  caused  in  the  male  through  epididvmitis,  which  is  a  very  com- 
mon complication,  and  in  the  female  by  salpingitis,  which  closes  or  ob- 
structs the  Fallopian  tube.  Stricture  of  the  urethra  in  the  male  is  a 
frequent  sequel. 


54  SPECIAL    PROPHYLACTIC    MEASURES 

Gonorrhea  is  usually  transmitted  by  sexual  congress;  however,  ac- 
cidental or  innocent  infections  are  not  infrequent.  Paul  Bendig  '  reports 
the  following  instance :  Of  40  girls  sent  for  convalescence  to  a  brine 
bath,  15  showed  signs  of  gonorrhea  after  tlie  return.  The  infection 
came  from  an  eight-year-old  girl,  who  apparently  had  been  suffering 
from  gonorrhea  for  several  years,  and  was  spread  through  indiscriminate 
batliing  in  one  bath  tub  and  the  use  of  the  same  bath  towel. 

Gonorrheal  infections  in  children  require  special  consideration.  The 
frequency  of  such  infections  may  be  judged  from  the  observations  of 
Pollack,  who  reports  187  cases  treated  in  the  Woman's  Venereal  De- 
partment of  Johns  Hopkins  Hospital  during  the  year  1909.'  Pollack 
estimates  that  800  to  1,000  children  are  infected  each  year  in  Balti- 
more, and  that  the  same  proportion  probably  holds  good  for  other  cities. 
The  cause  of  the  frequent  infection  among  children  is  in  part  the  su- 
perstition that  a  person  infected-  with  syphilis  or  gonorrhea  may  get 
rid  of  it  by  infecting  another — especially  a  virgin. 

When  gonorrhea  enters  a  children's  hospital  or  an  infants'  home  it 
is  prone  to  become  epidemic  and  is  very  difficult  to  eradicate.  The 
story  of  the  infection  in  the  Babies'  Hospital,  Xew  York,  for  eleven 
years,  as  told  by  Holt,^  illustrates  the  singular  obstinacy  of  the  infec- 
tion. In  spite  of  the  greatest  care  and  precaution,  there  were,  in  1903, 
65  cases  of  vaginitis  with  2  of  ophthalmia  and  12  of  arthritis.  In 
1904  there  were  52  cases  of  vaginitis,  only  IG  of  which  would  have 
been  recognized  without  the  bacteriological  examination.  In  all.  in 
the  eleven  years,  there  were  273  cases  of  vaginitis;  6  with  ophthalmia 
and  26  with  arthritis.  Holt  urges  isolation  and  prolonged  quarantine 
as  the  only  measures  to  combat  successfully  the  disease  (Osier).  It  is 
impossible  to  control  such  epidemics  without  bacteriological  diagnosis. 

Chancroid  is  not  discussed  separately  because  its  prevention  is  sim- 
ilar to  the  measures  used  against  syphilis  and  gonorrliea.  Chancroid 
sometimes  directly  results  in  severe,  even  fatal,  results,  but  does  not,  as 
a  rule,  leave  dangerous  sequelae. 

VENEREAL    PROPHYLAXIS    AND    HYGIENE    OF    SEX 

The  same  principles  apply  to  the  prevention  of  the  venereal  diseases 
as  apply  to  the  prevention  of  other  communicable  diseases.  The  fight 
against  venereal  diseases,  however,  is  especially  complicated  and  difficult 
because  of  the  close  association  with  prostitution,  the  problems  of  sex 
hygiene,  and  alcoholism — in  fact,  the  question  pervades  the  woof  and 

'  M-iinchener  med.   Wochenschr.,   1909,  p.   1846. 
''Johns  Hopkins  Hospital  Bulletin,  May,  1909,  p.  142. 
^  New  York  Med.  Jour.,  March,  1905. 


VENEEEAL    PEOPHYLAXIS    AND    SEX    HYGIENE       55 

warp  of  society.  There  are  three  primitive  appetites  of  man — hunger, 
thirst,  and  the  sexual  appetite.  The  first  two  persist  throughout  life; 
the  last  comes  on  at  puberty,  grows  stronger  during  adolescence,  and 
wanes  with  age.  Any  program  for  the  control  of  the  venereal  diseases 
or  the  hygiene  of  sex  must  take  into  account  the  fact  that  we  are  deal- 
ing with  a  primal,  impulsive,  and  natural  passion  which  is  the  greatest 
force  for  social  good,  when  used  in  accordance  with  the  laws  of  nature, 
but  may  result  in  dire  consequences  when  these  laws  are  transgressed. 
The  venereal  diseases  are  among  the  most  widespread  and  universal  of 
all  human  ills,  and  enter  more  largely  in  the  making  and  marring  of 
domestic  happiness  than  any  other  disease  known  to  man.  The  diffi- 
culties of  the  situation  should  not  deter  the  health  officer  and  all  those 
who  labor  for  social  uplift,  for  there  is  no  more  pressing  j^roblem  in 
preventive  medicine. 

Attitude. — Our  attitude  toward  the  venereal  diseases  is  very  incon- 
sistent. There  is  a  natural  aversion  toward  these  afflictions.  The  sani- 
tarian should  make  no  distinction  between  the  venereal  diseases  and 
other  epidemic  diseases;  he  should  regard  the  greatpox  in  the  same 
light  that  he  regards  the  smallpox.  The  principles  for  the  control  of 
syphilis  and  gonorrhea  differ  in  no  wise  from  those  used  to  control 
smallpox,  leprosy,  tuberculosis,  measles,  diphtheria,  etc.  The  health 
officer  must  not  regard  venereal  disease  as  a  punishment  for  sin  and 
crime — the  victim  or  culprit  needs  heljD  and  sympathy.  The  immediate 
problem  is  the  prevention  of  further  spread  of  the  infection.  A  person 
afflicted  with  a  venereal  disease  should  be  treated  in  the  same  humane 
spirit  that  actuates  the  physician  in  other  diseases.  Eurthermore,  the 
interests  of  the  community  require  that  the  patient  be  accorded  the  best 
possible  care  and  attention.  The  usual  attitude  toward  the  venereal 
diseases  may  well  startle  us  when  we  consider  that  in  most  of  our  large 
cities  no  hospital  will  take  a  case  of  syphilis  or  gonorrhea  during  the 
acute  stages,  when  these  diseases  are  especially  communicable.  Morrow 
holds  that  the  notoriously  inadequate  provision  made  for  the  reception 
and  treatment  of  venereal  patients  is  a  disgrace  to  our  civilization. 
Formerly  lepers  were  segregated  in  vile  lazarettos  and  cases  of  smallpox 
isolated  in  horrible  pest  houses;  now  we  have  comfortable  and  congenial 
isolation  wards  or  special  sanatoria  for  these  diseases.  From  the  stand- 
point of  prevention  suitable  hospital  accommodations  should  be  provided 
for  the  venereal  diseases. 

Education. — Education  in  sex  hygiene  and  the  venereal  peril  accom- 
plishes a  certain  amount  of  good.  It  may  be  questioned  how  much  a 
knowledge  of  the  consequences  will  prevent  some  persons  committing 
crime.  However,  the  old-style  innocence  must  be  regarded  as  present- 
day  ignorance.  Every  boy  and  girl,  before  reaching  the  age  of  pu- 
berty, should  have  a  knowledge  of  sex,  and  every  man  and  woman  be- 


56  SrECIAL    PROrHYLACTIC    MEASURES 

fore  the  marriageable  age  should  he  informed  on  tlie  suhject  of  repro- 
duction and  tlie  dangers  of  venereal  diseases.  Superficial  information 
is  not  true  education.  On  the  other  hand,  it  is  a  mistake  to  dwell  un- 
duly upon  the  subject,  for  in  many  instances  the  imagination  and 
passion  of  youth  are  inflamed  by  simply  calling  attention  to  the  sub- 
ject. One  of  the  ol)jects  of  cducatiou  is  to  avoid  the  dangers  of  sex 
impurities,  and  all  agree  that  this  may  often  best  be  accomplished  by 
keeping  the  mind  clean,  that  is,  away  from  the  subject.  The  education 
must,  therefore,  be  clear,  ])ointed,  brief,  and  direct.  The  object  of 
education  is  not  alone  to  help  the  individual  to  help  himself,  l)ut  to 
influence  necessary  legislation  and  concerted  public  action ;  also  to  les- 
sen the  influence  of  quacks.  A  simple  knowledge  of  the  facts  is  a  suffi- 
cient deterrent  for  some;  others  may  be  influenced  through  fear  of 
the  consequences. 

In  general,  it  may  be  said  that  the  best  plan  of  education  in  mat- 
ters sexual  is  to  answer  the  questions  of  children  upon  the  subject  of 
maternity  frankly  and  truthfully,  but  to  offer  them  no  information  on 
the  subject.  The  growing  child  at  the  age  of  puberty  shoidd  be  offered 
a  certain  amount  of  information  concerning  unnatural  habits  and  should 
study  physiology,  biology,  especially  botan}',  and  the  facts  of  fertiliza- 
tion. At  about  the  age  of  sixteen  or  eighteen  girls  as  well  as  boys 
should  be  instructed  as  to  the  venereal  peril.  The  pamphlets  issued 
by  the  Committee  on  Sex  Hygiene  of  the  Massachusetts  Association  of 
Boards  of  Health  are  admirable.  One  circular  is  for  young  uu'n,  an- 
other for  young  women,  and  a  third  for  those  having  venereal  disease. 

Some  of  the  facts  all  young  men  should  know  are:  that  the  true 
purpose  of  the  sex  function  is  reproduction  and  not  s^ensual  ])lcasure; 
that  the  testicles  have  a  twofold  function,  (a)  reproduction  and  (b)  to 
supply  force  and  energy  to  other  organs  of  the  body;  that  occasional 
seminal  emissions  at  night  are  evidences  of  normal  physiological  activ- 
ity; that  sexual  intercourse  is  not  essential  to  the  preservation  of  virility; 
that  chastity  is  compatible  with  health;  and  that  the  sex  instinct  in 
man  may  be  controlled. 

The  primary  function  of  the  testicles  is  to  build  the  boy  into  the 
man.  Castration  in  early  life,  as  in  the  case  of  eunuchs,  results  in 
a  loss  of  the  internal  secretion  of  the  testicles  and  a  failure  in  develop- 
ment of  the  secondary  sexual  characters  which  distinguish  the  male. 
There  are  an  alteration  in  physical  conformation  and  in  the  voice,  lack 
of  beard,  development  of  the  mamma,  etc. — in  other  words,  an  ap- 
proach to  the  feminine  type.  Healthy  sexuality  stimulates  the  imagina- 
tion, sentiment,  the  esthetic  sense,  and  the  higher  creative  functions. 
Excesses  or  any  influence  which  weakens  the  sexual  system  impair  the 
will  power,  influence  self-respect,  and  diminish  mental  force.  Experi- 
ence shows  that  arduous  physical  and  mental  labor,  even  after  maturity 


VEIsTEEEAL    PBOPHYLAXIS    AND    SEX    HYGIENE       57 

is  attained,  is  best  performed  when  the  sex  organs  are  not  exercised; 
while  sexual  excess  distinctly  impairs  muscular  strength  and  mental 
efficiency.  It  is  unwise  to  frighten  boys  by  exaggerating  the  results  of 
self-abuse,  which  is  rather  the  effect  and  not  the  cause  of  idiocy,  insanity, 
degeneracy,  and  other  defects  of  the  central  nervous  organization.  Self- 
abuse  is  no  worse  in  its  effects  than  natural  coitus,  except  for  its  influ- 
ence upon  character.  Both  are  alike  harmful  when  indulged  in  to 
excess. 

Eegistration  of  Cases.— It  is  not  possible  to  control  any  communi- 
cable disease,  especially  one  that  is  pandemic,  such  as  syphilis  or  gonor- 
rhea, without  a  knowledge  of  the  cases  and  deaths.  It  is  perhaps  even 
more  imjoortant  to  collect  morbidity  and  mortality  statistics  of  the  great- 
pox  than  it  is  of  the  smallpox.  But  the  public  registration  of  private 
disease  at  once  defeats  its  own  object.  Compulsory  methods  have  here- 
tofore failed,  and  little  may  be  expected  from  voluntary  registration. 
When  we  consider  that  in  our  country  we  have  no  means  of  knowing 
the  amount  and  distribution  of  smallpox,  except  to  a  limited  degree  in 
the  registration  area  (which  is  less  than  one-third  of  our  domain),  what 
can  we  expect  from  the  registration  of  the  closely  guarded  secrets  of 
the  underworld  ?  The  public  registratian  of  ophthalmia  neonatorum  is 
successful  because  this  form  of  gonorrhea  is  so  apparent  and  the  con- 
sequences so  immediate  and  serious.  The  difficulties,  however,  need  not 
deter  us,  and  registration  should  be  attempted  even  though  the  returns 
are  incomplete.  A  start  should  be  made,  and,  though  the  returns 
will  be  only  partial  at  first,  a  gradual  improvement  may  be  ex- 
pected. Every  case  known  and  properly  cared  for  is  a  focus  of  infection 
neutralized. 

Continence. — One  of  the  important  facts  to  teach  boys  is  that  con- 
tinence is  compatible  with  health.  The  testicles  are  like  the  tear  glands 
and  the  sweat  glands,  in  that  they  do  not  atrophy  with  disuse.  Ben- 
jamin Franklin  taught,  as  many  another  man  of  influence  believes  to- 
day, that  the  exercise  of  the  sexual  functions  is  necessary  for  health. 
This  is  a  mistake  and  has  done  much  harm. 

The  sex  principle  is  universal  in  nature.  It  is  the  force  behind 
the  constructive  and  progressive  processes  of  all  life,  from  the  color 
adaptations  of  birds  and  flowers  to  the  highest  leadership  in  men.  Ee- 
production  is  only  one  of  its  many  functions;  and  the  man  who  as- 
sumes that  the  so-called  physical  desire  that  at  times  thrills  him  indi- 
cates a  need  of  sexual  intercourse  is  in  danger  of  depleting  and  wasting 
from  his  life  a  chief  source  of  physical  and  mental  growth. 

The  single  standard  for  men  and  women  must  be  insisted  upon,  and 
the  parent  or  guardian  is  justified  in  demanding  a  clean  bill  of  health 
of  the  3"oung  man  who  proposes  marriage.  The  young  man,  in  turn,  is 
entitled  to  the  same  from  his  prospective  father-in-law.     One  of  the 


58  SPECIAL    r  I  ;u  PHY  LACTIC    MEASURES 

defects  of  our  artiiicial  civilization  wliich  leads  to  harm  is  the  post- 
ponement of  the  marriage  age. 

Carnal  lust  may  be  cooled  and  quelled  bv  hard  work  of  the  body, 
as  well  as  attention  to  personal  hygiene — hence,  one  of  the  great  ad- 
vantages of  athletic  sports  for  growing  young  men. 

Personal  Hygiene. — Idleness,  stimulating  food,  overeating,  impure 
thought.-,  evil  associates,  and  alcohol  excite  the  passions  and  are  the  bed- 
fellows of  the  venereal  diseases.  Purity  of  mind  and  cleanliness  of 
body  are  heljjful  prophylactics.  Physical  exercise  and  an  out-of-door  life 
divert  the  mind  and  help  the  body;  it  is  a  good  safety  valve  for  the 
excess  animalism  of  youth. 

The  public  should  be  taught  the  necessity  for  thorough  daily  cleans- 
ing of  the  external  genitals  in  both  sexes,  even  in  children.  The  large 
number  of  secreting  glands  and  the  decomposition  of  their  secretions 
are  liable  to  induce  irritation  and  even  minute  lesions  which  open 
portals  to  infection  of  all  kinds. 

Alcohol. — The  strongest  indictment  against  alcohol  is  that  it  excites 
the  passions  and  at  the  same  time  diminishes  the  will  power.  The  fact 
that  alcohol  lowers  moral  tone  does  much  more  harm  than  all  the 
cirrhotic  livers,  hardened  arteries,  shrunken  kidneys,  inflamed  stomachs, 
and  other  lesions  believed  to  be  caused  by  its  excessive  use. 

Prostitution. — The  regulation  of  prostitution  by  means  of  medical 
inspection  has  been  tried  and  largely  abandoned.  In  other  words,  it  is 
a  failure,  for  the  reason  that  it  makes  vice  easy  and  is,  therefore,  morally 
wrong.  It  gives  a  false  sense  of  security  and  does  not  reach  clandestine 
prostitution,  which  is  the  great  source  of  the  venereal  diseases.  Under 
certain  limited  conditions,  such  as  in  army  encampments,  where  clan- 
destine prostitution  can  be  eliminated,  regulation  has  markedly  dimin- 
ished the  prevalence  of  venereal  disease. 

The  elimination  of  prostitution  is  bcA'ond  the  dream  of  even  the 
theoretical  reformer.  Its  control  resolves  itself  into  questions  of  per- 
sonal hygiene  and  public  hygiene;  it  is  inextricably  mixed  up  with  alco- 
holism, and,  like  the  abuse  of  alcohol,  the  question  may  best  be  reached 
by  that  slower,  surer  process  of  improving  the  moral  and  physical  fiber 
of  man. 

Medical  Prophylaxis. — In  accordance  with  the  researches  of  Metch- 
nikoff  and  IJoux  a  reasonably  efficient  prophylaxis  against  the  venereal 
diseases  is  now  possible.  In  the  United  States  Navy  the  following 
method  is  employed :  The  entire  penis  is  scrubbed  with  liquid  soap  and 
water  for  several  minutes,  and  then  washed  well  with  a  solution  of 
mercuric  bichlorid,  1  to  2,000  in  strength.  If  there  are  any  abrasions 
present,  they  are  sprayed  with  hydrogen  peroxid  from  a  hand  atomizer. 
The  man  is  then  placed  in  a  sitting  position,  well  forward  in  a  chair 
in  front  of  a  convenient  receptacle,  and  given  two  injections  of  a  10 


YEXEEEAL    PEOPHYLAXIS    AXD    SEX    HYGIEXE       59 

per  cent,  solution  of  argyrol.  He  is  required  to  retain  each  injection 
in  the  urethra  for  five  minutes.  After  taking  the  injections^  the  entire 
penis  is  thoroughlj'-  anointed  with  a  33  per  cent,  calomel  ointment.  He 
is  told  not  to  urinate  for  at  least  two  hours,  and  to  allow  the  ointment 
to  remain  on  the  penis  for  some  hours.  A  temporary  dressing  is  placed 
on  the  parts  to  protect  his  clothes. 

The  measures  which  will  prevent  gonorrhea  will  not  ward  off  syphilis, 
and  vice  versa. 

The  results  attending  such  prophylactic  treatment  are  very  good. 
Thus  Ledbetter  ^  reports  that  at  Cavite,  before  medical  prophylaxis 
was  instituted,  the  percentage  of  venereal  diseases  of  all  classes  among 
the  men  averaged  from  25  to  30  per  cent,  annually,  and  at  times  even 
higher.  The  percentage  of  gonorrhea  was  reduced  to  8  per  cent,  annu- 
ally, and  this  percentage  included  about  30  patients  who  did  not  report 
for  treatment.  Chancroid  was  reduced  from  5  to  2  per  cent.,  which 
included  2  patients  not  reporting  for  treatment.  Syphilis  has  been  re- 
duced from  about  20  cases  annually  to  one  case  for  the  entire  year 
1910,  and  this  patient  did  not  report  for  proph5dactic  treatment.  The 
results  speak  for  themselves  and  show  the  efficiency  of  the  prophylactic 
measures  if  properly  and  thoroughly  carried  out. 

Holcomb  and  Gather  -  report  the  following  as  a  result  of  treatment 
used  by  them  in  3,268  persons  in  the  U.  S.  Navy  between  May  1,  1910, 
and  August  31,  1911.  The  experience  is  considered  to  be  a  fair  index 
of  the  results  of  medical  prophylaxis.  The  treatment  used  by  them 
is  as  follows  :  ( 1 )  Wash  the  penis,  head,  shank,  and  under  f renum  with 
1-5,000  bichlorid  of  mercury  solution  with  a  cotton  sponge.  (2)  Pass 
water.  Take  urethral  injection  of  2  per  cent,  protargol  solution  and 
hold  to  count  60.  (3)  Eub  50  per  cent,  calomel  ointment  well  into 
foreskin,  head,  and  shank  of  penis,  with  particular  care  about  the  fre- 
num.  Treatment  taken  within  eight  hours  after  exposure  in  1,385 
cases  shows  19  infections,  or  but  1.37  per  cent.  In  the  interval  of 
from  eight  to  twelve  hours  after  exposure  in  741  cases  shows  25  infec- 
tions, or  3.31  per  cent.  Between  twelve  and  twent}"-four  hours  in  920 
cases  shows  -16  infections,  or  5  per  cent.  Of  the  56  cases  of  gonorrhea 
occurring  in  the  first  twenty-four-hour  interval,  26  were  recurrent  cases; 
the  remaining  30  were  primary  infections. 

The  use  of  salvarsan  early  in  syphilis  will  prevent  the  further  spread 
of  the  infection. 

Segregation. — Theoretically,  every  case  of  syphilis  or  gonorrhea 
should  be  isolated  until  the  danger  of  infection  is  passed.     Practically, 

^Ledbetter,  Eobert  E.,  "Venereal  Prophylaxis  in  the  U.  S.  Xavy, "  Jour. 
A.  M.  A.,  April  15,  1911,  Vol.  LVI,  No.  15,  p.  1098. 

=  Holeomb,  E.  C,  and  Gather,  D.  C,  U.  S.  N.,  "Study  of  3,268  Venereal 
Prophylactic  Treatments,"  Jour.  A.  M.  A.,  Vol.  LVIII,  No.  5,  Feb.  3,  1912, 
p.  368. 


60  SPECIAL    rEOrHYLACTIC    MEASURES 

however,  segregation  is  impracticable  except  with  a  limited  number  of 
cases.  With  better  and  more  attractive  hospital  facilities  and  free  beds 
a  certain  amount  of  segregation  may  be  accomplished  voluntarily  and 
humanely.  An  alert  health  officer  can  trace  the  source  of  infection  in 
certain  cases  and  induce  the  women  responsible  to  take  the  salvarsan 
treatment  in  the  case  of  syphilis,  or  to  submit  to  hospital  care  in  the 
case  of  gonorrhea  or  chancroid. 

Routine  circumcision  and  a  medical  examination  as  a  necessary  pre- 
liminary to  marriage  are  further  liygienic  reforms  advocated. 

Finally,  in  considering  venereal  prophjdaxis,  it  should  be  remem- 
bered that  these  diseases  are  of  great  antiquity  and  seem  likely  to  con- 
tinue indefinitely,  that  they  already  affect  a  large  number  of  the  popu- 
lation, and  are  spreading;  that  the  existing  means  for  the  treatment 
of  them  among  the  poor  is  insufhcient ;  that  the  common  mode  of 
propagation  is  irregular  and  illicit  intercourse;  that  prostitution  arose 
in  response  to  the  strongest  instincts  and  passions  in  the  human  breast; 
and  that  prostitutes  themselves  need  protection  and  have  claims  on 
the  humanity  of  the  law. 

PREVENTABLE    BLINDNESS 

Preventable  blindness  is  considered  in  this  jilace  because  the  lar- 
gest single  factor  causing  needless  loss  of  eyesight  is  gonorrhea.  Among 
the  infectious  eye  troubles  the  most  destructive  is  ophthalmia  neona- 
torum. 

There  are  64,000  registered  blind  persons  in  the  United  States. 
Of  these  about  1-0  per  cent,  (between  six  and  seven  thousand)  are 
blind  as  the  result  of  ophthalmia  neonatorum.  From  25  to  30  per 
cent,  of  all  the  blind  children  in  all  the  blind  schools  of  this  country 
owe  their  infliction  to  gonorrhea.  It  has  been  estimated  that  probably 
one-half  of  the  blindness  in  the  world  is  preventable. 

Emphasis  upon  the  great  harm  done  by  ophthalmia  neonatorum 
should  not  blind  us  to  the  fact  that  there  are  other  causes  of  blindness 
and  eye  deterioration  which  are  preventable;  thus  we  have  to  consider 
the  later  pus  infections,  syphilis,  sympathetic  inflammations,  indus- 
trial accidents,  accidents  at  play,  progressive  nearsightedness  caused 
by  violation  of  ocular  hygiene,  and  a  variety  of  inflammatory  condi- 
tions. Functional  disturbances  of  vision  (amaurosis)  and  atrophy  of 
the  optic  nerve  may  be  brought  about  by  poisoning  with  lead,  alcohol, 
tobacco,  and  other  toxic  substances.  This  form  of  dimness  of  vision, 
or  even  loss  of  sight,  occurs  rather  frequently,  and  in  many  instances  is 
preventable. 

Trachoma  is  a  menace  to  the  integrity  of  sight.     It  is  an  infection 


PEEVENTABLB    BLINDNESS  61 

caused  by  a  filterable  virus.^  It  flourishes  best  where  sanitary  conditions 
are  worst.  The  disease  is  slow  and  insidious  in  its  development.  A  mass 
of  sago-like  granulations  gradually  fills  in  the  retrotarsal  fold,  thereby 
limiting  the  lid  movements  and  leaving  the  eye  half  closed.  The  infec- 
tion is  rubbed  into  the  eye  by  roller  towels,  handkerchiefs,  fingers,  and 
other  ways.  When  once  established,  the  disease  is  chronic,  and  per- 
manent cures  are  doubtful.  Trachoma  is  much  more  prevalent  in  the 
United  States  than  ordinarily  supposed.  The  public  eye  clinics  of 
Chicago  are  filled  with  patients  showing  the  resulting  deformities. 
Wilder  located  a  center  in  southern  Illinois,  and  it  has  also  been  found 
in  the  mountains  of  Kentucky  and  Tennessee,  while  in  Oklahoma  it  has 
become  a  public  menace.  It  is  more  or  less  prevalent  in  the  poorer 
sections  of  all  the  large  centers. 

Trachoma  is  of  such  a  serious  nature  that  all  immigrants  arriving 
at  our  shores  have  their  eyelids  everted  and  conjunctivae  examined  for 
evidence  of  this  infection.  An  alien  with  trachoma  is  deported  and  the 
steamship  is  liable  to  a  fine  of  one  hundred  dollars  for  bringing  every 
case  of  trachoma  where  it  can  be  shown  that  the  disease  might  have 
been  recognized  at  the  port  of  departure. 

Wood  alcohol  is  one  of  the  causes  of  blindness.  As  small  a  quan- 
tity as  a  teaspoonful  has  caused  loss  of  vision.  Wood  alcohol  is  used 
as  an  adulterant,  especially  in  liquors.  The  excessive  use  of  tobacco 
also  leads  to  dimness  of  vision. 

In  New  York  State  about  200  industrial  accidents  resulting  in 
total  blindness  occur  annually.  Besides  this,  there  is  a  large  number 
of  accidents  occurring  on  railroads  in  construction  work,  and  in  the 
field  and  forest.  Many  of  the  accidents  to  the  eyes  occurring  in  fac- 
tories are  preventable.  The  majority  of  such  accidents  are  due  to  small 
flying  particles. 

A  material  proportion  of  blindness  is  caused  by  accidents  to  chil- 
dren at  play;  sometimes  the  eyeball  is  torn  by  a  buttonhook  or  pierced 
by  a  knife  or  awl ;  or  a  scissors  blade,  used  to  untie  a  knot,  slips.  Some 
eyes  have  been  injured  by  the  crack  of  a  whip,  by  a  shot  from  an 
air-gun  or  toy  pistol.  Accidents  also  occur  to  the  eyes  from  fireworks, 
especially  on  the  Fourth  of  July. 

OPHTHALMIA    NEONATORUM 

Ophthalmia  neonatorum  or  inflammation  of  the  eyes  of  the  new- 
born includes  all  the  inflammatory  conditions  of  the  conjunctiva  that 
occur  shortly  after  birth — usually  before  the  end  of  the  flrst  month. 

^Bertarelli  and  Caechetto,  Centr.  fur  BaM„  Orig.,  I  Abt.,  Bd.  XLVIII, 
1908,  p.  432. 


62  SrECTAT.    rnoPTIYLACTIC    MIvVST^RES 

The  conjunctivae  of  tlie  ne\\l)orn  are  peciiliarly  liable  to  infections.  This 
delicate  membrane  rapidly  acquires  an  immunity  of  a  high  order.  The 
gonococcus  is  usually  the  cause  of  severe  conjunctivitis  occurring  in 
a  baby  a  few  days  old.  The  gonococcus  has  been  demonstrated  in  65 
per  cent,  of  all  cases,  mild  and  severe. 

Ophthalmia  neonatorum  is  not  always  gonorrheal,  but  may  be  pro- 
duced by  other  virulent  microorganisms  or  by  irritating  substances. 
The  microorganisms  other  than  the  gonococcus  that  sometimes  cause 
conjunctivitis  during  the  early  days  of  life  are :  streptococci,  the  menin- 
gococcus, the  Koch-Week's  bacillus,  the  pneumococcus,  the  diphtheria 
bacillus,  and  even  staphylococci.  These  are  relatively  so  rare  that  we 
may  disregard  their  etiological  significance  for  our  present  purpose. 
The  diagnosis  of  gonorrheal  ophthalmia  may  readily  be  made  by  simply 
examining  a  stained  smear  of  the  secretion. 

The  infection  commonly  occurs  during  the  passage  of  the  child 
through  the  genital  tract  of  the  mother  and  usually  just  before  deliv- 
ery. It  is  caused  by  the  entrance  of  the  vaginal  secretion  containing 
gonococci  into  the  conjunctival  sac.  It  may  also  be  caused  after  de- 
livery by  infected  hands,  towels,  sponges,  or  other  objects. 

The  disease  varies  in  severity;  sometimes  it  is  very  mild,  with  slow 
onset  and  spontaneous  recovery.  Usually,  however,  it  is  severe  and 
serious.  The  inflammation  may  extend  from  the  conjunctiva  to  the 
cornea  and  invade  the  deeper  structures  of  the  eye.  Corneal  ulcers 
and  opacity  may  result,  with  complete  loss  of  vision.  In  a  typical 
case  both  the  ocular  and  palpebral  conjunctivae  are  red  and  very  much 
swollen;  the  eyelids  and  surrounding  tissues  are  infiltrated  and  there 
is  a  thick,  creamy,  abundant  secretion. 

There  are  many  grades  of  mild  inflammatory  condition,  which  must 
not  be  mistaken  for  gonorrhea.  At  birth  the  eyelids  are  almost  always 
glued  together  with  the  normal  sticky  secretions.  It  is  common,  too, 
for  the  lids  to  remain  red  and  sticky  for  a  day  or  so.  The  diagnosis 
may  be  made  in  a  few  minutes  by  a  microscopic  examination. 

Prevalence. — Kerr  calls  attention  to  the  fact  that  there  are  no  com- 
plete statistics  showing  the  prevalence  of  ophthalmia  neonatorum,  and 
only  an  approximate  idea  can  be  had  of  the  number  of  cases  by  study- 
ing the  admissions  to  schools  for  the  blind.  A  committee  of  the  Brit- 
ish Medical  Association  found  that  more  than  one-third  of  those  in 
blind  schools  of  Great  Britain  owed  their  affliction  to  this  disease.^ 

In  the  United  States  and  Canada,  in  1907,  out  of  224  admissions 
to  10  schools  for  the  blind,  59,  or  24.38  per  cent.,  were  blind  as  a  re- 
sult of  ophthalmia  neonatorum;-  and  out  of  351  admissions  to  certain 


*  British  Medical  Journal,  May  8,  1909. 
''Jour.  A.  M.  A.,  May  23,  1909,  p.  1745. 


PEEVENTABLE    BLIXDXESS  63 

schools  in  the  United  States  and  Canada  in  1910,  84,  or  23.9  per  cent., 
were  blind  from  this  cause. ^ 

* 

As  a  result  of  studies  made  of  ophthalmia  neonatorum  in  10  man- 
ufacturing cities  of  Massachusetts,  Greene  has  presented  figures  which 
show  that  the  minimum  morbidity  rate  for  this  disease  was  6.4  per 
1,000  births.  A  more  complete  census  made  by  him  for  the  practice 
of  173  physicians  in  9  cities  revealed  an  average  morbidity  rate  of 
10.8  per  1,000  births.^ 

It  is  estimated  that  the  total  annual  loss  from  gonorrheal  ophthalmia 
in  the  United  States  is  seven  million  dollars,  and  that  an  amount  of 
more  than  one  million  dollars  annually  is  spent  in  partially  caring  for 
its  victims.  A  blind  child  costs  the  community  an  excess  of  about 
$1,500  for  its  schooling. 

Prevention.— Crede^s  Method. — Crede  in  1881  introduced  an  effi- 
cient method  of  preventing  ophthalmia  neonatorum  at  the  Lying-in 
Hospital  at  Leipzig,  thereby  connecting  forever  his  name  with  the  pre- 
vention of  the  disease  and  the  subsequent  saving  of  the  sight  of  many 
infants.  Crede's  original  method  consisted  simply  in  placing  one  or 
two  drops  of  a  2  per  cent,  solution  of  silver  nitrate  in  each  conjunc- 
tival sac,  as  soon  as  practicable  after  the  birth  of  the  head. 

In  order  to  prevent  gonococcic  as  well  as  other  infections  of  babies' 
eyes,  the  following  procedure  is  recommended:  During  pregnancy 
women  should  be  instructed  to  practice  daily  external  cleansing  with 
soap  and  water  and  a  clean  wash-cloth.  In  case  of  any  irritating  dis- 
charge or  even  profuse  white  discharge,  a  physician  should  at  once  be 
consulted. 

Immediately  after  labor  the  eyelids  should  be  carefully  cleaned  with 
sterile  absorbent  cotton  or  gauze  and  a  saturated  solution  of  boracic 
acid.  A  separate  pledget  should  be  used  for  each  eye  and  the  lids 
washed  from  the  nose  outward  until  quite  free  of  all  mucus,  blood,  or 
meconium  without  opening  the  lids.  Xext  the  lids  should  be  separated 
and  one  or  two  drops  of  a  one  per  cent,  silver  nitrate  solution  should  be 
dropped  into  each  eye,  between  the  outer  ends  of  the  lids.  The  lids  should 
be  separated  and  elevated  away  from  the  eyeball  so  that  a  lake  of  silver 
nitrate  solution  may  lie  for  one-half  minute  or  longer  between  them, 
coming  in  contact  with  every  portion  of  the  conjunctival  sac.  One 
application  only  of  the  silver  nitrate  should  be  made,  and  ordinarily 
no  further  attention  need  be  given  to  the  eyes  for  several  hours.  Each 
time  the  child  is  bathed  the  eyes  should  first  be  wiped  and  cleaned  with 
pledgets  of  sterile  absorbent  cotton  wet  with  a  saturated  solution  of 
boracic  acid. 

"^lUd.,  July  1,  1911,  p.  72. 

^Monograph  Series  of  the  American  Association  for  Conservation  of  Vision, 
Vol.  I,  No.  1. 


64  SPECIAL    rROPHYLACTIC    MEASURES 

Crede  used  a  2  per  cent,  solution  of  silver  nitrate,  but,  as  this  is 
sometimes  irritating,  a  1  per  cent,  solution  is  now  commonly  employed, 
and  seems  to  afford  equally  efficient  prophylaxis.  The  silver  nitrate 
solution  should  be  instilled  into  each  conjunctival  sac  but  once.  Re- 
peated applications  may  cause  serious  inflammations.  In  fact,  a  single 
treatment  sometimes  causes  a  conjunctivitis,  known  as  "silver  catarrh," 
Because  of  the  silver  catarrh  the  strength  of  the  silver  nitrate  solution 
has  not  only  been  reduced  from  a  2  to  a  1  per  cent,  solution,  but  this 
may  be  neutralized  after  instillation  with  salt  solution.  Other  prophy- 
lactic substances  have  been  proposed.  The  best  substitutes  are  a  few 
drops  of  the  newer  silver  compounds,  as  argyrol  (25  per  cent.)  or 
protargol  (5  per  cent.).  The  following  have  also  been  recommended: 
Bichlorid  of  mercur}%  1-2,000  or  1-5,000,  silver  acetate,  0.23  per  cent., 
recommended  by  Zweifel,  who  used  it  in  5,222  cases.  Schmidt  and 
Rimpler  recommend  aqua  chlorini.  Carbolic  acid  (1  per  cent.)  or  other 
antiseptics  have  also  been  tried.  No  substance,  however,  is  known  to 
be  as  relial)le  as  silver  nitrate,  which  should  be  used  in  all  cases  where 
there  is  any  reason  for  believing  that  the  mother  is  infected  witli  the 
gonococcus. 

If  a  conjunctivitis  is  present,  a  bacteriological  examination  of  the 
discharge  should  at  once  be  made.  If  the  inflammation  is  due  to  the 
gonococcus  a  2  per  cent,  silver  nitrate  solution  should  be  used.  In  cer- 
tain mild,  non-gonorrheal  infection  0.5  per  cent,  is  usually  sufficient. 
If  the  Klebs-Loeffler  bacillus  is  found,  diphtheria  antitoxin  should  be 
given  without  delay.  If  the  diplococcus  is  present,  a  weak  solution 
(1  grain  to  the  ounce)  of  zinc  sulphate  should  be  instilled  frequently. 

As  a  general  rule,  it  is  advisable  to  use  a  prophylactic  as  a  mat- 
ter of  routine  in  hospital  and  private  practice.  To  use  Crede's  method 
upon  every  case  necessitates  the  unpleasant  suspicion  that  every  woman 
is  a  possible  source  of  gonococcus  infection.  If  statements  of  the  father 
about  his  previous  life  can  be  relied  upon,  an  eye  prophylactic  can  be 
safely  omitted.  In  his  private  work  Williams  uses  a  boric  acid  solution 
except  where  there  is  special  reason  for  believing  that  the  mother  has 
gonorrhea.  The  responsibility  for  risking  the  baby's  eyes  rests  upon 
the  medical  attendant.  There  can  only  be  one  safe  rule  in  case  of 
doubt.  It  should  be  remembered  that  gonococcic  infections  of  the  con- 
junctiva occur  in  about  one  to  every  two  hundred  births  (Edgar). 

The  good  results  of  Crede's  method  are  sufficiently  convincing  to 
justify  criminal  proceedings  upon  those  who  fail  to  apply  this  simple 
prophylactic.  Haab  reduced  the  frequency  of  ophthalmia  neonatorum 
in  hospital  practice  from  9  to  1  per  cent.,  while  the  statistics  of  many 
hospitals  show  only  a  very  small  fraction  of  1  per  cent.  Stephenson's 
results  are  typical.  In  2,265  births,  ophthalmia  neonatorum  developed 
in  10  per  cent,  of  the  cases  preceding  the  use  of  Crede's  method.     In 


PEEVENTABLE    BLINDNESS  65 

1,160  births  after  this  method  only  0.17  per  cent,  developed  any 
trouble.  A  small  number  of  cases  may  develop  despite  the  use  of 
silver  nitrate. 

The  technique  of  applying  the  nitrate  of  silver  is  very  important, 
for,  in  the  opinion  of  Edgar,  when  ophthalmia  neonatorum  develops 
after  the  use  of  nitrate  of  silver,  it  is  due  either  to  a  secondary  infec- 
tion or  to  the  fact  that  the  solution  does  not  really  bathe  the  mucous 
membranes,  but  remains  upon  the  lashes.  The  lids  must  be  everted 
and  the  silver  solution  placed  in  the  conjunctival  sac  either  from  a 
glass  rod  or  a  pipette.  Care  must  be  taken  not  to  touch  or  injure  the 
delicate  membrane. 

Crede's  method  does  not  strike  at  the  root  of  the  evil.  It  would, 
of  course,  be  much  better  to  eradicate  gonorrhea  from  men  and  women 
than  to  be  compelled  to  drop  silver  nitrate  into  babies'  eyes.  Wrapped 
up  with  the  question  of  ophthalmia  neonatorum  is  the  question  of 
midwives,  for  to  prevent  blindness  we  must  have  intelligent  and  con- 
scientious obstetrical  attendants,  especially  for  the  poor  and  ignorant 
classes.  Midwifery  practice  needs  regulation,  supervision,  and  eleva- 
tion. Education  is  one  of  the  bulwarks  of  prevention  in  this  as  well 
as  other  preventable  infections. 

Legislation. — Ophthalmia  neonatorum  is  an  instance  in  which  "the 
protection  of  the  citizen  from  the  assaults  of  ignorance,  indifference, 
or  neglect,  when  they  threaten  his  well-being  and  even  his  economic 
efficiency,  is  a  duty  which  the  state  cannot  evade  and  which  he  has  a 
right  to  exact." 

Laws  for  the  prevention  of  the  blindness  of  newborn  infants  are 
making  progress  slowly.  Among  the  states  in  which  the  disease  is 
notifiable  are  Connecticut,  Massachusetts,  Minnesota,  Nebraska,  New 
York,  Oregon,  South  Carolina,  Utah,  Vermont,  and  Wisconsin.  In 
some  states  the  nurse,  midwife,  or  parent  is  required  to  report  the  dis- 
ease, in  other  states  the  attending  physician. 

Maine  was  the  first  state  to  take  legal  steps  in  1891  to  control 
ophthalmia  neonatorum.  In  1892  New  York  followed,  with  an  amend- 
ment to  the  law  relative  to  midwives  and  nurses.  Subsequently  most 
of  the  other  states  took  legislative  action.^  The  provisions  of  the  several 
laws  are  quite  varied.  In  all  of  them,  however,  the  object  is  to  insure 
early  treatment,  and  to  this  end  compulsory  notification  is  generally 
required.  The  health  authorities  of  Massachusetts,  New  Jersey, 
Vermont,  Ehode  Island,  New  York,  and  the  District  of  Columbia 
furnish  prophylactic  outfits  to  physicians.  The  outfit  ordinarily 
consists  of  a  small  vial  containing  a  1  per  cent,   solution   of  nitrate 

^  Kerr,  J.  W.,  "Ophthalmia  Neonatorum:  An  Analysis  of  the  Laws  and  Reg- 
ulations Relating  Thereto  in  Force  in  the  United  States,"  Public  Health  Bull. 
No.  49,  U.  S.  P.  H.  &  M.  H.  S.,  Oct.,  1911. 


66  SPECIFIC    PROPHYLACTIC    MEASURES 

of   silver,   a   sterilized    dropper   and    hull),    and    a   circular   of    instruc- 
tions. 

In  order  to  make  material  progress  against  ophthalmia  neonatorum, 
as  well  as  against  infant  mortality,  it  is  essential  that  laws  require 
prompt  report  of  all  hirths;  it  is  the  duty  of  the  health  authorities  to 
see  to  it  that  such  laws  are  effectively  carried  out.^ 


TETANUS 

Compared  with  the  major  plagues  of  man,  lockjaw  has  always  been 
a  rare  disease.  It  is  on  account  of  the  characteristic  and  fatal  spasms 
that  it  early  attracted  attention.  The  student  Avill  be  well  repaid  by 
a  study  of  the  historical  development  of  the  theories  that  have  been 
advanced  since  the  time  of  Hippocrates  to  explain  the  cause  of  tetanus. 
These  theories  mirror  the  prevailing  thought  upon  the  nature  of  dis- 
ease as  it  developed  from  that  of  evil  spirits,  through  the  humoral 
theory,  the  realm  of  miasms  and  noxious  effluvia,  to  the  germ  theory. 
Tetanus  could  not  escape  the  rheumatism  theory  which  has  been  such 
an  alluring  catchall  for  symptoms  and  diseases  difficult  of  explanation. 
"Taking  cold"  was  assigned  its  usual  role  here  as  elsewhere.  When  no 
assignable  cause  seemed  at  hand,  the  disease  was  given  the  learned 
title— id iojiathic  tetanus. 

Etiology. — In  1889,  with  the  aid  of  anaerobic  technique,  Kitasato  * 
for  the  first  time  grew  the  tetanus   bacillus  in  pure  culture,  and  by 

*  The  Massachusetts  law  reads  as  follows: 

Section  49.  .  .  .  Shouid  one  or  both  eyes  of  an  infant  become  in- 
flamed, swollen  and  red,  and  show  an  unnatural  discharge  at  any  time  vnih- 
in  two  weeks  after  its  birth,  it  shall  be  the  duty  of  the  nurse,  relative,  or 
other  attendant  ha\4ng  charge  of  such  an  infant  to  report  in  writinc:  within 
six  hours  thereafter,  to  the  board  of  health  of  a  city  or  town  in  which  the 
parents  of  the  infant  reside,  the  fact  that  such  inflammation,  swelling,  and 
redness  of  the  eyes  and  unnatural  discharge  exist.  On  receipt  of  such  re- 
port, or  of  notice  of  the  same  s;\anptoms  given  by  a  physician  as  provided 
by  the  following  section,  the  board  of  health  shall  take  such  immediate 
action  as  it  may  deem  necessary  in  order  that  blindness  may  be  prevented. 
Whoever  violates  the  provisions  of  this  section  shall  be  punished  by 
a  fine  of  not  more  than  one  hundred  dollars. 

Section  50.  ...  If  a  physician  knows  that  ...  if  one  or  both 
eyes  of  an  infant  whom  or  whose  mother  he  is  called  to  visit  become  in- 
flamed, swollen,  and  red,  and  show  an  unnatural  discharge  within  two  weeks 
after  birth  of  such  infant,  he  shall  immediately  give  notice  thereof  in  writ- 
ing over  his  own  signature  to  the  selectmen  or  board  of  health  of  the  town; 

AND    IF    HE    REFUSES    OR    NEGLECTS    TO    GIVE    SUCH    NOTICE,    HE    SHALL    FORFEIT 
NOT    LESS    THAN    FIFTY    NOR    MORE    THAN    TWO    HUNDRED    DOLLARS    FOR    EACH 

OFFENCE.     (Revised  Laws,  Chapter  75.) 
^Zeitschr.  f.  Eyg.,  Vol.  VII,  18S9,  p.  225. 


TETANUS  er 

successfiTl  inoculation  experiments  proved  that  this  hacilliis  was  the  real 
cause  of  tetanus.  Kitasato  further  showed  that  the  tetanus  bacillus  is 
not  found  in  the  heart's  bloody  of  mice  dead  of  tetanus,  and  therefore 
concluded  that  we  are  dealing  with  an  intoxication,  and  not  an  infec- 
tion. We  now  regard  tetanus  as  a  type  of  the  true  toxemias.  This 
work  of  Kitasato's  was  one  of  great  importance,  and  led  up  to  the  epoch- 
making  discovery  of  Behring  and  Kitasato  ^  in  the  following  3-ear  (1890) 
upon  tetanus  and  diphtheria  toxines  and  antitoxins,  laying  the  founda- 
tion of  serum  therapy. 

Tetanus  may  be  regarded  almost  solely  as  a  wound  complication. 
All  wounds  are  not  equally  liable  to  this  complication,  even  though 
tetanus  spores  are  present.  Punctured,  lacerated,  and  contused  wounds 
are  much  more  susceptible  to  tetanus  than  cleancut  or  superficial  wounds. 
The  size  of  the  wound  is  of  much  less  consequence  than  its  character. 
Fatal  tetanus  may  develop  from  trivial  wounds,  such  as  pin  scratches, 
small  splinters,  insect  bites,  vaccinations,  etc. 

S3'mbiosis  is  an  important  factor  in  tetanus.  Wounds  infected  with 
pyogenic  organisms  and  other  bacteria  favor  anaerobic  conditions  and 
permit  the  tetanus  spores  to  germinate,  and  seem  to  encourage  the 
growth  of  the  bacillus  and  the  development  of  toxine.-  A  few  tetanus 
spores  free  of  tetanus  toxin  in  a  clean  wound  may  be  taken  care  of  by 
the  phagocytic  cells.  This  may  readily  be  demonstrated  experimentally 
by  injecting  animals  with  tetanus  spores  washed  free  of  toxine. 

The  normal  habitat  of  tetanus  is  in  the  intestinal  tract  of  herbiv- 
orous animals.  Sanchez,  Toledo,  and  Veillon  ^  found  tetanus  in  the 
feces  of  4  out  of  6  horses  and  in  the  feces  of  1  of  2  cows.  Park  found 
tetanus  bacilli  in  the  intestines  of  about  15  per  cent,  of  horses  and 
calves  living  in  the  vicinity  of  New  York  City.  They  are  present  to 
a  somewhat  less  extent  in  the  intestines  of  other  animals  and  of  man. 

It  is  rather  a  curious  paradox  that  the  horse,  which  is  the  most 
susceptible  of  all  animals  to  tetanus  toxin,  is  one  of  the  principal  hosts 
of  the  tetanus  bacillus. 

The  spores  taken  in  the  food  are  not  affected  by  gastric  digestion, 
and  in  the  small  intestines  find  ideal  anaerobic  conditions,  food  supply 
and  temperature  for  growth  and  development.  Here  they  very  prob- 
ably multiply  and  pass  in  the  dejecta  to  pollute  the  soil.  The  soil, 
therefore,  in  all  regions  inhabited  by  nnan  and  domestic  animals  is 
more  or  less  contaminated  with  tetanus.  The  bacilli,  however,  do  not 
multiply  in  the  soil.  While  the  soil  acts  only  as  a  vehicle,  it  is  the 
immediate  source  of  the  large  proportion  of  tetanus  spores. 

^  Deutsch.  med.   Wochens.,  Vol.  XVI,  No.  40,  p.  1113. 

-  In  the  laboratory  some  of  the  strongest  tetanus  toxins  have  been  prepared 
from  mixed  or  contaminated  cultures. 
^  La  Semaine  Med.,  1890,  X,  p.  45. 


C8  SPECIFIC    PEOPHYLACTIC    MEASURES 

It  is  assumed,  but  not  proven,  that  tetanus  bacilli  grow  in  tlie  in- 
testinal tract  of  herbivora.  It  is  conceivable  that  the  spores  simply  pass 
tlirouiih  the  intestines  without  multiplying  at  all,  but  it  is  known  that 
tetanus  is  capable  of  multiplying  in  symbiotic  relation  with  otlier  bac- 
teria wherever  protein  matter  undergoes  ])utrefaction  under  anaerobic 
conditions. 

On  account  of  the  great  resistance  of  the  spores,  they  are  blown  about 
in  dust  and  are  spread  everywhere  by  dirt  and  manure.  Tetanus 
has  been  found  in  hay  dust,  on  horses'  hair,  in  the  dust  of  houses,  bar- 
racks, and  hospitals,  in  the  mortar  of  old  masonry,  in  street  dust,  in 
gelatin,  and  in  the  greatest  variety  of  places. 

One  of  the  agencies  in  the  distribution  of  tetanus  spores  over 
limited  areas  is  undoubtedly  the  common  house  fly.  The  arrow  heads 
of  certain  savages  in  the  Kew  Hebrides  contain  tetanus  spores  obtained 
by  smearing  the  arrowheads  with  dirt  from  crab  holes  in  the  swamps 
(Le  Dantic). 

Tetanus  bacilli  are  not  equally  numerous  in  all  localities.  The  in- 
fection is  much  more  prevalent  in  warm  than  in  cold  countries.  It  is 
especially  severe  in  the  tropics,  yet  Iceland  at  one  time  suffered  severely 
from  tetanus  neonatorum.  Some  parts  of  Long  Island  and  New  Jer- 
sey have  become  noticeable  for  the  number  of  cases  of  tetanus  caused 
by  small  wounds.  Tetanus  spores  are  widely  disseminated  in  India. 
Goodrich  states  that  in  Bombay  alone  there  were  1,955  cases  of  tetanus 
in  five  years.     These  do  not  include  the  puerperal  cases. 

Tetanus  occurs  either  sporadically  or  in  epidemic  form.  Formerly 
epidemics  in  hospitals  (especially  in  lying-in'  hospitals)  and  in  wars 
were  rather  common.  Before  the  days  of  antisepsis  the  infection  was 
readily  spread  through  instruments,  fingers,  bandages,  etc. 

Trismus  neonatorum ,  or  tetanus  of  the  newborn,  was  a  common  and 
very  fatal  infection,  especially  in  the  tropics.  Before  the  days  of 
asepsis  the  infection  was  permitted  to  enter  through  the  umbilical 
wound.  In  certain  of  the  West  Indian  islands  more  than  one^half  of 
the  mortality  among  the  negro  children  has  been  due  to  this  cause. 
Since  the  introduction  of  proper  methods  of  treating  the  cord  the 
disease  is  rare. 

The  wounds  produced  by  blank  cartridges  are  especially  liable  to 
develop  tetanus.  The  source  of  the  tetanus  spore  in  these  cases  is  not 
entirely  clear.  Wells  examined  200  cartridges  from  five  firms  without 
finding  the  tetanus  bacillus.  It  is  probable  that  the  spore  is  upon  the 
skin  and  is  carried  along  with  the  paper  and  powder  from  the  blank 
cartridge.  The  peculiar  character  of  the  wound  favors  the  develop- 
ment of  tetanus. 

The  great  decrease  in  the  number  of  cases  of  tetanus  following 
Fourth  of  July  wounds  is  due  to   the   vigorous  campaign  carried  on 


TETANUS  69 

by  the  American  Medical  Association.  In  1903  there  were  406  deaths 
from  tetanus;  in  1904,  91;  1905,  87;  1906,  75;  1907,  73;  1908,  76; 
and  in  1911  only  18  cases  and  10  deaths.  Eighty  per  cent,  of  these 
followed  blank  cartridge  wounds.  The  good  results  are  attributed 
to  the  more  thorough  and  careful  treatment  of  the  wounds  and  especially 
the  use  of  tetanus  antitoxin  as  a  prophylactic — and  more  recently  to 
safer  and  saner  methods  of  celebration. 

Tetanus  spores  or  toxine  may  contaminate  bacterial  vaccines,  anti- 
toxic sera,  vaccine  virus,  and  other  biologic  products  used  in  human 
therapy.  The  possible  association  of  tetanus  with  bacterial  vaccines  was 
demonstrated  in  the  unfortunate  outbreak  at  Mulkowal,  India,  in  1902.^ 
One  hundred  and  seven  persons  were  inoculated  with  Haifkine's  plague 
prophylactic.  Of  these  19  were  affected  with  symptoms  of  tetanus  and 
died.  In  this  case  the  tetanus  probably  grew  as  a  contamination  in  the 
plague  culture,  for  it  is  now  well  known  that  the  anaerobic  conditions 
produced  in  B.  diplitherice ,  B.  pesfis,  B.  siibUlis,  and  other  organisms  in 
liquid  culture  media  favor  the  growth  of  tetanus  and  the  development 
of  its  toxin. 

In  St.  Louis  (1901)  diphtheria  antitoxin  was  taken  from  a  horse 
during  the  period  of  incubation  of  tetanus  and  used  in  amounts  from 
5  to  10  c.  c.  upon  7  children,  all  of  whom  died  of  tetanus.  Bolton, 
Fiseh,  and  Walden  -  found  that  the  serum  was  sterile,  but  contained 
tetanus  toxin  in  considerable  amount.  If  the  serum  had  first  been 
tested  upon  animals,  its  poisonous  properties  would  have  been  discov- 
ered. This  test  is  now  required  by  the  United  States  law  of  July  1, 
1902,  for  all  serums  and  vaccines  sold  in  interstate  traffic.  As  a  fur- 
ther precaution  against  this  complication  horses  undergoing  treatment 
for  the  production  of  immune  sera  are  given  prophylactic  doses  of  te- 
tanus antitoxin  from  time  to  time. 

Tetanus  sometimes  occurs  as  a  complication  of  vaccination.  It  is 
not  clear  in  these  cases  whether  the  tetanus  spores  are  contained  in 
the  vaccine  virus  or  subsequently  enter  the  wound.  In  many  hundreds 
of  special  examinations  made  in  the  Hygienic  Laboratory  at  Washing- 
ton tetanus  spores  have  not  been  found  in  a  single  vaccine  virus.  Ex- 
periments show  that  in  vaccine  virus  purposely  contaminated  the  te- 
tanus spores  remain  alive  and  active  for  a  long  time  (see  page  19). 

It  is,  of  course,  not  the  rust  on  a  nail  that  is  dangerous,  so  far  as 
tetanus  is  concerned,  but  the  spore-bearing  dirt  it  carries  into  the  deep, 
contused  wound  that  causes  the  trouble.  Ge]atin  may  contain  tetanus 
spores,  and  the  subcutaneous  injection  of  imperfectly  sterilized  gelatin 
as  a  hemostatic  has  sometimes  resulted  in  accidents. 

''Jour.   Trop.   Med.   and  Hyg.,   1907,  X,   p.' 33. 

^Bolton,  Fisch,  and  Walden  in  St.  Louis  Medical  Beview,  Vol.  XLIV,  No. 
21,  Nov.  23,  1910,  p.  361. 

7 


70  SPECIFIC    PROPHYLACTIC    MEASURES 

Tetanus  is  harmless  \vlien  taken  1)}'  tlie  mnntl).  Susceptible  animals 
may  be  given  enormous  doses  of  tetanus  toxine  hy  the  mouth  without 
producing  the  disease.  The  l)acillus  and  its  spore  may  be  regarded  as 
a  saprophyte  in  the  intestinal  tract.  There  is,  however,  a  suspicion 
that  tetanus  spores  sometimes  invade  the  organism  through  small  wounds 
in  the  digestive  or  res])iratory  tract.  Perhaps  some  of  the  cases  follow- 
ing surgical  operations  may  be  accounted  for  in  this  way  rather  than 
by  infection  of  the  catgut  used  for  ligatures. 

Tetanus  sometimes  occurs  in  which  no  wound  can  be  found.  This 
is  the  so-called  "idiopathic  or  rheumatic  tetanus."  One  ex{)lanation 
of  these  eases  is  to  be  found  in  the  fact  that  the  spores  are  numerous 
in  street  dust  and  may  enter  the  reP]uratory  tract.  They  cannot  do 
harm  so  long  as  the  mucous  membrane  is  healthy,  but  may  enter  through 
inflamed  membranes  or  through  small  wounds  in  the  nose.  Tetanus 
bacilli  have  been  found  in  the  bronchial  mucus  of  idiopathic  eases.  Tet- 
anus spores  have  recently  been  found  in  the  lymph  glands,  liver,  and 
other  parts  of  the  body,  upsetting  our  previous  view  that  they  are  strictly 
confined  to  the  site  of  the  wound.  These  spores  may  remain  latent  for 
a  long  time,  awaiting  favorable  conditions  to  grow  and  produce  toxin, 
thus  giving  another  plausible  explanation  of  some  cases  of  idiopathic 
tetanus. 

Incubation.' — The  period  of  incubation  in  man  is  usually  from  6  to 
14  days.  The  period  is  directly  proportional  to  the  amount  of  toxin  and 
the  severity  of  the  disease.  This  can  readily  bo  demonstrated  ujion 
susceptible  animals.  In  a  study  of  600  serial  tests,  Rosenau  and  Ander- 
son found  this  direct  relation  between  the  period  of  incubation  and  the 
severity  of  symptoms  by  the  subcutaneous  injection  of  varying  amounts 
of  toxin  into  guinea-pigs.  Thus,  guinea-pigs  that  showed  symptoms  on 
the  third  day  usually  died,  a  very  small  percentage  recovering.  The 
smaller  the  dose  the  longer  the  onset  of  symptoms  is  delayed,  the 
milder  is  the  disease,  and  the  greater  the  chances  of  recovery.  With  a 
short  period  of  incubation,  6  days  or  less,  the  disease  in  man  is  almost 
invariably  fatal.  With  longer  periods  the  disease  is  milder  and  recovery 
frequently  takes  place  without  the  use  of  antitoxin  or  other  measures. 
Tetanus  toxin  travels  up  the  axis  cylinders  of  the  nerves  to  the  cord 
and  brain.  It  is  also  distril)uted  in  the  blood.  The  period  of  incuba- 
tion, therefore,  depends  somewhat  upon  the  point  of  entrance  of  the 
poison  and  its  proximity  to  large  motor  nerve  endings. 

Resistance. — The  tetanus  bacillus  is  readily  destroyed  by  all  the  or- 
dinary agencies  that  kill  spore-free  bacteria.  It  is  killed  almost  at  once 
in  contact  with  the  free  oxygen  of  the  air.  On  the  other  hand,  few, 
if  any,  forms  of  life  have  a  greater  resistance  than  the  tetanus  spore. 
Hours  of  exposure  to  60°  or  70°  C.  do  not  affect  them.  They  usually 
survive  an  exposure  of  one  hour  to  80°  C,  but,  as  a  rule,  are  killed  in 


TETANUS  71 

streaming  steam  or  boiling  water  in  60  minutes.  Tetanus  spores,  how- 
ever, vary  greatly  in  the  power  to  resist  the  boiling  temperature.  Kita- 
sato  ^  found  them  to  resist  80°  C.  for  one  hour,  but  to  be  killed  in 
streaming  steam  in  5  minutes.  Vaillard  and  Vincent  ^  found  that  the 
spores  heated  in  the  presence  of  moisture  in  a  closed  vessel  would  resist 
destruction  at  80°  C.  for  6  hours,  at  90°  C.  for  2  hours,  and  100°  C. 
3  to  4  minutes,  that  they  were  not  always  destroyed  in  5  minutes,  but 
never  resisted  more  than  8  minute?  at  100°  C.  Levy  and  Bruns^  found 
that  destruction  begins  at  8^^  minutes  at  100°  C;  after  15  minutes 
few  survive,  after  30  minutes  none.  Falcioni  ^  studied  the  subject  in 
view  of  the  dangers  of  the  subcutaneous  injection  of  gelatin.  He  im- 
pregnated gelatin  with  spores  of  tetanus  bacilli  grown  in  agar  or  broth 
for  10  or  13  days,  and  used  Koch's  steam  sterilization.  He  found  the 
spores  to  resist  destruction  for  2%:.  I^^^t  not  for  3,  hours  in  streaming 
steam. 

The  experimental  results  are,  therefore,  sufficiently  varied  and  con- 
flicting to  suggest  that  races  of  tetanus  bacilli  exist,  the  spores  of  which 
vary  widely  in  their  resistance  to  moist  heat  at  100°  C.  Theobald 
Smith  ^  found  that  under  certain  conditions  of  cultivation  some  tetanus 
spores  survive  a  single  boiling  or  streaming  steam  for  20  minutes  reg- 
ularly, usually  for  40  minutes,  and  occasionally  for  60  minutes;  in  one 
case  70  minutes'  exposure  did  not  destroy  the  spores.  He  also  showed 
the  possibility  of  tetanus  spores  surviving  in  culture  fluids  sterilized  by 
discontinuous  boiling  or  steaming  in  routine  laboratory  work  for  fully 
20  minutes  on  three  successive  days. 

Tetanus  spores  resist  the  action  of  5  per  cent,  carbolic  acid  for  10 
hours,  but  are  killed  in  15  hours.  A  5  per  cent,  solution  of  carbolic 
acid,  however,  to  which  0.5  per  cent,  of  hydrochloric  acid  has  been 
added,  destroys  them  in  2  hours.  Bichlorid  of  mercury,  1-1,000,  kills 
the  spores  in  3  hours,  and  in  30  minutes  when  0.5  per  cent,  of  hydro- 
chloric acid  is  added  to  the  solution.  According  to  Park,  silver  nitrate 
solution  destroys  the  spores  of  average  resistance  in  1  minute  in  1  per 
cent,  solution,  and  in  about  5  minutes  in  a  1  to  1,000  solution.  Tetanus 
spores  are  destroyed  with  certainty  when  exposed  to  dry  heat  at  or 
above  160°  C.  for  one  hour,  or  to  steam  at  120°  C.  for  20  minutes.  En- 
tire confidence  may  be  placed  upon  either  of  these  two  methods. 

Direct  sunlight  does  not  kill  the  spores,  but  seems  to  diminish  their 
virulence.  Under  certain  circumstances  they  may  live  a  very  long  time; 
Henrijean  reports  that,   by  means  of  a  splinter  of  wood  which  once 


^Zeitschr.  f.  Byg.,  VII,  p.  225. 

^  Annales  de  I'lnstitut  Pasteur,  1891,  V,  p.  1. 

^Grensgeb.  d.  Med.  u.  Chir.,  1902,  X,  p.  235. 

* Annali  d'igiene  sperimentale,  1904,  N.  S.,  XIV,  p.  319. 

'  Jour.  A.  M.  A.,  March  21,  1908,  Vol.  L,  pp.  929-934. 


72  SPECIFIC    PROPHYLACTIC    MEASUPES 

caused  tetanus,  he  was  able  after  11  years  again  to  cause  the  disease 
I)v  inoculating  an  animal  with  the  infective  material. 

Prophylaxis. — Local  Tredlijicnt  of  Wounds. — Wounds,  however  in- 
significant, should  be  thoroughly  cleansed.  Punctured  or  lacerated 
wounds  in  which  there  is  special  danger  of  tetanus  shoidd  be  freely 
opened,  and  every  particle  of  foreign  matter  carefully  removed.  Prompt- 
ness in  cleansing  the  wcnmd  surgically  is  almost  as  important  as  thor- 
oughness. Wounds  containing  garden  earth,  street  dust,  or  other  mate- 
rial liable  to  contain  tetanus  spores  sho\dd  receive  special  consideration. 
After  laying  open  and  thoroughly  cleansing  siich  wounds,  it  may  be  ad- 
visable to  disinfect  them  with  the  actual  cautery  or  strong  chemical 
agents.  For  this  purpose  carbolic  acid  (from  25  per  cent,  to  pure)  or  a 
strong  solution  of  formalin  may  be  used.  Silver  nitrate  destroys  the  tet- 
anus spores  in  laboratory  experiments,  but  lacks  penetration  in  the  pres- 
ence of  albuMiinous  matter.  It  is  sometimes  good  practice  to  totally  excise 
the  wound,  and  even  amputation  must  be  considered  in  certain  eases. 
The  division  of  the  und)ilical  cord  and  the  treatment  of  the  navel  in  the 
newborn  must  be  done  under  the  strictest  asepsis.  All  wounds  in  which 
there  is  any  suspicion  of  tetanus  should  be  kept  open  and  freely  drained, 
and  otherwise  treated  so  as  to  discourage  anaeroljic  conditions. 

Tetanus  spores  gain  entrance  into  wounds  not  only  from  manure, 
garden  soil,  street  dust,  and  similar  sources,  but  also  from  the  hands, 
instruments,  bandages,  suture  material,  or  other  objects.  It  is  impor- 
tant to  remember  that  the  tetanus  spiu-e  is  exceedingly  resistant  to  heat 
and  chemical  agents,  and  that  in  surgical  and  obstetrical  practice  con- 
fidence should  not  be  placed  simply  upon  boiling  to  destroy  the  spores. 
Very  particular  care  must  be  exercised  in  the  disinfection  of  substances 
injected  into  the  body,  such  as  gelatin  and  other  organic  materials. 
For  the  destruction  of  tetanus  spores  complete  confidence  may  be  placed 
in  the  autoclave,  in  which  a  temperature  of  120°  C.  for  20  minutes  is 
attained,  or  exposure  to  dry  heat  at  160°  C.  for  1  hour. 

It  should  be  remembered  that  tetanus  toxin  is  manufactured  in  the 
wound  and  is  thence  transported  mainly  along  the  nerve  roots  to  the 
spinal  cord  and  brain.  It  is  therefore  important  to  destroy  or  neutral- 
ize the  toxin  in  the  wound.  For  this  purpose  dry  tetanus  antitoxin  may 
be  dusted  upon  the  wound.  Formaldehyde,  even  in  comparatively  weak 
solutions,  destroys  the  activity  of  tetanus  toxin. 

Specific  Prophylaxis. — Tetanus  antitoxin  is  a  specific  and  trustworthy 
preventive.  Its  use,  however,  must  be  understood  to  achieve  satisfactory 
results.  The  antitoxin  must  be  administered  before  the  advent  of 
symptoms,  for  after  the  tetanus  toxin  has  combined  with  the  motor 
nerve  cells  in  the  central  nervous  system  it  can  neither  be  displaced  nor 
neutralized  with  antitoxin.  In  such  cases  the  most  that  the  antitoxin 
can  do  is  to  combine  with  and  neutralize  the  free  toxin  and  thus  pre- 


TETANUS  73 

vent. further  damage.  This  in  itself  is  quite  worth  while  in  the  treat- 
ment of  tetanus.  At  least  1,500  units  of  tetanus  antitoxin  should  be 
given  as  a  prophjdactic  dose.^  It  is  important  to  remember  that  the 
tetanus  antitoxin  is  eliminated  or  otherwise  disposed  of  in  the  body 
in  the  course  of  10  days  or  2  weeks.  Therefore,  in  cases  in  which  the 
wound  does  not  heal  well,  as  a  result  of  mixed  infection,  or  for  other 
reasons,  it  is  desirable  to  repeat  the  injection.  This  may  be  done  at 
intervals  as  long  as  the  danger  persists.  Occasionally  tetanus  bacilli 
persist  in  the  i^us-infected  tissues,  and,  when  the  injected  antitoxin  has 
been  exhausted,  there  may  occur  a  late  development  of  tetanus.  Kowan  ^ 
reports  a  fatal  case  of  tetanus  in  spite  of  the  prophylactic  use  of  2,000 
units  of  antitetanic  serum,  given  5  hours  after  the  accident.  In  this 
case,  however,  the  symptoms  appeared  25  days  later.  The  wound  in 
this  case  was  a  compound  fracture  with  a  free  discharge  of  rather 
foul-smelling  pus.  Instances  in  which  1,500  units  of  tetanus  antitoxin 
have  failed  to  prevent  the  development  of  tetanus  in  this  country  are 
rare.  The  few  failures  in  France  and  Germany  may  be  attributed  to  the 
fact  that  in  those  countries  it  is  customary  to  use  a  smaller  amount  or 
a  less  potent  serum  than  is  used  in  this  country. 

Wounds  produced  by  blank  cartridges  and  other  Fourth  of  July 
accidents  should  always  be  regarded  as  suspicious,  and  should  be  given 
careful  local  treatment,  supplemented  with  a  prophylactic  injection  of 
antitoxin.  The  prevention  of  tetanus  complication  of  vaccine  wounds 
consists  in : 

1.  The  use  of  a  reliable  vaccine  which  has  been  biologically  tested 
in  accordance  with  the  federal  act. 

2.  Proper  methods  of  vaccination  to  avoid  unnecessary  scabs  and 
anaerobic  wound  conditions. 

3.  Surgical  asepsis  of  the  operation  and  after-treatment. 

Tetanus  and  other  wound  infections  may  be  avoided,  in  those  ex- 
posed to  accidents,  by  cleanliness  of  body  and  clothing.  A  bath  before 
a  battle  is  a  reasonable  protection  said  to  be  adopted  in  the  Japanese 
Army  and  Navy.  The  common  experience  of  mankind  teaches  him 
that  most  wounds  heal  without  tetanus,  and  that  tetanus  is,  in  fact, 
a  relatively  rare  infection.  The  physician,  however,  is  in  no  case  jus- 
tified in  taking  chances,  and  it  is  one  of  the  duties  of  the  medical  pro- 
fession to  teach  the  public  that  it  pays  to  thoroughly  cleanse  and  care 
for  wounds,  however  trivial,  at  once,  and  in  accordance  with  modern 
methods. 

^As  soon  as  symptoms  appear  20,000  units  or  more  of  tetanus  antitoxin 
should  be  introduced  directly  into  the  circulation  by  intravenous  injection;  some 
antitoxin  may  also  be  injected  into  the  nerves  leading  from  the  wound.  In 
tetanus,  as  in  diphtheria,  time  is  the  important  element.  A  few  units  introduced 
early  are  worth  more  than   thousands  late. 

■"Jour,  A.  M.  A.,  XIV,  No.  7,  Feb.  12,  1910,  p.  533. 


CHAPTER   II 

DISEASES    SPREAD    LARGELY    THROUGH    THE    ALVINE    DIS- 
CHARGES 

TYPHOID    FEVER 

Typlioid  fever  is  a  sanitary  problem  of  first  magnitude,  especially 
in  this  country,  where  it  is  unduly  prevalent.  In  the  United  States 
typhoid  fever  stands  fourth  on  tlie  list  of  mortality  tables :  tuberculosis 
comes  first,  then  pneumonia,  cancer,  and  typhoid  fever.  The  aver- 
age fatality  from  typhoid  fever  being  nearly  10  per  cent.,  it  would, 
therefore,  take  still  higher  rank  on  the  morbidity  tables.  In  1910 
there  were  25,000  deaths  from  typhoid  fever  in  the  United  States, 
representing  at  least  250,000   cases. 

Our  general  attitude  toward  typhoid  fever  is  inconsistent;  familiar- 
ity has  bred  a  remarkable  indifference  to  the  disease.  Every  case  of 
typhoid  fever  means  a  short  circuit  between  the  alvine  discharges  of 
one  person  and  the  mouth  of  another.  The  physician  has  a  dual  duty 
in  the  care  of  a  case  of  typhoid  fever:  one  is  to  assist  the  patient, 
the  other  is  to  protect  the  community.  On  the  other  hand,  the  people 
should  learn  the  lesson  that  a  case  of  typhoid  fever  should  be  regarded 
as  seriously  as  a  case  of  cholera.  These  two  diseases  present  many 
features  in  common.  Both  are  intestinal  infections  of  bacterial  na- 
ture; in  both  diseases  the  alvine  discharges  contain  the  microorgan- 
isms which  reinfect  another  person  when  taken  by  the  mouth.  Both 
diseases  prevail  especially  in  hot  weather,  both  diseases  are  peculiar 
to  man,  so  that  the  patient  is  the  fountainhead  of  each  infection. 
Water,  food,  fingers,  and  flies  play  a  similar  role  in  both  instances. 
In  the  case  of  cholera  the  dread  of  the  disease  is  an  important  factor 
in  keeping  it  out  of  the  country  or  in  preventing  its  spread  when  once 
introduced.  By  strange  contrast,  there  is  a  remarkable  indifference 
to  typhoid  fever.  A  wholesome  fear  of  typhoid  fever  would  materially 
assist  the  health  authorities  in  combating  what  may  be  considered 
one  of  the  greatest  health  problems  of  the  age.  From  the  standpoint 
of  preventive  medicine,  it  is  proper  to  regard  an  outbreak  of  typhoid 
fever  as  a  reproach  to  the  sanitation  and  civilization  of  the  community 
74 


TYPHOID    FEYEE  75 

in  which  it  was  contracted.  When  the  matter  is  better  nnderstood  health 
authorities  will  be  held  responsible  for  this  and  other  preventable  infec- 
tions, just  as  some  one  is  now  held  responsible  for  preventable  accidents. 

Much  harm  has  been  done  by  insisting  that  typhoid  fever  is  in- 
fectious^ but  not  contagious;  it  is  both — ^that  is,  communicable.^ 

Typhoid  fever  occurs  both  in  endemic  and  epidemic  forms.  It 
may  truly  be  regarded  as  pandemic.  Xormally,  typhoid  fever  is  a 
warm  weather  disease.  It  recurs  as  an  annual  crop  from  July  to  Octo- 
ber.- Epidemics  caused  by  infected  water  occur  especially  in  the 
early  spring,  late  fall,  or  winter  months.  Milk  outbreaks  may  occur 
at  any  time  of  the  year.  Autumnal  typhoid  in  our  cities  is  due  partly 
to  infection  contracted  at  health  resorts,  and  has,  therefore,  been  called 
a  vacation  disease. 

Typhoid  fever  is  more  prevalent  in  rural  districts  than  in  cities. 
In  the  United  States  there  is  more  typhoid  fever  in  the  southern 
states  than  in  the  northern  zone.  The  only  explanation  to  account 
for  this  is  the  influence  of  temperature,  rural  conditions,  and  asso- 
ciation with  the  negro.  Typhoid  fever  is  no  respecter  of  rich  or  poor; 
it  attacks  those  in  robust  health,  all  ages,  both  sexes. 

Typhoid  fever  is  a  disease  which  ordinarily  attacks  the  individual 
during  the  period  of  greatest  economic  value  to  the  community.  The 
economic  loss,  therefore,  is  appalling,  and  has  been  estimated  to  reach 
the  sum  of  no  less  than  $100,000,000  annually  in  the  United  States. 
Again,  typhoid  fever  is  an  infection  against  which  the  individual* alone 
cannot  protect  himself  wholly   without   the   aid  of  the  community. 

Prevalence. — Typhoid  fever  prevails  more  or  less  in  all  countries — 
the  amount  of  the  disease,  however,  varies  greatly.  It  appears  to  be 
a  disease  of  defective  civilization,  for  those  communities  paying  least 
attention  to  sanitation,  as  a  rule,  suffer  most.  In  the  United  States 
there  are  comparatively  few  communities  of  1,000  inhabitants  or  more 
which,  during  any  period  of  twelve  consecutive  months  within  the  last 
decade,  have  been  entirely  free  from  typhoid  fever.  According  to  the 
United  States  census  report  for  1900,  the  average  typhoid  death  rate 
in  the  United  States  was  46.5  per  100,000  inhabitants.  In  1908  the 
death  toll  from  typhoid  fever  was  no  less  than  35,000  in  the  United 
States.  In  other  words,  one  person  in  about  200  in  the  United  States 
contracted  tv'phoid  fever  that  year.  It  is  estimated  that  in  1910-11  the 
number  of  deaths  was  reduced  to  about  25,000.  The  seriousness  of 
these  figures  may  be  judged  by  estimating  the  probable  number 
of  cases  of  typhoid  fever  among  persons  handling  the  milk  supply. 
Take,  for  instance,  a  city,  as  Washington,  receiving  its  milk  from  a 


^  For  distinction  between  these  terms  see  page  317. 

^  In  the  southern  hemisphere  the  typhoid  season  is  during  our  winter. 


76 


DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 


thousand  dairy  farms.  On  the  average  there  will  be  about  four  per- 
sons on  each  farm  who  in  one  way  or  another  come  in  contact  with 
the  milk.  That  makes  4,000  persons  among  whom  about  200  cases  of 
typhoid  may  be  expected  to  occur  annually.  No  wonder  that  milk- 
borne  outbreaks  of  typhoid  fever  are  common  occurrences. 

The  rate  of  prevalence  of  typhoid  fever  in  the  United  States  in 
comparison  with  the  rates  of  many  other  countries  is  very  high.  Thus, 
the  annual  death  rate  from  typhoid  fever  per  100,000  population  for  the 
period  1901-1905  was:  in  Scotland,  6.2;  in  Germany,  7.6;  in  England 
and  Wales,  11.2;  in  Belgium,  16.8;  in  Austria  (1901-1904),  19.9;  in 
Hungary,  28.3 ;  in  Italy,  35.2 ;  while  the  rate  in  the  United  States  during 
the  same  period  was  about  46.5. 

A  comparison  between  the  prevalence  of  typhoid  fever  in  this 
country  and  abroad  is  impressive.  The  following  ten  European  cities 
with  a  total  population  of  about  15,000,000  have  an  average  typhoid 
rate  of  2.4  per  100,000  during  the  10  years  1901-10 1^ 


ANNUAL    DEATH  RATES   FROM  TYPHOID  FEVER  PER  100,000   POPULATION    IN    10 

EUROPEAN  CITIES 


Average 

for  10 

years, 

1901-1910 

Average 

for  5 

years, 

1901-1905 

1906 

1907 

1908 

1909 

1910 

1.7 
2.4 
2.5 
2.9 
3.7 
3.7 
3.8 
4.2 
4.5 
4.7 

3 
3 
4 

8 
4 

4 
4 
4 
8 
8 

2 
4 
2 
3 
5 
4 
4 
7 
4 
6 

2 
2 
3 
3 
3 
3 
4 
2 
2 
4 

1 
2 
3 
2 
4 
4 
4 
6 
7 
5 

5 

1.7 

1.9 

1.2 

2.8 

3.3 

4.2 

4.2 

2.7 

2.2 

1.8 

1.6 

1  4 

.3 

3  8 

4  1 

2  9 

2.2 

Copenhagen 

3.6 
3  3 

The  following  fifteen  European  cities  with  a  population  of  about 
9,000,000  had  a  typhoid  death  rate  of  5.3  per  100,000  in  1909  and 
only  4.5  in  1910 : 


'These  facts  and  the  following  instructive  tables  are  taken  from:  "The 
Necessity  of  a  Safe  Water  Supply  in  the  Control  of  Typhoid  Fever,"  by  Allan 
J.  McLaughlin,  U.  S.  Pub.  Health  lieports,  XXVII,  12,  March  22,  1912. 


TYPHOID    FEVER 


77 


ANNUAL  DEATH  RATES  FROM  TYPHOID   FEVER  PER   100,000  POPULATION    IN   15 
OTHER  EUROPEAN  CITIES 


City 

1909 

1910 

1.5 
1.0 
2.8 
,     2.6 
5.0 
5.2 
5.8 
7.2 
8.4 
9.4 
6.4 
3.8 
8.4 
4.3 
8.3 

0.9 

» 

2.3 

2.1 

3.9 

Belfast  

3.9 

4.4 

3.8 

3.9 

Sheffield                   

3.0 

6.5 

6.7 

5.6 

9.2 

7.5 

5.3 

4.5 

The  following  eight  European  cities  with  a  total  population  of 
7,500,000  had  a  typhoid  death  rate  of  13.9  in  1909  and  15.6  in  1910. 
These  rates  would  be  considered  low  in  America,  but  the  European 
officials  consider  the  persistence  of  such  rates  to  be  a  reflection: 


ANNUAL  DEATH  RATES  FROM    TYPHOID   FEVER    PER    100,000   POPULATION    IN    8 
OTHER  EUROPEAN   CITIES 


City 

1909 

1910 

12.5 
9.4 
7.4 
15.7 
13.9 
13.8 
13.5 
25.2 

6.4 

13.6 

16.1 

Dublin 

12.2 

10.3 

15.0 

17.4 

33.7 

13.9 

15.6 

To  recapitulate,  in  northern  Europe  the  33  principal  cities,  with 
an  aggregate  population  of  31,500,000,  had  an  average  typhoid  death 
rate  per  100,000  population  of  6.5  in  1909  and  1910.  This  includes 
such  notorious  typhoid  centers  as  St.  Petersburg,  which  had  a  rate  of 
33.7  in  1910.  The  rate  in  St.  Petersburg  is  considered  to  be  due  to 
the  water  supply,  which  is  partly  filtered  and  partly  raw  ISTeva  water. 

Let  us  now  compare  these  rates  with  typhoid  fever  in  America: 


78        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 


ANNUAL  DEATH  RATES  FROM  TYPHOID  FEVER  PER  100,000  POPULATION   IN   50 
CITIES  OF  THE  UNITED  STATES  HAVING  MORE  THAN   100,000   INHABITANTS 


City 


Birmingham,  Ala.  .  . 
Los  Angeles,  Cal. . .  . 

Oakland,  Cal 

San  Francisco,  Cal. . 

Denver,  Colo 

Bridgeport,  Conn. .  . 
New  Haven,  Conn. . 
Washington,  D.  C.  . 

Atlanta,  Ga 

Chicago,  111 

Indianapolis,  Ind.  .  . 

Louisville,  Ky 

New  Orleans,  La.  .  . 

Baltimore,  Md 

Boston,  Mass 

Cambridge,  Mass. .  . 
Fall  River,  Mass .  .  . 

Lowell,  Mass 

Worcester,  Mass..  .  . 

Detroit,  Mich 

Grand  Rapids,  Mich 
Minneapolis,  Minn 

St.  Paul,  Minn 

Kansas  City,  Mo.  .  . 

St.  Louis,  Mo 

Omaha,  Nebr 

Jersey  City,  N.  J.  .  . 

Newark,  N.J 

Paterson,  N.  J 

Albany,  N.  Y 

Buffalo,  N.  Y 

New  York,  N.  Y .  .  . 

Rochester,  N.  Y 

Syracuse,  N.  Y 

Cincinnati,  Ohio..  .  . 
Cleveland,  Ohio.  .  .  . 
Columbus,  Ohio.  .  .  . 

Dayton,  Ohio 

Toledo,  Ohio 

Portland,  Oreg 

Philadelphia,  Pa 

Pittsburgh,  Pa 

Scranton,  Pa 

Providence,  R.  I..  .  . 
Memphis,  Tenn.  .  .  . 
Nashville,  Tenn .... 

Richmond,  Va 

Seattle,  Wash 

Spokane,  Wash 

Milwaukee,  Wis.  .  .  . 


These  50  registration  cities  in  the  United  States  have  an  aggregate 
population  of  over  20,000,000.  The  average  typhoid  death  rate  in 
these  cities  for  1910  was  25  per  100,000  inhabitants. 


TYPHOID    FEVER 


79 


Unit  of  comparison 

Aggregate 
population 

Deaths  per 
100,000  from 

typhoid 
fever,  1910 

33  principal  European  cities  in  Russia,  Sweden,  Norway,  Austria- 
Hungary,  Germany,  Denmark,  France,  Belgium,  Holland,  Eng- 
land, Scotland,  and  Ireland 

31,500,000 
20,250,000 

6  5 

50  American  cities  of  100,000  inhabitants  or  over 

25.0 

Excess  of  deaths  from  typhoid  fever  in  American  cities 

18.5 

The  excess  of  18  deaths  per  100,000  in  the  urban  population  alone 
shows  that  we  have  had,  in  the  50  cities  mentioned  above,  at  least  3,600 
deaMis,  and  probably  36,000  cases  of  typhoid  fever,  which  were  pre- 
ventable and  should  never  have  occurred.  For  the  whole  United  States 
the  number  of  cases  for  each  year  readily  preventable  by  methods  within 
our  grasp  would  probably  reach  175,000,  and  the  deaths  so  avoided  would 
total  about  16,000.  In  1909  there  were  more  cases  of  typhoid  fever 
in  the  United  States  than  there  were  cases  of  plague  in  India,  in 
spite  of  the  fact  that  India's  population  is  two  and  one-half  times  that 
of  the  United  States. 


180 
160 


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rTRA 

TION 

Fig.  10. — Curve   Showing  Death  Rate  from  Typhoid  Fever  in  Albany  before 

AND    AFTER    FILTRATION    OF    WaTER.       (WHIPPLE.) 

Eesidual  or  "Normal"  Typhoid. — When  a  city  such  as  Albany, 
Chicago,  Lawrence,  Lowell,  or  Pittsburg,  which  has  been  using  grossly 
polluted  water,  is  furnished  with  a  water  supply  of  good  sanitary 
quality,  there  at  once  results  a  marked  reduction  in  the  amount  of 
typhoid  fever.  The  curve  is  not  only  lowered,  but  changed  in  char- 
acter   (Fig.    10 — Albany).      The   remaining   typhoid   after  the  water- 


80        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

borne  infection  has  been  removed  is  known  as  residual  typlioid,  and 
the  curve  in  such  cases  is  spoken  of  as  the  "normal"  typhoid  curve. 
The  normal  curve  shows  a  distinct  summer  prevalence  recurring  with 
marked  regularity  each  year,  and  lacks  the  great  irregularities  which 
characterize  the  curve  of  a  community  drinking  badly  infected  water. 
Normal  typhoid  is  endemic  typhoid;  Sedgwick  has  proposed  the  name 
'"prosodemic"  {proso,  through,  and  demos,  the  people)  as  more  ex- 
pressive of  this  type  of  the  disease.  The  amount  of  residual  typhoid 
varies  markedly  in  different  localities;  thus  it  is  twice  as  high  in  the 
southern  as  in  the  northern  part  of  our  countiy;  it  is  much  greater 
here  than  in  most  parts  of  Europe. 

Channels  of  Entrance  and  Exit. — The  typhoid  bacillus  probably  al- 
ways enters  by  the  mouth.  Typhoid  fever  is  generally  regarded  as 
primarily  a  gastrointestinal  infection,  although  the  disease  itself  is 
not  produced  unless  the  blood,  glands,  and  other  structures  of  the 
body  are  invaded  with  the  specific  microorganism.  The  typhoid  bacil- 
lus grows  and  multiplies  in  the  intestinal  tract,  penetrates  the  mu- 
cosa, and  thus  invades  the  body.  The  bacillus  leaves  the  body  mainly 
in  the  feces  and  urine,  occasionally  in  the  sputum  and  other  discharges. 
Typhoid  bacilli  appear  in  the  feces  early  in  the  disease;  sometimes  be- 
fore the  fever.  Later  in  the  disease  they  diminish  in  number  and 
usually  disappear  during  convalescence,  although  they  may  continue  in- 
definitely (see  "Bacillus  Carriers,"  page  83).  The  feces  may  contain 
only  a  few  typhoid  bacilli ;  usually  they  are  present  in  consid- 
erable numbers;  occasionally  they  occur  almost  in  pure  culture,  prac- 
tically replacing  the  colon  bacillus. 

Typhoid  bacilli  commonly  appear  in  the  urine  about  the  second, 
third,  or  fourth  week.  They  grow  well  in  this  fluid  both  within  and 
without  the  body,  and  may  be  present  in  such  enormous  numbers  that 
the  urine  resembles  a  24-hour-old  bouillon  culture.  From  the  stand- 
point of  prevention,  it  is  very  important  not  to  neglect  the  virus  in 
the  urine.  Urotropin  (hexamethylenamin)  in  ten-grain  doses  or  more 
three  times  a  day  diminishes  the  frequency  of  typhoid  bacilluria,  and  is 
also  effective  in  curing  this  condition  when  once  established. 

The  sputum  ordinarily,  does  not  contain  the  bacilli  unless  there  is 
a  pneumonia  or  severe  bronchitis.  The  bacilli  may  be  eliminated  with 
the  discharges  from  abscesses,  such  as  periostitis,  months  and  even  years 
after  the  disease. 

Diagnosis.' — An  early  diagnosis  of  typhoid  fever  is  important  not 
only  for  the  successful  treatment  of  the  patient,  but  is  of  vital  impor- 
tance in  controlling  the  spread  of  the  infection.  The  early  diagnosis 
can  only  be  assured  tlirough  laboratory  methods.  Typhoid  bacilli 
may  be  isolated  either  from  the  blood  or  the  feces. 

Blood  Cultures. — Probably  the  easiest  method,  as  well  as  the  one 


TYPHOID    FEVER  81 

giving  the  maximum  information,  is  through  blood  cultures.  The  tak- 
ing of  a  little  blood  for  this  purpose  is  no  more  difficult  or  annoying 
to  the  patient  than  swaljbing  the  throat  for  diphtheria.  A  few  drops 
of  blood  may  be  obtained  by  puncturing  the  lobe  of  the  ear  or  the 
finger,  with  the  usual  precautions  to  prevent  bacterial  contamination. 
A  much  better  method,  however,  consists  in  withdrawing  5  to  10  c.  c. 
of  blood  by  means  of  a  syringe  from  one  of  the  veins  at  the  bend  of 
the  elbow.  The  technique  is  very  simple,  and,  if  the  needle  is  sharp, 
the  patient  scarcely  feels  the  puncture.  In  fact,  if  the  attention  of 
the  patient  is  distracted  a 'skillful  operator  can  withdraw  10  c.  c.  of 
blood  in  this  way  before  the  patient  is  aware  that  anything  has  been 
done.  The  blood  may  be  planted  in  bouillon,  or,  better,  in  bile.  After 
24  hours  in  the  incubator,  any  growth  that  occurs,  is  transplanted  to 
other  media,  a  pure  culture  obtained,  and  tested  for  agglutination. 
Usually  a  pure  culture  is  obtained  in  the  first  medium,  so  that  the  diag- 
nosis may  be  established  in  2-1  hours — at  most,  2  or  3  days. 

Typhoid  bacilli  appear  in  the  blood  early  in  the  disease,  perhaps 
occasionally  during  the  prodromal  symptoms.  Kayser  obtained  posi- 
tive results  from  90  per  cent,  in  the  first  week,  65  per  cent,  in  the 
second,  42  per  cent,  in  the  third,  35  per  cent,  in  the  fourth.  Our 
results  in  Washington  were  approximately  the  same.  The  typhoid 
bacilli  probably  do  not  gi'ow  in  the  blood  during  life.  Their  presence 
in  the  blood  stream  represents  an  overflow  from  the  spleen  and  lym- 
phatic tissues.  The  presence  of  typhoid  bacilli  in  the  blood  may  be 
taken  to  mean  typhoid  fever.  The  same  cannot  always  be  said  if 
found  in  the  feces  or  urine. 

The  FECES.^From  the  feces  or  urine  typhoid  bacilli  are  best 
isolated  upon  Endo's  medium.  This  consists  of  a  4  per  cent,  alkaline 
agar  containing  fuchsin,  which  has  been  decolorized  with  sodium  sul- 
phite. Upon  the  surface  of  this  medium  typhoid  colonies  appear  in 
24  hours  as  translucent,  dewdrop-like  colonies,  whereas  colon  bacilli 
and  other  organisms  that  produce  acid  and  split  the  fuchsin  appear 
as  red  colonies.  Suspicious  colonies  are  fished  and  may  be  tested  at 
once  under  the  microscope  for  agglutination,  or  may  be  planted  in 
bouillon  to  obtain  a  growth  sufficient  for  macroscopic  agglutination 
tests.  In  any  critical  case  pure  cultures  should  be  obtained  and  studied 
for  morphological,  cultural,  and  other  biological  characters.  A  modi- 
fied Endo's  medium  and  a  rapid  technique  for  diagnostic  purposes, 
described  by  Kendall  and  used  with  success  in  my  laboratory,  are  sum- 
marized  as  follows : 

Technique. — Make  plain,  nutrient,  sugar-free  agar  as  follows :  Tap 
water  (cold),  one  thousand  cubic  centimeters;  powdered  agar,  fifteen 
grams;  peptone  (Witte),  ten  grams;  meat  extract  (Liebig),  three 
grams.     Oook  in  double  boiler  one  hour.     Make  the  reaction  just  al- 


82        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

kuline  to  litimis  by  the  cautious  addition  of  NaOH.  Cook  fifteen 
minutes  to  set  the  reaction,  and  then  liltcr  throui^di  absorbent  cotton. 

Tlie  tap  water  should  be  as  cold  as  possible  and  the  agar  should  be 
"dusted""  on  the  surface  and  allowed  to  settle  into  the  medium  before 
heat  is  applied  and  before  the  other  ingredients  are  added. 

After  filtrati(m,  the  medium  is  stored  in  flasks  containing  known 
amounts,  conveniently  in  one  hundred-cubic-centimeter  lots,  and  steril- 
ized in  the  autoclave. 

To  use  the  medium:  (a)  Prepare  a  ten  per  cent,  solution  of  fuch- 
sin  in  ninety-six  per  cent,  alcohol,  (b)  Prepare  a  ten  per  cent,  solu- 
tion of  sodium  sulphite  in  water. 

Add  one  cubic  centimeter  of  (a)  to  ten  cubic  centimeters  of  (b) 
and  heat  in  the  Arnold  sterilizer  for  twenty  minntes=(c). 

Add  one  per  cent,  of  lactose  (which  must  be  chemically  pure)  to 
the  agar  medium  described  above,  and  heat  in  the  Arnold  sterilizer 
until  the  medium  is  melted  and  the  lactose  thoroughly  distributed  in 
it.  The  decolorized  fuchsin  solution  (c)  is  then  added  in  the  pro- 
portion of  one  cubic  centimeter  of  the  mixture  to  each  one  hundred 
cubic  centimeters  of  medium;  then  thoroughly  mixed. 

Plates  are  then  poured  and  allowed  to  harden  (with  the  covers 
removed)  in  the  incubator  for  thirty  minutes,  after  which  time  they 
are  ready  for  inoculation. 

Preparation  of  Feces  for  Inoculntion. — The  feces  are  collected 
preferably  in  the  small  rectal  tubes  described  by  Kendall.^  A  small 
portion  of  feces  (about  a  loopful)  is  thoroughly  emulsified  in  ten  cubic 
centimeters  of  sugar-free  broth,  and  preferably  incubated  one  hour  at 
37°  C.  prior  to  the  inoculation  of  the  ])lates.  This  preliminary  in- 
cubation does  two  things :  the  clumps  of  bacteria  settle  down,  leaving 
a  more  uniform  suspension  of  bacteria  in  the  supernatant  fluid  for 
inoculation,  and  the  bacteria  undergo  a  slight  development  in  a  medium 
particiilarly  suited  for  their  growth.  The  thin  suspension  of  the  stool 
is  now  rubbed  upon  the  surface  of  the  agar  plates  by  means  of  a  bent, 
sterile,  glass  rod,  and  the  plates  incubated  for  18  hours  at  37°  C.  The 
suspicious  translucent,  colorless  colonies  are  removed  entire  to  small 
test-tubes  containing  one  cubic  centimeter  of  broth  and  incubated  for 
two  hours  at  37°  C.  At  the  end  of  this  time  there  will  bq  sutlicient 
growth  to  make  the  customary  microscopic  agglutination  tests.  Con- 
firmatory cultural  characters  may  be  obtained  by  inoculating  suitable 
media  from  the  same  tubes  as  those  from  which  the  organisms  for 
agglutination  were   obtained. 

Physicians  should  encourage  boards  of  health  to  furnish  diagnostic 
aids  of  a  laboratory  nature.     Such  work   should  be  in  the  hands   of 
^Boston  Med.  and  Surg.  Jour.,  CLXIY,  No.  1,  Sept.,  1911. 


TYPHOID    FEVEE  83 

specialists  rather  than  entrusted  to  those  who  make  occasional  anal- 
yses. Early  and  accurate  diagnosis  is  just  as  important  to  prevent  the 
spread  of  other  communicable  diseases  as  it  is  with  typhoid.  These 
facts  emphasized  here  will  not  be   repeated  under  each   disease. 

Bacillus  Carriers. — In  about  4  per  cent,  of  all  cases  of  typhoid 
fever  the  patient  continues  to  shed  typhoid  bacilli  in  the  urine  or 
feces  during  and  after  convalescence.  Some  persons  shed  typhoid  bacilli 
without  a  clinical  history  of  having  had  the  disease.  We  therefore 
recognize  three  kinds  of  carriers :  acute^  chronic,  and  temporary.  An 
acute  typhoid  bacillus  carrier  continues  to  discharge  the  infection  not 
longer  than  6  weeks  follov/ing  convalescence.  A  chronic  carrier  con- 
tinues to  discharge  the  bacilli  6  weeks  or  longer.  A  temporary  carrier 
is  a  person  who  has  not  had  clinical  typhoid  fever  but  who  discharges 
typhoid  bacilli  for  a  short  period.  Albert  states  that  25  per  cent,  of  all 
chronic  typhoid  carriers  have  never  had  typhoid  fever;  and  further 
estimates  that  one  in  every  1,000  of  the  general  population  is  a  carrier. 

While  it  would  seem  that  typhoid  bacilluria  should  be  especially 
dangerous,  a  study  of  the  cases  indicates  that  most  of  the  outbreaks 
that  have  been  traced  have  been  due  to  carriers  who  discharge  the 
organisms  in  their  feces  rather  than  in  the  urine.  It  seems  that 
typhoid  carriers  are  more  dangerous  in  certain  seasons.  More  cases 
are  traced  to  women  ^  than  to  men.  This  is  probably  owing  to  the 
fact  that  the  chief  danger  lies  in  handling  foodstuffs,  so  that  a  carrier 
occupied  as  a  cook  or  waitress  is  a  special  menace. 

The  question  of  preventing  the  spread  of  the  disease  through  bacil- 
lus carriers  is  important  and  difficult.  Surgical  methods  fail  to  cure 
carriers,  for  the  typhoid  bacillus  may  continue  to  grow  in  other  parts 
of  the  intestinal  tract  than  the  gall  bladder.  Medical  measures,  such  as 
urotropin,  are  efficient  for  bacilluria,  but  are  of  no  avail  in  the  fecal 
carriers.  Attempts  have  been  made  to  relieve  the  condition  by  the  use 
of  bacterial  vaccines.  Petruschky  -  and  also  Meader  have  reported  en- 
couraging results,  especially  with  the  use  of  autogenous  cultures.  So 
far  certain  cases  resist  all  attempts  to  relieve  the  condition.  It  is  unnec- 
essary to  place  bacillus  carriers  incommunicado.  It  is  sufficient  to  re- 
strict their  activities  so  that  they  may  neither  infect  food  nor  their  sur- 
roundings. With  proper  care  and  cleanliness  typhoid  carriers  may  pre- 
sent little  danger  to  their  fellow  men.  The  problem,  at  present,  is  to 
detect  the  carriers,  so  as  to  establish  a  sanitary  isolation,  if  not  an 
actual  quarantine.^ 

Resistance  of  the  Virus.- — The  typhoid  bacillus  has  no  spore.     It  is, 

therefore,  comparatively  easy  to  destroy.     The   only  difficulty  present- 

^  Women  are  more  subject  to  gall-stones. 
""Deut.  med.  Wochschr.,  July  11,  1912,  XXXVIII,  28. 

^  The  facts  covering  the  infectivity  of  carriers  are  summed  up  by  Ledingham, 
39th  An.  Eeport  Local  Gov.  Board,  1909-10,  Supplement,  p.  249. 


84        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

ing  itself  is  getting  at  the  bacillus  Avlien  imbedded  in  fecal  masses. 
Wlien  dry,  most  typhoid  bacilli  die  in  a  few  hours;  occasionally  a 
few  survive  for  months.  The  fact  that  typhoid  bacilli  are  killed  by 
drying  renders  infection  through  dust  unlikely. 

When  a  moist  medium,  such  as  water,  milk,  or  urine,  is  lieated  to 
60°  C,  practically  all  the  typhoid  bacilli  such  a  medium  may  contain 
are  killed.  An  exposure  at  (50°  C.  for  20  minutes  will  surely  kill  all 
of  these  microorganisms.  They  are  not  destroyed  by  freezing  (see 
"Relation  to  Ice,"  pages  837  et  seq. 

Jn  their  resistance  to  germicides  tyi)hoid  bacilli  behave  like  the 
average  non-spore-bearing  bacilli.  Thus  bichlorid  of  mercury,  1- 
1,000,  phenol,  2i/2  per  cent.,  formaldehyde,  10  per  cent.,  are  effective 
upon  the  naked  germs.  In  order  to  kill  the  typhoid  bacilli  in  feces 
special  precautions  or  stronger  solutions  are  necessary   (see  page  1030). 

The  viability  of  typhoid  bacilli  in  feces  is  very  variable,  depending 
on  the  composition  of  the  feces  and  the  varieties  of  other  bacteria 
present.  Sometimes  the  typhoid  bacilli  in  feces  perish  in  a  few  hours, 
usually  in  a  day;  under  exceptional  circumstances  they  may  live  for 
much  longer  periods.  In  the  Plymouth  epidemic  typhoid  bacilli  prob- 
ably remained  alive  and  virulent  in  the  feces,  exposed  to  the  winter's 
cold,  for  several  months.  Levy  and  Kayser  found  they  remained  alive 
in  feces  for  5  months  in  the  winter.  The  life  of  the  organism  in 
privies  and  in  water  is  usually  comparatively  short.  In  nature  they 
die,  as  a  rule,  in  water  in  about  7  days  and  often  after  48  hours.  They 
probably  live  longer  in  clean  water  than  in  contaminated  water.  In 
the  outer  world  symbiosis  plays  an  important  part,  also  the  presence 
of  deleterious  chemicals,  temperature,  light,  desiccation,  dryness,  and 
other  factors  known  to  be  injurious  to  spore-free  bacteria.  As  a  rule, 
the  typhoid  bacillus  does  not  survive  long  in  the  soil  under  the  usual 
conditions. 

Typhoid  Bacillus  in  Nature.' — The  typhoid  bacillus  should  be  re- 
garded as  a  pathogen,  not  as  a  saprophyte.  It  lives  and  grows  prin- 
cipally in  the  human  body.  It  has  a  tendency  to  die  in  water,  air, 
soil,  upon  fomites,  or  in  nature  generally.  The  grand  exception  to 
this  statement  is  in  the  case  of  milk,  in  which  the  typhoid  bacillus 
grows  well. 

The  typhoid  bacillus  is  much  more  widely  distributed  in  man  than 
the  cases  indicate.  Thus,  in  the  District  of  Columbia,  of  1,000  healthy 
persons  examined  during  the  typhoid  season  of  1908,  typhoid  bacillus 
was  found  in  the  feces  in  3  instances.  At  least  one  and  perhaps  two  of 
these  individuals  were  regarded  as  temporary  carriers.  In  each  instance 
the  organisms  were  found  only  once.  The  population  of  the  District  of 
Columbia  in  1908  was  300,000,  and  at  the  ratio  of  1  per  1,000  this 
would   represent  about   300   healthy   persons   in   that    community   har- 


TYPHOID   FEVER:  1902    TO    1906 
Death  Rate  per  100,000  of  Population 


'Richmon6  borough.K.y. 

Su«nst»rouflh.flf.». 

camien.ar.J. 


5outti3en6,ln6. 
San  Anfonio.  Taos 
^flyaTinah.Ga. 


Meu)  Orleans,  Ua. 
Covington. Ky. 
Ricfjmon6.Ua. 
LouisuiUc.Ky. 
AHant-d,Ga. 


ciTy 


Lincotn;Cct>r. 
Payton.Ohlo 
Memphis,  T£nn 


weioton.Mass. 
rorHi)atfne,ln& 


Sfattle.Wosh. 
EuansuilU.ln6. 
Springfield,  111. 
Gran6'Rap\6s,«icfe. 
li)ilminai-on,Del. 
Uancasrer.Pa. 
Harrisburg.  Pa. 
li)tif{litio.u).Vd, 


Mmneapolis.Minn. 
ToU6o,Ohio 
Cincinnati, Ohio 
Ph\la6elphia,Pa. 
AUegticny.Pa. 


Chester 


RochesterA'.y. 

Suracuse,j;.y. 

Fall  River,<Hass. 

BrocKton.Mass. 

Taunton.Mass. 

Maverhill.aass. 

PorHan6,(Hc. 

Salfin.Mass. 


MilwauKec  U)is. 
Pctroit.Mich. 
Chicago,  II  I. 
Buffalo, «.«. 
Erie,  Pa. 
Cleuclan6,Ohio 
Puluth,Mmn. 


am 


Btchburg.^ass. 

carabri6ae,Ma5s. 

5omeTuine,Mass. 

Worcester,  Mass. 

Bri6acport,Conn. 

>larfTor6,Conn. 

nal6en.Mas5. 

Boston,  aass. 

Chelsea  Mass. 

Wtu)Be6for6,(Hass. 

lOaterbury  Conn. 


Scranf  on. Pa. 
Porllan6.0rcg. 
Johnstown.Pa. 
AUoona.Pa. 


KolyoKc.^lass. 
Bronx  borougd. (ST. y. 
ilanliaUan  forough.JT.y, 
Pawtucket.n.i. 

JerscuCily,Sf.3. 
BaUimon-  MA 


St.Pttul.iniun. 
(Tanton.Ohio 
Broohlyn  toxoush.X.M. 
Columtius.Ohio 


PETERS  CO.,  WASttli 


Fig.  11. — Influence  of  Public  Water  Supplies  on  the  Typhoid  Fever  Death  Rate. 
(Diagram  prepared  by  Marshall  O.  Leighton,  U.  S.  Geological  Survey,  from  figures 
furnished  by  Dr.  Cressy  L.  Wilbur,  Chief  Statistician  of  Vital  Statistics,  Bureau 
of  the  Census — from  Kober.) 

8  85 


86         DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

boring  and  shedding  typhoid  bacilli  for  a  brief  period  of  time  during 
the  typhoid  season. 

Modes  of  Spread. — Typhoid  fever  is  spread  either  by  direct  or  in- 
direct contact — indirectly  through  water,  milk,  and  other  foods;  through 
"contacts,"  and  also  flies,  fingers,  and  fomites.  Each  of  these  modes 
of  spread  needs  separate  consideration. 

Water. — Water-borne  typhoid  is  a  common  occurrence.  Xot  long 
ago  it  was  regarded  as  the  sole  or  usual  mode  of  spread;  now  we  know 
that  this  was  a  mistake.  Most  fecal  matter  ultimately  finds  its  way 
to  water;  most  water  courses  draining  inhabited  regions  are  contam- 
inated with  human  feces.  Surface  water  is,  therefore,  apt  to  contain 
typhoid  bacilli.  The  fact  that  there  may  be  no  clinical  case  of  typhoid 
fever  in  the  drainage  area  is  no  guarantee  that  the  water  may  not  be 
infected — in  view  of  the  prevalence  of  missed  cases  and  bacillus  car- 
riers. 

Fortunate]}'',  typhoid  bacilli  do  not  grow  and  multiply  in  water 
under  natural  conditions.  They  usually  die  in  a  few  days,  and  rarely 
persist  longer  than  T  days.  They  succumb  more  quickly  in  some  waters 
than  others,  more  quickly  in  summer  than  winter.  Thus  Reudiger  ^ 
has  shown  that  typhoid  bacilli  die  less  quickly  in  the  Red  Lake  River 
in  ^Minnesota  when  exposed  in  dialyzing  membranes  in  the  river  with 
ice  than  in  the  open  river.  He  also  showed  that  colon  bacilli  as  well 
as  typhoid  bacilli  disappear  much  more  rapidly  from  polluted  water 
during  the  summer  months  than  during  the  winter  months  when  the 
river  is  protected  with  a  covering  of  ice  and  snow.  Reudiger  considers 
that  the  destruction  of  the  typhoid  bacillus  in  river  water  during 
the  summer  months  is  in  a  large  measure  due  to  the  growth  of  micro- 
scopic plants,  and  other  organisms  which  give  off  dialyzable  substances 
which  are  harmful  to  B.  tj/phosiis.  One  of  the  reasons  for  believing 
in  the  existence  of  such  poisons  in  water  is  the  fact  that  typhoid  cul- 
tures in  a  collodion  sac  placed  in  water  die  more  quickly  than  other- 
wise. Further,  the  effect  of  the  direct  rays  of  the  sun  are  entirely 
lost  when  the  river  is  covered  with  ice  and  snow. 

Water  plays  a  large  but  diminishing  role  in  the  spread  of  the 
typhoid  bacillus.  The  great  water-borne  epidemics  have  overshad- 
owed the  other  media  of  communication.  We  know  that  the  larger 
part  of  the  typhoid  now  prevalent  in  tliis  country  is  not  water-borne; 
Whipple  in  1908  estimated  it  at  35  per  cent. ;  it  is  now  no  doubt  much 
less.  Typhoid  fever  may  be  excessively  prevalent,  even  epidemic,  in 
a  city  having  a  water  supply  of  good  sanitary  quality. 

In  the  vast  majority  of  cases  water-borne  typhoid  is  contracted 
from  a  surface  supply,  that   is,  a   river,  small  stream,  pond,  or  lake. 

Wour.  Am.  Puh.  Health  Ass.,  June,  1911,  Vol.  I,  No.  16,  p.  411. 


TYPHOID    FEVER 


87 


Ground  water  becomes  a  source  of   clanger  onh'  under  special  condi- 
tions (see  chapter  on  water). 

Water-borne  epidemics  present  certain  definite  characteristics.  They 
almost  always  occur  in  the  spring,  fall,  or  winter,  when  the  water 
is  cold.  Most  of  the  great  water-borne  epidemics  have  occurred  in 
northern  cities,  both  in  this  country  and  in  Europe.  They  usually 
have  a  sharp  onset,  the  curve  rises  to  a  peak,  and  declines  rapidly. 
The  pollution  is  usually  nearby;  that  is,  there  is  a  rather  direct  trans- 
fer of  fresh  virulent  infection.  Granting  that  the  typhoid  bacillus 
does  not  grow  in  cold  water,  there  must  be  a  very  considerable  dilution 
in  most  of  the  epidemics. 


Pitt. 

JBURGH,  Pfl.  - 

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-Immediate  and  Striking  Effect  of  Purifying  a  Badly  Infected  Water 
Supply  upon  the  Typhoid  Situation. 


The  following  examples  are  given  of  the  fact  that  water-borne  out- 
breaks of  typhoid  fever  occur  during  the  winter,  fall,  or  early  spring, 
when  the  water  is  cold.  Thus  we  have  the  water-borne  epidemic  in 
Plymouth,  Penn.,  in  1885,  which  began  with  the  spring  thaw  and 
was  doubtless  produced  from  the  frozen  accumulation  of  typhoid  ex- 


88        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

crement  from  a  single  case.  Very  similar  to  the  Plymouth  outbreak 
was  that  at  Xew  Haven,  Conn.,  in  1901.  The  outbreak  at  Ithaca, 
X.  Y.,  started  in  epidemic  proportions  in  January,  The  epidemic 
in  Shorbourno,  England,  in  1873,  likewise  started  in  January.  Four 
acute  epidemic  exacerbations  are  recorded  in  Philadelphia  in  Decem- 
ber of  the  years  1884,  1890,  1899,  and  1903.  Several  similar  epi- 
demics have  occurred  in  the  winter  time  in  Chicago — one  in  January, 
1890,  another  in  January,  189(5,  and  one  in  March,  1891.  Another 
striking  instance  is  the  epidemic  in  Xewark.  X.  J.,  in  February,  1899, 
and  one  in  December,  1891.  Abroad,  epidemics  are  recorded  in  Ber- 
lin in  February,  1899,  in  Paris  in  February,  1894,  and  in  Vienna  in 
Xovember,  1888.  All  of  these  are  generally  believed  to  have  been 
water-borne  and  must  have  taken  place  when  the  water  was  very 
cold.  In  fact,  as  previously  pointed  out,  extensive  water-borne  epidemics 
of  typhoid  fever  rarely  occur  in  the  summer  time. 

The  epidemiology  of  water-borne  typhoid  caused  by  distant, 
diluted  and  attenuated  infection  is  not  understood.  It  was  formerly 
thought  that  a  high  typhoid  rate  necessarily  meant  badly  infected 
water.  We  know  now  that  this  does  not  necessarily  follow,  as  has  been 
proven  by  the  experiences  in  Washington,  Winnipeg,  army  camps,  and 
many  southern  cities. 

Almost  all  the  water-borne  epidemics  of  typhoid  fever  rest  upon 
circumstantial  evidence.  It  is  difficult  to  isolate  the  typhoid  bacillus 
from  water,  and  the  damage  is  usually  done  before  suspicion  points  to 
the  water.^ 

It  is  clear  that  in  cities  which  have  had  safe  water  supplies  for  a 
period  of  years  the  rate  should  not  be  above  5  per  100,000,  unless  some 
unusual  condition  exists,  such  as  poor  control  of  milk  or  lack  of  con- 
trol over  patients  and  carriers,  and  disregard  of  modern  sanitary  knowl- 
edge. 

Xo  single  measure  in  reducing  typhoid  fever  on  a  large  scale  ap- 
proaches the  effect  of  substituting  a  safe  for  a  polluted  water  supply. 
As  an  instance  of  this  wholesale  saving  of  human  life,  tlie  reduction  of 
typhoid  fever  in  four  American  cities  is  shown  in  Fig.  13,  p.  89. 

Ice. — Ice  may,  under  exceptional  circumstances,  occasionally  be  the 
vehicle  by  which  typhoid  bacilli  are  transferred.  Freezing  does  not 
kill  B.  typhosus,  but  there  is  a  great  quantitative  reduction  not  only 
in  the  act  of  freezing,  but  during  storage,  hence  the  danger  is  greatly 
lessened.  The  most  suggestive  outbreak  of  typhoid  fever  attributed  to 
ice  was  reported  by  Hutchins  and  Wlieeler  in  1903  in  the  St.  Law- 
rence Hospital,  three  miles  below  Ogdensburg.  A  few  other  instances 
in  which  ice  is  believed  to  have  conveyed  the  infection  have  been  re- 

*  Examples  of  Trater-borne  outbreaks  of  typhoid  fever  will  be  found  in  the 
chapter  on  water. 


TYPHOID    FEVER 


89 


ported,  but  are  based  upon  flimsy  evidence.  The  fact  that  natural 
ice  is  usually  stored  many  weeks  or  months  before  it  is  used  is  a  sani- 
tary safeguard.  Manufactured  ice  made  from  distilled  water  and 
handled  with  cleanly  methods  is  above  reproach.  For  a  discussion  of 
ice  in  relation  to  typhoid  fever  and  other  infections  see  page  840. 


Q          SO         4.0        6  0         80        lOO       120        140        |60       ISO       200         | 

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CtncinnaVu  Ohio. 

Fig.  13. — ^Abeupt  Reduction  in  Death  Rates  from  Typhoid  Feveh  Incident  to 
Water  Purification  in  Four  American  Cities. 

Milk. — Trask  collected  317  typhoid  epidemics  up  to  1908  caused 
by  infected  milk.  Since  then  many  more  instances  have  come  to  light. 
Doubtless  many  milk  outbreaks  have  escaped  attention  or  have  been 
attributed  to  water  or  other  sources.  The  typhoid  bacillus  grows  well 
in  milk,  and  it  is  now  realized  that  this  medium  is  a  frequent  and 
important  mode  of  communication.  Most  milk  outbreaks  are  reported 
either  in  England  or  America.  On  account  of  the  almost  universal 
custom  of  boiling  the  milk  in  European  and  tropical  countries,  milk 
outbreaks  are  rarely  reported  from  these  regions.  During  the  four  years' 
study  of  typhoid  fever  in  Washington,  it  was  found  that  at  least  10 
per  cent,  of  the  cases  were  milk-borne. 

The  milk  usually  becomes  contaminated  on  the  farm,  from  a  case 
or  a  carrier.  It  may  also  become  infected  in  transportation,  at  the 
city  dairy,  or  in  the  home.  Milk  outbreaks  come  abruptly,  rise  to  a. 
peak  like  a  water  epidemic,  and  subside  rather  sharply.  There  are 
comparatively  few  secondary  cases.  Milk-borne  epidemics  of  typhoid 
fever  have  certain  characteristics  which  permit  ready  recognition. 

(a)  There  is  a  special  incidence  of  the  disease  on  the  track  of  the 
implicated  milk  supply.     The  outbreak  is  localized  to  such  areas. 

(b)  The  better  class  of  houses  are  invaded,  and  persons  in  better  cir- 
cumstances generally  suffer  most. 


90        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

(c)  Those  who  drink  milk  are  chiefly  affected  and  those  suffer 
most  who  are  hirge  consumers  of  raw  milk. 

(d)  The  incidence  is  high  among  women  and  children. 

(e)  The  incubation  period  is  shortened  perhaps  on  account  of  the 
large  amount  of  infection  taken. 

(f)  More  than  one  case  occurs  simultaneously  in  a  house.  This 
is  a  very  suspicious  circumstance  to  the  epidemiologists.  The  first  in- 
dication of  a  milk  outbreak  in  a  city  with  a  good  water  supply  is 
usually  the  fact  that  two  or  more  persons  in  a  household  came  down 
with  typhoid  fever  within  a  few  days  of  each  other. 

(g)  Clinically  the  disease  usually  runs  a  mild  course,  owing  to  the 
fact,  no  doubt,  that  the  virus  becomes  attenuated  in  the  process  of  multi- 
plication in  the  milk.  In  water-borne  typhoid  the  same  germs  are  in- 
gested that  were  passed;  in  milk-borne  typhoid  it  is  the  succeeding  gen- 
erations that  are  ingested. 

Milk-borne  outbreaks  are  sometimes  very  extensive.  One  of  the 
largest  epidemics  occurred  in  Boston  (Jamaica  Plain)  in  March  and 
April,  1908.  Four- hundred  and  ten  cases  were  reported;  348  of  them 
drank  the  suspected  milk.  Among  the  first  victims  of  the  disease  was 
the  milkman,  who  was  believed  to  have  infected  the  milk  through 
tasting  it.  The  number  of  persons  involved  in  a  milk-borne  epidemic 
varies  greatly,  depending  upon  the  amount  of  milk  infected  and  other 
factors.  It  must  not  be  uncommon  for  a  single  bottle  of  milk  or  a 
small  quantity  to  become  infected,  and  thus  transmit  the  disease  to  one 
or  two  persons.  Such  instances  are  exceedingly  difficult  to  trace.  Oft- 
times  the  milk  becomes  infected  from  a  carrier.  An  instance  of  this 
occurred  in  Washington  (Georgetown)  in  1908.  In  this  case  the  milk- 
maid had  typhoid  fever  18  years  previously.  Examinations  showed 
almost  pure  culture  of  B.  typhosus  in  her  feces.  Fifty-five  persons 
who  drank  the  infected  milk  contracted  the  disease. 

Milk  Products. — Fresh  milk  products,  such  as  cream,  ice-cream, 
butter,  and  buttermilk,  and  fresh  cheese,  may  contain  the  typhoid 
bacillus,  and   are   occasionally   media   of  communication. 

Cream  contains  more  bacteria  than  the  milk  from  which  it  is  taken. 
The  use  of  infected  cream  in  coffee,  on  cereals,  etc.,  is  sufficient  to 
cause  the  disease.  Several  instances  in  the  Washington  studies  were 
traced  to  such  use  of  cream.  As  a  rule,  coffee  in  the  cup  is  not  hot 
enough  to  kill  the  typhoid  bacillus. 

Freezing  kills  only  a  certain  percentage  of  the  typhoid  bacilli.  In 
Washington  several  cases  of  the  disease  were  traced  to  ice-cream. 

Bruck  has  shown  that  the  typhoid  bacillus  will  live  in  butter  for 
27  days. 

Buttermilk  may  be  quite  as  dangerous  as  the  cream  from  which  it 
is  derived.     In  cheese  the  time  of  fermentation,  symbiosis,  etc.,  les- 


TYPHOID    FEVER  91 

sens  the  likelihood  of  survival  of  the  typhoid  bacillus.  Fresh  cream- 
cheese,  such  as  Cottage  cheese,  may  be  responsible  for  an  occasional 
case. 

Oysters,  Mussels,  and  Shellfish. — The  first  outbreak  of  typhoid 
fever  attributed  to  this  source  was  investigated  by  Conn  at  Wesleyan 
University,  Middletown,  October,  1894.  Twenty-five  cases  were  at- 
tributed to  eating  infected  oysters;  4  died.  Not  all  of  those  who  took 
sick  had  clinical  typhoid  fever.  Some  had  gastrointestinal  disturbances 
with  illness  lasting  but  a  few  days.  About  one-quarter  of  those  at- 
tending the  dinners  at  which  the  oysters  were  served  were  made  ill. 

A  similar  instance  occurred  at  the  Mayors'  banquets  at  South 
Hampton  and  Winchester,  in  1903. 

In  the  Washington  studies  it  seems  that  oysters  and  shellfish  play 
a  minor  role  in  the  spread  of  the  disease,  which  occurs  mostly  in 
the  summer  time,  while  oysters  and  similar  sea  food  are  relished  mainly 
in  winter.  Comparatively  few  of  the  cases  studied  gave  a  history  of 
having  eaten  oysters  within  30  days  prior  to  the  onset  of  the  disease. 
Oysters  become  especially  dangerous  when  consumed  soon  after  tak- 
ing them  from  a  polluted  bed,  or  when  floated  or  bloated  in  infected 
water.     (For  further  discussion  of  this  topic,  see  page  566.) 

Fruits  and  Vegetables. — Vegetables,  such  as  celery,  lettuce,  and 
radishes,  partaken  of  raw,  and  grown  on  land  fertilized  with  fresh  night 
soil,  may  be  dangerous,  and  this  probably  accounts  for  an  occasional 
case.  In  large  cities  it  is  practically  impossible  to  trace  this  source 
of  infection.  It  therefore  remains  more  a  suspicion  than  a  conviction. 
In  Hackney,  London,  two  local  outbreaks  were  traced  to  watercress 
taken  from  a  polluted  stream.  In  Springfield,  Mass.,  an  outbreak 
which  occurred  in  the  summer  of  1905  was  attributed  to  infected  fruits 
and  vegetables. 

Creel  ^  found  typhoid  bacillus  upon  the  tips  of  leaves  of  plants 
cultivated  in  contaminated  soil.  Under  conditions  most  unfavorable  to 
the  B.  typhosus  the  infection  lasted  at  least  31  days — a  period  suffi- 
ciently long  for  some  varieties  of  lettuce  and  radishes  to  mature. 

Flies. — The  evidence  is  now  complete  that  the  common  house  fly 
(Musca  domestica)  may  convey  the  infection  of  typhoid.  It  is  not 
inappropriately  called  the  typhoid  fly.  The  typhoid  bacilli  may  be 
smeared  upon  the  feet  or  other  parts  of  the  insect,  or  may  live  in  the 
intestinal  tract  and  pass  in  the  dejecta  in  almost  pure  culture.  Flies 
live,  feed,  and  breed  in  fecal  matter  and  decomposing  organic  substances 
of  all  kinds.  It  is  easy  to  see  how  they  may  convey  infections  from 
this  source  to  our  food,  lips,  or  fingers.  Alice  Hamilton  isolated  typhoid 
bacilli  from  5  out  of  18  house  flies  captured  in  Chicago  in  the  privy 
and  on  a  fence  near  a  sick  room.    It  has  been  shown  experimentally  that 

"-PuUic  Health  Reports,  Feb.  9,  1912,  p.  187,  XXVII,  6. 


92        DISEASES   SPREAD   TllKUL'CJli   A].\IXK   DISCHARGES 

living  typhoid  bacilli  may  remain  upon  the  bodies  of  flies  for  as  long 
as  23  days.  Special  attention  to  the  role  played  by  the  fly  was  given 
by  Reed,  Vaughan,  and  Shakespeare  in  their  studies  of  the  prevalence 
of  typhoid  fever  in  our  army  camps  in  1898.  They  concluded  that 
flies  undoubtedly  served  as  carriers  of  the  infection  and  attributed 
about  15  per  cent,  of  the  cases  to  this  mode  of  communication.  They 
found  that  "flies  swarm  over  infected  fecal  matter  in  the  pits  and  then 
deposit  it  and  feed  upon  the  food  prepared  for  the  soldiers  at  the  mess 
tents.  In  some  instances,  where  lime  had  recently  been  sprinkled  over 
the  contents  of  the  pits,  flies  with  their  feet  whitened  with  lime  were 
seen  walking  over  the  food."  The  danger  from  fly  transmission  varies 
very  much,  and  depends  upon  circumstances.  In  a  camp  it  is  con- 
siderable; in  a  well  sewered  city  the  risk  is  diminished.  In  our  Wasii- 
ington  studies  we  could  find  no  relation  between  fly  abundance  in  the 
simimer  of  1908  and  typhoid  prevalence.  It  is  not  possible  to  express 
mathematically  the  percentage  of  cases  caused  by  flies — the  figures  would 
vary  greatly,  depending  upon  circumstances.  The  danger  of  typhoid 
from  flies  in  cities  has  doubtless  been  overstated.  However,  if  only 
one  per  cent,  of  the  cases  were  thus  transmitted,  the  suppression  of 
flies  would  still  be  quite  worth  while  (page  223). 

Dust. — Typhoid  bacilli  soon  die  when  dried,  especially  when  ex- 
posed to  the  sun  and  air.  Dust-borne  infection  in  this  disease  must 
be  rare.  In  the  South  African  war  there  were  frequent  dust  storms 
in  some  localities,  so  that  the  food  was  covered  with  dust  and  sand. 
Some  of  the  infection  was  believed  to  have  been  conveyed  in  this  way. 

FoMiTES. — The  infection  may  be  conveyed  upon  soiled  linen,  blan- 
kets, and  other  objects.  It  was  believed  by  Reed,  Vaughan,  and  Shake- 
speare that  the  clothing,  blankets,  and  tents  in  the  Spanish-American 
war  became  infected  and  were  a  prime  factor  in  spreading  the  dis- 
ease. After  the  South  African  war  some  of  the  blankets  used  by  the 
troops  were  sent  back  to  England  and  used  on  a  training  ship,  on 
which  typhoid  fever  appeared.  The  blankets  were  found  to  be  dirty 
and  soiled  with  fecal  matter,  from  which  Klein  is  reported  to  have 
obtained  living  typhoid  bacilli.  The  danger  of  fomites  contaminated 
with  fresh  infection  is  real,  and  emphasizes  the  importance  of  dis- 
infecting bedding,  towels,  and  other  fabrics. 

Soil. — The  soil,  long  regarded  as  the  most  important  factor  in  the 
spread  of  typhoid  fever,  and  by  Pettenkofer  and  others  considered  an 
essential  element,  is  now  given  scant  consideration.  Pollution  of  the 
soil,  however,  cannot  be  disregarded.  The  typhoid  bacillus  may  live 
for  a  long  time  in  sewage-soaked  earth.  A  surcharged  soil  may  en- 
danger the  water,  milk,  and  other  foods,  or  infect  through  flies  and 
other  means  (see  Soil). 

Contact  Infection. — "Contact"  is  a  convenient  term  to  indicate 


TYPHOID    FEVEE  93 

the  spread  of  infection  directly  or  indirectly  as  a  result  of  close  asso- 
ciation between  the  sick  and  the  sound.  Actual  contact  is  not  neces- 
sarily implied.  The  term  is  used  to  indicate  the  transfer  of  the  in- 
fection through  a  short  intervening  space  in  a  brief  period  of  time 
(see  page  31i).  Thus  the  infection  may  be  passed  from  one  to  an- 
other through  kissing,  soiled  hands,  remnants  of  food,  infected  ther- 
mometers, or  tongue  depressors,  contaminated  towels  or  other  fabrics, 
cups,  spoons,  glasses,  etc.  If  the  nurse  infects  a  cup  of  milk  or  glass 
of  water  that  carries  the  infection  to  another  member  of  the  house- 
hold, such  cases  are  included  under  ''contacts."  The  infection  may  also 
be  spread  in  the  household  hj  flies,  fingers,  and  various  other  means, 
usually  difficult  to  trace,  and  which  are,  therefore,  all  included  under  this 
group.  Eegarded  in  this  light,  contacts  play  a  major  role  in  the  spread 
of  the  disease. 

Extensive  municipal  outbreaks  have  been  reported  as  largely  or  en- 
tirely due  to  contact  infection.  Winslow  in  1901  studied  such  an  out- 
break in  Newport.  Others  have  been  reported  from  Knoxville,  Winni- 
peg, Springfield,  and  from  Germany  and  England.  Koch  regarded 
the  spread  of  typhoid  in  Trier  in  the  light  of  contact  infection.  Free- 
man says  that  the  majority  of  outbreaks  in  the  smaller  towns  of  Vir- 
ginia are  due  to  this  cause.  Extensive  outbreaks  in  institutions  are 
often  due  to  contact  with  mild  cases  or  carriers.  Flies,  fingers,  and 
food  (Sedgwick),  and  dirt,  diarrhea,  and  dinner  (Chapin),  which  too 
often  get  sadly  confused,  explain  the  occurrence  of  many  a  case  of  con- 
tact infection  in  typhoid  fever  and  other  infections. 

In  army  camps  with  clean  water  and  good  milk,  contact  infection 
may  rise  to  epidemic  proportions.  In  the  Spanish-American  war,  of 
107,000  of  our  troops  in  camp,  20,000  contracted  typhoid,  mostly  by 
"contact/*  Similar  conditions  prevail  in  rapidly  growing  cities,  in 
crowded  apartments,  and  congested  regions  with  a  susceptible  population 
and  other  favoring  conditions.  The  danger  of  contact  is  well  shown 
by  the  frequency  with  which  nurses,  ward  attendants,  house  physi- 
cians, and  others  similarly  exposed  take  typhoid  fever.  Studies  of  the 
incidence  of  the  disease  in  the  Massachusetts  General  Hospital,  Bos- 
ton, in  the  Presbyterian  Hospital,  Philadelphia,  and  the  Johns  Hop- 
kins Hospital,  Baltimore,  show  that  typhoid  fever  is  at  least  twice  and 
may  be  8  times  as  prevalent  among  those  who  come  in  close  and  fre- 
quent association  with  the  patient  as  among  the  population  at  large. 
Further,  the  disease  contracted  under  such  conditions  seems  to  run  a 
course  of  more  than  ordinary  severity,  with  a  greater  number  of  com- 
plications and  with  a  high  mortality.  This  is  doubtless  due  largely  to 
the  fact  that  the  contactors  receive  fresh  virulent  virus. 

In  our  studies  of  typhoid  fever  in  Washington  we  were  impressed 
with  the  importance   and  frequency   of   contact  infection  in   that  en- 


94        DISEASES   SPREAD   THROUGH   ALVIXE   DISCHARGES 

demic  center.  In  1907  we  attributed  6  per  cent,  of  the  cases  to  con- 
tacts; in  1908,  15  per  cent.,  and  in  1909,  17  per  cent.  This  included 
only  contact  with  cases  during  the  febrile  stage  of  the  disease.  In 
Strassburg.  Kayser  attributed  1G.8  per  cent,  of  the  cases  occurring 
during  3  years  in  that  city  to  contact  infection.  Little  groups  of  4, 
6,  to  12  or  more  cases  following  a  primary  case  in  a  suburban  focus, 
in  my  experience,  frequently  fall  in  the  category  of  contacts. 

According  to  Conradi,  the  infection  is  transmissible  most  often 
during  the  early  stages  of  the  disease,  sometimes  even  during  the 
period  of  incubation.  The  Washington  studies  do  not  support  this 
view,  for  we  found  the  disease  is  communicated  during  all  stages,  and 
especially  during  convalescence.  This  may  be  due  to  the  fact  that 
during  this  time  the  patient  moves  about  and  scatters  the  infection 
over  a   wider  radius. 

Typhoid  fever,  in  view  of  all  the  facts,  must  now  be  regarded  as  a 
"contagious"  disease.  We  will  never  have  an  end  of  it  until  it  is  so 
regarded  and  treated  accordingly. 

Preventive  Typhoid  Inoculations.- — An  active  immunity  to  typlioid 
fever  may  be  artificially  induced  by  introducing  dead  typhoid  bacilli 
into  the  subcutaneous  tissue.  Living  cultures  or  bacillary  extracts 
may  also  be  used.     The  procedure  is  harmless,  rational,  and  effective. 

Our  knowledge  of  inoculations  against  typhoid  fever  began  with 
the   work   of    Pfeiffer   and   Kolle,^    who    inoculated   two   volunteers   in 

1896.  About  the  same  time  Almroth  Wright  ^  inoculated  several  per- 
sons, and  in  1898  continued  the  work  upon  an  extensive  scale  in  India 
upon  4,000  British  soldiers.  In  1900,  during  the  Boer  war.  Wright, 
together  with  Leishman,  prepared  a  vaccine  ^  and  supervised  the  inocu- 
lation of  100,000  British  troops.  The  results  in  India  were  quite  en- 
couraging, but  for  various  reasons  the  same  procedure  in  South  Africa 
was  not  as  satisfactory  as  had  been  anticipated.  Prophylactic  inocula- 
tion on  the  advice  of  Koch  was  used  by  the  Germans  in  the  Herero 
campaign  in  southern  West  Africa  in  1904.  The  prophylactic  was 
voluntary  and  only  about  half  of  the  command  (7,287  men)  availed 
themselves  of  it.  The  results,  while  good,  fell  short  of  expectations. 
In  this  country  Richardson  was  the  first  to  advocate  and  practice 
inoculations  as  a  means  of  protection  against  typhoid  fever.  The  best 
results  have  been  obtained  in  the  United  States  Army  under  the  direc- 
tion of  Major  Russell. 

Leishman*  in  his  Harben  lecture   (1910)   explains  the  lack  of  suc- 

•Pfeiflfer  and  Kolle:    Deutsche  med.  Wochnschr.,  1896,  XXII,  735. 

=  Wright:    Lancet,  London,  Sept.   19,   1896,  807;   Brit.  Med.  Jour.,  Jan.   ,30, 

1897,  16. 

^  The  material  injected  is  called  a  vaccine  and  the  process  spoken  of  as  vacci- 
nation.    The  term  in  this  connection  is  a  little  confusing.     Inoculation  is  better. 
*  Leishman,  W.  B.:  Jour.  Eoy.  Inst.  Pub.  Health,  London,  1910,  XVIII,  394. 


TYPHOID    FEVER  95 

cess  in  early  years  by  saying  tliat  the  vaccine  may  have  been  made  less 
efficient  by  the  use  of  too  great  heat  in  killing  the  bacilli.  Further,  it 
should  be  noted  that  smaller  doses  and  fewer  injections  were  given  then 
than  now. 

The  typhoid  vaccines  may  be  prepared  in  a  number  of  different 
ways.  Usually  dead  bacilli  are  used,  although  live  bacilli  have  been 
inoculated.  The  bacilli  may  be  killed  either  with  the  aid  of  heat  or 
germicidal  substances;  the  dead  or  live  bacilli  may  be  sensitized  by  the 
addition  of  antityphoid  serum ;  the  vaccines  may  be  prepared  with  pul- 
verized bacilli,  from  bacillary  extracts,  or  by  the  use  of  various  chem- 
ical methods. 

Usually  the  vaccine  is  made  from  a  twenty-four-hour-old  culture 
killed  by  heating  to  60°  C.  for  one  hour  or  less.  Overheating  prob- 
ably impairs  the  immunizing  power  of  the  vaccine.  Most  typhoid 
bacilli  die  before  the  temperature  reaches  60°  C.  Some  of  the  strains 
have  a  lower  thermal  death  point.  Stone  heats  only  to  53°  C.  for  one 
hour,  depending  upon  phenol  (0.5  per  cent.)  to  sterilize  the  culture. 
Cultures  killed  without  heat  have  perhaps  greater  protective  properties. 

Certain  cultures  seem  to  cause  the  production  of  more  antibodies 
than  others.  In  the  earlier  work  it  was  believed  that  the  more  viru- 
lent strains  produce  a  greater  protection.  This  is  doubtful,  for  it  ap- 
pears that  the  protection  afforded  is  not  in  proportion  to  the  local  or 
general  reaction,  but  to  the  amount  and  variety  of  antibodies  stim- 
ulated. 

The  injections  are  given  subcutaneously  at  intervals  of  five  days. 
From  50,000,000  to  100,000,000,  sometimes  1,000,000,000,  dead  typhoid 
bacilli  are  injected  at  each  inoculation.  The  number  of  inoculations 
varies  with  different  authorities.  At  least  3,  preferably  4,  should  be 
given;  the  greater  the  number  of  injections  the  greater  the  immunity 
induced. 

A  reaction  at  the  site  of  the  inoculation  occurs  in  about  10  per 
cent,  of  persons.  The  reactions  are  ■  usually  moderate  and  never  se- 
rious. They  consist  of  local  manifestations,  of  irritation,  and  inflam- 
mation about  the  site  of  inoculation,  such  as  pain,  redness,  swelling, 
edema;  also  general  symptoms,  such  as  malaise,  pains  in  the  back  and 
limbs,  and  fever.  Children,  as  a  rule,  react  less  than  adults.  Of  1,101 
persons  inoculated  by  Hartsock,  11  per  cent,  showed  no  reaction,  83 
per  cent,  mild  reaction,  5  per  cent,  a  moderate  reaction,  and  1 
per  cent,  a  severe  reaction.  All  the  cases  had  a  slight  local  tenderness 
and  redness  at  the  point  of  inoculation.  The  symptoms  of  the  reac- 
tion usually  pass  in  24  hours.  The  number  and  character  of  the  re- 
actions in  the  experience  of  the  United  States  Army  ^  are  shown  in  the 
following  table: 

^Eussell,  F.  P.:   Jour.  A.  M.  A.,  LVIII,  No.  18,  May  4,  1912. 


96 


DISEASES   SPREAD   THROUGH   AIAIXE   DISCHARGES 


Number  of 
doses 

Reaction, 
Absent 

Reaction, 
Mild 

Reaction, 
Moderate 

Reaction, 
Severe 

45,680 
44.321 
38,902 

68.2% 
71.3% 
78.0% 

28.9% 
25.7% 
20.3% 

2.4% 
2.6% 
1.5% 

0.3% 

0.2% 

Third  dose 

0.1% 

The  best  time  to  give  the  treatment  is  late  in  the  afternoon,  for 
then  tlie  severest  part  of  the  reaction  is  over  by  the  morning.  The 
injections  are  usually  given  into  the  subcutaneous  tissue  of  the  outer 
side  of  the  arm  or  into  the  abdominal  wall;  sometimes  the  interscapular 
space. 

There  is  no  laboratory  inde.x  of  the  degree  or  duration  of  the  im- 
munity produced  as  a  result  of  the  inoculations.  The  following  anti- 
bodies appear  in  the  blood:  agglutinins,  precipitins,  opsonins,  lysins, 
stimulins.  There  are  factors  involved  in  the  immunity  not  understood, 
and,  therefore,  the  presence  or  absence  of  typhoid  fever  among  in- 
dividuals protected  in  this  manner  is  the  only  index  of  value. 

The  negative  phase  advanced  by  Wright  and  denied  by  Leishman 
and  others  probably  does  not  occur.  At  least  there  appears  to  be  no 
increased  susceptibility  to  the  disease  during  the  so-called  negative 
phase.  There  is,  therefore,  no  known  objection  to  giving  the  prophy- 
lactic to  those  exposed  to  the  disease  or  during  an  epidemic.  In  fact, 
the  vaccines  have  been  used  as  a  therapeutic  agent  during  the  illness. 

The  immunity  varies  in  degree  and  also  in  duration;  at  least  one 
year  (Pfeiffer  and  Kolle's  vaccine) ;  four  years  (Wright's  vaccine). 
On  the  average,  the  immunity  may  probably  be  depended  upon  for  2  or 
3  years  when  produced  by  4  injections  of  dead  bacilli.  The  immunity 
may  be  prolonged  or  renewed  by  recourse  to  reinoculation.  One  attack 
of  typhoid  fever,  however  mild,  produces,  as  a  rule,  a  lasting  immunity. 
Second  attacks,  however,  occur.  Draschfeld's  figures,  based  on  2,000 
persons  in  the  Antwerp  Hospital,  show  that  only  0.7  per  cent,  of  that 
number  were  affected  twice. 

The  results  of  typhoid  inoculations  can  no  longer  be  questioned. 
The  morbidity  is  lowered  in  those  who  have  been  properly  "vaccinated"; 
the  figures  are  too  recent  to  state  just  how  much.  The  most  striking 
effect  is  in  the  lowering  of  the  mortality.  The  latest  summing  up 
of  the  antityphoid  inoculations  is  by  Leishman  in  the  July  and  Sep- 
tember, 1910,  numbers  of  the  Journal  of  the  Royal  Institute  of  Public 
Health,  xviii,  Nos.  7,  8,  and  9;  also  Report  of  the  French  Commis- 
sion, Public  Health  Reports,  P.  H.  &  M.  H.  S.,  October  6,  1911,  xxvi, 
40,  1507. 

The  best  results  have  been  obtained  in  the  United  States  Army, 


TYPHOID    FEVER  9"^ 

where  the  vaccinations  are  done  under  the  supervision  of  Major  Rus- 
sell/ 

The  health  record  established  by  the  Maneuver  Division  of  the 
United  States  Army  at  San  Antonio,  Texas,  during  the  summer  of 
1911,  is  a  triumph  in  preventive  medicine.  The  division  had  a  mean 
strength  of  12,801  men.  All  were  treated  with  the  typhoid  vaccines. 
The  result  was  that  from  ]lilarch  10th  to  July  10th  only  two  cases 
of  typhoid  fever  developed;  no  deaths.  One  patient  was  a  private 
of  the  hospital  corps  w'ho  had  not  completed  his  immunization,  having 
taken  only  two  doses.  His  case  was  very  mild  and  probably  would 
have  been  overlooked  but  for  the  rule  that  blood  cultures  were  made 
in  all  cases  of  fever  of  over  18  hours'  duration.  The  other  case  was 
a  teamster  who  had  not  been  inoculated.  Among  the  12,801  men 
there  were  only  11  deaths  from  all  diseases.  Typhoid  fever  prevailed 
at  the  time  in  the  neighborhood.  Thus,  there  were  19  cases  of  tj^phoid 
fever  with  19  deaths  in  the  city  of  San  Antonio  during  this  period. 
This  contrasts  markedly  with  the  typhoid  record  of  the  United  States 
Army  during  the  Spanish-American  war,  when  the  typhoid  record 
of  a  division  of  volunteer  troops  camped  at  Jacksonville,  Florida,  in 
1898,  under  conditions  similar  to  those  at  San  Antonio,  was  as  fol- 
lows :  The  division  at  Jacksonville  had  2,693  cases  with  218  deaths, 
which  was  about  the  average  typhoid  incidence  of  the  camps.  Since  the 
year  1904,  with  an  improved  vaccine,  more  than  100,000  British  troops 
have  been  inoculated  without  any  untoward  result.  The  protection 
afforded  may  be  seen  from  the  most  recent  figures  from  India,  re- 
ported by  Col.  R.  H.  Firth.2 

"In  that  period  there  were,  in  all  India,  112  cases  of  typhoid,  with 
six  deaths,  among  the  protected  men,  and  forty-five  cases  with  four 
deaths  among  the  non-protected.  The  protected  population  was  63,624 
persons,  and  the  non-protected  8,481.  From  these  data  we  find  the 
case  incidence  per  thousand  among  the  protected  to  be  1.7  and  among 
the  non-protected  to  be  5.3.  If  we  take  the  mortality  and  express  it 
as  per  million,  then  the  ratio  for  the  protected  is  94,  and  for  the  non- 
protected 471.  That  is  to  say.  the  incidence  for  typhoid  for  the  first 
half  year  was  roughly  five  times  as  great  among  the  non-protected  as 
among  the  protected." 

Spooner  reports  that  in  the  Massachusetts  General  Hospital,  among 

the  nurses  and  others  exposed  to  typhoid  fever,  80  per  cent,  of  whom 

have  been  inoculated  during  the  past  three  years,  not  a  case  has  been 

contracted,  and  for  the  first  year  in  the  history  of  the  institution  there 

were  no  cases  among  the  nurses  or  attendants.     The  case  morbidity  in 

training   schools  for  nurses   in  Massachusetts   during  three   years  was 

nearly  nine  times  greater  in  the  uninoculated  than  among  the  inoculated. 

^  Loc.  cit.,  p.  95. 

-Firth,  E.  H. :  Jour.  Boy.  Army  Med.  Corps,  London,  1911,  XVII,  495. 


98        DISEASES  SPREAD  THROUGH  ALVINE   DISCHARGES 

Melchnikolf  and  Besredka  *  failed  to  protect  chimpanzees  against 
typhoid  infection  by  means  of  killed  bacilli,  but  obtained  immunity  ap- 
parently as  definite  as  tiiat  produced  by  an  attack  of  the  disease  by  the 
use  of  living  cultures. - 

Summary. — Pi'evcntive  typhoid  inoculations  involve  no  risk  what- 
ever, and  are  especially  applicable  to  those  unduly  exposed  to  the  in- 
fection, such  as  nurses,  hospital  attendants,  physicians,  travelers,  sol- 
diers in  camps,  persons  in  epidemic  localities,  and  persons  in  the  fam- 
ily of  a  bacillus  carrier.  The  method  has  been  proposed  for  general 
use  among  the  public  in  endemic  foci,  but  it  is  a  question  whether  this 
artificial  method  of  acquiring  immunity  would  serve  as  good  a  purpose 
in  the  end  as  fighting  the  disease  along  the  lines  of  general  sanitation 
— which  has  been  so  successfully  done  in  many  European  centers.  It 
would  certainly  be  a  mistake  to  immunize  the  population  with  this 
artificial  method  to  the  neglect  of  general  sanitary  improvements,  such 
as  good  water,  clean  milk,  fly  suppression,  cleanliness,  and  personal 
hygiene.  The  question  as  to  whether  the  vaccinations  may  or  may 
not  increase  the  number  of  bacillus  carriers  should  also  be  determined. 
Because  a  person  has  received  the  protection  aflforded  by  typhoid  inocu- 
lations is  no  reason  for  reckless  disregard  of  other  prophylactic  meas- 
ures. 

Management  of  a  Case  so  as  to  Prevent  Spread.— Success  depends 
upon  an  early  and  accurate  diagnosis.  All  cases  of  typhoid  fever  and 
all  cases  suspected  of  being  typhoid  fever  should  be  isolated.  This 
does  not  mean  imprisonment  in  a  lazaretto.  The  proper  place  to  care 
for  typhoid  fever  is  in  a  suitable  hospital.  A  private  home  is  a  poor 
makeshift  for  a  hospital,  and  it  is  unreasonable  to  turn  a  household 
into  a  hospital  for  4  to  8  weeks  or  longer.  The  room  in  which  the 
patient  is  treated  should  be  large  and  well  ventilated,  and  should  con- 
tain no  unnecessary  furniture,  curtains,  carpets,  etc.  It  must  be  kept 
scrupulously  clean,  dry  sweeping  and  dusting  prohibited;  and  well 
screened. 

The  case  should  be  reported  to  the  health  authorities  without  de- 
lay, and  the  house  should  be  placarded  so  as  to  warn  others,  and  visit- 
ing discouraged.  Under  no  circumstances  should  visitors  be  admitted 
into  the  sick  room. 

The  disinfection  of  the  stools,  urine,  sputum,  and  other  excretions 
is  of  the  first  importance,  and  should  be  carried  out  with  great  care 
and  conscientiousness.  For  the  urine,  sufficient  bichlorid  may  be  added 
to  make  a  1-1,000  solution,  or  carbolic,  2.5  per  cent.,  formalin,  10  per 
cent.,  and  allowed  to  stand  one  hour  before  discarding.  Stools  may 
be  disinfected  with  bleaching  powder,  3  per  cent.;  milk  of  lime  (1  to  8)  ; 

^Annales  de  I'lnst.  Pasteur,  Dec,  1911,  XXV,  12,  p.  865. 
''Ann.  de  I'lnst.  Pasteur,  Mar.  25,  1911,  and  Dec,  1911. 


TYPHOID    FEVEH  99 

cresol,  1  per  cent.;  carbolic  acid,  5  per  cent.;  or  formalin,  10  per  cent. 
The  discharges  should  be  received  in  a  glass  or  earthenware  vessel  con- 
taining some  of  the  germicidal  solution.  Then  add  more  of  the  solution 
so  that  it  shall  be  present  in  twice  the  volume  of  the  excreta  to  be 
disinfected;  let  stand  at  least  one  hour,  protected  from  flies.  Masses 
are  so  difficult  to  penetrate  that  they  should  be  broken  up  by  stirring. 
It  takes  a  carbolic  acid  solution  some  12  hours  to  penetrate  the  in- 
terior of  a  fecal  mass. 

The  sputum  may  be  burned  or  boiled.  Strong  carbolic  acid,  tri- 
cresol, or  formalin  are  also  applicable. 

The  patient  should  have  his  own  dishes,  cups,  spoons,  glasses,  etc., 
which  should  be  scalded  after  each  use.  Eemnants  of  lunch,  especially 
meat,  milk,  gelatin,  broths,  and  other  organic  food  in  which  the  in- 
fection may  live  and  even  grow  should  not  be  eaten  by  others.  Such 
remnants  may  be  burned  or  first  boiled  and  then  discarded.  Those 
who  nurse  the  sick  should  keep  out  of  the  kitchen  on  account  of  the 
risk  of  contaminating  the  food. 

Towels,  sheets,  nightgowns,  and  all  fabrics  used  about  the  patient 
should  be  disinfected  either  by  boiling,  or  immersion  for  one  hour  in 
bichlorid  of  mercury,  1-1,000,  carbolic  acid,  2.5  per  cent.,  or  formalin, 
10  per  cent. 

The  water  used  to  bathe  the  patient  should  be  disinfected  before 
it  is  allowed  to  run  into  the  sewer.  This  may  be  done  by  adding  suffi- 
cient carbolic  acid  or  bleaching  powder;  the  latter  is  cheapest  and  most 
practical. 

Milk  bottles  must  be  kept  out  of  the  sick  room.  In  any  case,  they 
should  be   scalded  before   returning  to  the   dairy. 

The  thermometer  should  be  kept  in  formalin  or  other  suitable  ger- 
micidal solution.  Eectal  tubes,  especially  in  hospital  practice,  must  be 
carefully  disinfected  each  time  before  using. 

The  nurse  must  protect  herself  as  well  as  others;  a  solution  of  bi- 
chlorid should  be  kept  constantly  at  hand.  Every  time  the  patient  is 
bathed,  his  mouth  cleaned,  or  his  buttocks  washed,  the  hands  must  be 
disinfected  and  washed  in  soap  and  water.  The  nurse  must  exercise 
especial  care  if  she  is  to  go  to  the  kitchen  or  to  the  ice-box,  etc.,  as  is 
frequently  the  case  in  private  houses,  where  a  special  diet  kitchen  can- 
not be  provided.  The  nurses,  physicians,  ward  attendants,  and  others 
particularly  exposed  may  protect  themselves  with  preventive  typhoid 
inoculations.  The  physician  should  be  quite  as  careful  as  the  nurse, 
not  only  so  that  he  may  not  carry  the  infection  to  himself  or  other 
patients,  but  also  that  his  practice  may  serve  as  a  stimulating  example. 

At  the  conclusion  of  the  case  a  general  terminal  disinfection  of 
the  room  and  its  contents  may  be  practiced.  This  is  best  done  with 
formaldehyde  gas,  followed  by  a  general  mechanical  cleansing. 


100      DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

Convalescents  should  not  be  given  liberty  until  the  danger  of  bacil- 
lus carrying  has  passed.  This  may  be  determined  oidy  by  baeteriologic 
examinations  of  the  stools  and  urine.  Four  successive  negative  results 
at  intervals  of  several  days  are  required  before  a  conclusive  report  may 
be  vouchsafed  in  the  case  of  the  stools.  One  examination  of  tlie  urine 
is   ordinarily   sufficient. 

Tlie  UFc  of  urotro))in  (hexamethylenamin)  diminishes  the  incidence 
of  bacilluria,  and  is  becoming  a   routine  practice. 

Summary — Personal  Prophylaxis. — The  prevention  of  typhoid  fever 
may  be  summed  up  in  the  word  cleanliness — physical  and  biological 
cleanliness.  By  this  is  meant  not  only  clean  food,  especially  water  and 
milk,  but  also  cleanliness  of  person  and  environment.  Typhoid  fever 
has  always  prevailed  where  cleanliness  is  neglected  and  has  diminished 
where  it  has  been  intelligently  observed.  It  is  true  that  typlioid  bacilli 
do  not  breed  in  the  rubbish  and  dirt  of  back  yards  and  alleys,  or  in 
unkempt  city  lots,  but  these  conditions  in  a  city  may  be  taken  as  an 
index  of  the  general  cleanliness  of  its  inhabitants. 

The  eradication  of  typhoid  fever  is  easier  in  cities  than  in  country 
districts;  clean  cities  now  have  less  typhoid  fever  than  the  surrounding 
rural  region.  Cities  can  well  afford  extensive  and  expensive  sanitary 
works  which  are  beyond  the  financial  possibilities  of  sparsely  settled 
districts.  ]f  a  clean  water  from  natural  sources  is  not  available,  then 
large  volumes  of  a  polluted  water  may  be  rendered  reasonably  safe 
for  municipal  use  by  slow  sand  filtration  or  by  bleaching  powder.  Fur- 
ther, cities  can  afford  to  inspect  their  milk  supply  and  to  supervise  the 
pasteurization  of  all  that  is  not  safe.  These  two  measures  would  prac- 
tically eliminate  typhoid  infection  coming  into  cities  in  its  food  supply 
— especially  if  in  addition  to  this  a  supervision  is  maintained  over  oysters 
and  shellfish,  and  vegetables  partaken  in  their  raw  state.  Further,  cities 
can  well  afford  to  employ  skilled  and  experienced  health  officials  and 
are  financially  able  to  engage  the  services  of  experts.  On  the  other 
hand,  each  farmhouse  represents,  in  miniature,  all  the  problems  with 
which  the  city  deals  by  wholesale,  and  is  often  not  financially  able  to 
meet  its  sanitary  requirements.  The  country  is  the  weakest  link  in 
our  sanitary  chain.  Cities  will  find  it  a  paying  proposition  to  sup- 
press flies,  rats,  and  other  vermin,  which  may  be  done  much  more  easily 
than  in  rural  or  suburban  conditions.  This  should  be  done  not  only  on 
account  of  the  suppression  of  typhoid  fever,  but  other  diseases  tlnis 
conveyed.  The  city  beautiful  must  also  be  the  city  clean  in  its  cellars, 
garrets,  back  yards,  empty  lots,  alleys,  and  stables. 

To  sum  up,  the  main  factors  in  the  spread  of  typhoid  fever  in  our 
large  cities  are:  (1)  water;  (3)  milk;  (3)  contact;  (4)  miscellaneous. 
In  a  city  having  a  clean  water  supply  the  residual  typhoid  must  be 
attacked  along  two  definite  lines,  viz.,  improvement  of  the  milk  supply 


CHOLEEA  101 

and  its  pasteurization,  and  a  warfare  against  the  disease  in  the  light 
of  an  infection  spread  from  man  to  raan. 

The  health  officer  should  establish  a  laboratory  for  the  early  diag- 
nosis of  cases  and  for  the  discovery  of  carriers.  The  health  officer 
should  at  once  send  a  trained  agent  to  every  house  from  which  a  case 
of  typhoid  fever  is  reported.  The  visit  should  be  made  as  early  as 
practicable  and  with  the  object  of  seeing  that  the  stools  and  urine  are 
properly  disinfected,  patients  isolated,  milk  bottles  scalded,  sick  rooms 
screened,  house  placarded,  visiting  discouraged,  and  other  necessary 
measures  taken  to  prevent  the  spread  of  the  infection.  Convalescents 
should  not  be  released  until  the  absence  of  typhoid  bacilli  from  the 
urine  and  stools  has  been  demonstrated  by  four  successive  examina- 
tions. Carriers  need  not  be  indefinitely  quarantined,  but  should  be 
prohibited  from  engaging  in  any  employment  having  to  do  with  foods, 
or  in  which  close  personal  contact,  as  in  nursing,  is  required.  Carriers 
should  be  instructed  concerning  the  danger  and  educated  to  thoroughly 
wash  and  disinfect  their  hands,  especially  after  a  visit  to  the  toilet. 
The  health  officer  alone  cannot  eliminate  typhoid  fever  from  a  city. 
He  needs  the  help  of  the  community.  Much  can  be  done  through 
education.  A  stimulating  leader  may  accomplish  a  world  of  good 
through  voluntary  effort,  but  in  the  end  it  requires  comprehensive  laws 
and  an  energetic  enforcement  of  them,  without  fear  or  favor. 

The  personal  prevention  of  typhoid  fever  resolves  itself  into  boil- 
ing the  water,  if  suspicious;  partaking  only  of  milk  or  fresh  milk 
products  that  have  first  been  pasteurized,  and  otherwise  assuring  one- 
self that  all  food  has  been  thoroughly  cooked.  In  addition  to  this, 
direct  and  indirect  contact  with  persons  who  have  the  disease,  or  who 
are  known  to  be  carriers,  must  be  avoided.  Sanitary  habits  should  be 
encouraged,  especially  the  one  simple  precaution  of  washing  the  hands 
before  eating,  and  of  keeping  the  fingers  and  other  unnecessary  objects 
away  from  the  mouth  and  nose.  In  certain  circumstances  in  which 
there  is  unusual  exposure  protection  may  be  had  by  increasing  immu- 
nity through  typhoid  inoculations. 

CHOLERA 

The  prevention  of  cholera  corresponds  to  the  prevention  of  typhoid 
fever.  In  the  case  of  cholera  vigorous  measures  have  been  rewarded 
with  signal  success.  It  is  quite  possible  to  live  in  the  midst  of  a  raging 
cholera  epidemic  without  contracting  the  disease.  Within  recent  years 
epidemics  have  been  suppressed  and  the  spread  of  the  infection  limited. 

The  home  of  true  cholera  is  the  delta  of  the  Ganges,  hence  it  is 
usually  called  "Asiatic  cholera"  to  distinguish  it  from  Cholera  nostras 
or  Cholera  morlus.  During  the  sixteenth,  seventeenth,  and  eighteenth 
9 


102      DISEASES   SPREAD   THROUGH   ALVIXE   DISCHARGES 

centuries  cholera  was  epidemic  at  various  times  in  India.  It  is  only 
in  the  nineteenth  century  that  cholera  has  spread  along  the  routes  of 
trade  and  travel  to  Europe  (first  in  1830),  Africa,  and  America  in 
1832.  There  have  been  four  pandemics;  one  from  1817-1823,  another 
1826-1837,  a  third  181G-1862,  and  a  fourth  from  1864-1875.  In  1832 
it  entered  the  United  States  by  way  of  New  York  and  Quebec  and 
reached  as  far  west  as  the  military  posts  of  the  upper  Mississipj)!.  The 
disease  recurred  in  1835  and  1836,  In  1848  it  entered  the  country 
through  New  Orleans  and  spread  widely  up  the  Mississippi  and  was 
dragged  across  the  continent  by  the  searchers  for  gold  all  the  way  to 
California  (1849).  It  again  prevailed  widely  through  this  country  in 
1854,  having  been  introduced  by  immigrant  ships  into  New  York.  In 
1866  and  1867  there  were  less  extensive  epidemics.  In  1873  it  again 
appeared  in  the  United  States,  but  did  not  prevail  widely.  In  1892 
the  great  epidemic  of  Hamburg  occurred,  and  the  disease  threatened 
to  become  pandemic  in  Asia,  Africa,  and  Europe.  Cases  were  brought 
by  transatlantic  liners  to  New  York,  and  a  few  cases  occurred  in  the 
city,  but  its  spread  was  prevented  by  aggressive  measures.  Cholera 
has  prevailed  for  years  in  the  Philippines,  but  is  now  under  control. 
While  the  home  of  cholera  is  in  the  tropics,  there  is  scarcely  a  country 
in  the  world  that  has  not  been  visited  some  time  or  other  by  the  ravages 
of  this  fatal  disease. 

The  incubation  period  of  cholera  is  short,  frequently  1  or  2  days, 
rarely  over  5.  The  period  of  detention  in  quarantine  is  5  days.  One 
attack  produces  a  mild  grade  of  immunity  which  is  not  lasting.  The 
disease  is  peculiar  to  man. 

The  Cause  and  Contributing-  Causes  of  Cholera.^ — The  Vibrio  cholerce 
or  the  "comma  bacillus"  of  Koch  is  the  undisputed  cause  of  the  dis- 
ease. The  conditions  of  infection,  however,  are  complex.  Not  everyone 
who  takes  the  specific  microorganism  Ijv  tlie  mouth  necessarily  gets 
the  disease,  but  without  it  there  can  be  no  cholera.  Many  cholera 
vibrios  probably  die  in  the  acid  juices  of  the  stomach.  There  is,  there- 
fore, perhaps  less  danger  in  taking  small  amounts  of  infection  during 
active  digestion  than  upon  an  empty  stomach,  for  it  has  been  shown  ex- 
perimentally that  cold  drinks  do  not  stay  long  in  an  empty  stomach,  but 
pass  quickly  through  the  pylorus.  After  the  cholera  vibrio  has  passed  the 
pylorus  and  reaches  the  alkaline  juices  of  the  intestines,  it  may 
find  ideal  conditions  for  growth  or  may  still  have  a  hard  struggle  for 
existence.  Here  symbiosis  must  play  a  dominant  role.  It  is  well  known 
in  all  cholera  epidemics  that  a  deranged  digestion  is  an  important  pre- 
disposing factor  to  the  disease.  In  the  Hamburg  epidemic  a  marked 
access  of  cases  on  Monday  following  the  Sunday  dissipations  was  noted. 
Raw  fruits,  crude  fibrous  vegetables,  and  other  fermentable  food,  difficult 
of  digestion,  seem  to  favor  the  growth  and  multiplication  of  the  cholera 


CHOLERA  103 

yibrio  in  the  intestinal  tract.  In  the  light  of  this  view  raw  fruits  and 
vegitables  may  often  be  the  predisposing  factor  rather  than  the  medium 
v^hich  conveys  the  infection.  Just  what  the  factors  are  that  favor  or 
^ndicap  the  growth  of  the  cholera  vibrio  in  the  intestinal  tract  are 
undetermined.  Pettenkofer  stoutly  maintained  that  the  "comma  bacil- 
lus" was  only  one  of  the  factors  in  the  etiology  of  the  disease.  He 
placed  special  importance  upon  the  condition  of  the  host  and  his  en- 
vironment, and  considered  at  least  three  fundamental  factors  in  his 
X,  Y,  Z  theory.  X  is  the  germ,  Y  the  host  or  soil,  Z  the  environment. 
In  this  connection  disease  may  aptly  be  compared  to  fermentation, 
in  which  X  represents  the  yeast,  Y  the  carbohydrate,  and  Z  the  tem- 
perature, moisture,  reaction,  and  other  essential  conditions  for  the 
growth  and  activity  of  the  yeast.  Pettenkofer  maintained  that  X 
without  Y  and  Z  would  not  produce  cholera,  that  is,  while  the  cholera 
vibrio  was  pathogenic  in  India  or  Hamburg  (1892),  where  Y  and  Z 
were  favorable,  it  would  be  harmless  in  Munich,  where  Y  and  Z 
were  unfavorable.  To  prove  this  theory,  he  and  his  assistant,  Em- 
merich, drank  pure  cultures  of  cholera  after  first  rendering  the  stomach 
contents  alkaline.  Pettenkofer,  then  an  old  man,  had  a  diarrhea; 
Emmerich,  on  the  other  hand,  had  a  sharp  attack  from  which  he  almost 
lost  his  life.  Similar  convincing  experiments  have  occurred  among  lab- 
oratory workers,  who  have  accidentally  gotten  jjure  cultures  of  cholera 
into  their  mouths.  On  the  other  hand,  a  number  of  persons  who  imi- 
tated Pettenkofer's  experiment  were  not  affected.  Pettenkofer  did  not 
regard  his  own  case  as  cholera,  and  insisted  that  the  negative  results 
lent  confirmation  to  his  theory  of  the  importance  of  contributing  factors 
(Y  and  Z). 

Diagnosis. — The  diagnosis  of  cholera  depends  upon  isolation  and 
identification  of  the  cholera  vibrio  in  pure  culture.  This  has  become 
comparatively  simple,  but  great  care  must  be  taken  not  to  confuse  the 
true  vibrio  of  cholera  witli  a  great  host  of  other  microorganisms  which 
closely  resemble  it. 

A  presumptive  diagnosis  of  cholera  may  be  made  by  finding  large 
numbers  of  comma-shaped  bacilli  in  direct  microscopic  examination 
of  stained  preparations,  or  in  hanging  drops  of  the  mucous  flakes 
ordinarily  found  in  cholera  stools.  This  test  is  only  presumptive,  the 
final  criterion  being  the  biological  reactions  of  the  microorganism  ob- 
tained in  pure  culture.  The  two  reactions  which  are  specific  and  re- 
liable  are   Pfeiffer's   phenomenon   and  agglutination. 

Dependence  should  not  be  placed  upon  morphological  characters, 
cultural  peculiarities,  or  pathogenicity  upon  laboratory  animals,  for 
these  do  not  furnish  the  means  of  certainly  defining  the  cholera  vibrio. 
For  the  isolation  of  the  cholera  vibrio  agar  is  preferable  to  gelatin, 
formerly  so  much  used.     The  suspected  material  should  be  planted  upon 


104     DISEASES  SPREAD  THROUGH  ALVINE   DISCHARGES 

the  surface  of  ordinary  alkaline  agar  or  upon  Dieudonne's  niedimn, 
using  one  of  the  small  rice-like  flakes  or  an  equivalent  quantity  of 
feces. 

Dieudonne's  medium  is  prepared  as  follows: 

Sol.  A. — Equal  parts  of  a  normal  solution  of  potassium  hydroxid 
and  defihrinated  ox-blood  are  mixed  and  sterilized  in  the  autoclave. 

Sol.  B. — Ordinary  nutrient  agar,  exactly  neutral  to  litmus. 

Seven  parts  of  B  are  mixed  with  3  parts  of  A  and  poured  into 
Petri  dishes.  The  plates  should  not  be  used  immediately  after  their 
preparation.  Dieudonne  recommends  keeping  them  several  hours  in  the 
incubator  at  37°  C,  uncovered  and  face  down,  or  to  heat  them  for  5 
minutes  at  65°  C.  Equally  good  results  can  be  obtained  by  keeping 
them  48  hours  at  room  temperature.  Tlie  surface  of  the  agar  should 
be  slightly  dry.  Once  in  condition,  the  plates  should  be  used  in  a 
period  not  exceeding  5  or  6  days. 

Upon  this  medium  cholera  vibrios  grow  abundantly.  On  the  con- 
trary, the  organisms  which  most  often  accompany  them  on  plate  cul- 
tures, especially  B.  coli,  grow  either  very  poorly  or  not  at  all. 

When  it  is  suspected  that  the  cholera  vibrios  are  few  in  number, 
they  may  be  enriched  by  first  planting  in  Dunham's  solution.  Ap- 
proximately 1  c.  c.  of  fecal  matter  should  be  placed  in  50  c.  c.  of  the 
peptone  solution.  This  is  incubated  at  37°  C,  and  in  from  6  to  8 
hours  a  loopful  is  taken  from  the  surface  and  transferred  to  ordinary 
agar  or  Dieudonne's  medium.  Suspicious  colonies  are  fished  and  studied 
further.    A  quick  method  of  detecting  carriers  is  given  on  page  108. 

Kolle  and  Gotchlich  have  shown  from  a  large  number  of  observa- 
tions that  with  strongly  agglutinative  serum,  the  power  of  which  reaches 
1-4,000,  the  agglutinative  power  for  common  vibrios,  not  cholera,  does 
not,  as  a  general  rule,  exceed  1-50  and  rarely  reaches  1-200;  agglu- 
tination in  dilutions  of  1-500  has  been  only  very  exceptionally  ob- 
served. On  the  contrary,  the  true  cholera  vibrios  agglutinate  in  dilu- 
tions varying  from  1-1,000  and  1-20,000.  Therefore,  with  a  specific 
agglutinating  serum  having  a  titer  of  1-4,000,  any  organism  which  is 
agglutinated  in  1-1,000  may  be  considered  true  cholera.  Organisms 
agglutinating  in  dilutions  of  1-500  and  1-1,000  should  be  regarded  as 
doubtful. 

In  any  critical  case  Pfeiffer's  reaction  (see  page  389)  should  be 
tried.     This  is  specific. 

Modes  of  Transmission. — Cholera  is  spread  by  man  from  place  to 
place.  It  follows  the  lines  of  trade  and  travel.  Seaports  are  in- 
variably first  attacked.  The  epidemic  at  Hamburg  in  1892  was  brought 
to  that  port  by  immigrants  on  board  vessels  from  Russia.  There  are 
many  similar  instances.  In  1849  many  a  gold  hunter  found  another 
Eldorado  than  the  one  he  was  searching  for,  as  cholera  was  dragged 


CHOLEEA  105 

across  the  continent  by  the  caravans  seeking  fortunes  in  California. 
The  same  thing  takes  place  in  the  Indian  pilgrimages  to  Mecca. 

The  cholera  vibrio  enters  the  digestive  tract  through  the  mouth. 
It  is  taken  in  the  food  and  drink.  Infected  water  is  a  frequent  me- 
dium of  transference,  and  probably  the  sole  vector  of  the  great  epi- 
demic outbursts.  Cholera,  however,  may  be  transferred  from  man  to 
man  directly,  also  indirectly  by  flies,  fingers,  food,  and  all  the  innu- 
merable channels  from  the  anus  of  one  man  to  the  mouth  of  another 
that  have  been  described  in  the  case  of  typhoid. 

In  endemic  or  residual  cholera,  water-borne  infection  plays  a  minor 
role.  This  was  well  proven  in  the  recent  sanitary  campaign  against 
the  disease  in  the  Philippine  Islands,  in  which  the  water  was  practically 
ignored  and  the  disease  conquered  in  the  light  of  an  infection  com- 
municated rather  directly  from  man  to  man.  Cholera  was  spreading 
rapidly  despite  active  measures.  Its  progress  was  stopped  by  throwing 
a  sanitary  corps  across  a  narrow  neck  of  land  some  miles  in  advance 
of  the  march  of  the  disease.  Here  a  quarantine  was  established  and 
persons  held  5  days  under  observation  before  they  were  permitted  to 
pass.  The  usual  disinfection  and  other  measures  were  practiced  and 
the  disease  effectively  stopped. 

The  cholera  vibrio  leaves  the  body  in  enormous  numbers  in  the 
dejecta,  also  sometimes  in  the  matter  vomited.  The  cholera  vibrio  does 
not  invade  the  blood  and  tissues  generally,  and,  therefore,  is  not  voided 
in  the  urine.  Disinfection  in  this  disease  must,  therefore,  be  concen- 
trated upon  the  discharges  from  the  bowels  and  mouths,  at  the  bedside. 

Water. — The  cholera  vibrio  may  live  and  even  multiply  in  water. 
Koch  in  his  original  investigations  found  the  organism  in  the  foul 
water  of  a  tank  in  India  which  was  used  by  the  natives  for  drinking 
purposes.  It  has  been  shown  by  experiment  that  the  cholera  vibrio  may 
multiply  to  some  extent  in  sterilized  river  water  or  well  water;  and 
that  it  preserves  its  vitality  in  such  water  for  several  weeks  or  even 
months.  In  recent  times  diolera  organisms  have  been  found  not  in- 
frequently in  the  water  of  wells,  water  mains,  rivers,  harbors,  canals, 
and  even  sea  water  (the  North  Sea  near  the  mouth  of  the  Elbe),  which 
have  become  contaminated  with  the  discharges  of  cholera  patients.  It 
is  plain  from  the  nature  of  the  ease  that  infected  water  must  play  a 
very  large  role  in  spreading  this  infection. 

The  Broad  Street  Case  in  London. — The  earliest  and  now  classic 
instance  in  favor  of  the  water-borne  theory  we  owe  to  the  late  Dr. 
John  Snow.  This  is  the  well  known  Broad  Street  pump  outbreak  in 
London  in  18 54-,  an  account  of  which  will  be  found  on  page  815. 

The  best  example  of  water-borne  cholera  is  the  Hamburg  epidemic 
of  1892,  which  I  was  fortunate  enough  to  see  in  part.  In  this  case 
no  link  in  the  chain  of  evidence  is  missing.     Cholera  was  brought  to 


106      DISEASES   SPREAD   THKOUGH  ALVINE   DISCHARGES 

Hamburg  by  immigrants  either  from  Russia  or  France.  The  water 
of  the  Elbe  was  infected  with  their  discharges.  The  Vibrio  choleroe 
was  readily  isolated  from  the  river  water  wliich  was  distributed  through- 
out the  city  for  drinking  purposes  without  purification.  The  sewers  of 
Hamburg  emptied  into  the  river  Elbe  near  the  water  intake,  which 
produced  an  increased  concentration  of  the  infection.  An  account  of 
the  epidemic  will  be  found  on  page  819. 

Other  Modes  of  Transference. — The  fact  that  water-borne  in- 
fection is  practically  the  only  cause  of  the  large  cholera  epidemics 
must  not  overshadow  the  importance  of  other  modes  of  transmission. 
In  addition  to  tlic  violent  outbreaks,  cholera  occurs  in  nests  or  smoul- 
ders like  endemic  typhoid.  It  is  difficult  to  trace  the  connection  be- 
tween cases  in  endemic  areas.  Thus,  a  careful  study  of  the  cholera 
situation  in  Manila  disclosed  the  fact  that  isolated  cases  would  crop 
up  at  widely  different  points  without  any  evident  connection  hetween 
them.  Cholera  carriers  were  suspected  but  not  proved  in  this  instance. 
At  irregular  intervals  of  several  years  the  disease  would  gather  force, 
and  cases  multiply,  until  it  assumed  epidemic  proportions,  it  is  be- 
lieved entirely  independent  of  the  water  supply.  The  way  cholera  was 
dragged  across  our  continent  by  the  "forty-niners,"  and  its  occurrence 
among  the  Mecca  pilgrims,  are  instances  of  its  spread  largely  inde- 
pendent of  infected  water. 

Contact  Infection. — Contact  infection  in  cholera  must  not  be 
underestimated.  Persons  frequently  become  infected  by  handling  the 
dejecta  or  through  freshly  infected  fomites,  such  as  soiled  linen.  Di- 
rect transmission  from  person  to  person  is  not  infrequent  among  physi- 
cians and  nurses.  In  congested  quarters,  where  many  persons  live  un- 
der uncleanly  conditions,  contact  infection  plays  an  important  part. 
The  same  thing  may  be  seen  on  board  vessels,  in  which  case  the  dis- 
ease may  be  confined  to  the  firemen,  stewards,  or  some  other  limited 
group  who  are  required  to  live  in  close  contact  with  each  other.  Epi- 
demic outbreaks  due  to  contact  infection  have  been  recorded,  such  as 
the  30  cases  which  occurred  in  the  fall  of  1892  in  Boizenburg. 

Cholera  is  not  highly  "contagious,"  for  physicians,  nurses,  and 
others  in  close  contact  with  patients  need  not  become  infected  pro- 
vided intelligent  measures  are  adopted.  On  the  other  hand,  there  is 
great  danger  of  tlie  spread  of  the  disease  through  devious  and  hidden 
routes,  as  is  the  case  with  typhoid  and  dysentery.  Washerwomen  and 
those  who  are  brought  in  very  close  contact  with  the  linen  of  cholera 
patients  or  with  their  stools  are  prone  to  contract  the  disease.  Koch,  in 
his  original  investigations,  found  that  the  "comma  bacillus"  may  mul- 
tiply rapidly  upon  the  surface  of  moist  linen. 

Milk  may  be  contaminated,  but  is  probably  not  a  frequent  medium 
of  infection,  for  the  reason  that  its  acid  reaction  is   inimical  to  the 


CHOLEEA 


107 


cholera  vibrio.  Green  vegetables  and  fruit  that  have  been  washed  in 
an  infected  water  may  convey  the  disease.  The  bacilli  live  on  fresh 
bread,  butter,  and  meat  for  from  6  to  8  days. 

Flies,  Etc. — It  has  been  shown  that  the  cholera  vibrios  may  live  in 
the  intestines  of  flies  for  at  least  3  days,  and  these  and  other  insects  may 
also  spread  the  infection  mechanically.  The  cholera  vibrio  is  a  frail 
organism  and  dies  rapidly  when  dried  or  exposed  to  light  and  other 
injurious  influences.  Infection  through  the  air  is,  therefore,  not  to  be 
dreaded.  Fomites,  such  as  bed  and  body  linen  or  other  objects,  including 
floors,  walls,  toys,  etc.,  contaminated  with  the  dejecta,  can  be  regarded  as 
possible  sources  of  infection.  There  is,  however,  a  special  limitation 
in  this  case,  owing  to  the  fact  that  this  organism  is  so  readily  de- 
stroyed by  desiccation  and  crowded  out  by  saprophytic  microorganisms. 
Thus,  as  a  rule,  only  fresh  dejecta  and  freshly  contaminated  objects 
are  liable  to  convey  the  infection. 

Bacillus  Carriers. — The  cholera  vibrios  are  passed  in  the  feces 
during  the  early  part  of  the  disease.  They  usually  disappear  after 
the  fourth  to  the  fourteenth  da}",  but  may  remain  a  much  longer  time. 
The  following  are  the  longest  cited  by  Pf eiff er :  ^ 


persistence  of  cholera  vibrios  in  stools  of  convalescents,  or 

BACILLUS    carriers 


Name  of  Observer. 


Name  of  Observer. 


Longest 

Duration 

(days). 


Guttman 

Lazarus  and  Pulicke 

Michailow 

Simonds 

Rumpel 

Rommelaere 


Kolle 

Donitz 

Abel  and  Clausen 

Pfeiffer 

Biirgers 


48 
49 
15 
13 
69 


McLoughlin  found  bacillus  carriers  numerous  in  epidemic  centers. 
Thus  he  found  6  to  7  per  cent,  of  carriers  among  healthy  individuals 
living  in  the  infected  neighborhoods  in  Manila.  On  the  other  hand, 
carriers  were  exceedingly  rare  in  neighborhoods  having  few  cases. 
Persons  in  good  health  may  harbor  the  cholera  organism  in  their  in- 
testines. Cholera  carriers,  therefore,  play  a  similar  role  to  typhoid  car- 
riers in  spreading  the  infection.  Less,  however,  is  known  concerning 
cholera  carriers  than  typhoid  carriers. 

Several  different  methods  for  the  detection  of  cholera  carriers  are 
applicable.  All  of  them  are  based  upon  the  facility  with  which  the 
vibrio  grows  upon  Dunham's  solution.  Particles  of  feces  are  planted 
in  this  medium  and  subsequently  examined  for  comma-shaped  mi- 
croorganisms.     If   found,    the    diagnosis    is    presumptive.      Pure    cul.- 

^  Hygienische  Eundschau,  February,  1910,  Vol.  XX,  No.  4. 


108      DISEASES   SPREAD   THROUGH   ALVIXE   DISCHARGES 

hires  should  then  he  made  and   studied   for  agglutination.     See  page 
104. 

The  routine  bacteriological  examination  of  immigrants  from  cholera- 
infected  ports,  as  practised  at  the  Quarantine  Station  at  New  York, 
in  1912,  was  as  follows:^ 

1.  Inoculation  of  feces  into  Dunham's  peptone  solution  (at  37°  C). 

2.  Subinoculation  at  the  end  of  six  hours  of  one  loop  of  the  sur- 
face growth  into  a  second  Dunham's  peptone  tube. 

3.  Examination  of  a  smear  taken  from  the  surface  growth  of  the 
second  Dunham's  peptone  tube,  after  it  has  been  incubated  six  to  nine 
hours  at  37°  C. 

Bendick  uses  a  modified  Dunham's  solution  containing  sodium  car- 
bonate, 1  gram;  saccharose,  5  grams;  and  phenolphthalein  solution, 
5  c.  c,  in  addition  to  the  usual  amount  of  water,  peptone  and  salt.  The 
cholera  vibrios  ferment  the  saccharose ;  the  acid  produced  unites  with  the 
sodium  carbonate  and  the  medium  becomes  neutral,  hence  the  red  color 
of  the  phenolphthalein  disappears. 

Immunity  and  Prophylactic  Inoculations.— The  immunity  produced 
by  an  attack  of  tlie  disease  is  of  short  duration.  Attempts  have 
been  made  to  produce  an  artificial  immunity  by  the  injection  of  cholera 
cultures.  These  were  first  made  by  Ferran  of  Spain  in  1884,  but 
the  cultures  used  by  him  obtained  directly  from  cholera  stools  were 
not  pure.  Haffkine  tested  the  method  on  a  large  scale  in  India;  over 
40,000  persons  were  inoculated  with  attenuated  cultures  up  to  1895. 
Haffkine  proceeded  in  accordance  with  the  well  known  methods  of 
Pasteur  in  anthrax,  by  using  two  vaccines  of  different  strengths. 
The  first  was  obtained  by  growing  the  culture  at  a  heightened  tem- 
perature, which  produced  a  very  attenuated  strain.  The  second  con- 
tained living  vibrios  weakened  by  passage  through  guinea-pigs.  The  re- 
actions produced  were  generally  slight  in  degree  and  consisted  of  a  brief 
elevation  in  temperature,  headache,  malaise,  as  well  as  redness,  swell- 
ing, and  pain  at  the  site  of  injection.  The  results  were  not  clear  cut 
on  account  of  the  difficulty  of  comparing  the  disease  in  the  inoculated 
with  suitable  controls.  However,  the  general  impression  is  that  the 
method  has  some  prophylactic  value.  This  opinion  has  been  confirmed 
by  the  later  work  in  various  parts  of  India,  where,  up  to  the  year 
1899,  of  5,778  inoculated  persons,  only  27  had  cholera  and  14  died, 
whereas,  of  5,549  non-inoculated,  198  had  cholera,  of  which  124  died. 
Kolle  showed  that  the  blood  serum  of  the  inoculated  persons  contains 
a  specific  bacteriolysin  similar  to  that  contained  in  the  blood  serum 
of  those  who  have  recovered  from  the  disease.  Kolle  uses  2  mg.  of 
an  agar  culture  suspended  in  1  c.  c.  of  physiological  salt  solution  and 
killed  at  58°  C.  for  one  hour  for  the  first  injection,  and  twice  this 
•Bendick:     Jour,  of  Am.  Pul).  Health  Assn.,  I,  No.  12,  906,  Dec,  1911. 


CHOLEEA  109 

dose  (4  Tag.)  for  the  second;  0.5  per  cent,  of  phenol  is  added  as  a 
preservative.  The  immunity  produced  by  these  protective  inoculations 
lasts  a  long  time,  but  after  a  year  the  specific  antibodies  begin  to 
diminish  in  the  blood  serum. 

There  seems  to  be  little  doubt  in  Japan  concerning  the  value  of  the 
protection  afforded  by  the  inoculation  of  dead  cultures;,  for  in  the 
district  of  Hiogo,  during  the  epidemic  of  1902^  77,907  persons  were 
inoculated.  Of  these  47,  or  0.06  per  cent.,  took  cholera,  and  20,  or 
0.02  per  cent,  died,  whereas,  among  825,287  persons  not  inoculated, 
1,152,  or  0.13  per  cent.,  took  the  disease,  and  863,  or  0.1  per  cent., 
died.  It  is  especially  noteworthy  that  all  the  cases  among  the  inocu- 
lated group  were  in  those  who  received  an  injection  of  2  mg.  of  the 
dead  culture.  Later  4  mg.  were  used,  and  in  this  group  no  cases  oc- 
curred. 

Protective  inoculations  as  a  proph3dactic  measure  against  cholera 
will  never  be  popular  or  necessary  in  communities  with  sufficient  sani- 
tation. It  may,  however,  be  of  value  in  camps,  armies  on  the  march,  for 
physicians,  nurses,  ward  tenders,  and  others  especially  exposed. 

Quarantine. — Cholera  is  an  infection  which  fully  Justifies  maritime 
quarantine  practice.  The  disease  may  be  blocked  by  a  careful  system 
of  inspection,  detention,  and  disinfection  at  the  seaport.  In  order 
for  maritime  quarantine  to  be  effective  for  cholera,  it  must  have  the 
assistance  of  a  bacteriological  laboratory  to  diagnose  cases  and  recog- 
nize carriers.  A  strict  watch  must  be  kept  for  mild  and  ambulant 
cases  of  the  disease. 

In  the  summer  of  1912  the  quarantine  authorities  at  the  large  sea- 
ports on  our  Atlantic  littoral  examined  about  34,000  specimens  of 
bowel  discharges  from  passengers  and  crew  from  cholera-infected  ports. 
At  the  New  York  quarantine  the  cholera  vibrio  was  isolated  from  28 
persons  sick  with  the  disease,  and  27  healthy  persons  were  found  to  be 
discharging  vibrios  in  their  feces.  These  carriers  could  not  have  been 
discovered  except  by  laboratory  examination.  Seven  cases  of  cholera 
were  detected  at  other  ports  by  the  same  methods.  There  can  be  no 
doubt  that  the  adoption  of  this  measure  kept  cholera  out  of  the 
country. 

The  Foreign  Inspection  maintained  by  the  United  States  Govern- 
ment during  the  epidemic  of  1892-93  was  a  convincing  demonstration 
of  the  value  of  this  service  as  one  of  the  safeguards  against  cholera. 
Officers  of  the  Public  Health  and  Marine  Hospital  Service  stationed 
at  foreign  ports  supervised  the  water  and  food  supply  of  the  depart- 
ing vessels,  inspected  the  crew  and  passengers  as  to  their  health;  those 
coming  from  infected  localities  were  detained  under  observation  5 
days  before  they  were  permitted  to  embark.  On  practically  none  of 
the    vessels    complying   with   these    requirements    did    cholera    appear. 


110      DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

whereas  it  broke  out  comparatively  frequently  on  vessels  which  did 
not  comply  with  the  restrictions,  but  sailed  from  the  same  ports  under 
similar  conditions.  A  similar  experience  demonstrating  the  value  of  a 
sanitarv  inspection  of  vessels  leaving  an  infected  port  was  demonstrated 
in  the  Philippines,  where,  since  the  American  occupation,  cholera  has 
been  kept  off  the  returning  transports  and  its  interisland  spread  has 
been  checked  by  a  sanitary  supervision  of  vessels  at  both  the  ports  of 
departure  and  arrival. 

Personal  prophylaxis  requires,  first  of  all,  scrupulous  cleanliness  on 
the  part  of  the  pcr.-on  and  iiis  surroundings.  Those  who  handle  cholera 
patients,  their  dejecta,  or  infected  articles  must  carefully  disinfect  their 
hands  each  time,  and  should  under  no  circumstances  eat  or  drink  any- 
thing in  the  sick  room.  During  cholera  times  all  water  and  food  of 
every  description  should  be  boiled  or  thoroughly  cooked  just  before 
it  is  partaken  of.  Great  care  must  be  exercised  that  the  water  or  food 
does  not  become  infected  after  it  has  been  boiled  or  cooked.  The  usual 
measures  should  be  taken  to  guard  against  flies  and  other  vermin. 
With  strict  attention  to  these  measures,  it  is  possible  to  avoid  the  in- 
fection. In  addition,  however,  attention  to  general  hygiene  and  espe- 
cially to  the  character  of  the  food  and  regularity  of  meals  should  be 
given.  Slight  attacks  of  indigestion  and  diarrhea  should  receive  prompt 
medical  attention. 

Summary — Prevention. — Preventive  measures  should  first  of  all 
be  focused  upon  the  cholera  cases  in  order  to  prevent  the  spread  of  the 
infection  at  the  bedside.     This  includes  early  and  controlled  diagnosis. 

Cholera  patients  should  be  cared  for  in  special  hospitals  where  all 
these  necessary  measures  may  be  carried  out  by  trained  assistants.  The 
infection  in  cholera  stools  may  be  destroyed  with  formalin  (10  per 
cent.),  carbolic  acid  (5  per  cent.),  milk  of  lime  (1  to  8),  or  chlorinated 
lime  (3  per  cent.). 

Persons  leaving  a  cholera  region  should  either  be  detained  in  quar- 
antine for  5  days  or  be  watched  this  length  of  time  after  arrival  at 
the  place  of  destination.  This  m.ay  be  accomplished  by  requiring  them 
to  report  twice  daily  to  the  sanitary  authorities.  It  is  unnecessary  to 
disinfect  merchandise  shipped  from  a  cholera  town. 

For  the  control  of  a  cholera  outbreak  it  is  important  to  require  that 
all  cases,  as  well  as  all  suspicious  cases,  be  reported.  A  bacteriolog- 
ical laboratory  is  necessary  to  confirm  the  diagnosis  and  arrangements 
must  at  once  be  made  to  isolate  the  cases  and  to  disinfect  the  dejecta, 
the  body  and  bed  linen,  and  other  materials.  Convalescents  are  not 
released  until  two  successive  examinations  at  5-day  intervals  show  the 
absence  of  the  cholera  vibrios. 

On  account  of  the  frail  character  of  the  vibrio  a  general  disinfec- 
tion of  the  house  is  not  necessary  in  cholera.     The  room  itself  may 


DYSENTEEY  111 

be  treated  with  formaldehyde  or  the  surfaces  washed  down  with  a  bi- 
chlorid  solution  or  one  of  the  alkaline  coal-tar  creosotes.  The  water- 
closets  may  be  disinfected  with  formalin,  carbolic  acid,  milk  of  lime^ 
or  chlorinated  lime.  Sjjoons,  cups,  saucers,  and  remnants  of  food 
should  be  treated  as  in  the  case  of  typhoid.  Otherwise  the  preven- 
tion of  cholera  is  a  strict  counterpart  of  that  of  typhoid. 

A  summary  of  the  preventive  measures  necessary  to  control  an  out- 
break of  cholera  are :  centralization  of  authority  in  one  person ;  estab- 
lishment of  a  system  of  securing  and  reporting  information;  organiza- 
tion of  the  personnel  for  the  sanitary*  work ;  enactment  of  necessary 
ordinances;  house  to  house  inspection;  safe  disposal  of  feces  of  entire 
population;  provision  for  a  safe  water  supply;  supervisory  control  of 
food  and  drink:;  a  search  for,  anjl  control  of  carriers;  isolation  and  care 
of  patients  in  special  hospitals;  separate  hospitals  or  wards  for  suspects; 
a  laboratory;  detention  camps  or  barracks  for  those  desiring  to  leave 
the  infected  area;  disinfection,  etc.  For  further  discussion  concerning 
the  control  of  epidemics,  see  page  319. 

DYSENTERY 

Classification. — For  the  purpose  of  prevention  we  may  consider  all 
dysenteries  under  three  heads:  (1)  bacillary  dysentery,  (2)  amebic 
dysentery,   (3)  symptomatic  dysentery. 

Bacillary  dysentery  is  an  acute  infectious  disease  caused  by  the 
B.  dysenterioE,  an  organism  that  closely  resembles  the  typhoid  bacillus 
in  cultural  resp.ects.  It  differs  from  typhoid  in  that  it  has  limited  or 
no  motility.  More  fundamental  differences  are  found  in  its  biological 
properties,  such  as  specific  agglutination  and  pathogenic  power.  There 
are  at  least  two  well  recognized  types  of  B.  dysenterice.  One  corre- 
sponds to  the  original  organism  discovered  by  Shiga  in  1897  in  the 
Japanese  epidemic,  and  the  other  to  that  found  by  Flexner  in  Manila. 
The  Shiga  bacillus  does  not  ferment  mannite,  while  the  Flexner  feiTnents 
that  "sugar"  with  the  production  of  acid.  Further,  the  two  organisms 
differ  in  their  properties  of  agglutination  toward  specific  sera.  A  very 
strong  endotoxin  may  be  extracted  from  the  Shiga  type  which,  when 
injected  intravenously  into  rabbits,  produces  a  fatal  intoxication  with 
a  faithful  reproduction  of  the  symptoms  and  lesions  of  bacillary  dysen- 
tery. Kraus  and  Dorr  and  also  Todd  have  found  that  the  Shiga  strain 
produces  such  a  soluble  toxin,  which  is  not  the  case  with  the  Flexner 
strain. 

Amebic  dysentery  results  from  infection  with  the  Entamoeha  hys- 
tolytica.  There  are  marked  differences"  between  the  amebic  and  the 
bacillary  types  of  the  disease.  The  former  is  a  chronic  infection  which 
starts  insidiously,  is  characterized  by  relapses  and  recurrences^  is  fre- 


112      DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

quently  associated  with  sequelae,  such  as  liver  abscesses,  and  occurs 
sporadically  or  in  endemic  foci,  mainly  in  the  tropics.  Epidemic  out- 
breaks of  the  amebic  form  of  dysentery  are  not  known.  Bacillary 
dysentery,  on  the  other  hand,  is  an  acute  febrile  disease,  usually  self- 
limited,  with  marked  symptoms  of  toxemia,  sudden  onset,  no  sequelae, 
and  occurs  in  widespread  and  severe  epidemics.  The  bacillary  disease 
occurs  in  the  temperate  regions  as  well  as  in  the  tropics,  and  is  almost 
always  the  cause  of  dysentery  outbreaks  in  ships,  camps,  jails,  etc.  The 
lesions  of  the  two  diseases  also  differ  markedly.  In  amebic  dysentery 
the  ulcers  arc  undermined,  whereas  in  the  bacillary  disease  the  inflam- 
mation is  diffuse  and  of  varying  grades  of  severity,  which  may  reach 
coagulation  necrosis  or  gangrene.  There  are  also  notable  differences  in 
tlie  treatment;  for  example,  ipecac  given  early  or  rectal  injections  are  of 
service  in  amebic  dysentery,  but  are  of  questionable  use  and  may  even 
do  harm  in  the  bacillary  form.  So  far  as  prevention  is  concerned,  how- 
ever, both  diseases  may  be  regarded  as  intestinal  infections  entering  by 
the  moutli,  and  therefore  the  prophylaxis  is  practically  the  same  and 
corresponds  closely  to  that  of  typhoid  or  cholera. 

Under  symptomatic  dysentery  are  grouped  all  other  conditions  with 
dysenteric  symptoms  resulting  from  a  great  variety  of  causes. 

Modes  of  Transmission. —The  dysentery  bacillus  enters  the  body  by 
the  mouth  and  leaves  the  body  in  the  alvine  discharges.  So  far  as 
known,  the  dysentery  bacillus  does  not  penetrate  deeply  into  the  tis- 
sues, and  is  seldom  found  in  the  circulating  blood.  It  therefore  does 
not  appear  in  the  urine. 

The  infection  is  transferred  from  man  to  man  directly  or  in- 
directly in  precisely  the  same  ways  described  for  typhoid.  Undoubt- 
edly drinking  water  frequently  contains  the  infection,  and  well  marked 
water-borne  epidemics  have  been  reported  in  recent  years,  particularly 
in  Japan.  Contacts,  food,  and  flies  also  play  an  important  role.  The 
epidemiology  of  bacillary  dysentery  is  about  the  same  as  that  of  typhoid. 
It  is  largely  a  summer  disease.  In  wars  it  used  to  cause  great  ravages; 
as  in  the  Crimean  war,  our  own  civil  war,  the  Franco-Prussian 
war,  and  the  recent  Russian-Japanese  war.  Overcrowding,  lack  of 
cleanliness,  and  other  unhygienic  conditions  favor  the  spread  of  bacil- 
lary dysentery,  so  that  it  is  sometimes  called  famine,  asylum,  ship, 
or  jail  dysentery.  The  mortality  varies  greatly,  from  6  or  7  to  26 
or  30  per  cent.  Bacillus  carrying  in  dysentery  occurs,  and  probably 
plays  a  more  important  part  in  spreading  the  disease  than  we  now 
suspect.  As  a  rule,  the  bacilli  soon  disappear  from  the  stools  in  the  light 
cases,  but  Shiga  has  found  them  more  persistent  in  some  instances, 
von  Drigalski  reports  an  outbreak  in  Germany  caused  by  a,  returning 
soldier.    Recent  convalescents  are  particularly  apt  to  spread  the  infection. 

The  3ntamocba   liystolytica   is    also   taken  in   by   the   mouth   and 


BYSENTEEY  ll3 

passed  by  the  bowels.  It  probably  exists  in  its  free  living  state  in 
water,  upon  vegetables  and  fruits,  and  other  moist  surfaces.  There  is 
some  suspicion  that  the  buds  of  the  entameba  may  be  carried  by  the 
air.  There  are  still  large  lapses  in  our  knowledge  concerning  the 
free  living  stages,  and  other  facts  in  the  life  history  of  the  ameba,  so 
that  our  preventive  measures  lack  finality. 

Resistance. — The  dysentery  bacillus  has  about  the  same  resistance 
to  germicides  and  other  unfavorable  conditions  as  the  general  class 
of  spore-free  bacteria.  It  dies  in  about  8  to  10  days  when  dried.  It 
may  live  for  months  when  moist.  It  is  sensitive  to  acids.  Phenol, 
0.5  per  cent.,  kills  the  dysentery  bacillus  in  6  hours,  1  per  cent,  in 
30  minutes,  3  per  cent,  in  1  to  2  minutes.  Bichlorid  of  mercury, 
1-1,000,  kills  it  at  once,  and  direct  sunlight  in  about  one-half  an  hour. 
I  have  found  certain  strains  of  the  dysentery  bacilli  somewhat  more 
resistant  to  heat  than  the  typhoid  bacillus.  They  are  killed  with  cer- 
tainty at  58°  C.  for  one  hour,  or  at  60°  C.  for  20  minutes.  The  dysen- 
tery bacillus  resists  cold  and  may  live  for  months  when  frozen. 

The  Entamceha  hystolytica  is  probably  less  resistant  to  heat  and 
germicides  than  the  B.  dysenierice.  Our  knowledge  concerning  the 
effects  of  drying,  sunlight,  and  other  deleterious  influences  is  still  un- 
certain. 

Immunity. — The  susceptibility  to  dysentery  varies  greatly.  This  is 
doubtless  due  in  part  to  the  bacterial  flora  of  the  intestinal  tract  as 
well  as  the  conditions  of  the  intestinal  mucosa.  Symbiosis  must  play 
a  very  important  role  either  in  permitting  or  hindering  the  dysentery 
bacillus  to  grow  in  the  intestinal  tract.  There  is  still  a  qiiestion  whether 
a  true  immunity  is  acquired  by  one  attack  of  bacillary  dysentery.  This 
seems  probable,  although  it  is  not  unusual  for  a  j)erson  to  have  two  or 
more  attacks  of  dysentery  in  one  season.  Kolle  looks  upon  this  as  an 
exacerbation  of  a  chronic  type  brought  on  by  errors  of  diet,  exposure, 
etc.  The  experiments  on  animals  indicate  that  dysentery  probably 
belongs  to  that  group  of  diseases  which  leave  a  certain  amount  of  pro- 
tection after  one  attack.  A  definite  and  high  grade  of  immunity  can 
be  produced  experimentally  in  several  of  the  lower  animals.  Upon  this 
question,  however,  we  need  light.  Horses  may  be  immunized  to  a  high 
degree,  and  their  sera  contain  a  certain  amount  of  antitoxin  and  other 
antibodies.  This  serum  has  been  used  in  treatment,  but  has  no  par- 
ticular value  as  a  preventive.  There  is  evidently  no  immunity  in 
amebic  dysentery. 

Personal  Prophylaxis. — To  avoid  dysentery  the  two  essentials  are: 
scrupulous  cleanliness  and  the  boiling  of  all  water  and  cooking  of  all 
food  that  passes  the  mouth.  The  usual  precautions  against  flies  and 
vermin,  and  care  as  to  personal  hygiene,  especially  diet,  are  indicated. 

Bacillary  dysentery  is  a  common  disease  in  infants,  and  it  would  be 


Ill      DISEASES   SPREAD   THROUGH   ALVIXE   DISCHARGES 

a  wise  precaution  to  consider  all  cases  of  infantile  diarrhea  as  infectious 
and  to  take  precautions  accordingly. 

Dysentery  should  he  included  in  the  notifiahle  diseases  and  laboratory 
aid  furnished  by  the  Board  of  Health  to  assist  diagnosis.  Cases  should 
be  isolated  in  the  same  sense  that  cases  of  typhoid  are  isolated  and  dis- 
infection practiced  at  the  bedside.  Outbreaks  in  institutions  should 
always  be  investigated  and  vigorous  measures  taken  to  check  further 
spread  and  to  prevent  recurrences.  In  all  respects  the  prevention  of 
dysentery  is  a  close  parallel  to  that  of  typhoid. 


HOOKWORM    DISEASE 

(Uncinariasis  or  Anchylostomiasis) 

Theoretically  the  prevention  of  hookworm  disease  is  comparatively 
simple,  for  here  we  have  an  infection  of  which  we  know  the  parasite 
and  its  life  history,  its  mode  of  exit  and  entrance  into  the  body,  and 
we  possess  a  satisfactory  cure  for  the  disease  within  reach  of  all.  Prac- 
tically, however,  we  have  ignorance,  apathy,  poverty,  and  uncleanliness 
to  deal  with  before  satisfactory  prevention,  much  less  eradication,  can 
be  achieved.  It  is  now  plain  that  hookworm  disease  presents  a  sani- 
tary problem  of  first  magnitude,  not  alone  in  our  southland,  but  in 
practically  all  tropical  and  subtropical  countries.  Further,  there  is  a 
large  economic  and  industrial  aspect  to  this  question  in  medical  biology. 

Distribution. — Hookworm  disease  encircles  the  globe  in  the  tropical 
and  subtropical  climes;  it  diminishes  toward  the  temperate  regions. 
It  is  not  endemic  in  the  colder  latitudes,  except  in  mines,  especially  those 
of  Wales,  Germany,  Xetherlands,  Belgium,  France,  and  Spain.  The 
infection  belts  the  earth  in  a  zone  about  66°  wide,  extending  from 
parallel  36  north  to  parallel  30  south  latitude.  The  amount  of  infec- 
tion is  great  in  American  Samoa,  where  it  is  found  in  70  per  cent, 
of  the  population;  in  the  southern  two-thirds  of  China,  in  75  per  cent, 
of  the  population;  in  India  from  60  to  80  per  cent,  of  the  300.000.000 
population  have  the  disease;  in  Ceylon,  90  per  cent,  in  many  parts; 
in  Xatal,  50  per  cent,  of  the  coolies  on  sugar  and  tea  estates ;  in  Egypt, 
50  per  cent,  of  the  laboring  cla^s;  in  Dutch  Guiana,  90  per  cent,  in 
many  parts;  in  British  Guiana.  50  per  cent,  of  all;  in  Co- 
lombia, 90  per  cent,  of  those  living  between  sea-level  and  3,000  feet, 
which  includes  most  of  the  population;  in  1904  the  Porto  Rican  Anemia 
Commission  found  that  90  per  cent,  of  the  rural  population  of  Porto 
Rico  were  infected.  Stiles  estimates  that  in  this  country  2.000,000  in- 
dividuals have  the  infection  from  the  Potomac  to  the  Mississippi,  along 
the  Atlantic  littoral  and  the  Gulf  states.    In  some  German  mines  from 


HOOKWOEM    DISEASE 


115 


(  ) 


Fig    14. — H  o  o  k  - 

WORMS,  Natural 
Size. 


30  to  80  per  cent,  of  the  miners  have  been  found  to  be  infected.  Gunn  ^ 
has  shown  that  from  50  to  80  per  cent,  of  those  working  in  the  Cali- 
fornia mines  are  infected.  It  is  probable  that  all  the  older  mines  em- 
ploying foreign  laborers  sooner  or  later  become  endemic 
foci. 

In  1879  an  outbreak  of  hookworm  disease  (miner's 
anemia)  occurred  among  the  laborers  in  St.  Gotbard"s 
tunnel.  This  aroused  the  interest  of  the  whole  scien- 
tific world.  The  polluted  soil  of  the  tunnel  was  found 
to  be  impregnated  with  the  eggs  and  larvae.  Interest  in  the  disease  in 
this  country  was  aroused  through  the  work  and  enthusiasm  of  Stiles. 
Varieties  of  Hookworm. — Almost  all  mammalian  animals 
have  hookworms,  but  each  host  species  has  a  different  kind  of 
hookworm;  that  is,  the  hookworms  of  the  dog,  fox,  horse,  the 
seal,  etc.,  differ  from  each  other,  and  are  specific.  The  hook- 
worm of  the  dog  will  not  infest  man  or  other  mammalian  host; 
the  hookworms  of  man  do  not  develop  to  maturity  in  the  lower 
animals,  etc. 

Two  species  of  hookworm  are  found  in  man — the  old  world 
form    (Anchylostoma   duodenale),    and    the    new    world    form 
(Necator    americanus) .      The    distinction    between    these    two 
worms  has  a  zoological  rather  than  a  practical  bearing,  for  both 
produce  the  same  symptoms,  require  the  same  treatment,  have 
the  same  life  history,  and  call  for  the  same  preventive  measures. 
The  chief  differences  between  these  two  hookworms  consist  in 
the  fact  that  the  old  world  form  has  one  pair  of  ventral  hooks, 
two  conical  dorsal  teeth,  and  the  posterior  ray  of  the  caudal 
l)ursa  divides  two-thirds  its  way  from  the  base,  and  each  divi- 
sion has  three  tips  (tripartite).     The  new  world  form  has  ven- 
tral lips,  a  dorsal  median  tooth,  and  one  pair  of  dorsal  and  one 
pair  of  ventral  lancets  deep  in  the  buccal  cap- 
sule.     The    posterior    ray   of   the    caudal    bursa 
divides  at  its  base  and  each  division  has  two  tips 
(bipartite). 

According  to  Stiles,  the  vast  majority  of  cases 
of  hookworm  disease  in  man  in  the  United  States 
are  due  to  the  new  world  form  (Necator  ameri- 
canus). 

Modes  of  Transmission. — The  usual  mode  of 

transmission,  perhaps  in  90  per  cent,  of  the  cases, 

is  through  the  skin.     The  infection  may  also  be 

taken  by  the  mouth  in  drinking  water  or  soiled 

food,  or  from  contaminated  objects,  such  as  dirty  fingers.     It  has  been 

^Jour.  A.  M.  A.,  Vol.  LVI,  No.  4,  Jan.  28,  1911,  p.  259. 


Fig.  15.- 


-HooKWOEM  Em- 
bryo. 


116      DISEASES   SPREAD   THROUGH   ALVIXE   DISCHARGES 

shown  by  experiment  that  animals  can  be  infected  by  drinking  water 
containing  the  embryos.  While  this  source  of  infection  plays  a  minor 
role,  it  is  not  to  be  disregarded. 

The  infection  leaves  the  body  exclusively  in  the  feces,  which  con- 
tain the  eggs  of  the  parasite. 

The  Parasite. — For  a  correct  understanding  of  the  prevention  of 
hookworm  disease  it  is  necessary  to  have  a  knowledge  of  the  essential 
features  of  the  life  history  of  the  parasite. 

Hookworms  are  round  worms  (nematodes)  belonging  to  the  sub- 
family Uncirmnince.  The  adult  worm  is  about  one-half  to  three-quar- 
ters of  an  inch  long,  and  about  the  diameter  of  a  wire  hairpin. 

The  adult  hookworm  lives  in  the  intestinal  tract,  usually  in  the 
small  intestine.  It  attaches  itself  to  the  intestinal  wall,  wounds  the 
mucosa,  sucks  blood,  eats  the  epithelium,  and  probably  produces  a  toxic 
substance  which  injures  the  host. 

The  female  worm  lays  a  prodigious  number  of  eggs  in  a  never- 
ending  stream,  which  pass  from  the  host  in  the  feces.  The  embryo 
does  not  mature  within  the  egg  except  in  the  presence  of  oxygen.  Hook- 
worm embryos,  therefore,  do  not  undergo  full  development  until  the 
eggs  are  discharged  into  the  outer  world.  On  the  other  hand,  the  eggs 
of  Strongyloides  stercoralis,  the  parasite  of  Cochin-China  diarrhea,  con- 
tain fully  developed  embryos  in  the  freshly  passed  feces.  The  hook- 
worm embrj'os  become  mature  within  the  egg  in  6  to  8  hours  in  the 
presence  of  moisture,  warmth,  and  oxygen.  It  is,  therefore,  necessary 
to  examine  the  fresh  stools  in  order  that  this  difference  between  the  two 
infections  may  be  of  value  in  differential  diagnosis. 

Under  favorable  conditions  the  embryo  escapes  from  the  egg  and 
becomes  a  larva  in  about  24  hours.  This  free-living  larva  exists  and 
moves  in  moist  soil  and  feeds  upon  the  organic  matter  found  there. 
In  the  course  of  two  days  or  more  the  larva  sheds  its  skin  (ecdysis) 
and  thus  passes  to  the  first  molt.  The  larva  continues  as  a  free-living 
parasite,  and  in  about  a  week  again  sheds  its  skin,  but  now  continues 
to  live  encysted  inside  this  discarded  skin.  This  is  the  second  ecdysis 
and  this  encysted  larva  no  longer  takes  food.  This  stage  in  the  life 
history  of  the  parasite  is  of  special  importance  for  the  reason  that  it 
is  capable  of  piercing  the  skin;  that  is,  it  is  the  infecting  stage.  In 
this  condition  the  parasite  may  live  in  a  dormant  condition  for  five 
months,  perhaps  longer. 

The  hookworm  larva  passes  in  all  through  five  ecdyses  or  molts. 
Two  of  them  occur  during  its  free-living  stage  and  three  of  them 
during  its  residence  in  the  host.  With  each  ecdysis  the  larva  approaches 
more  nearly  the  appearance  and  structure  of  the  adult  worm. 

The  larva  has  a  slow  motion  and  under  favorable  conditions  prob- 
ably travels  a  number  of  yards,  increasing  the  radius  of  soil  pollution. 


HOOKWOPtM    DISEASE  117 

The  larva  pierces  the  skin  and  passes  by  a  circuitous  route  to  the 
intestinal  tract.  The  parasite  may  enter  the  skin  at  any  place,  but  it 
usually  goes  through  the  soft  and  thin  skin  between  the  toes.  In  its 
passage  through  the  skin  the  larva  produces  an  inflammatory  reaction 
(ground-itch)  which  results  partly  from  the  irritating  action  of  the 
presence  of  the  foreign  body,  but  mainly  from  the  bacteria  carried 
along  with  the  larva.  These  primary  lesions  may  consist  of  a  few 
itching  papules  or  pustules  to  a  severe  dermatitis.  Of  4.741  patients 
questioned  by  Ashford,  King,  and  Gutierrez  in  Porto  Eico,  4,664,  or 
about  98  per  cent.,  gave  a  history  of  ground-itch,  which  is  now  recog- 
nized as  the  first  stage  of  the  disease. 

The  fact  that  the  infection  with  hookworm  disease  is  usually  con- 
tracted through  the  skin  was  discovered  by  Looss  in  Cairo,  Eg3'pt.  He 
also  unraveled  the  course  of  the  parasite  from  the  skin  to  the  intes- 
tines. This  brilliant  discovery,  which  is  one  of  the  romances  of  med- 
ical biology,  is  the  foundation  upon  which  prevention  against  the  in- 
fection depends.  In  1895  Looss  accidentally  spilled  a  drop  of  water 
containing  many  larvge  upon  his  hand,  and  noted  that  they  disappeared, 
leaving  their  delicate  sheaths  behind  them.  Seventy-one  days  subse- 
quently he  developed  intestinal  uncinariasis.  The  experiment  was  then 
repeated  upon  a  volunteer,  and  hookworm  eggs  appeared  in  his  stools 
in  74  days.  Claude  Smith  found  eggs  in  the  feces  6%  weeks  and  7 
weeks  after  experimental  skin  infection  on  two  persons  with  the  Amer- 
ican parasite  (Xecator  americanus). 

The  wanderings  of  the  parasite  from  the  skin  to  the  intestine  were 
worked  but  by  Looss  partly  by  placing  larvae  upon  an  amputated  leg 
and  also  by  studying  the  question  upon  puppies.  The  hookworm  larva 
usually  pierces  the  skin  through  a  hair  follicle,  enters  the  subcutaneous 
tissue,  and  then  finds  its  way  through  the  lymphatics  to  the  neighbor- 
ing lymph  nodes.  The  larvae  are  able  to  squirm  through  the  lymph 
nodes,  pass  to  the  thoracic  duct,  and  thence  to  the  vena  cava  and  the 
right  heart.  From  the  right  heart  they  are  carried  in  the  blood  stream 
to  the  lungs.  The  larva  are  too  large  to  pass  the  capillaries  of  the 
lungs.  They  pierce  the  capillar}^  walls  and  appear  in  the  alveoli  and 
are  now,  to  all  intents  and  purposes,  again  in  the  outer  world.  They 
pass  up  the  bronchi  and  trachea  to  the  throat,  whence  they  are  swal- 
lowed, and  finally  lodge  in  the  small  intestines.  During  their  travel 
through  the  body  they  pass  through  three  ecdyses. 

The  adult  worm  attaches  itself  to  the  mucous  membrane  by  means 
of  the  powerful  buccal  lancet.  The  epithelium  is  drawn  into  the  buc- 
cal cavity  as  though  by  a  powerful  suction.  The  worms  are  usually 
found  in  the  small  intestine,  especially  in  the  jejunum,  less  often  in 
the  duodenum,  and  rarely  in  the  ileum  and  lower  reaches  of  the  in- 
testinal tract;  they  are  occasionally  met  with  in  the  stomach. 
10 


118     DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

The  parasites  imbibe  large  amounts  of  blood,  some  of  which  passes 
through  the  worm  unaltered.  Tlie  wound  continues  to  bleed  after  the 
worm  releases  its  hold,  owing  perhaps  to  a  hemolytic  substance  in  the 
mouth  parts  of  the  parasite.  The  worm  does  not  remain  fastened 
to  one  place  indefinitely,  but  releases  its  hold  and  attaches  itself  anew. 
This  produces  numerous  minute  wounds,  favoring  secondary  infections. 
The  hookworm  probably  produces  a  poison  which  is  absorbed  and  which 
accounts,  in  part,  for  the  anemia  and  other  symptoms  of  the  disease. 
The  severity  of  the  symptoms  bears  no  definite  relation  to  the  number 
of  worms.  The  number  varies  greatly  in  individual  cases;  from  one 
or  two  to  thousands.  Sandwith  counted  250  worms  and  575  bites  in 
one  case;  2,000  are  not  an  uncommon  number.  The  Porto  Rico  Com- 
mission counted  as  many  as  4,000  passed  by  one  individual. 

Immunity. — There  is  no  acquired  immunity  to  this  disease.  There 
is,  however,  a  definite  racial  immunity,  as  shown  by  the  negroes  and  the 
Filipinos,  who  are  often  infected  but  have  comparatively  slight  symp- 
toms. Stiles  found  that  in  this  country  the  negro  is  the  great  reser- 
voir for  hookworm  disease  in  that  he  is  frequently  infected  but  slightly 
affected.  Perhaps  the  negro  has  had  the  disease  so  many  generations 
in  Africa  that  he  has  become  immune.  It  is  conjectured  that  the  in- 
fection was  brought  to  America  through  the  negro  slave  trade.  Hook- 
worm disease  lowers  resistance  and  greatly  increases  the  chances  of 
other  infections,  especially  tuberculosis.  The  secondary  results  are  often 
more  disastrous  than  the  primary  effects. 

Resistance  of  the  Parasite. — The  adult  worm  in  the  intestinal  tract 
may  be  benumbed  or  killed  with  thymol,  betanaphthol,  chloroform, 
gasoline,  eucalyptus  oil,  and  other  of  the  usual  vermifuges. 

From  the  standpoint  of  prevention,  it  is  more  important  to  know 
the  resistance  of  the  eggs  and  larvae  during  their  free-living  stages. 
Stiles  and  Gardner  have  shown  that  the  soil  under  and  around  privies 
is  not  entirely  free  from  infection  with  hookworm  even  five  months 
after  the  privy  was  last  used,  although  the  infection  is  considerably 
reduced  at  tlie  end  of  four  months.  When  the  fecal  matter  has  un- 
dergone decomposition  under  water  most  of  the  hookworm  eggs  are 
dead  in  about  ten  weeks,  though  some  still  survive,  but  probably  all 
are  dead  in  three  months.  It  would  not  be  safe  to  use  such  material  as 
a  fertilizer  in  less  than  three  months.  The  larvae  may  live  in  water 
at  least  thirty  days.  The  encysted  stage  is  most  resistant,  surviving 
five  months;  perhaps  longer. 

The  larvag  are  readily  killed  by  dryness  and  freezing.  The  infec- 
tion was  once  considered  to  be  dust-borne,  but  the  fact  that  the  para- 
sites are  killed  by  drying  renders  the  danger  from  dust  negligible. 
The  fact  that  freezing  kills  the  larvae  largely  explains  why  the  disease 
is  not  endemic  in  this  countrv  north  of  the  Potomac. 


HOOKWORM    DISEASE  119 

It  has  been  shown  that  chlorinated  lime  fails  to  kill  hookworm 
eggs  in  22  to  40  hours.  Schiiffler  kept  the  larvae  alive  almost  four 
months  in  water  with  two  or  three  drops  of  a  one  per  cent,  quinin 
solution  to  10  c.  c.  Oliver  found  that  sea  water  killed  the  larvae  in  37 
minutes. 

Prevention. — The  prevention  of  hookworm  disease  consists  in  pre- 
venting pollution  of  the  soil  and  in  treating  existing  cases  so  as  to 
diminish  the  amount  of  infection.  The  principles  of  prevention  are 
easy  in  theory,  but  their  application  is  difficult  in  practice  on  account 
of  the  widespread  and  enormous  amount  of  the  disease.  The  suppres- 
sion of  hookworm  disease  means  the  social  and  economic  uplift  of  na- 
tions, the  education  of  millions  of  people,  and  an  entire  change  in  their 
daily  hygienic  habits.  Education  of  the  masses  is  an  important  factor;, 
calling  for  cooperation  between  the  health  authorities,  civic  forces,  the 
medical  profession,  schools,  and  philanthropic  agencies;  it  is  something 
for  the  preacher  and  teacher. 

Soil  Pollution. — The  prevention  of  soil  pollution  is  the  essential 
factor;  it  is  the  key  to  the  situation.  This  one  line  of  prevention 
would  blot  hookworm  disease  out  of  existence.  This  requires  the  build- 
ing of  proper  privies,  and  insisting  upon  their  being  used  in  country 
districts.  In  warm  countries  direct  pollution  of  the  soil  is  much  more 
common  and  also  much  more  dangerous  than  in  cold  countries.  Add 
to  this  the  custom  of  going  barefooted  and  we  have  all  the  factors  neces- 
sary for  the  dissemination  of  hookworm  infection. 

Stiles  estimates  that  68  per  cent,  of  the  rural  homes  in  the  South 
are  without  privies.  Even  some  schools  do  not  have  these  accom- 
modations, and  are,  therefore,  hotbeds  of  infection.  For  the  care  and 
disposal  of  night  soil  see  chapter  on  sewage. 

The  Eradication  of  the  Infection  in  Man. — Hookworms  may 
be  expelled  from  the  intestinal  tract  by  the  use  of  thymol,  betanaph- 
thol,  or  other  anthelmintic.  The  eradication  of  the  infection  through 
the  treatment  of  all  infected  persons  is  an  essential  factor  in  preventive 
measures.  The  usual  treatment  is  as  follows :  Saturday  evening  a 
full  dose  of  magnesium  sulphate  or  other  purge  is  given  to  permit 
direct  access  of  the  thymol  to  the  worms,  which  are  often  imbedded  in 
the  mucus  or  chyme.  The  object  is  to  treat  the  parasite  and  not  the 
host.  On  Sunday  morning,  at  8  o'clock,  2  grams  (30  grains)  of  thy- 
mol, for  an  adult,  finely  powdered  in  capsules,  are  given  by  the  mouth. 
Two  hours  later,  at  10  o'clock,  2  more  grams  are  administered;  and  at 
12  o'clock  another  dose  of  salts.  During  the  treatment  it  is  impor- 
tant to  avoid  alcohol,  fats,  and  oils,  as  thymol  is  soluble  in  these  sub- 
stances and  they  are,  therefore,  dangerous,  as  they  thus  favor  absorption. 
The  treatment  is  repeated  every  Sunday  until  the  eggs  disappear.  One 
treatment   usually   suffices.      The    Porto   Eican    Commission   sometimes 


120     DISEASES   SPREAD   THROUGH   ALVIXE   DISCHARGES 

found  it  necessary  to  use  two,  three,  four,  and  up  to  eleven  treatments. 

The  eradication  of  the  infecti&n  in  man  was  carried  out  on  a 
wholesale  scale  by  the  Porto  Rican  Anemia  Commission,  consisting  of 
Ashford,  King,  and  Gutierrez.  Their  methods  were  highly  successful 
and  will  doubtless  serve  an  equally  useful  purpose  in  other  places. 
They  established  a  clinic  for  the  microscopic  diagnosis  and  free  treat- 
ment of  the  disease.  The  good  results  of  treatment  spread  rapidly, 
so  that  the  facilities  of  the  clinic  were  soon  taxed  to  its  utmost  capac- 
ity. Not  the  least  important  function  of  the  clinic  was  to  educate 
the  profession  qs  well  as  the  people.  In  a  little  while  the  clinic  was 
moved  to  another  point,  and  so  on,  until  it  gradually  covered  the  entire 
island. 

Education. — Education  is  one  of  the  most  important  factors  in 
eradicating  hookworm  disease,  for  the  reason  that  its  final  control  de- 
pends upon  improvements  in  the  sanitary  habits  of  the  people,  espe- 
cially in  the  rural  districts.  To  change  the  daily  habits  of  half  a  na- 
tion is  an  uplift  that  requires  time  and  patience.  It  is  perhaps  best 
to  begin  with  the  school  children;  even  then  it  will  take  a  generation 
for  results.  Very  little  can  be  accomplished  by  force,  and,  if  the 
customs  and  prejudices  of  the  people  are  ignored,  the  reformer  and 
benefactor  meet  with  rebuff  and  failure.  It  is  a  good  idea  to  have 
a  public  health  day  or  a  public  health  week  in  the  schools,  during  which 
time  lectures  and  educational  work  upon  hookworm,  typhoid,  tubercu- 
losis, and  other  prevalent  infections  are  considered.  The  children  carry 
the  lesson  into  the  home.  Pamphlets,  posters,  lectures,  exhibits,  and 
popular  articles  in  the  magazines  and  newspapers  all  contribute  their 
share.  The  medical  profession  in  the  infected  areas  may  need  in- 
struction and  a  little  prodding  to  awaken  interest  in  the  problem.  In 
the  popular  education  on  health  matters  the  medical  profession  should 
lead,  especially  through  the  health  authorities.  This  has  also  become 
one  of  the  manifest  duties  of  the  practitioner. 

Cleanliness. — After  all,  the  prevention  of  hookworm  disease  is  a 
question  of  decency  and  cleanliness.  Water  sometimes  carries  the  in- 
fection, hence  it  should  be  clean  or  cleansed  by  filtration  or  boiling. 
Soiled  hands  may  carry  the  infection  to  the  mouth,  hence  they  should 
be  washed  before  eating.  Vegetables  fertilized  with  night  soil  may  be 
infected.  This  practice  is  not  clean  and  should  be  forbidden,  especially 
in  the  case  of  those  vegetables  usually  eaten  raw.  With  cleanly  habits 
there  would  be  no  soil  pollution,  and  the  disease  would  be  checked. 

Personal  Prophylaxis. — Personal  prophylaxis  consists  in  wearing 
shoes  and  otherwise  avoiding  contact  with  the  infected  soil.  Brick 
makers,  miners,  and  others  compelled  to  work  in  infected  soil  should 
wear  gloves.  Other  measures,  such  as  boiling  the  water,  eating  only 
cooked  or  clean  food,  washing  the  hands,  and  avoiding  the  infected  area. 


HOOKWORM    DISEASE  131 

have  either  been  dwelt  upon  or  are  too  obvious  to  need  further  em- 
.phasis. 

Immigratiox. — An  important  factor  in  the  spread  of  hookworm 
disease  in  the  United  States  is  immigration.  Every  country  that  brings 
laborers  from  infected  regions  is  bringing  in  a  constant  stream  of  infec- 
tion. California  has  established  quarantine  measures  against  Indian 
coolies,  90  per  cent,  of  whom  are  infected. 

Collateral  Benefits. — The  best  part  of  a  hookworm  campaign  is 
the  collateral  good  it  does.  This  applies  as  well  to  a  sanitary  campaign 
directed  against  almost  any  disease.  The  suppression  of  hookworm 
disease  will  diminish  the  amount  of  tuberculosis,  typhoid  fever,  dysen- 
tery, and  other  infections.  Thus,  in  Bilibid  prison,  Manila,  the  death 
rate  was  formerly  excessive — 234  per  thousand  when  the  Americans 
took  charge.  This  Avas  reduced  to  75  per  thousand  by  sanitary 
measures,  such  as  boiled  water,  screens,  disinfection,  improved  food, 
less  crowding,  better  air,  more  sunlight,  etc.,  but  despite  these  sani- 
tary improvements  the  death  rate  could  not  be  hammered  doAvn  below 
75  per  thousand.  Then  it  was  found  that  many  of  the  prisoners  were 
infected  with  hookworms.  Thymol  was  administered  and  the  death 
rate  fell  to  13.5  per  thousand.  Another  instance  of  the  collateral  bene- 
fits resulting  from  sanitary  work  is  the  plague  campaign  in  San  Fran- 
cisco, which  cut  typhoid  fever  in  half,  although  no  special  attention 
whatever  was  paid  to  the  latter  disease.  The  purification  of  the  water 
supply  in  Hamburg  by  filtration  cut  down  the  general  death  rate  and 
diminished  the  morbidity  of  diseases  not  water-borne.  One  of  the  most 
encouraging  phases  of  sanitary  work  directed  against  tuberculosis,  ty- 
phoid fever,  and  hookworm  disease  is  the  assurance  that  a  successful 
campaign  will  result  in  fundamental  and  permanent  control  or  eradi- 
cation of  other  communicable  diseases.  The  prevention  of  tuberculosis 
deals  especially  with  personal  hygiene,  and  the  prevention  of  typhoid 
fever  and  hookworm  with  the  sanitation  of  the  environment.  The  com- 
bination of  the  two,  therefore,  embraces  almost  the  entire  range  of  pre- 
ventive medicine. 


CHAPTER    III 

DISEASES    SPREAD    LARGELY    THROUGH    DISCHARGES    FROM 
THE    MOUTH    AND    NOSE 

TUBERCULOSIS 

Tuberculosis  is  the  most  frequent  and  widespread  of  all  the  major 
infections.  In  this  country  9  per  cent,  of  all  deaths,  and  in  Germany 
12  per  cent.,  are  caused  by  tuberculosis.  The  toll  falls  heaviest  dur- 
ing the  period  of  life  of  greatest  usefulness — thus  30  per  cent,  of  all 
deaths  between  the  years  of  15  and  60  are  due  to  pulmonary  tuber- 
culosis alone.  Xaegeli,  from  a  careful  examination  of  a  large  number 
of  bodies  in  Zurich,  found  evidence  of  tuberculosis  in  over  90  per  cent. 
The  lowest  figures  based  on  the  evidence  of  pathologic  anatomy  are 
those  of  Bitzke,  who  examined  1,100  bodies  in  Berlin.  In  children 
under  15  he  found  evidence  in  27.3  per  cent.,  and  in  persons  over  15 
58.2  per  cent.  The  difference  between  Naegeli's  figures  and  Bitzke's 
is  due  to  a  difference  in  the  interpretation  of  the  pulmonary  scars 
and  adhesions  at  the  apices,  and  the  small  fibrous  nodules  in  the 
lungs.  Bitzke  does  not  consider  such  lesions  as  of  tuberculous  origin, 
and  leaves  them  out  of  his  figures.  If  these  were  included,  his 
percentage  would  also  be  very  much  higher.  The  frequency  with 
which  we  become  tuberculized  is  indicated  by  the  fact  that  practically 
all  persons  more  than  a  few  years  old  give  the  von  Pirquet  cutaneous 
reaction. 

In  the  United  States  it  is  estimated  that  160,000  persons  die  each 
year  of  tuberculosis.  Of  the  90.000,000  people  now  living  in  this 
country,  it  is  estimated  that  8,000,000  are  doomed  to  die  of  tuber- 
culosis, unless  the  disease  is  checked.  The  loss  in  life  and  treasure  is 
appalling.  It  is,  therefore,  most  encouraging  that  preventive  measures 
based  upon  modern  conceptions  of  the  disease  as  a  communicable  in- 
fection are  giving  encouraging  results. 

Tuberculosis  began  to  decline  before  the  nature  of  the  infec- 
tion was  known.  The  decline  is  gradual.  Modern  methods  have 
so  far  made  little  apparent  impression  upon  the  gross  amount 
of  the  infection.  The  social  and  economic  conditions  of  the 
122 


TUBERCULOSIS  123 

mass  of  the  population  must  be  improved  before  any  great  decline 
in  the  mortality  rate  can  be  expected,  as  will  presently  be  pointed 
out. 

Tuberculosis  is  fast  becoming,  in  fact  already  is,  a  class  disease; 
it  is  much  more  prevalent  among  the  poor  than  the  well-to-do.  Hence 
the  prevention  of  tuberculosis  has  become  a  sociological  problem.  Pov- 
erty with  all  its  attendant  hardships,  such  as  poor  food,  bad  housing, 
overwork,  and  worry,  diminishes  resistance  to  the  infection;  while  pros- 
perity, which  buys  good  food,  rest,  change  of  air  and  scene,  choice  of 
occupation,  and  diversion,  increases  our  resistance  to  the  infection. 
An  increase  of  wage  or  decrease  in  the  cost  of  living;  shortening  the 
hours  of  work;  improving  the  conditions  of  industrial  hygiene;  adding 
to  the  number  of  holidays;  playgrounds,  parks,  and  wholesome  recrea- 
tion, all  help  to  increase  our  resistance  against  and  diminish  the 
prevalence  of  tuberculosis.  Science  has  shown  the  way;  it  remains 
for  society  to  apply  the  knowledge. 

The  Difference  Between  the  Human  and  the  Bovine  Tuhercle  Bacilli. 
— There  are  at  least  three  kinds  of  tubercle  bacilli :  human,  bovine,  and 
avian.  The  human  and  bovine  varieties  resemble  each  other  closely; 
the  essential  difference  lies  in  the  fact  that  the  human  type  is  very 
pathogenic  for  man,  but  has  little  pathogenicity  for  cattle,  rabbits, 
guinea-pigs,  monkeys,  and  other  animals.  On  the  other  hand,  the 
bovine  type  is  very  pathogenic  for  almost  all  mammalian  animals  ex- 
cept man;  it  is  pathogenic  for  man,  but  less  so  than  the  human  bacil- 
lus. Even  when  large  numbers  of  the  human  variety  are  injected 
into  a  calf,  a  general  disease  does  not  usually  result;  at  most  only  a 
local  lesion  is  produced.  One  one-hundredth  of  a  gram  of  a  pure  cul- 
ture of  a  bovine  race  injected  subcutaneously  is  sufficient  to  cause 
generalized  tuberculosis  and  death  in  a  rabbit  in  about  6  weeks;  while 
ten  or  a  hundred  times  this  quantity  of  a  human  strain  produces  at 
most  a  slight  localized  tuberculosis. 

The  human  bacillus  grows  more  luxuriantly  upon  culture  media, 
covering  the  entire  surface  of  the  medium  with  a  rich,  dry,  crinkled, 
mold-like  vegetation.  The  growth  of  the  bovine  bacillus  upon  artificial 
culture  media  is  more  sparse,  thinner,  less  extensive,  and  somewhat 
slower.  According  to  Theobald  Smith,  who  first  pointed  out  the  differ- 
ences between  these  two  types,  the  human  bacillus  produces  more  acid 
in  artificial  culture  media  and  a  different  reaction  curve  than  that  pro- 
duced by  the  bovine  bacillus. 

Morphologically  the  bovine  bacillus  is  usually  shorter,  plumper,  and 
stains  more  uniformly  than  the  human  bacillus,  which  is  ordinarily 
club-shaped,  irregular,  and  stains  with  interrupted  markings.  The 
morphological  and  tinctorial  characters  are  not  sufficiently  distinctive 
to  distinguish  one  type  from  the  other. 


124  DISCHARGES    FROM    MOUTH    AND    NOSE 

It  is  doubtful  \vheth(ir  there  are  any  specific  differences  between 
the  tuberculins  of  bovine  and  lunnan  origin. 

The  avian  tubercle  harillu.s  is  found  most  frequently  in  chickens 
and  also  in  pigeons,  pheasants,  and  guinea-fowl.  Geese  and  ducks  ap- 
pear immune.  The  avian  bacillus  is  quite  pleomorpliic  and  stains  some- 
what more  readily  tlian  either  the  human  or  bovine  types.  The  avian 
bacillus  grows  luxuriantly  upon  artificial  culture  media  at  45°  C.  and 
even  multiplies  at  temperatures  as  high  as  50°  C,  which  is  in  marked 
contrast  to  the  mammalian  types,  which  do  not  vegetate  above  40°  C. 
The  avian  bacillus  grows  rapidly,  so  that  upon  glycerin-agar  or  upon 
blood  serum  there  is  an  abundant  growth  in  10  days,  which  consists 
of  a  white,  moist,  and  fatty  mass  quite  different  in  young  cultures  from 
the  dried  and  crinkled  appearance  of  the  human  type.  Guinea-pigs 
show  a  decided  resistance  to  the  avian  cultures,  but  rabbits  are  suscep- 
tible. Chickens  and  pigeons  may  be  infected  with  certainty  by  feeding, 
and  it  is  probable  that  in  nature  avian  tuberculosis  is  generally  trans- 
mitted in  this  way. 

Fish  tuberculosis  shows  a  marked  difference  to  the  races  found  in 
warm-blooded  animals.  The  bacillus  grows  between  12°  and  36°  C, 
the  optimum  temperature  being  25°  C.  It  was  first  found  in  a  carp 
and  is  pathogenic  for  frogs.  Neither  the  avian  nor  the  fish  tubercle 
bacilli  are  pathogenic  for  man. 

Bovine  Tuberculosis  in  Man. — Concerning  bovine  tuberculosis  in 
man  we  now  possess  definite  knowledge  which  permits  of  precise  state- 
ments. At  one  time  the  danger  of  bovine  tuberculosis  to  man  was 
greatly  exaggerated.  Koch  went  too  far  on  the  other  side  when  he 
announced  at  London  before  the  International  Congress  on  Tuberculosis 
in  1901  that  there  was  practically  no  danger  of  man  contracting  tuber- 
culosis from  cattle.  In  recent  years  Koch  modified  this  dictum,  for  it 
was  soon  proven  that  the  bovine  bacillus  has  a  certain  amount  of  patho- 
genic power  for  man  and  that  some  of  the  tuberculosis  in  man  is  con- 
tracted from  bovine  sources.  If  only  1  per  cent,  of  the  deaths  from 
tuberculosis  in  the  United  States  were  caused  by  bovine  tubercle  bacilli, 
it  would  mean  1,600  deaths  yearly.  It  is  now  estimated  that  perhaps  7 
per  cent,  of  the  tuberculosis  in  man  is  of  bovine  origin. 

Pulmonary  tuberculosis  in  man  is  practically  never  associated  with 
the  bovine  bacillus.  Bovine  tuberculosis  in  man  is  usually  a  disease 
of  the  lymph  glands — the  l}Tnph  nodes  of  the  cervical  region  and  the 
lymph  nodes  in  the  abdomen  being  especially  attacked.  This  is  doubt- 
less due  to  the  fact  that  the  portal  of  entry  of  the  bovine  bacillus  is 
usually  through  the  tonsils  or  the  small  intestines.  Bovine  tubercu- 
losis may  become  a  fatal  infection  in  man  when  it  is  generalized  through 
the  blood  in  the  form  of  acute  miliary  tuberculosis  or  when  it  localizes 
in  the  meninges  or  other  vital  parts.     About  one-quarter  to  one-half 


TUBEECULOSIS 


125 


of  all  cases  of  tuberculosis  in  children  under  5  years  of  age  is  associated 
with  the  bovine  type.  It  is  probable  that  all  these  cases  derive  their 
infection  through  the  tubercle  bacilli  in  cow's  milk.  There  is 
little  danger  from  meat,  as  this  is  usually  cooked,  and  tubercu- 
losis of  the  muscles  is  exceedingly  rare.  Meat  may  become  con- 
taminated with  tubercle  bacilli  as  a  result  of  unclean  butcher's 
tools  or  unsanitary  methods  of  handling,  or  from  tuberculosis  of 
attached    glands. 

The  following  table  shows  the  relation  between  bovine  and  human 
tuberculosis  in  1,040  cases.  Six  hundred  and  six  of  these  cases  were 
collected  from  the  literature  and  include  those  studied  by  the  English 
and  German  Commissions;  434  of  the  cases  were  studied  in  the  re- 
search laboratory  of  the  New  York  Board  of  Health  by  Park  and 
Krumwiede : 

TABULATION  OF  CASES  EXAMINED  AT  THE  RESEARCH    LABORATORY,    NEW  YORK  CITY 
DEPARTMENT   OF   HEALTH,    BY   PARK   AND    KRUMWIEDE 


Diagnosis  of  Cases  Examined. 

Adults 
16  Years 
and  Over. 

Children 
5  Years  to 
16  Years. 

Children 

Under 
5  Years. 

H. 

B. 

H. 

8 

B. 

H. 

B. 

Pulmonary  tuberculosis 

278 

5 

Tuberculous  adenitis,  inguinal  and  axil- 
lary  

1 

4 

Tuberculous  adenitis,  cervical 

9 

19 

8 

6 

12 

Abdominal  tuberculosis 

1 

1 

1 

3 

Generalized     tuberculosis,     alimentary 
origin 

1 

1 

Generalized  tuberculosis 

2 

1 

12 

4 

Generalized  tuberculosis  including  men- 
inges  

18 

1 

Tubercular  meningitis 

1 

14 

1 

Tuberculosis  of  bones  and  joints 

1 

10 

6 

Genitourinary  tuberculosis 

3 

1 

1 

Tuberculous  abscesses 

1 

Totals 

296 

1 

45 

9 

62 

22 

Total  Cases,  426. 


12G  DISCHARGES    FROM    MOUTH    AND    NOSE 

TABULATED    SUMMARY    OP   CASES    COLLECTED    FROM   THE    LITERATURE 


Diagnosis  of  Cases  Examined. 

Adults 
16  Years 
and  Over. 

Children 
5  Years  to 
16  Years. 

Children 

Under 
5  Years. 

H. 

B. 

H. 

B. 

H. 

B. 

Pulmonary  tuberculosis 

290 

K?) 

3 

7 

Tuberculous  adenitis,  axillary 

1 

2 

Tuberculous  adenitis,  cervical 

13 

1 

14 

12 

9 

8 

Abdominal  tuberculosis 

14 

3 

6 

6 

6 

10 

Generalized     tuberculosis,     alimentary 
origin           

6 

1 

2 

3 

12 

9 

Generalized  tuberculosis.. 

26 

3 

1 

16 

1 

Generalized  tuberculosis  including  men- 
inges  alimentary  origin 

• 

1 

3 

8 

Generalized  tuberculosis  including  men- 
inges   

4 

7 

27 

Tubercular  meningitis 

1 

1 

Tuberculosis  of  bones  and  joints 

17 

1 

16 

1 

15 

Genitourinary  tuberculosis 

8 

Tuberculosis  of  skin 

1 

1 

1 

Miscellaneous  Cases: 

Tuberculous  tonsils 

1 

1 

1 
1 

Tuberculosis  of  mouth  and  cervical 
nodes               

Tuberculous  sinus 

Sepis   latent  bacilli 

Totals 

381 

8 

54 

24 

99 

37 

Mixed  or  Double  Infections,  3  ca.ses: 

Generalized  tuberculosis.     Alim.  Orig.     30  yrs.     Human  and  bovine  type  in 

mesenteric  node.     Human  type  in  bronchial  node. 
Generalized    tuberculosis.     Alim.    Orig.     5^    yrs.     Human    type    in    spleen. 

Bovine  type  in  mesenteric  node. 
Generalized  tuberculosis  incl.  meninges.     Alim.  Orig.     4  yrs.     Human  type  in 
meninges  and  bronchial  nodes.     Bovine  type  in  mesenteric  nodes. 

Total  Cases,  606. 

From  a  study  of  these  1,040  cases  we  find : 

16  years  and  over 686  cases —  9  with  bovine  bacilli —  1.3% 

Between  5  and  16  years 132      "   —33     "  "  "     —25.0% 

Under   5  years...." 120      "    —59     "  "  "      — 19.1% 

Of  568  cases  of  pulmonary  tuberculosis,  none  had  the  bovine  bacil- 
lus.    Cases  under  5  years  of  age,  15  per  cent. 


TUBEECULOSIS 


127 


It  should  be  remembered  that  many  of  the  cases  included  in  the 
above  total  were  selected  cases.  The  436  cases  studied  in  the  Eesearch 
Laboratory  in  New  York,  however,  were  not  selected;  of  these  cases 
the  following  were  found  associated  with  the  bovine  bacillus: 


Diagnosis 


Adults 


Five  to 
Sixteen 


Under 
Five 


Pulmonary  tuberculosis 

Tuberculous  adenitis,  cervical 

Abdominal  tuberculosis 

Generalized  tuberculosis 

Tubercular   meningitis    with    or   without    generahzed 

lesions 

Tuberculosis  of  bones  and  joints 


None 
4% 

16% 
3% 


5% 


None 
37% 
50% 
40% 


3% 


None 
57% 
68% 
26% 

15% 


Since  the  above  tabulations  Park  and  Krumwiede  ^  have  collected  a 
total  of  1,511  cases  which  give  the  following: 

PERCENTAGE   INCIDENCE   OF   BOVINE   INFECTION 


Diagnosis. 


Adults  16 

Years  and 

Over. 


Children 
5  to  16 

Years. 


Children 
Under  5 
Years. 


Pulmonary  tuberculosis 

Tuberculous  adenitis,  cervical 

Abdominal  tuberculosis 

Generahzed  tuberculosis,  ahmentary  origin .... 

Generahzed  tuberculosis 

Generahzed    tuberculosis,  including    meninges, 
ahmentary  origin 

Tubercular  meningitis  (with  or  without  general- 
ized lesions  other  than  preceding) 

Tuberculosis  of  bones  and  joints 

Tuberculosis  of  skin 


.4% 
2.7% 

20% 

14% 
0% 

0% 

0% 
3.3% 
23% 


0% 
38% 
53% 
57% 
16% 

0% 

0% 
6.8% 
60% 


2.8% 
61% 
58% 
47% 

8.6% 

66% 

4.6% 

0% 

0% 


As  is  evident  from  the  table  summarizing  the  total  cases  reported, 
many  of  those  in  children  had  slight  or  latent  infections,  found  on  their 
death  from  other  causes.  The  percentages  deduced,  therefore,  only  give 
the  incidence  of  infection,  nothing  more. 

Weber,  of  the  Imperial  Board  of  Health  of  Germany,  has  made 
observations  to  determine  just  how  much  danger  there  is  in  drinking 
milk  containing  bovine  tubercle  bacilli.  The  milk  coming  from  all 
known  cases  of  udder  tuberculosis  was  traced  to  the  consumer  and  all 
the  persons  drinking  such  milk  or  using  fresh  milk  products  from  in- 

Wour.  Med.  Research,  XXVII,  1,  Sept.,  1912, 


128  DISCHARGES    FROM    MOUTH    AND    NOSE 

fected  sources  were  examined  with  reference  to  tuberculosis.  In  all 
113  separate  investigations  were  made,  including  628  persons  (284  of 
whom  were  children,  335  were  adults,  and  9  of  unstated  age),  all  of 
whom  had  undoubted  opportunities  of  consuming  milk  or  fresh  milk 
products  from  cows  having  tuberculosis  of  the  udder.  The  evidence 
presented  is  not  equally  valuable  in  each  investigation.  In  44  of  the 
113  investigations  cited,  the  milk  was  either  heated,  used  in  coffee  or 
tea,  or  mixed  with  milk  from  apparently  tuberculosis-free  cows  before 
it  was  consumed. 

Three  hundred  and  sixty  persons  (of  whom  151  were  children,  200 
adults,  and  9  of  unknown  age)  were  known  to  use  milk  or  milk  prod- 
ucts, such  as  butter,  buttermilk,  sour  milk,  and  cheese,  which  came 
from  cows  having  undoubted  tuberculosis  of  the  udder.  Of  these  360 
persons  2  were  shown,  by  actual  animal  experimentation,  to  have  in- 
fections with  the  bovine  tubercle  bacillus.  Both  positive  cases  were 
children  with  tuberculous  neck  glands.  Six  other  children  and  1  adult 
had  glandular  swellings  in  the  neck,  and  in  4  other  children  and  1 
adult  there  was  a  strong  suspicion  on  the  part  of  the  attending  physi- 
cian that  abdominal  tuberculosis  was  present. 

In  another  series  of  360  persons,  12  children  and  1  adult  had  swell- 
ings of  the  lymph  glands  of  the  neck.  In  this  group  the  diagnosis  was 
not  confirmed  bacteriologically. 

Weber  concludes  from  these  studies  that  the  danger  which  man  un- 
dergoes through  the  consumption  of  uncooked  milk  and  milk  products 
of  cows  having  tuberculosis  of  the  udder  is  similar  to  the  danger  which 
persons  having  well-marked  pulmonary  tuberculosis  exhibit  for  their 
fellowmen,  although  very  much  less.  He  believes  it  is  fair  to  assume 
from  the  statistics  presented  above  that  the  danger  from  drinking  un- 
cooked milk  or  using  milk  products  of  cows  with  tuberculous  udders  is 
surprisingly  small. 

Woodward  voices  the  prevailing  opinion  when  he  maintains  that  the 
more  deeply  we  go  into  the  subject,  the  bovine  side  of  the  question  comes 
to  take  a  larger  and  larger  place,  especially  in  connection  with  surgical 
and  abdominal  tuberculosis,  not  only  in  the  child  but  even  in  the 
adult. 

From  the  standpoint  of  our  present  knowledge  we  must  consider 
that  practically  every  case  of  bovine  tuberculosis  in  man  is  ingestion 
tuberculosis,  contracted  from  milk  or  fresh  milk  products.  How  the 
tubercle  bacilli  get  into  milk  and  the  frequency  with  which  it  is  in- 
fected are  discussed  on  page  513. 

Occasionally  butchers  and  also  pathologists  at  autopsies  become  in- 
fected with  the  bovine  bacillus  through  wounds.  These  accidents  fur- 
nish further  experimental  proof  that  the  bovine  type  of  the  tubercle 
bacillus  possesses  a  certain  degree  of  pathogenicity  for  man. 


TUBEECULOSIS  129 

MODES  OF  INFECTION 

There  are  two  great  sources  of  human  tuberculosis:  the  principal 
source  is  man  himself;  the  secondary  source  is  cattle. 

From  man  tubercle  bacilli  leave  the  body  mainly  in  the  sputum, 
where  they  are  found  in  great  numbers  in  all  open  cases  of  pulmonary 
tuberculosis.  Tubercle  bacilli  may  also  leave  the  body  in  the  discharges 
from  any  open  tuberculous  lesion  wherever  situated,  especially  in  dis- 
charges from  the  lymphatic  glands,  bones,  intestinal  or  genitourinary 
tracts,  or  the  skin.  In  pulmonary  tuberculosis  some  of  the  sputum  is 
swallowed  and  the  bacilli  appear  in  the  feces,  therefore  any  or  all  of 
the  discharges  from  the  body  may  be  infective.  But,  from  the  prac- 
tical standpoint  of  prevention,  the  bacilli  in  the  matter  brought  up 
from  the  lungs  is  the  source  of  the  danger  in  the  overwhelming  ma- 
jority of  cases. 

Practically  all  observers  agree  with  Koch  that  human  sputum  is 
the  main  source  of  human  tuberculosis.  Whether  the  tubercle  bacillus 
is  usually  transferred  directly  or  indirectly,  in  moist  or  in  dry  state, 
by  inhalation  or  ingestion,  are  questions  still  undetermined.  The  ques- 
tion at  issue  is  a  quantitative  one;  that  is,  how  often  are  we  infected 
by  the  direct  aerogenic  route,  how  often  through  the  tonsils  and  upper 
respiratory  passages,  how  often  through  the  digestive  tube,  etc.  ? 

Aerogenic  Infection.' — The  belief  that  tuberculosis  is  air-borne,  that 
is,  that  pulmonary  tuberculosis  is  a  primary  inhalation  tuberculosis, 
has  long  been  the  natural  and  favorite  theory,  from  the  fact  that  the 
lungs  are  most  frequently  affected.  This  opinion  was  strongly  ex- 
pressed by  Koch  in  1884,  and  repeated  by  him  in  1901,  at  the  British 
Congress  on  Tuberculosis.  For  many  years  it  found  practically  uni- 
versal acceptance.  Cornet  taught  that  the  tubercle  bacilli  entered  the 
lungs  in  the  dust  of  dried  and  pulverized  sputum. 

The  evidence  of  pathologic  anatomy  strengthens  the  belief  in  the 
importance  of  aerogenic  infections  as  the  chief  portal  of  entry.  Thus, 
the  recent  studies  by  Ghon,^  at  the  St.  Anne's  Children's  Hospital  in 
Vienna,  indicate  very  strongly  that  the  actual  path  of  infection  is  by 
the  aerogenic  route.  Approximately  95  per  cent,  of  184  autopsies  studied 
by  him  represent  a  primary  localization  of  the  bacilli  in  the  lungs.  On 
the  other  hand,  it  seems  that  direct  aerogenic  infection  has  been  greatly 
overestimated,  and  some  students  of  the  subject  go  so  far  as  to  state 
it  is  of  little  or  no  practical  importance.  It  is  supposed  that  very  few 
bacteria  suspended  in  the  air  actually  reach  the  lungs,  being  caught 
on  the  moist  mucous  membranes  of  the  upper  air  passages.  Fur- 
ther, tuberculosis  of  the  lungs  is  usually  at  the  apex,  which  is  not 
in  the  direct  line  that  floating  particles  in  the  air  would  usually  be 
^"Der  primare  Lungenherd  bei  der  Tuberkulose  der  Kinder,"  Berlin,   1912. 


130  DISCHARGES    FROM    MOUTH    AND    NOSE 

meclianically  carried.  It  is  true  that  dust  under  certain  conditions 
may  contain  tubercle  bacilli,  but  it  is  now  known  (hat  this  organism 
soon  dies  when  exposed  to  tlic  sun  and  air,  and  that  the  dust  out  of 
doors  is  not  a])t  to  contain  the  live  bacilli,  and  when  it  does  so  the 
dilution  must  be  enormous.  It  is  difTerent  witli  liouse  dust.  Tul)ercle 
bacilli  may  live  a  long  time  in  dark,  moist  })laces,  but  even  here  the 
danger  cannot  be  as  great  as  might  be  supj)Osed  when  we  study  the  na- 
ture of  tulx-rculous  sputum.  This  substance  is  usually  tenacious  and 
gummy,  and  dries  into  tough,  glue-like  masses,  which  are  pulverized 
with  great  ditRculty.  It  therefore  seems  imlikely  that  dust  under  ordi- 
nary circumstances  wouhl  contain  dangerous  numbers  of  live  tubercle 
bacilli.  'J'lie  danger  from  this  source  is  further  diminished  when  we 
consider  that  a  large  nuinl)er  of  tubercle  bacilli  die  in  sputum  even 
when  protected  from  sunlight  and  other  injurious  influences.  It  is 
now  known  that  even  under  most  favorable  conditions  in  artificial  cul- 
ture media  the  great  majority,  perhaps  99  per  cent.,  of  the  bacilli  die 
within  three  months.  Transplants  made  from  cultures  over  three  months 
old  usually  do  not  grow.  The  danger  of  house  dust  containing  live 
tubercle  bacilli   from  a   quantitative  standpoint  is,  therefore,   reduced. 

It  is  quite  possible  that  the  first  infection  does  not  produce  the  dis- 
ease; that  is,  when  a  few  tubercle  bacilli  land  upon  the  lungs  the  tis- 
sues do  not  react  and  the  bacilli  are  carried  to  the  bronchial  lymph 
glands.  This  first  infection,  however,  sensitizes  the  parts,  so  that  the 
second  time  the  bacilli  lodge  the  tissues  react  vigorously  and  a  local  le- 
sion may  result.  A  dusty  atmosphere,  even  though  it  contains  no  tu- 
bercle bacilli,  is,  however,  exceedingly  dangerous,  in  that  it  irritates  the 
delicate  mucous  membranes  and  thus  opens  the  door  for  infection. 

One  point  of  importance  in  this  controversy  is  the  experimental 
evidence  that  it  requires  very  few  tubercle  bacilli  by  inhalation  to  pro- 
duce the  disease,  whereas  it  requires  hundreds  and  even  thousands  to 
cause  intestinal  infection.  This  is  given  as  a  reason  why  infection  via 
the  digestive  tract  is  comparatively  rare  in  man,  for  he  fortunately 
would  seldom  receive  the  necessary  numbers  of  human  bacilli  by  the 
mouth. 

Cornet  and  others  have  actually  found  live  tubercle  bacilli  in  the 
dust  and  upon  objects  of  rooms  where  tuberculous  patients  are  care- 
less with  their  sputum.  In  one  of  Cornet's  experiments  47  out  of  48 
guinea-pigs  exposed  to  the  dust  produced  by  sweeping  a  carpet  with  a 
stiff  broom  became  tuberculous.  The  carpet  had  been  purposely  in- 
fected with  tuberculous  sputum  shortly  before.  Dust  containing  tu- 
bercle bacilli  may  also  enter  the  atmosphere  from  soiled  linen,  uphol- 
stery, handkerchiefs,  and  other  fabrics  containing  the  dried  tuberculous 
sputum.  Tuberculous  dust  may  also  be  stirred  up  by  walking  over 
floors  and  the  dragging  of  the  infection  by  ladies'  skirts. 


TUBEECULOSIS  131 

Droplet  Infection. — When  it  was  found  that  the  danger  from  dust 
theoretically  was  not  as  great  as  was  supposed,  Fliigge  called  attention 
to  the  fact  that  in  speaking,  coughing,  sneezing,  and  in  other  violent 
expiratory  efforts  the  fluid  contents  of  the  mouth  are  sprayed  into  the 
air  in  the  form  of  a  fine  mist.  These  tiny  droplets  contain  tubercle 
bacilli  or  germs  of  any  other  infection  that  may  be  in  the  mouth.  Or- 
dinarily these  droplets  are  carried  several  feet,  but  under  exceptional 
circumstances  may  be  carried  30  or  40  feet  or  more;  however,  at  these 
distances  the  dilution  is  enormous  and  the  danger,  therefore,  much 
diminished.  The  tubercle  bacilli  contained  in  the  droplets  sprayed  from 
the  mouth  are  fresh  and  virulent,  and  may  land  directly  upon  the 
mucous  membranes  of  the  healthy  individual  or  may  be  conveyed  in- 
directly through  food,  fingers,  and  other  objects.  There  is  danger  from 
droplet  infection,  but  it  cannot  be  the  usual  mode  of  transmission  in 
tuberculosis  from  the  nature  of  the  circumstances.  The  danger  from 
droplet  infection  is  increased  by  close  association  with  the  patient  in 
stuffy,  ill-ventilated  rooms,  especially  if  the  individual  docs  not  take 
proper  care  in  coughing  and  sneezing.  For  a  further  discussion  of 
droplet  infection  see  page  632. 

Ingestion  Infection. — Little  by  little  the  view  gained  ground  that 
some  cases  of  tuberculosis,  particularly  in  children,  might  be  due  to 
bacilli  entering  through  the  mucous  membrane  of  the  alimentary  canal. 
Now  we  recognize  that  much  of  the  tuberculosis  in  children  comes  through 
the  alimentary  tract.  Many  years  before  the  discovery  of  the  tubercle 
bacillus  Chauveau  (1868)  Avas  inclined  to  the  belief  that  the  alimentary 
canal  may  be  the  portal  of  entry  in  tuberculosis.  Woodward  in  1894 
maintained  that  the  infecting  bacilli  might  reach  the  lungs  through 
some  part  of  the  alimentary  canal.  He  drew  attention  to  the  fact  that 
in  many  children,  and  also  in  animals  fed  on  tuberculous  material,  the 
lungs  may  be  markedly  affected.  He  traced  the  course  of  the  infection 
through  caseous  or  old  calcareous  mesenteric  glands  up  through  the 
diaphragm  to  the  posterior  mediastinal  glands,  and  so  to  the  lungs. 
Still  in  1899  analyzed  259  fatal  cases  of  tuberculosis  occurring  in  the 
Hospital  for  Sick  Children,  London,  and  concluded  that  the  infection 
had  occurred  through  the  alimentary  canal  in  20.5  per  cent,  of  the 
cases.  Shennan  in  1900,  dealing  with  316  autopsies  at  the  Eoyal  Hos- 
pital for  Sick  Children  in  Edinburgh,  found  this  ratio  to  be  28.1  ner 
cent. 

There  is  no  doubt  that  the  lungs  are  more  or  less  involved  in  all 
cases  of  generalized  infection,  especially  in  children,  but  these  are  not 
cases  of  pulmonary  tuberculosis  (phthisis)  in  the  usual  meaning  of  the 
term.  It  is  phthisis  or  pulmonary  tuberculosis  which  causes  70  per 
cent,  of  all  the  mortality  from  tuberculosis  and  whose  mode  of  origin 
is  now  in  question. 


132  DISCHARGES    FROM    MOUTH    AND    NOSE 

Behring  in  1903  maintained  that  the  tubercle  bacilli  might  be  taken 
up  from  the  intestine  and  pass  through  the  mesenteric  glands,  so  gain- 
ing access  by  the  blood  stream  to  the  lungs  without  leaving  any  le- 
sion in  the  gut  or  glands  to  mark  the  portal  through  which  they  had 
entered  or  the  route  by  which  they  had  traveled,  and  that  pulmonary 
tuberculosis  was  commonly  caused  in  this  way.  Behring's  theory  of 
the  origin  of  phthisis  did  not  find  a  ready  acceptance.  Nevertheless, 
the  belief  that  phthisis  may  be  caused  by  bacilli  which  have  been  swal- 
lowed and  absorbed  from  the  digestive  tube  gradually  gained  ground. 
Vallee  in  1904  concluded  from  his  own  investigations  that  ingestion 
of  dust  or  food  infected  with  tubercle  hacilli  was  the  quickest  and 
surest  method  of  infection.  A  little  later  Calmette  (1905)  of  Lille 
appeared  as  a  strong  supporter  of  this  view.  Calmette  went  so  far  as 
to  assert  that  the  immense  majority  of  cases  of  pulmonary  tul)ercul()sis 
in  man  are  caused  by  ingested  bacilli  and  not  by  inhalation.  Whitla, 
in  1908,  and  Symmers  repeated  some  of  this  work  and  became  con- 
verted to  Calmette's  doctrine,  and  these  views  have  gained  a  number 
of  adherents.  Cobbett  (1910)  considers  that  the  ingestion  theory  is 
based  on  a  slender  substructure  of  experiments  from  which  too  sweep- 
ing conclusions  have  been  found.  Thus  Calmette  and  his  colleagues 
claim  that  even  anthracosis  is  caused  not  by  the  carbon  particles  in- 
haled, but  the  particles  ingested,  which  pass  through  the  intestinal 
mucosa  and  lodge  in  the  lungs.  Cobbett  showed  the  experimental  error 
and  demonstrated  that  India  ink  intimately  mixed  with  cream  is  not 
absorbed  in  any  great  amount  from  the  intestine,  for  the  cream  reap- 
pears of  a  normal  color  in  the  lacteals.  He  found,  however,  that  feed- 
ing finely  divided  carbon  matter  caused  traces  of  pigmentation  in  the 
lung  and  bronchial  glands  when  long  continued.  Heller  and  Vulcan- 
stein  showed  that  the  feeding  of  large  amounts  of  coal  dust  never  pro- 
duces that  grade  of  anthracosis  which  is  found  after  the  inhalation  of 
much  smaller  amounts. 

There  is  now  sufficient  proof  to  state  definitely  that  tubercle  bacilli, 
when  taken  in  food  or  drink,  may  pierce  the  mucous  membrane  of  the 
digestive  tube  and  produce  lesions  in  distant  parts  of  the  body.  It  is 
also  demonstrated  that  the  tubercle  bacillus  may  thus  travel  without  leav- 
ing macroscopic  evidence  of  its  passage  in  its  wake.  Fraenkel  ^  and 
others  have  shown  that  the  tubercle  bacilli  may  jjass  through  the  un- 
injured skin  of  guinea-pigs,  leaving  no  trace  of  their  passage  at  the 
place  where  they  had  rubbed  upon  the  skin,  but  causing  tuberculosis 
of  the  internal  organs.  Ravenel  and  others  have  shown  that  tubercle 
bacilli  may  pass  through  the  intestinal  wall  without  leaving  a  trail  be- 
hind them.     It  does  not,  therefore,  necessarily  follow  that  the  seat  of 

'^Hyg.  Bundschau,  XX,  15,  Aug.  1,  1910,  p.  817. 


TUBEECULOSIS  133 

the  primary  lesion  in  tuberculosis  is  the  site  of  the  entrance  of  the  in- 
fection. 

It  is  also  claimed  that,  no  matter  how  the  tubercle  bacillus  reaches 
us,  whether  in  dust  or  droplets,  by  kissing  or  through  fingers,  flies, 
cups,  handkerchiefs,'  or  milk,  it  either  passes  through  the  tonsils  or 
mucous  membrane  of  the  ujjper  respiratory  passages,  or  is  carried  into 
the  intestinal  tract  and  absorbed  from  the  intestines.  A^iewed  in  this 
light,  the  portal  of  entry  even  in  dust  infection  may  be  through  inges- 
tion rather  than  through  direct  aerogenic  infection  of  tbe  lungs.  Ex- 
perimentally it  is  easy  to  prove  that  tubercle  bacilli  given  by  the  mouth 
may  produce  a  generalized  and  fatal  tuberculosis;  thus,  of  100  guinea- 
pigs  given  one  large  feeding  of  a  bovine  culture  by  Eosenau  and  An- 
derson, 99  died  of  tuberculosis.  That  infection  by  ingestion  does 
not  tell  the  whole  story  is  judged  from  the  fact  that  primary  tu- 
berculosis of  the  mesenteric  nodes  in  man  is  not  as  common  as  we 
might  expect.  On  the  other  hand,  it  is  claimed  that  the  tubercle  bacil- 
lus may  pass  these  lymph  glands,  leaving  little  or  no  trace  behind  them. 
Thus  the  work  of  Weichselbaum  and  his  pupils,  Bartel,  Xeuman,  and 
Spieler,  strengthens  the  importance  of  ingestion  as  the  portal  of  entry. 
These  investigators  found  that  the  tubercle  bacillus  produces,  in  addi- 
tion to  the  specific  tubercles,  other  lesions  of  a  simple  lymphatic  hyper- 
plastic character.  These  earty  lesions  are  called  the  ''lymphoid  stage" 
("hTQphoide  stadium").  The  recognition  of  this  early  stage  is  of 
importance  in  determining  the  point  of  invasion.  The  evidence  ob- 
tained from  the  macroscopic  appearance  of  the  lesions  at  autopsy  must 
be  supplemented  by  microscopic  studies.  Bartel  and  Spieler  found  that 
in  ingestion  experiments  the  different  lymphatic  groups  were  infected 
with  the  following  frequency,   judged  by  the  hmphoid  stage: 

Tonsils   and   surrounding.  ..  .11.7  per  cent. 

Cervical   glands    58.8  per  cent. 

Bronchial  glands    52.9  per  cent. 

Mesenteric  glands    100.0  per  cent. 

These  investigators  assume  that  the  tubercle  bacillus  is  carried  from 
the  mesenteric  or  the  neck  glands  either  through  the  lymphatics  di- 
rectly or  through  the  thoracic  duct  and  the  arterial  circulation  to  the 
lungs  and  other  tissues  and  organs  of  the  body.  The  disease  usually 
localizes  itself  in  the  lung  because  this  organ  presents  the  least  re- 
sistance. 

"Weichselbaum  believes  that  ingestion  tuberculosis  occurs  much  more 

often  in  man  than  is  commonly  supposed  and  especially  in  children.    He 

assumes  that  the  tubercle  bacilli  may  pass  through  the  mouth,  nose,  or 

throat.     It  seems  immaterial  whether  the  bacillus  is  taken  with  food 
11 


134  DISCHAKQES    FROM    MOUTH    AND    NOSE 

or  other  substances  placed  in  the  mouth,  or  is  contained  in  the  inspired 
air,  or  enters  the  mouth  and  nose  through  any  other  medium.  The 
first  lesions  do  not  consist  in  the  formation  of  specific  tubercles,  but  in 
the  so-called  lymphatic  tuberculosis.  This  stage  lasts  a  variable  time 
and  may  end  in  recovery  or  may  lead  to  specific  tuberculosis  either 
through  reinfection,  or  it  may  light  up  itself  without  a  new  infection. 
The  specific  tubercles  may  occur  cither  at  the  portal  of  entry  or  in  the 
lungs  and  bronchial  glands  or  in  other  organs. 

Bchring  (1903)  brought  forward  the  theory  that  alimentary  infec- 
tion occurs  in  the  early  months  of  life.  The  tender  mucous  membrane 
of  babies  permits  the  bacillus  to  pass  readily.  The  bacilli  remain  latent 
in  the  tissues  and  acquire  increased  activity  later  in  life.  According  to 
this  view  tuberculosis  of  adults  is  the  "end  of  a  song,  the  beginning  of 
which  for  the  unfortunate  patient  was  sung  in  the  cradle.''  If  this 
view  were  correct,  the  majority  of  cases  of  tuberculosis  in  adults  would 
be  associated  with  the  bovine  bacillus,  unless  the  bovine  bacillus  has  the 
power  of  changing  to  the  human  type  during  its  long  stay  in  the  body. 
This  is  not  likely. 

It  is  clear  from  the  evidence  at  hand  that  ])ulmonary  tul)erculosis 
may  arise  either  by  inhalation  or  by  ingestion.  The  problem  for  \\s  now 
to  solve  is  a  quantitative  one;  that  is,  what  percentage  of  eases  are 
air-borne  and  what  percentage  come  through  the  mucosa  of  the  digestive 
tract?  Opinions  differ  widely,  but  opinions  are  of  little  value.  We 
must  have  the  facts  before  we  can  give  the  final  answer  to  this  very 
important  and  practical  question.^ 

Flies. — Under  certain  circumstances  flies  may  readily  transfer  tu- 
bercle bacilli  from  exposed  sputum  to  fingers,  lips,  or  food.  This  may 
account  for  an  occasional  case. 

Water. — Large  quantities  of  tuberculous  sputum  that  escape  dis- 
infection and  an  additional  large  number  of  tubercle  bacilli  in  the  ex- 
creta finally  reach  the  drinking  water.  The  tubercle  bacillus  is  particu- 
larly resistant  to  putrefactive  processes,  and  may  live  a  long  time  in 
water.  The  use  of  contaminated  water  can,  therefore,  not  be  disre- 
garded. A  study  of  the  vital  statistics  of  Hamburg,  Lowell,  and  Law- 
rence seems  to  show  a  diminution  in  tuberculosis  following  a  purification 
of  the  water  supply  by  filtration  (Mills-Iieinke  Phenomenon,  page  804). 

Contact  Infection. —The  majority  of  cases  of  tuberculosis  contract 
the  disease  through  "contact."  Contact  infection  is  a  general  and  con- 
venient term ;  it  implies  the  rather  quick  transference  of  fresh  infec- 
tion in  which  the  bacilli  pass  from  one  individual  to  the  other  in  a 
brief  space  of  time  and  through  a  short  distance.     Contact  infection 

^  An  exhaustive  and  able  summary  of  this  question  will  be  found  in  Bulloch's 
article  in  Allbutt  's  ' '  System  of  Medicine, ' '  from  which  some  of  the  facts  in 
this  article  have  been  used. 


TUBERCULOSIS  135 

may  be  either  direct  or  indirect;  through  dust^  through  bacilli  in  the 
air,  or  through  contaminated  food,  through  soiled  fingers  or  objects; 
through  flies,  as  well  as  in  numerous  other  ways.  The  infections  trans- 
ferred through  kissing,  pencils,  pipes,  toys,  cups,  and  other  objects  all 
come  under  the  convenient  category  of  "contacts."  Even  the  infection 
through  droplets  is  included  in  the  present-day  conception  of  contact 
infection.  The  term  is  a  practical  one,  and  implies  close  association, 
though  not  necessarily  actual  contact,  between  the  sick  and  the  well. 
Viewed  in  this  sense,  tuberculosis  is  a  house  disease  or  a  family  disease. 
With  this  conception  it  makes  little  practical  difference  whether  the 
infection  enters  the  body  through  the  respiratory  tract  or  the  digestive 
tube.  Either  or  both  would  be  possible  in  regarding  the  disease  as  con- 
tagious in  the  sense  of  contact  infection. 

Although  there  is  some  doubt  concerning  the  exact  mode  of  trans- 
mission and  the  portal  of  entry  that  the  tubercle  bacillus  usually  takes, 
we  have  sufficient  knowledge  to  guide  our  preventive  measures  with 
every  assurance  of  success.  One  thing  is  certain :  tuberculosis  is  an 
infection  spread  mainly  from  man  to  man,  usually  through  direct  as- 
sociation between  the  sick  and  the  well;  and  secondarily  from  cows, 
through  milk, 

IMMUNITY 

Man  possesses  a  considerable  resistance  to  tuberculosis.  This  is 
shown  by  the  fact  that  many  cases  recover  spontaneously  and  that  per- 
haps all  individuals  who  reach  the  age  of  30  years  and  who  spend  most 
of  this  time  in  association  with  their  fellowmen  under  the  usual  urban 
conditions  have  at  one  or  more  times  been  infected.  The  resistance  to 
tuberculosis  increases  after  middle  life,  due  perhaps  to  the  immunity 
which  is  induced  by  these  prior  infections.  There  is  probably  no  true 
racial  immunity  to  tuberculosis.  Some  races  show  a  smaller  incidence 
to  the  disease,  owing  probably  to  modes  of  life,  habits  of  nutrition,  and 
conditions  of  exposure. 

The  human  organism  is  capable  of  taking  care  of  a  certain  amount 
of  infection.  The  dose,  that  is,  the  number,  of  tubercle  bacilli  and 
their  virulence,  is,  therefore,  a  very  important  factor  in  determining  in- 
fection. This  may  readily  be  demonstrated  upon  susceptible  animals 
and  is  doubtless  true  of  man.  Frequent  reinfections  occurring  at  short 
intervals  with  small  numbers  of  tubercle  bacilli  doubtless  break  down 
the  immunity.  In  man  the  balance  between  immunity  and  susceptibility 
to  tuberculosis  is  delicately  adjusted :  there  is  a  very  small  factor  of 
safety.  The  resistance  to  the  infection  may  be  increased  by  attention 
to  personal  hygiene,  fresh  air,  and  good  food;  immunity  may  readily 
be  broken  down  by  any  weakening  influence;  herein  lies  the  keynote  of 
personal  prophylaxis. 


.136  DISCHARGES    FROM    MOUTH    AND    NOSE 

Tlie  immunity  to  tuberculosis  is  not  sufficiently  strong  to  overcome 
a  large  amount  of  infection.  As  in  all  other  infectious  j)rocess-es,  the 
strongest  and  most  robust  individuals  in  the  jiriine  of  life  succumb  to 
the  disease  in  a  short  time  if  they  receive  into  their  system  a  large 
number  of  virulent  tubercle  bacilli.  Hence  the  avoidance  of  the  in- 
fection  is  one  of  the  most  important  of  our  preventive  measures. 

The  mechanism  of  the  immunity  to  tuberculosis  is  ])robably  exceed- 
ingly complex.  There  is  no  antitoxic  immunity.  The  tuberculins  are 
not  true  toxins.  Phagocytosis  and  cellular  reactions  play  a  very  im- 
portant role.  The  recent  studies  upon  anaphylaxis  throw  a  certain 
amount  of  light  upon  the  mechanism  of  immunity  in  tuberculosis.  The 
phenomenon  of  hypersusceptibility  is  beautifully  illustrated  in  the  action 
of  tuberculin,  which  is  a  comparatively  harmless  substance  to  a  normal 
individual,  but  produces  a  marked  reaction  in  a  sensitized  individual. 
This  reaction  must  be  useful  in  protecting  the  organism  against  the 
invasion  of  the  tubercle  bacillus,  and  also  in  guarding  it  against  the 
spread  of  the  disease  after  it  has  become  localized.  Thus,  if  tuberculin 
is  placed  upon  a  normal  conjunctiva  no  reaction  follows.^  This  first 
application,  however,  sensitizes  the  tissues  of  the  conjunctiva  so  that, 
if  the  application  is  repeated  after  the  lapse  of  a  few  weeks,  there  is  a 
violent  reaction.  The  same  phenomenon  doubtless  occurs  when  a  tubercle 
bacillus  lodges  in  a  lymph  gland  or  in  the  lung  or  some  other  part  of  the 
bod}'.  The  first  time  it  meets  with  little  resistance;  the  next  time  the 
tissues  react  immediately  and  vigorously.  All  of  nature's  protecting 
agencies,  such  as  the  germicidal  substances  in  the  blood,  the  phagocytic 
cells,  and  antibodies,  are  concentrated  upon  the  point  where  they  are 
most  needed.  In  the  same  way  the  body  protects  itself  against  the  ex- 
tension of  a  tuberculous  focus.  The  parts  surrounding  a  tubercle  become 
sensitized  and  react  so  as  to  encapsulate  the  focus  with  a  cellular  and 
fibrous  coat  of  mail.  This  reaction  is  probably  stimulated  by  small 
amounts  of  tuberculin  produced  within  the  tuberculous  focus.  ^Yhen 
the  tuberculin  is  not  produced  autogenously  in  sufficient  amounts,  as  in 
chronic  lesions  of  the  bones,  or  inactive  processes  of  the  glands  or  skin, 
the  specific  reaction  may  be  stimulated  to  advantage  by  the  injection  of 
small  quantities  of  tuberculin.  If,  however,  the  tuberculin  is  given  in 
too  large  amounts  or  too  frequently,  the  power  of  reaction  is  readily 
broken  down.  When  this  occurs  the  mechanism  of  immunity  has  been 
destroyed,  there  is  little  resistance  left  to  the  extension  of  the  infection, 
and  death  soon  occurs.  Clinical  experience  has  demonstrated  the  danger 
of  large  doses  of  tidjerculin  or  small  amounts  too  often  repeated  in  tuber- 
culosis. The  same  may  readily  be  demonstrated  experimentally  in  the 
lower  animals.  These  facts  are  of  fundamental  importance  in  the  use 
of  tuberculin. 

'  Eosenau  and  Anderson,  J.  A.  M.  A.,  Vol.  I,  March  28,  1908,  p.  961, 


TUBEECULOSIS  137 

It  is  quite  proper  to  deny  dogmatically  the  hereditary  transmission  of 
tuberculosis  in  educational  pamphlets  for  popular  use.  The  infection 
is  not  transmitted  hereditarily,  although  it  occasionally  passes  from 
mother  to  fetus  congenitally.  Tubercle  bacilli  do  not  occur  in  the  sper- 
matozoon, and  do  not  appear  in  the  seminal  fluid.  They  are  not  found 
in  the  ovum;  in  fact,  a  tubercle  bacillus  in  the  ovum  would  doubtless 
result  in  the  death  of  the  egg.  The  bacilli,  however,  may  pass  from 
mother  to  fetus  through  the  placenta.  Warthin  shows  that  placental 
tuberculosis  is  more  common  than  is  supposed.  The  lesions  in  the 
placenta  are  not  those  of  t3qoical  tubercle  formation. 

While  the  tubercle  bacillus  itself  is  rarely  transmitted  from  parent 
to  offspring,  an  hereditary  tendency  or  disposition  to  the  disease  may 
be  transmitted.  We  have  no  definite  knowledge  as  to  what  this  de- 
creased resistance  consists  in;  it  may  be  a  diminished  power  of  reac- 
tion. For  this  view  there  is  analogy  in  the  experiments  upon  anaphy- 
laxis in  guinea-pigs,  in  which  it  has  been  shown  that  hypersusceptibility 
to  a  foreign  protein  such  as  tuberculin  may  be  transmitted  from  mother 
to  young. 

A  mild  infection  with  bovine  tuberculosis  in  early  life  seems  to 
leave  a  certain  degree  of  immunity  against  the  human  strain.  At  least 
children  who  have  glandular  tuberculosis  of  the  bovine  type  in  child- 
hood are  said  to  be  less  apt  to  have  tuberculosis  of  the  lungs  in  later 
life.  Likewise,  the  human  strain  injected  into  cattle  produces  a  defi- 
nite immunity  against  the  bovine  type.  Cattle  are  now  immunized 
by  the  intravenous  injection  of  2  c.  c.  of  a  suspension  of  a  pure  cul- 
ture of  the  human  tubercle  bacillus.  This  produces  an  immunity  which 
probably  lasts  for  1  to  2  years.  It  should  be  remembered  that  the  hu- 
man bacillus  under  these  circumstances  remains  alive  for  a  very  long 
time,  and  may  appear  in  the  milk  provided  there  is  a  lesion  in  the 
udder.     This  presents  a  danger  which  cannot  be  disregarded. 

Trudeau  long  ago  showed  that  the  only  definite  immunity  that  could 
be  induced  in  experimental  animals  was  through  the  use  of  live  tubercle 
bacilli.  Webb  and  Williams  ^  have  produced  a  certain  amount  of  im- 
munity in  guinea-pigs  and  monkeys  by  the  injection  of  live  tubercle 
bacilli.  The  first  injection  consists  of  the  introduction  of  a  few  bacilli 
(from  1-200),  which  is  repeated  subcutaneously  at  varying  intervals. 
Two  children  have  also  been  successfully  "vaccinated"  with  upward  of 
600  virulent  human  tubercle  bacilli  without  infection  being  produced. 

RESISTANCE   OF  THE   VIRUS 

We  have  no  easy  method  of  determining  just  when  the  tubercle  bacil- 
lus dies.     The  criterion  of  death  depends  upon  animal  experimentation. 

^"Immunity  in  Tuberculosis,"  J.  A.  M,  A.,  Oct.  28,  1911,  Vol.  LVII, 
No.  18,  p.  1431. 


138  DISCHARGES    FROM    MOUTH    AND    NOSE 

Tlie  tubercle  bacillus  has  no  spore  and  may  be  classed  with  other  non- 
spore-bearing  organisms  so  far  as  its  viability  is  concerned.  Its  virulence 
fades  before  it  dies.  It  is  doubtful  whether  the  waxy  substances  protect 
the  bacillus  against  external  harmful  influences  to  any  unusual  extent. 
The  thermal  death  point  is  60°  C.  for  20  minutes.  This  is  much  less 
than  was  once  considered.^  Failure  to  recognize  the  lesions  produced  by 
the  dead  tubercle  bacillus  is  responsible  for  some  of  the  false  conclusions 
reached  by  experimenters  upon  this  sul)ject. 

From  a  practical  standpoint  the  resistance  of  the  tubercle  bacillus 
in  sputum  is  of  prime  importance.  Protected  from  the  sunlight  it  is 
now  known  that  they  may  live  in  dried  sputum  for  months.  All  tlie 
bacilli  do  not  survive  under  these  conditions,  but  we  lack  methods  to 
determine  the  quantitative  reduction. 

The  tubercle  bacillus  withstands  cold  very  well.  It  has  a  marked 
resistance  against  putrefactive  processes.  It  will  live  a  year  in  water, 
which  is  a  fact  not  to  be  neglected,  as  many  tubercle  bacilli  finally  find 
their  way  into  drinking  w'ater,  and  infection  through  this  source  is 
possible. 

For  the  destruction  of  the  bacilli  in  sputum  only  very  strong 
germicides  or  exposure  to  steam  or  boiling  water  should  be  depended 
upon.  Five  per  cent,  carbolic  acid  is  sufficient,  provided  equal  parts  of 
sputum  and  solution  are  mixed  and  the  exposure  continued  for  24  hours. 
Ten  per  cent,  lysol  acts  in  12  hours.  Bichlorid  of  mercury  is  not  ap- 
plicable for  sputum  disinfection,  as  it  cannot  penetrate  the  albuminous 
mass.     Formalin,  10  per  cent.,  may  be  used. 

Sunlight  is  one  of  the  best  germicides  and  often  destroys  tubercle 
bacilli  quickly.  In  direct  sunlight  the  bacilli  die  in  a  few  hours,  in 
diffuse  sunlight  in  a  few  days,  provided  the  sputum  masses  are  not  too 
thick. 

Antiformin  is  a  differential  germicide,  killing  most  non-spore-bear- 
ing bacteria,  but  acting  more  slowly  upon  the  tubercle  bacillus.  Anti- 
formin is  a  strongly  alkaline  solution  of  sodium  hypochlorite.  (Page 
1020.) 

PBEVENTION 

Preventive  measures  are  based  upon  two  important  facts :  that  tu- 
berculosis is  an  infection  mainly  spread  from  man  to  man  through 
direct  association,  and  secondarily  from  cattle  through  infected  milk. 
Preventive  measures  fall  into  two  categories:  (1)  avoiding  the  infec- 
tion, and  (2)  increasing  resistance  through  personal  hygiene.  Both 
are  necessary.  The  infection  may  be  avoided  through  segregation;  the 
use  of  milk  from  tuberculin-tested  cattle,  else  pasteurized;  education; 

'  The  thermal  death  point  of  pathogenic  microorganisms  in  milk.  M.  J. 
Rosenau,  Hyg.  Lab.  Bull.  U.  S.  Pub.  Health  and  Mar.  Hosp.  Serv.,  No.  42. 


TUBEECULOSIS  139 

disinfection;  proper  disposal  of  tuberculous  sputum;  the  avoidance  of 
contact  with  open  cases,  especially  with  those  who  do  not  use  proper 
precautions;  early  diagnosis,  etc.  Increased  resistance  may  be  gained 
through  fresh  air,  good  food,  rest,  and  compliance  with  the  dictates  of 
personal  hygiene.  This  part  of  the  subject  includes  sociologic  and 
economic  reforms,  without  which  the  warfare  against  tuberculosis  can- 
not succeed.  Improvement  in  housing  conditions,  lowering  of  the  cost 
of  living,  increase  in  the  scale  of  wages,  and  all  forms  of  uplift  help 
secondarily  to  diminish  the  amoi;nt  of  the  disease.  Furthermore,  it  Avill 
be  necessary  to  consider  secondary  agencies,  as  preventive  clinics,  indus- 
trial insurance,  notification,  open-air  schools,  day  and  night  camps,  etc. 

It  is  well  to  remember  that  tuberculosis  has  gradually  declined  in 
England  and  also  in  ]\Iassachusetts  since  about  1850 — before  the  tu- 
bercle bacillus  was  discovered. 

Segregation. — ^Tuberculosis  is  a  "contagious"  disease,  and  it  is  now 
perfectly  plain  that  one  of  the  most  important  single  preventive  meas- 
ures in  this  as  in  all  other  communicable  diseases  consists  in  isolation. 
A  case  isolated  is  a  case  neutralized,  hence  the  great  value  to  the  com- 
munity of  sanitarium  treatment.  Isolation  in  this  case  refers  only  to 
those  individuals  having  tubercle  bacilli  in  their  sputum,  and  especially 
to  the  advanced  and  helpless  cases.  The  isolation  in  tuberculosis  need 
not  go  to  the  extreme  practiced  in  the  acute  communicable  fevers.  In 
fact,  we  cannot  for  many  3-ears  to  come  object  to  giving  a  case  of  open 
pulmonary  tuberculosis  his  complete  liberty,  provided  he  is  careful 
and  cleanly  and  uses  proper  precautions  in  the  disposal  of  his  expectora- 
tion. When  the  disease  becomes  less  prevalent  more  stringent  and  ar- 
bitrary measures  may  then  be  enforced. 

'•'Every  case  of  tuberculosis  isolated  means  an  average  of  at  least 
three  less  new  infections."  Sanatoria  should,  therefore,  be  attractive 
and  as  cheap  as  it  is  possible  to  run  them.  Free  hospital  care  for 
the  incurable  cases  is  necessary,  especially  for  the  poor.  Tuberculosis 
has  diminished  most  in  those  countries  where  sanatoria  are  most  in  use. 

Personal  Prophylaxis. — Personal  prophylaxis  consists  in  avoiding  the 
infection  and  in  obeying  all  the  dictates  of  personal  hj^giene — that  is, 
living  a  clean,  normal,  and  temperate  life. 

Close  association  with  persons  known  to  have  tubercle  bacilli  in 
their  sputum  is  hazardous.  This  becomes  especially  dangerous  when 
the  contact  is  prolonged  and  intimate,  such  as  working  in  the  same 
room,  especially  if  it  is  small  and  ill-ventilated,  or  sleeping  in  the 
same  bed.  The  more  intimate  the  association  and  the  less  care  the  tu- 
berculous individual  takes  with  the  expectoration,  the  greater  is  the 
danger.  The  infection  may  further  be  avoided  by  refusing  to  drink 
from  common  cups,  by  taking  care  in  placing  objects  to  the  mouth  that 
do  not  belong  there,  by  avoiding  dusty  atmospheres,   and  refusing  to 


140  DISCHARGES    FROM    MOUTH    AND    NOSE 

drink  milk  that  docs  not  come  from  tuberculin-tested  cattle  unless  it  is 
pasteurized. 

Meclianical  obstructions  to  breathing  should  be  corrected,  by  surgical 
methods  if  necessary.  Functional  lack  of  proportion  in  the  chest  and 
lungs  of  young  people  favor  infection,  and  every  effort  should  be  made 
to  help  the  child  to  outgrow  them.  Breathing  exercises  and  outdoor 
play  are  especially  useful. 

A  generous  diet  is  one  of  the  best  prophylactics  against  tuberculosis. 
A  fat-rich  food  favors  the  development  of  a  water-poor  body,  and  it  is 
known  from  experimental  observation  that  animals  with  the  largest  pro- 
portion of  water  in  their  tissues  yield  to  infection  more  readily  than 
others. 

Resistance  to  the  disease  is  increased  by  rest,  fresh  air,  good  food, 
sunshine,  the  avoidance  of  all  depressing  influences,  such  as  worry, 
overwork,  intemperance,  and  excesses  of  all  kinds.  Attention  should 
be  given  to  slight  colds  and  other  conditions  known  to  be  predisposing 
causes  to  the  disease. 

Education. — The  prevention  of  tuberculosis,  like  all  other  wide- 
spread infections,  depends  for  its  success  upon  the  education  of  the 
people.  We  are  now  in  possession  of  sufficient  information  of  a  pre- 
cise nature  to  place  the  facts  in  plain  words  before  the  pul)lic.  This 
has  been  done  in  numerous  excellent,  pamphlets  and  popular  articles  in 
the  daily  press  and  magazines,  through  lectures,  exhibits,  and  meet- 
ings, so  that  there  is  now  a  widespread  and  correct  understanding  of 
the  proldem.  The  modern  message  in  tuberculosis  has  been  one  of 
hope,  in  that  the  disease  is  curable;  and  one  of  fear,  in  that  it  is  trans- 
missible. The  former  has  been  a  great  encouragement  and  has  added 
strength  to  the  movement;  the  latter  is  also  helpful,  although  it  has 
run  to  extremes  in  some  quarters.  An  unwarranted  fear  of  tubercu- 
losis (phthisiophobia)  has  subjected  the  tuberculous  individual  to  se- 
vere hardships  by  branding  him  as  a  leper.  Even  cured  cases  of  the 
disease  now  find  difhcidty  in  obtaining  work,  A  wholesome  regard  for 
the  infection  is  useful  and  helpful  in  preventive  medicine,  but  an  hys- 
terical fear  of  tuberculosis  is  quite  as  unwarranted  as  a  total  disregard 
for  the  infection. 

Notification. — Tuberculosis  should  be  included  among  the  list  of 
diseases  requiring  compulsory  notification.  '  Without  this  important  fea- 
ture preventive  measures  are  handicapped.  The  objection  to  compul- 
sory notification  is  based  largely  upon  sympathy  with  the  large  num- 
ber of  individuals  affected  and  the  sensitiveness  of  the  afflicted.  Com- 
pulsory notification  may  result  in  unnecessary  harm,  in  that  the  knowl- 
edge of  the  fact  may  result  in  loss  of  occupation  and  an  avoidance  by 
his  fellowmen  on  account  of  the  fear  people  now  have  of  associating 
with  a  tuberculous  individual.     These  effects  may,  for  the  present,  be 


TUBERCULOSIS  141 

neutralized  by  considering  the  records  as  confidential  communications 
between  physician  and  health  officer. 

Tuberculosis  is  required  to  be  reported  in  Maine,  Michigan,  Massa- 
chusetts (since  1907)  ;  many  cities:  Alameda,  California;  Asbury  Park, 
N.  J. ;  Boston,  Buffalo,  Cincinnati,  New  York,  Salt  Lake  City,  Trenton, 
Yonkers — also  in  Washington,  D.  C,  Minneapolis,  San  Francisco,  and 
Syracuse.    The  list  is  growing  and  the  returns  are  gradually  improving. 

Disposal  of  the  Sputum. — As  the  tuberculous  sputum  is  the  principal 
source  of  the  infection,  it  should  be  disinfected  or  disposed  of  so  that 
it  will  be  harmless  to  others.  Perhaps  the  best  way  is  to  receive  the 
expectorated  matter  into  cloths,*  which  may  be  burned,  or  the  material 
may  be  received  into  one  of  the  various  forms  of  sputum  cups  and 
finally  burned  or  disinfected.  Persons  with  pulmonary  tuberculosis 
must  be  warned  against  the  possible  danger  to  others  of  coughing  with- 
out holding  the  handkerchief  before  the  mouth  and  nose;  under  no  cir- 
cumstances should  they  spit  upon  the  floor.  Penalty  for  spitting  upon 
the  sidewalk,  upon  the  floor  of  public  buildings,  and  in  street  cars  serves 
a  useful  purpose  in  diminishing  the  spread  of  tuberculosis  as  well  as 
other  diseases. 

In  sanatoria  and  hospitals  the  infected  material  may  be  burned  or 
disinfected  with  steam  under  pressure  in  a  special  autoclave,  or  disin- 
fected with  phenol  (5  per  cent.),  lysol  (2  per  cent.),  tricresol  (2  per 
cent.),  or  formalin   (10  per  cent.). 

Disinfection. — Eooms  occupied  by  tuberculous  individuals  should  be 
kept  clean  and  disinfected  from  time  to  time.  A  thorough  disinfec- 
tion and  cleansing  should  also  be  practiced  before  such  rooms  are  oc- 
cupied by  other  persons.  This  may  be  accomplished  by  mopping  sur- 
faces with  the  usual  solutions  of  bichlorid  of  mercury  or  one  of  the 
coal-tar  preparations,  followed  by  formaldehyde  fumigation  and  a  me- 
chanical cleansing,  and  then  a  thorough  airing  and  sunning. 

Early  Diagnosis.— Early  diagnosis  plays  an  important  role  in  suc- 
cessful prevention;  not  only  does  it  give  the  individual  the  best  chances 
of  cure,  but  at  the  same  time  it  assures  the  possibility  of  maximum 
protection  to  others.  Through  the  use  of  tuberculin  and  through  re- 
finements of  clinical  methods  it  is  now  possible  to  diagnose  tubercu- 
losis at  a  stage  when  it  was  formerly  not  suspected.  It  is  a  great  mis- 
take, from  the  standpoint  of  prevention,  to  wait  until  tubercle  bacilli 
appear  in  the  sputum  before  making  a  diagnosis  of  tuberculosis.  Prob- 
ably many  cases  of  "a  slight  run-down  condition,"  of  transient  and 
irregular  febrile  attacks,  are  due  to  a  small  focus  of  tuberculosis  hid- 
den from  the  ken  of  the  clinician.  In  such  cases  a  course  of  rest, 
fresh  air,  and  better  food,  with  a  change  of  scene,  may  often  prevent 
irreparable  damage.  The  establishment  of  preventive  clinics  to  look 
after  such  cases  and  the  maintenance  of  medical  clinics  to  diagnose  and 


143  DISCHARGES    FROM    MOUTH    AND    NOSE 

care  for  the  early  cases  are  important  adjuncts  to  preventive  measures. 
Housing  Conditions. — It  has  long  been  realized,  even  before  the  rea- 
sons were  understood,  that  improvement  in  housing  conditions  dim- 
inishes the  incidence  to  tuberculosis.  This  is  a  common  observation 
in  the  stabling  of  cattle  as  Avell  as  the  domicile  of  man.  The  reasons 
why  improving  the  housing  conditions  diminishes  the  spread  of  tuber- 
culosis are  complex.  In  addition  to  raising  the  standard  of  living, 
better  houses  diminish  the  chances  of  contact  infection,  afford  better 
air  and  more  sunshine,  and  tend  generally  to  the  well-l)cing  and  up- 
lift of  mankind.  ]\Iunieipalities  do  well  to  enact  and  enforce  stringent 
laws  regulating  the  construction  of  houses,  offices,  stores,  and  work- 
shops. The  congested  and  squalid  slums  are  both  a  disgrace  and  a 
menace.  Germs  are  social  climbers,  and  many  a  palace  is  invaded  with 
an  infection  from  a  nearby  neglected  alley.  Philanthropists  cannot  do 
better  than  assist  in   improving  the  housing  conditions  of  the  poor. 

Bovine  Tuberculosis. — The  prevention  of  bovine  tuberculosis  con- 
sists simply  in  using  milk,  cream,  and  fresh  milk  products  from  tu- 
berculin-tested cattle.  The  cattle  should  be  tested  frequently;  at  least 
twice  a  year,  for  the  disease  may  develop  in  the  cow  in  a  few  months. 
WTien  milk  is  used  from  non-tested  cattle,  it  should  be  pasteurized,  and 
the  same  precaution  applies  to  the  milk  used  for  making  cream,  but- 
ter, ice-cream,  and  other  fresh  milk  products. 

Industrial  Insurance.- — ^Industrial  insurance  patterned  after  the  plan 
used  in  Germany  is  a  useful  adjunct  in  the  tight  against  tuberculosis. 
The  German  industrial  associations  under  government  supervision  do 
more  than  care  for  the  tuberculous  workman.  The  heavy  drains  upon 
the  funds  of  the  industrial  associations  have  been  checked  by  the  estab- 
lishment of  "preventoria."  These  are  attractive  country  places  where 
the  working  man  can  go  when  he  is  "run  down."  This  simple  meas- 
ure is  a  great  boon,  and  prevents  the  development  of  many  a  case  of 
tuberculosis  as  well   as  other  diseases. 

Day  camps,  night  camps,  visiting  nurses,  and  similar  agencies  are 
all  helpful.  In  addition  to  the  direct  benefits,  they  teach  the  patient 
how  to  prevent  the  spread  of  the  infection,  how  to  sleep  out  of  doors 
and  its  benefits. 

The  prevention  of  tuberculosis  is  no  longer  a  medical  problem — 
rather  a  sociological  problem.  The  battle  against  tuberculosis  has  been 
waged  with  enthusiasm  and  the  results  arc  encouraging.  Its  eradica- 
tion will,  however,  take  a  long  time  on  account  of  the  chronic  nature  of 
the  disease  and  its  widespread  prevalence.  We  should  be  satisfied  if  we 
diminish  the  amount  of  tuberculosis  appreciably  in  a  generation.  The 
momentum  thus  gained  will  increase  rapidly.  The  time  will  then  come 
when  the  comparatively  few  cases  left  may  be  treated  by  compulsory 
isolation  or  other  aggressive  measures.     Persistence  along  the  lines  now 


DIPHTHEKIA  143 

understood  will  in  time  control  the  disease,  which  will  be  the  crowning 
achievement  in  preventive  medicine. 

DIPHTHERIA 

Our  knowledge  of  diphtheria  is  most  satisfactory  in  that  we  know 
the  cause  of  the  disease  and  its  modes  of  transmission  ;  we  are  able  to 
check  its  spread,  and  possess  a  specific  preventive  and  curative  agent  of 
great  potency. 

Diphtheria  spreads  slowly  from  person  to  person  and  from  com- 
munity to  community.  It  is  not  necessary  to  consider  it  endemic  in 
special  indigenous  foci,  because  it  is  seldom  completely  absent  in  any 
large  community.  ISTewsholme  points  out  that  diphtheria  epidemics 
and  pandemics  occur  cyclically.  The  intervals  between  the  years  of  epi- 
demic prevalence  vary  greatly.  In  Boston  diphtheria  was  epidemic  in 
1863-64,  1875-76,  1880-81,  1889-90,  and  1894;  in  New  York  in  1876- 
78,  1880-82,  1886-88,  and  1893-94;  in  Chicago  in  1860-65,  1869-70, 
1876-79-81,  1886-87,  and  1890.  The  causes  of  these  epidemic  out- 
bursts are  not  clear.  They  may  be  due  to  a  fortuitous  combination 
of  such  circumstances  as  a  new  crop  of  susceptible  children,  a  particu- 
larly virulent  strain  of  the  bacillus,  the  opening  of  the'  schools,  and 
similar  factors  favoring  the  spread  of  the  infection.  On  the  other 
hand,  external  conditions,  such  as  dryness,  may  be  important,  for  "diph- 
theria only  becomes  epidemic  in  years  in  which  the  rainfall  is  deficient. 
There  is  no  instance  of  a  succession  of  wet  years  in  which  diphtheria 
was  epidemic."  It  is  more  than  likely  that  the  great  outbreaks  are  due 
to  a  combination  of  the  three  factors — man,  the  bacillus,  and  the  en- 
vironment. Just  as  a  spark  in  a  forest  may  cause  a  brush  fire  or  a  con- 
flagration, depending  upon  the  amount  of  vegetable  growth,  its  distribu- 
tion, its  condition  as  to  dryness,  the  direction  and  force  of  the  wind,  the 
topography  and  nature  of  the  soil,  and  a  thousand  and  one  other  con- 
ditions, so  diphtheria  and  other  infections  will  smolder  or  burst  into 
flame, '  depending  upon  many  factors. 

Diphtheria  is  said  to  prevail  more  in  rural  than  in  urban  dis- 
tricts. Sir  George  Buchanan  first  pointed  out  that  it  has  always  dis- 
played a  more  marked  tendency  to  prevail  in  sparsely  settled  districts 
than  in  centers  of  population,  although  outbreaks  in  congested  centers, 
schools,  camps,  on  board  ships,  and  in  other  crowded  places,  are  common. 
In  the  tropics  diphtheria  is  practically  absent.  ISTewsholme  pointed  out 
that  it  is  more  of  a  continental  than  an  insular  disease. 

The  fatality  from  diphtheria  has  been  greatly  lowered  since  1904, 
owing  to  the  use  of  antitoxin  and  owing  also  to  refinements  of  diagnosis, 
as  a  result  of  which  many  mild  cases  are  now  included  that  were  formerly 
omitted  from  the  statistical  records.    Whether  or  not  there  has  been  a 


lU 


DISCHARGES    FROM    MOUTH    AM)    NOSE 


natural  tendency  for  the  disease  to  become  milder  in  recent  years  can- 
not be  stated. 

Diphtlieria  reaches  its  maximum  prevalence  in  the  autumn  of  each 
year,,  which  corresponds  to  the  seasonal  prevalence  of  scarlet  fever. 

In  1878  Dr.  Thrushfield 
published  papers  illustrating 
the  way  in  .which  diplitlieria 
hung  about  damp  houses.  A 
damp  dwelling  favors  sore 
throats  and  colds,  and  may 
thus  open  a  way  for  invasion 
of  the  bacilli,  just  as  any  de- 
pressing influence  may  pre- 
dispose to  the  infection.  Chil- 
dren with  scarlet  fever  or 
measles  are  especially  prone 
to  take  diphtheria  if  the  in- 
fection is  around.  Formerly 
imperfect  drains  and  sewer 
gas  were  given  as  the  causes 
of  diphtheria ;  this  is  a  fetish 
which  dies  hard. 

Modes  of  Transmission. 
— The  diphtheria  bacillus 
almost  always  enters  by  the 
mouth  or  nose,  and  the 
lesions  are  usually  localized 
in  the  mucous  membranes  of 
the  throat,  nose,  larynx,  or 
upper  respiratory  tract.  The 
bacillus  leaves  the  body  in  the 
discharges  from  the  mouth 
and  nose.  Diphtheria  occa- 
sionally affects  other  mucous 
membranes  or  abraded  sur- 
faces, such  as  the  conjunctiva 
or  vaginal  mucous  membrane, 
or  open  wounds,  in  which  case  the  discharges  from  these  lesions  contain 
the  infection. 

The  bacillus  may  be  transmitted  directly  from  one  person  to  an- 
other, as  by  kissing,  or  exposure  to  droplet  infection  in  coughing,  speak- 
ing, and  sneezing;  or  the  infection  may  be  conveyed  indirectly  from 
one  person  to  another  in  a  great  variety  of  ways;  most  common  among 
children,  perhaps,  are  toys,  slate  pencils,  food,  fingers,  handkerchiefs, 


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Fig.  16. — Ch.\rt  Computed  from  the  Un'ited 
States  Census  Report  to  Show  how  the 
Opening  of  the  Schools  in  Autumn  In- 
creases Diphtheria. 

The  broken  line  shows  the  number  of  cases  among 
school  children  five  to  fourteen  years  old 
during  1900-04  in  the  registration  area  of  the 
United  States.  The  unbroken  line  shows  the 
number  of  cases  among  children,  from  birth 
to  five  years  of  age,  for  same  period  and  area. 

On  this  chart  the  augmented  increase  in  diphtheria 
among  school  children  from  five  to  fourteen 
years  of  age,  as  compared  with  children 
under  five  years,  is  strikingly  shown. 

(Mass.  State  Board  of  Health,  Monthly  Bull,  Sept., 
1910.) 


DIPHTHEEIA  145 

or  other  objects  that  have  been  mouthed  first  by  the  infected  child  and 
then  by  the  susceptible  child.  Experience  points  clearly  to  the  conclu- 
sion that  diphtheria  infection  is  transmitted  usually  l^y  direct  exchange 
of  the  flora  of  the  nose  and  throat,  rather  than  through  inanimate 
objects. 

Bacillus  carriers  play  a  large  role  in  spreading  the  infection.  Milk 
and  other  foods  may  become  infected  and  transmit  the  disease. 

The  diphtheria  bacillus  is  frail  and  soon  dies  when  dried  or  ex- 
posed to  sunlight,  therefore  air-borne  infection  is  probable  only  in  the 
case  of  close  association,  that  is,  within  a  few  feet  of  the  infected  per- 
son and  within  the  radius  of  the  possibility  of  droplet  infection. 

The  following  description  by  Chapin  illustrates  how  diphtheria 
and  all  other  infections  contained  in  the  secretions  from  the  mouth 
and  nose  may  be  transmitted ;  it  also  emphasizes  the  importance  of  edu- 
cation in  personal  hygiene  based  upon  habits  of  biological  cleanliness: 

"Not  only  is  the  saliva  made  use  of  for  a  great  variety  of  purposes, 
and  numberless  articles  are  for  one  reason  or  another  placed  in  the 
mouth,  but,  for  no  reason  whatever,  and  all  unconsciously,  the  fingers 
are  with  great  frequency  raised  to  the  lips  or  the  nose.  Wlio  can  doubt 
that  if  the  salivary  glands  secreted  indigo  the  fingers  would  not  con- 
tinually be  stained  a  deep  blue,  and  who  can  doubt  that  if  the  nasal 
and  oral  secretions  contain  the  germs  of  disease  these  germs  will  not 
be  almost  as  constantly  found  upon  the  fingers?  All  successful  com- 
merce is  reciprocal,  and  in  this  universal  trade  in  human  saliva  the 
fingers  not  only  bring  foreign  secretions  to  the  mouth  of  their  owner, 
but  there,  exchanging  it  for  his  own,  distribute  the  latter  to  everything 
that  the  hand  touches.  This  happens  not  once,  but  scores  and  hun- 
dreds of  times,  during  the  day's  round  of  the  individual.  The  cook 
spreads  his  saliva  on  the  muffins  and  rolls,  the  waitress  infects  the 
glasses  and  spoons,  the  moistened  fingers  of  the  peddler  arrange  his 
fruit,  the  thumb  of  the  milkman  is  in  his  measure,  the  reader  moistens 
the  pages  of  his  book,  the  conductor  his  transfer  tickets,  the  'lady' 
the  fingers  of  her  glove.  Everyone  is  busily  engaged  in  this  distribu- 
tion of  saliva,  so  that  the  end  of  each  day  finds  this  secretion  freely 
distributed  on  the  doors,  window  sills,  furniture,  and  playthings  in  the 
home,  the  straps  of  trolley  cars,  the  rails  and  counters  and  desks  of 
shops  and  public  buildings,  and,  indeed,  upon  everything  that  the  hands 
of  man  touch.  What  avails  it  if  the  pathogens  do  die  quickly?  A 
fresh  supply  is  furnished  each  day.  Besides  the  moistening  of  the 
fingers  with  saliva  and  the  use  of  the  common  drinking  cup,  the  mouth 
is  put  to  numberless  improper  uses  which  may  result  in  the  spread  of 
infection.  It  is  used  to  hold  pins,  string,  pencils,  paper,  and  money. 
The  lips  are  used  to  moisten  the  pencil,  to  point  the  thread  for  the 
needle,  to  wet  postage  stamps  and  envelopes.     Children  Wap'  apples;, 


146  DISCHARGES    FEOM    MOUTH    AND    NOSE 

cake,  and  lollipops,  while  men  exchange  their  pipes  and  women  their 
hat  pins.  Sometimes  the  mother  is  seen  'cleansing'  the  face  of  her 
child  with  her  saliva-moistened  handkerchief,  and  jierhaps  the  visitor 
is  shortly  after  invited  to  kiss  the  little  one. 

"Children  have  no  instinct  of  cleanliness,  and  tlieir  faces,  hands, 
toys,  clotliing,  and  everything  that  they  touch  must  of  necessity  he 
continually  dauhed  with  the  secretions  of  the  nose  and  mouth.  It  is 
well  known  that  children  between  the  ages  of  two  and  eight  years  are 
more  susceptible  to  scarlet  fever,  diphtheria,  measles,  and  whooping- 
cough  than  at  other  ages,  and  it  may  be  that  one  reason  for  this  is  the 
great  opportunity  that  is  afforded  by  their  habits  at  these  ages  for  the 
transfer  of  the  secretions.  Infants  do  not,  of  course,  mingle  freely 
with  one  another,  and  older  children  do  not  come  in  close  contact  in 
their  play,  and  they  also  begin  to  have  a  little  idea  of  cleanliness." 

Milk-borne  Diphtheria. — The  diphtheria  bacillus  grows  well  in 
milk  without  appreciably  changing  its  flavor  or  appearance.  Trask  col- 
lected 23  diphtheria  epidemics  from  the  literature  between  1895  and 
1907.  Fifteen  of  these  occurred  in  tlie  United  States  and  8  in  Great 
Britain.  The  milk  is  usually  contaminated  by  cases  of  the  disease  occur- 
ring on  the  farm  or  at  the  dairy  or  milk  shop.  In  some  cases  the  diseased 
person  milks  the  cows  or  the  same  person  nurses  the  sick  and  handles 
the  milk.  In  two  instances  the  outbreak  was  supposed  to  be  due  to 
disease  of  the  cow.  One  of  these  instances  studied  by  Dean  and  Todd 
is  instructive.  In  certain  families  supplied  with  milk  from  two  cows 
there  occurred  two  cases  of  clinically  typical  diphtheria  and  three  of 
sore  throat,  whereas  in  another  family  using  the  milk,  only  after  sterili- 
zation, no  case  occurred.  One  of  the  cows  had  mammitis  and  furnished 
a  scanty,  ropy,  semi-purulent,  and  slightly  blood-tinged  milk.  The 
Klebs-Loffler  bacilli  were  isolated  in  all  cases  and  also  from  the  milk 
of  the  cow  with  mammitis.  Experiments  justified  the  conclusion  that 
the  ulcers  upon  the  udder  of  the  cow  with  mammitis  had  become  secon- 
darily infected  with  B.  diplitJierice,  probably  accidentally  from  some  ap- 
parently healthy  person. 

As  a  rule  diphtheria  epidemics  caused  by  infected  milk  are  more 
limited  both  as  to  numbers  and  area  than  milk-borne  outbreaks  of  ty- 
phoid or  scarlet  fever. 

Bacillus  Carriers. — It  was  in  the  case  of  diphtlicria  that  tlie  dan- 
ger of  bacillus  carriers  was  first  realized.  It  is  now  known  that  per- 
sons who  come  in  contact  with  diphtheria  patients  are  very  apt  to 
harbor  diphtheria  bacilli,  though  they  may  remain  in  good  health.  It 
is  also  now  well  known  that  a  certain  percentage  of  the  population 
at  large  harbor  the  diphtheria  bacilli  in  their  nose  or  throat,  even 
though  they  have  had  no  known  association  with  the  disease.  Graham- 
Smith  found  that  66  per  cent,  of  the  members  of  the  family  to  which 


DIPHTHERIA  147 

the  diseased  jDerson  belonged  were  infected ;  the  proportion  being  higher 
(100  to  50  per  cent.)  in  families  in  which  no  precautions  were  taken 
to  isolate  the  sick,  and  much  lower  (10  per  cent.)  when  such  precau- 
tions were  taken.  Of  the  more  distant  relatives  examined,  29  per  cent, 
were  found  to  be  infected.  Bacilli  were  found  in  37  per  cent,  of  per- 
sons in  attendance  on  the  sick.  Observations  of  the  inmates  of  hos- 
pital wards  and  institutions  showed  that  14  per  cent,  are  likely  to 
give  positive  cultures  when  diphtheria  occurs  among  them.  In  in- 
fected schools  8.7  per  cent,  of  the  scholars  were  found  to  be  bacillus 
carriers.  In  New  York,  Scholley  examined  1,000  children  from  the 
tenement  districts,  and  found  18  with  virulent  and  38  with  non-viru- 
lent bacilli.  Slack,  Arms,  Wade,  and  Blanchard  took  cultures  at  the 
beginning  of  the  school  year  from  about  4,500  pupils  in  the  Brighton 
district,  Boston.  Diphtheria  was  not  prevailing  at  the  time.  ISTever- 
theless,  at  least  1  per  cent,  of  all  these  healthy  school  children  were 
found  to  carry  morphological  typical  diphtheria  bacilli.  It  is  estimated 
that  this  is  the  average  ratio  in  the  population  at  large. 

Ordinarily  the  bacilli  found  in  diphtheria  carriers  under  such  cir- 
cumstances have  little  or  no  virulence.  It  is  possible,  but  not  very 
likely,  that  the  virulence  of  such  strains  may  be  raised  by  passing 
through  a  susceptible  individual.  It  is  probable,  however,  that  diph- 
theria is  kept  alive  in  a  community  rather  by  the  virulent  organisms 
in  immune  persons  than  by  these  non-virulent  strains.  None  of  the 
children  in  the  Brighton  district  above  mentioned  had  any  known 
association  with  the  disease,  nor  did  they  afterward  develop  diphtheria. 
The  danger  of  such  carriers  is,  therefore,  problematic,  and,  on  account 
of  their  large  number,  it  is  a  question  whether  they  should  be  isolated. 
The  dangerous  carrier  is  he  who  harbors  the  virulent  strain,  and  this  is 
usually  obtained  from  the  patient,  convalescent,  or  from  a  third  person 
who  has  come  in  contact  with  the  patient.  From  our  present  standpoint 
it  seems  impractical  to  stamp  out  diphtheria  from  a  large  city  by  cul- 
tural tests  of  all  its  inhabitants  and  isolation  of  all  carriers,  especially 
where  dependence  is  placed  upon  morphological  diagnosis.  Some  harm- 
less bacteria  have  the  morphological  appearance  of  the  diphtheria  bacil- 
lus. On  the  other  hand,  the  control  of  diphtheria  outbreaks  in  institu- 
tions, camps,  on  shipboard,  schools,  and  in  similar  places,  where  a  num- 
ber of  people  are  crowded  together,  as  well  as  the  control  of  epidemic 
outbreaks  in  cities  and  towns,  depends  eventually  upon  the  recognition 
of  carriers  and  their  isolation. 

Park  points  out  that  diphtheria  bacilli  of  like  toxic  power  may 
differ  in  their  liability  to  infect  the  mucous  membrane.  Virulence, 
therefore,  has  two  distinct  meanings  when  used  in  connection  with 
the  diphtheria  bacillus.  The  virulence  of  the  bacilli  cannot  be  accu- 
rately determined  from  the  severity  of  an   isolated  case.     The  most 


148  DISCHARGES    ¥110^1    MOUTH    AXl)    XOSE 

virulent  bacillus  found  by  Park  was  obtained  from  a  mild  case  simu- 
lating tonsillitis.  In  localized  epidemics  tbe  average  severity  of  tbe 
cases  probably  indicates  roughly  tbe  virulence  of  tlio  l)acillus  causing 
the  infection.  However,  individual  susceptibility  and  the  character  of 
the  associated  bacteria  are  important  factors  in  determining  the  se- 
verity of  the  disease. 

The  length  of  time  it  requires  for  diphtheria  bacilli  to  disappear 
from  the  throat  and  nose  varies  greatly.  Beebe  and  Park  found  that 
in  304  of  605  consecutive  cases  the  bacilli  disappeared  within  3  days 
after  the  disappearance  of  the  false  membrane.  In  176  cases  they  per- 
sisted for  7  days,  in  64  cases  for  12  days,  in  36  for  15  days,  in  12 
cases  for  3  weeks,  in  4  cases  for  4  weeks,  and  in  2  cases  for  9  weeks. 
In  some  instances  the  virulent  organisms  may  remain  for  months. 
The  disappearance  of  the  bacilli  from  the  throat  and  nose  cannot  be 
hastened  by  the  usual  injections  of  antitoxin,  although  Price  states 
that  diphtheria  antitoxin  applied  locally  hastens  the  disappearance  of 
the  bacilli.  Diphtheria  antitoxin,  when  injected  subcutaneously,  pro- 
tects the  individual  but  does  not  harm  the  bacilli.  Careful  attention 
to  the  hygiene  and  cleanliness  of  the  mucous  membranes  may  hasten 
their  disappearance,  and  this  is  favored  by  copious  washing  of  the 
throat  and  nose  with  large  volumes  of  physiological  salt  solution.  Anti- 
septics, such  as  silver  nitrate,  applied  locally  seem  to  be  of  little  service. 

In  recent  years  other  measures  have  been  proposed  to  rid  the  mu- 
cous membranes  of  diphtheria  bacilli.  A  serum  containing  agglutinins 
has  been  used  with  some  success.  This  serum  in  powdered  form  is 
blown  into  the  throat.  The  diphtheria  bacilli  are  thereby  agglutinated 
and  may  then  be  more  readily  washed  away  by  gargling  and  douching. 
In  case  these  procedures  fail,  a  substance  proposed  by  Emmerich  known 
as  "pyocyanase"  may  be  used.  This  contains  a  ferment  from  bouillon 
cultures  of  the  Bacillus  pyocyaneiis.  It  is  ai)plied  locally  and  acts  by 
its  power  of  bacteriolysis. 

Encouraging  results  have  recently  been  reported  by  "over-riding" 
the  throats  of  diphtheria  carriers  with  suspensions  of  Staphylococcus 
pyogenes  aureus,  which  are  sprayed  into  the  throat  and  nose.  The 
method  was  introduced  by  Schiotz  in  1909.  who  reported  the  ])rompt 
disappearance  of  diphtheria  bacilli  in  six  carriers.  Page,  also  Catlin, 
Scott  and  Day,  Lorenz  and  Pavenel,  and  others,  have  reported  success- 
ful results. 

Hewlett  and  Nankivell,  and  also  Petruschky,  report  encouraging  re- 
sults in  clearing  up  diphtheria  carriers  by  the  subcutaneous  injection  of 
a  diphtheria  vaccine. 

We  must  acknowledge  that  all  these  measures  often  fail.  The  re- 
lief of  bacillus  carriers  is  one  of  the  rewardful  problems  in  preventive 
medicine. 


DIPHTHEEIA  149 

Resistance. — The  diphtheria  bacillus  has  less  resistance  to  adverse 
conditions  than  the  majority  of  the  spore-free  bacteria.  It  is  more  read- 
ily destroyed  by  light,  heat,  and  disinfecting  substances  than  the  typhoid 
bacillus.  In  this  regard  it  corresponds  more  to  the  frailer  streptococci. 
Under  certain  circumstances  the  diphtheria  bacillus  resists  drying  for  a 
long  time.  When  buried  in  the  false  membrane  or  other  albuminous 
substances,  they  may  remain  virulent  for  some  months. 

Immunity. — Immunity  to  diphtheria  is  very  largely  an  antitoxic  im- 
munity and  persists  for  some  months  or  years  following  a  natural  attack 
of  the  disease.  Frequently  immunity  is  of  short  duration,  and  second 
and  third  attacks  are  not  uncommon.  The  fact  that  healthy  persons 
may  harbor  virulent  bacilli  upon  their  mucous  membrane  for  a  long 
time  without  contracting  the  disease  shows  that  other  factors  are  in- 
volved. These  predisposing  causes  are  inflammations  or  lesions  of  any 
kind  of-  the  mucous  membrane,  depressed  vitality  due  to  bad  air,  over- 
crowding, poor  food,  etc.  Persons  vary  markedly  in  susceptibility. 
During  the  first  6  months  of  life  there  is  but  little  susceptibility. 
Children  between  the  ages  of  3  and  10  are  most  susceptible ;  after  that 
age  the  susceptibility  again  decreases.  It  is  known  that  guinea-pigs 
born  of  immunized  mothers  inherit  a  certain  degree  of  resistance,  which 
may  explain  the  relative  insusceptibility  of  children  under  6  months. 
This  may  also  be  accounted  for  by  the  diminished  danger  of  exposure 
of  babies  during  this  age,  especially  in  those  that  are  breast-fed.  Moth- 
er's milk,  even  colostrum,  contains  protective  antibodies,  which  are  ab- 
sorbed by  the  infant,  and  thus  may  protect  it. 

Prevention. — Control  of  Outbreaks  in  Institutions. — Diphtheria 
frequently  appears  in  asylums,  hospitals,  jails,  on  shipboard,  and  similar 
places.  Under  these  conditions  of  crowding  the  disease  has  a  highly 
contagious  tendency.  It  may,  however,  be  controlled  with  every  as- 
surance of  success  by  the  application  of  well-tried  measures.  It  is  cus- 
tomary first  of  all  to  give  a  prophylactic  dose  of  antitoxin  to  all  the 
persons  within  the  institution,  including  both  inmates  and  adminis- 
trative force.  This,  however,  must  be  regarded  more  as  a  measure  of 
temporary  personal  protection  than  as  a  radical  means  of  stamping  out 
the  infection.  It  is  not  possible  by  the  use  of  diphtheria  antitoxin 
alone  to  wipe  out  diphtheria.  The  bacilli  remain  in  the  throats  of  the 
immunized  and  the  disease  continues  to  crop  out  after  the  antitoxic 
immunity  has  passed  away,  which  may  be  a  matter  of  only  a  few 
weeks.  When  diphtheria,  antitoxin  is  used  as  a  prophylactic,  the  dose 
is  1,000  units,  which  should  be  repeated  every  ten  days  or  two  weeks — 
as  long  as  the  danger  persists. 

The  most  important  measure  to  suppress  diphtheria  in  an  institu- 
tion is  to  isolate  all  cases  and  all  carriers.  This  is  possible  in  an  in- 
stitution, although  not  very  practical  among  the  population  at  large. 
12 


150  DISCHARCxES    FROM    MOUTH    AND    NOSE 

The  isolation  of  both  cases  and  carriers  is  the  most  important  and  radical 
of  our  preventive  measures.  In  the  case  of  institutions,  jails,  ships, 
and  similar  places  all  those  who  show  cultures  containing  organisms 
which  morphologically  resemble  tlie  diphtheria  bacillus  should  be  iso- 
lated, w'hether  the  strains  are  virulent  or  not. 

The  bacilli  frequently  grow  in  the  mucous  membrane  of  the  nose 
and  nasal  pharynx  without  symptoms  indicating  their  localization.  Un- 
less cultures  are  taken  from  the  nose,  many  carriers  will  be  overlooked, 
leaving  a  large  loophole  in  our  preventive  measures.  Ward  and  Hen- 
derson in  a  public  school  epidemic  in  Berkeley  in  1907  found  that  all 
attempts  to  isolate  infected  children  had  no  effect  on  the  epidemic  so 
long  as  they  made  throat  cultures  alone.  When  they  took  bolli  nose 
and  throat  cultures  and  quarantined  all  the  children  showing  positive 
cultures,  the  epidemic  stopped. 

Convalescents  should  not  be  released  from  quarantine  until  at  least 
two  cultures  taken  from  both  the  nose  and  throat  are  negative. 

In  addition  to  the  above-mentioned  measures,  care  must  be  taken 
that  the  infection  is  not  spread  by  the  use  of  cups,  spoons,  dishes, 
towels,  handkerchiefs,  and  other  articles  used  in  common.  The  in- 
fected discharges  should  be  rendered  harmless  at  the  bedside,  and  all 
objects  that  come  in  contact  with  patients  or  carriers  should  be  disin- 
fected. A  general  disinfection  with  formaldehyde  may  be  practiced, 
but  in  a  well-ordered  institution  the  usual  cleanliness  of  floors,  walls, 
and  other  surfaces  will  suffice. 

Control  of  Epidemics. — The  principles  which  guide  us  for  the  con- 
trol of  outbreaks  among  the  population  at  large  are  precisely  the  same 
as  those  described  for  the  control  of  epidemics  in  institutions.  The 
only  difference  is  that  in  the  population  at  large  it  is  more  difficult, 
if  not  impossible,  to  apply  the  one  real  important  measure,  namely, 
that  of  isolating  the  carriers.  What  is  needed  is  a  convenient  and  re- 
liable method  of  distinguishing  the  virulent  and  dangerous  bacilli  from 
those  that  look  like  diphtheria  bacilli  but  lack  pathogenic  power  and 
danger  to  man. 

In  almost  all  communities  diphtheria  is  now  one  of  the  diseases 
which  must  be  reported  to  the  health  authorities.  The  houses  are 
placarded  and  the  cases  isolated.  There  is  no  great  objection  to  treat- 
ing a  case  of  diphtheria  in  the  household  provided  the  patient  and  the 
nurse  may  also  be  quarantined  from  the  rest  of  the  household.  Under 
these  circumstances  and  with  intelligent  care  and  disinfection  at  the 
bedside  there  is  little  danger  to  the  rest  of  the  family;  but  the  great 
menace  that  some  of  the  members  of  the  family  will  harbor  bacilli  of 
a  dangerous  type  and  transmit  them  to  others  makes  it  advisable  to 
treat  all  cases  of  diphtheria  in  a  special  hospital. 

The  prompt  and  early  diagnosis  of  diphtheria  has  now  become  one 


DIPHTHERIA  151 

of  the  routine  measures  of  board  of  health  laboratories.  This  example 
in  the  case  of  diphtheria  could  be  extended  with  advantage  to  the  other 
communicable  diseases  for  which  we  have  satisfactory  laboratory  aids. 
Especially  commendable  is  the  general  practice  of  refusing  to  lift  the 
quarantine  until  two  successive  cultures  prove  negative. 

Disinfection  in  diphtheria  should  be  applied  especially  to  the  se- 
cretions from  the  mouth  and  nose.  These  may  be  received  upon  a  piece 
of  gauze  and  burned.  For  the  hands  and  other  objects  bichlorid  of 
mercury  (1-1,000),  carbolic  (2^/2  per  cent.),  formalin  (10  per  cent.), 
tricresol  (1  per  cent.),  are  efficient.  As  a  terminal  disinfectant  for- 
maldehyde gas  may  be  used,  but  the  ordinary  fumigation,  as  practiced 
by  Boards  of  Health,  seems  to  have  little  influence  in  checking  the 
spread  of  the  disease.  Evidence  is  accumulating  that  the  infection 
usually  comes  from  persons  rather  than  from  things.  Bed  linen,  towels, 
and  other  fabrics  should  be  boiled  or  steamed. 

Personal  Prophylaxis. — In  individual  cases  diphtheria  may  be 
avoided  by  the  use  of  diphtheria  antitoxin.  The  antitoxic  immunity, 
however,  depends  upon  the  free  circulation  of  the  antibodies  in  the 
blood,  and  as  the  antitoxin  is  gradually  eliminated  it  cannot  be  de- 
pended upon  to  protect  more  than  2  or  3  weeks. 

Diphtheria  antitoxin  is  a  specific  and  sovereign  remedy.  When  given 
in  sufficient  amounts  during  the  first  24  hours  of  the  disease  it  reduces 
the  mortality  to  practically  nil.  Ordinarily  500  units .  are  sufficient 
for  prophylactic  purposes,  but  1,000  units  are  preferable,  as  this  amount 
produces  an  immunity  of  higher  degree  and  longer  duration.  When 
the  exposure  to  the  infection  continues  the  antitoxin  may  be  adminis- 
tered at  successive  intervals  of  about  2  or  3  weeks.  Upon  the  first  ap- 
pearance of  sore  throat,  fever,  or  other  suggestive  symptoms  in  persons 
who  are  exposed  to  diphtheria  a  full  dose  of  3,000  to  10,000  units  should 
be  administered  without  delay.  In  order  to  obtain  the  full  life-saving 
benefits  of  diphtheria  antitoxin,  it  should  be  given  early  in  the  disease. 
Time  is  the  most  important  factor.  When  the  damage  to  the  cells 
has  been  done,  it  may  be  too  late.  It  is  not  always  advisable  to 
wait  for  bacterial  confirmation.  Personal  prophylaxis  is  further  fa- 
vored by  the  individual  having  his  own  glass,  cups,  spoons,  towels,  etc., 
and  exercising  personal  cleanliness,  especially  concerning  the  hands 
and  all  objects  placed  in  the  mouth.  Physicians,  nurses,  and  others 
who  come  in  close  contact  with  the  patient  should  guard  against  drop- 
let infection. 

PREVENTION  OF  POST-DIPHTHERITIC  PARALYSIS 

It  has  been  observed  that  post-diphtheritic  paralysis  is  more  fre- 
quent since  the  use  of  antitoxin  than  before  the  days  of  serum  therapy. 


152  DISCHARGES    FROM    MOUTH    AND    NOSE 

This  is  due  to  the  fact  that  many  cases  now  recover  that  would  for- 
merly have  died.  It  is  also  due  to  the  fact  that  diphtheria  antitoxin 
is  sometimes  used  too  late,  thus  neutralizing  only  the  acute  effects  of 
the  toxin,  but  not  neutralizing  the  after-effects  of  the  toxon,  which 
acts  specifically  upon  the  nerves.  The  prevention  of  post-diphtheritic 
paralysis,  therefore,  consists  in  giving  sufficient  amounts  of  antitoxin 
early  in  the  disease.  The  antitoxin  does  not  influence  the  paralysis 
after  it  has  once  appeared. 

PREVENTION  OF  SEBUM  SICKNESS 

This  subject  may  appropriately  be  considered  here,  although  it  is 
a  condition  that  may  follow  the  injection  of  any  alien  serum  into 
the  system.  Serum  sickness  is  a  syndrome  which  frequently  follows 
the  injection  of  horse  serum  into  man.  The  symptoms  come  on  after 
about  8  or  10  days  following  the  injection.  They  consist  of  various 
skin  eruptions,  usually  urticarial  or  erythematous  in  character;  also 
fever,  edema,  glandular  enlargements,  rheumatic-like  pains  in  the  joints, 
and  albuminuria.  The  eruptions  may  be  either  local  or  general,  and 
sometimes  resemble  that  of  scarlet  fever  or  measles.  Serum  sickness 
has  nothing  to  do  with  the  antitoxin,  but  is  caused  entirely  by  the 
foreign  proteins  contained  in  the  horse  serum.  It  may  be  produced 
with  normal  horse  serum  as  well  as  with  antitoxic  horse  serum.  The 
studies  upon  anaphylaxis  have  thrown  much  light  upon  the  nature  of 
this  complication.  The  serum  of  some  horses  is  much  more  apt  to 
produce  the  syndrome  than  that  of  other  horses.  A  serum  that  is  sev- 
eral years  old  is  perhaps  less  apt  to  produce  these  reactions  than  a 
fresh  serum.  Manufacturers  of  antitoxin,  therefore,  prefer  to  keep 
their  serum  in  the  ice  chest  some  time  before  they  place  it  upon  the 
market,  although  this  a  doubtful  expedient.  The  occurrence  and  severity 
of  the  symptoms  are  in  direct  proportion  to  the  amount  of  foreign  pro- 
tein injected.  Fortunately,  this  form  of  anaphylactic  reaction  soon 
passes  away  and  is  never  serious.  Under  certain  circumstances,  however, 
there  may  be  an  accelerated  or  immediate  reaction  threatening  in  its 
consequence  or  even  leading  to  death.  Rosenau  and  Anderson  have  col- 
lected some  19  cases  of  sudden  death  following  the  injection  of  horse 
serum,  and  they  know  of  more  instances  which  have  not  appeared  in  the 
literature.  This  unusual  and  serious  complication  comes  on  within  5 
or  10  minutes  of  the  injection,  and  is  characterized  by  collapse,  uncon- 
sciousness, cyanosis,  labored  respiration,  and  edema.  The  heart  continues 
to  beat  after  respiration  has  ceased.  The  entire  picture  is  an  exact 
counterpart  of  the  anaphylactic  shock  so  readily  reproduced  by  second 
injection  of  horse  serum  or  other  foreign  protein  in  the  guinea-pig.  Con- 
trary to  the  experimental  work  on  the  lower  animals,  most  of  the  cases  of 


DIPHTHEKIA  153 

sudden  death  in  man  follow  the  first  injection  of  horse  serum.  The  seri- 
ous symptoms  and  death  in  these  cases  are  not  due  to  any  inherent  poison- 
ous property  in  the  antitoxic  serum,  but  result  entirely  from  a  hyper- 
susceptibility  of  the  individual.  Just  how  man  becomes  sensitized 
in  these  cases  is  not  known.  Most  of  the  cases,  however,  occur  in 
asthmatics  or  in  persons  who  gave  a  history  of  asthma  or  discomfort 
when  about  horses.  This  is  a  practical  and  important  point,  and  should 
be  inquired  into  before  horse  serum  of  any  kind  is  injected.  Horse 
serum  should  not  be  injected  into  such  individuals  unless  the  indica- 
tions are  clear,  and  then  only  with  a  statement  as  to  the  possible  out- 
come. 

In  order  to  prevent  this  serious  complication  a  small  quantity 
may  first  be  injected,  1  or  2  drops,  and  after  waiting  an  hour  the  re- 
mainder may  be  given.  Vaughan  proposed  0.5  c.  c.  as  the  trial  dose, 
but  this  is  excessive,  as  some  of  the  fatal  cases  have  followed  the  in- 
jection of  about  1  c.  c.  It  is  known  that  in  man,  as  in  the  experi- 
mental cases  in  the  guinea-pig,  the  severity  of  the  symptoms  bears  a 
definite  ratio  to  the  amount  of  serum  and  the  mode  of  injection.  Thus, 
second  injections  in  the  guinea-pig  are  much  more  fatal  when  given 
directly  into  the  circulation  than  into  the  subcutaneous  tissue.  It  is 
sometimes  advisable  to  give  antitoxic  sera  directly  into  the  circula- 
tion, but  in  the  susceptible  persons  under  discussion  this  would  be 
hazardous. 

Friedberger  and  Mita  ^  found  it  possible  to  avoid  all  symptoms  of 
anaphylaxis  in  experimental  work  with  guinea-pigs  by  injecting  the 
serum  extremely  slowly.  When  thus  introduced  animals  are  able  to 
tolerate  an  amount  far  beyond  the  ordinary  lethal  dose. 

Historical  Note.  — A  complete  summary  and  bibliography  of  diph- 
theria up  to  1908  will  be  found  in  the  system  edited  by  Nuttall  and 
Graham-Smith  entitled  "The  Bacteriology  of  Diphtheria,"  containing 
articles  by  Loffler,  ISTewsholme,  Mallory,  Graham- Smith,  Dean,  Park, 
and  Bolduan;  Cambridge  University  Press,  1908. 

The  original  clinical  description  of  the  disease  is,  by  common  as- 
sent, attributed  to  Bretonneau  in  1826 :  Traite  de  la  diphtherite.  Des- 
inflammations  speciales  du  tissu  muqueux  et  en  particulier  de  la  diph- 
therite ou  inflammation  pelliculaire,  connue  sous  le  nom  de  croup,  d'an- 
gine  maligne,  d'angine  gangreneuse,  etc.,  Paris. 

The  bacillus  of  diphtheria  was  first  cultivated  and  adequately  de- 
scribed by  Loffler,  1884 :  Untersuchungen  iiber  die  Bedeutung  der 
Mikroorganismen  fiir  die   Entstehung  der   Diphtheric   beim   Menschen 

'  Friedberger,  E.,  and  Mita,  S. :  "To  Prevent  Anaphylaxis  in  Serotherapy ' ' 
("Methode,  grossere  Mengen  artfremden  Serums  bel  iiberempfindlictien  Indi- 
viduen  zu  injizieren"),  Deutsche  med.  Wochenschr.,  Berlin,  Feb.  1,  XXXVIII, 
No.  5,  pp.  201-248. 


154  DISCHARGES    FROM    MOUTH    AND    NOSE 

bei  der  Taube  und  beim  Kalbe.  Mitth.  a.  d.  K.  Gesundheitsamte,  ii, 
451. 

The  classical  article  in  which  Behring  and  Kitasato  announced 
their  discovery  of  diphtheria  antitoxin  in  1890  will  be  found  in  Deutsche 
nied.  Wochenschr..  xvi,  1113.  Ueber  das  Ziistandekommen  der  Diph- 
therieimraunitat  und  die  Tetanusimmunitat  bei  Tieren. 

Ehrlich's  important  work,  in  which  he  laid  the  foundations  of  his 
side-chain  theory  and  established  the  present  satisfactory  method  of 
standardizing  diphtheria  antitoxin,  will  be  found  in  the  following: 
Die  Werthbemessung  des  Diphtherieheilserums  und  deren  theoretische 
Grundlagen.  Klin.  Jahrb.,  Jena,  v,  6  (2),  1897,  pp.  299-326.  Ueber 
die  Constitution  des  Diphtheriegiftes.  Deut.  nied.  Woch.,  Leipzig,  v, 
24  (38),  1898,  pp.  597-600.  Croonian  lecture.  On  Immunity  with 
Special  Reference  to  Cell  Life.  Proc.  Roy.  Soc,  London,  v,  66,  pp. 
424-448,  pis.  6-7. 

The  official  method  for  standardizing  diphtheria  antitoxin  in  this 
country  and  the  principle  upon  which  it  is  based  are  described  by 
Rosenau  (1905),  The  Immunity  Unit  for  Standardizing  Diphtheria 
Antitoxin  (based  on  Ehrlich's  normal  serum).  Hygienic  Laboratory 
Bull.  No.  21,  P.  H.  and  M.  H.  S.,  Washington,  Govt.  Print.  Office,  92  pp. 


MEASLES 

Measles  is  usually  taken  as  the  type  of  a  contagious  disease  because 
it  is  one  of  the  most  readily  communicable  of  all  diseases,  in  this  re- 
gard ranking  with  smallpox.  As  a  cause  of  death  it  ranks  high  among 
the  acute  fevers  of  children.  Measles  is  an  infection  peculiar  to  man, 
although  experimental  measles  has  recently  been  produced  in  monkeys. 
The  virus  is  contained  in  the  blood,  as  has  been  shown  by  Hektoen, 
who  thus  transmitted  the  disease  from  man  to  man.  More  important 
from  the  standpoint  of  prevention,  the  virus  has  been  demonstrated  in 
the  secretions  from  the  nose  and  mouth  by  Anderson  and  Goldberger. 
The  period  of  incubation  is  quite  constant  (from  9  to  11  days),  and 
the  rash  appears  quite  uniformly  on  the  13th  or  14th  day  after  the 
infection.  In  Hektoen's  two  experimental  cases  the  eruption  appeared 
on  the  14th  day.     The  cause  of  measles  is  not  known. 

Measles  is  more  or  less  constantly  present  in  all  large  cities  in 
the  temperate  zone ;  it  is  less  common  in  the  tropics.  Measles  fre- 
quently becomes  epidemic,  usually  in  the  cooler  months,  in  this  respect 
resembling  smallpox.  The  epidemics  recur  cyclically,  at  irregular  in- 
tervals. Levy  and  Foster  noticed  that  in  Richmond,  Va.,  epidemic 
outbreaks  recurred  at  intervals  of  about  3  years.  They  were  able  to 
predict  and  warn  against  an  epidemic  prevalence  of  the  disease  in  the 


MEASLES  155 

winter  of  1910.  During  1909,  iO  cases  of  measles  occurred  in  Eich- 
mond,  but  during  this  year  the  disease  showed  no  special  tendency  to 
spread.  In  the  middle  of  February,  1910,  8  cases  occurred  among  the 
pupils  of  one  school  and  the  infection  showed  a  high  degree  of  com- 
municability.  According  to  the  history  of  the  disease,  an  epidemic  year 
was  due  and  an  epidemic  was  predicted.  Over  2,000  cases  occurred 
with  26  deaths. 

Measles  is  highly  contagious  during  the  preeruptive  stage,  when 
the  nature  of  the  disease  is  not  recognized  and  when  most  of  the  dam- 
age is  done;  it  remains  contagious  for  a  variable  time  during  conva- 
lescence. Eecent  experimental  evidence  and  clinical  experience  plainly 
indicate  that  the  infection  of  measles  soon  dies  out,  and  that  there  is 
little  danger  of  transmitting  the  infection  after  the  temperature  re- 
turns to  normal.  An  isolation  of  two  weeks  from  the  onset  of  the  dis- 
ease is  sufficient  in  public  health  work;  health  officers,  however,  adopt 
arbitrary  times.  Thus,  in  Detroit  cases  of  measles  are  isolated  one 
week;  in  Buffalo,  Concord,  Xew  York,  Providence,  and  Yonkers,  two 
weeks ;  in  Brookline  and  Fall  Eiver,  two  weeks  after  the  eruption  fades ; 
in  Boston,  two  weeks  after  recovery;  and  three  weeks  in  Montclair, 
X.  J.,  Xew  Bedford,  Mass.,  Ottumwa,  Iowa. 

Immunity. — One  attack  of  measles  usually  confers  a  rather  definite 
protection  against  subsequent  attacks;  second  attacks,  however,  are 
more  common  than  in  the  other  eruptive  fevers.  Some  persons  have 
the  disease  three  or  four  times.  As  with  smallpox,  there  appears  to  be 
no  natural  immunity  to  measles — man  is  excjuisitely  susceptil^le  to  these 
two  infections.  There  appears  to  be  a  relative  immunity  sometimes  of 
a  high  grade  during  the  first  few  months  of  life,  although  measles  oc- 
casionally occurs  in  infants  of  a  month  or  six  weeks. 

Adults  are  susceptible  to  measles,  provided  they  have  not  had  a 
previous  attack.  Susceptibility  to  the  infection  does  not  diminish  with 
increasing  age;  the  disease  is  apparently  one  of  childhood  only  on  ac- 
count of  the  chances  of  exjDOsure  in  early  life.  Before  the  days  of  vac- 
cination smallpox  was  also  a  disease  mainly  of  childhood. 

The  following  instances  demonstrate  the  suscei^tibility  of  adults  to 
measles  and  also  the  serious  nature  of  the  disease :  Measles  was  intro- 
duced into  the  Faroe  Islands  in  1816  from  Copenhagen,  and  over  6,000 
of  the  7,782  inhabitants  were  stricken.  In  1775  it  was  introduced  into 
the  Sandwich  Islands,  and  in  4  months  40,000  of  the  population  of 
150,000  died. 

Measles  is  common  in  army  camps,  especially  among  troops  enlisted 
from  country  districts,  who  are  thus  exposed  to  the  infection  for  the 
first  time. 

Measles  is  often  fatal  both  in  adults  and  children  on  account  of 
pneumonic  complications.     It  also  seems  to  lower  the  resistance  to  tu- 


156  DISCHAKGES    FROM    MOUTH    AND    NOSE 

berculosis;  for  it  is  a  common  history  to  find  tuberculosis  develop  in 
children  following  an  attack  of  measles. 

Resistance  of  the  Virus. — In  general  the  virus  of  measles  is  known 
to  be  much  less  resistant  than  that  of  scarlet  fever  and  many  other  in- 
fections. The  virus  does  not  live  long  upon  fomites.  There  is  prac- 
tically no  danger  of  children  contracting  the  infection  from  the  room 
in  which  the  patient  was  treated,  even  though  no  disinfection  was 
practiced,  provided  two  weeks  have  elapsed. 

Goldberger  and  Anderson  ^  found,  as  the  result  of  experiments  upon 
monkeys,  that  the  virus  in  measles'  blood  is  filterable;  that  is,  may  pass 
through  a  Berkefeld  filter.  It  resists  desiccation  for  251/^  hours,  loses 
its  infectivity  after  15  minutes  at  55°  C,  resists  freezing  for  25  hours, 
and  possibly  retains  some  infectivity  after  24  hours  at  15°  C. 

From  the  standpoint  of  our  present  knowledge  it  is  evident  that 
any  of  the  ordinary  germicidal  agents  sufficient  to  kill  spore-free  bac- 
teria will  serve  as  effective  disinfectants  for  measles.  Aside  from  the 
few  scientific  observations  upon  the  viability  of  the  virus  of  measles, 
epidemiological  observations  have  long  pointed  out  the  fact  that  the 
virus  of  measles  is  frail  and  soon  dies  in  the  convalescent  as  well  as  in 
the  environment. 

Modes  of  Transmission. — The  virus  of  measles  is  contained  in  the 
nasal  and  buccal  secretions.  \Miile  it  is  possible  that  the  virus  may 
leave  the  body  in  other  secretions,  it  is  highly  probable  that  the  dis- 
charges from  the  nose  and  mouth  are  the  means  of  transmitting  the 
infection  in  the  vast  majority  of  cases.  We  are  less  certain  concerning 
the  modes  of  entrance  into  the  body,  although  it  is  presumed  that  the 
virus  also  enters  by  the  mouth  and  nose;  however,  we  lack  positive 
information  upon  this  point. 

MaAT  ^  showed  in  1852  by  experiments  on  the  human  subject  that 
the  buccal  and  nasal  secretions  were  infective.  Recently  Anderson  and 
Goldljerger  ^  have  demonstrated  by  experiments  upon  monkeys  that 
the  nasal  and  buccal  secretions  of  uncomplicated  cases  of  measles  may 
be  at  times,  but  are  not  always,  infective.  Hektoen  *  in  1905,  as  well 
as  Goldberger  and  Anderson,  1911,  demonstrated  that  the  virus  of 
measles  is  also  contained  in  the  circulating  blood.  The  virus  appears 
in  the  blood  at  least  24  hours  before  the  eruption  appears,  and  begins 
to  diminish  about  25  hours  after  the  first  appearance  of  the  eruption. 

It  has  long  been  assumed  that  the  virus  of  measles  is  carried  in 
the  fine  bran-like  desquamating  epithelium,  which  is  one  of  the  char- 
acteristics of  the  disease.     Mayr  long  ago  failed  in  his  attempts  to  in- 

'  J.  A.  M.  A.,  Vol.  LYII,  Xo.  12,  Sept.  16,  1911,  p.  971. 

'  Mavr,  Franz:  Zeitschr.  d.  Jc.  k.  Gesellsch.  de  Aertze  zu  Wien,  1852,  I,  13-14. 

»  J.  A.  M.  A.,  Vol.  LYII,  Nov.  11,  1911,  p.  1612. 

*  Experimental  Measles :  Jour.  Infect.  Dis.,  1905,  Vol.  II,  p.  238. 


MEASLES  157 

oculate  children  witli  measles  by  using  the  desquamating  epithelium. 
Anderson  and  Goldberger  also  obtained  absolutely  negative  results  in 
three  experiments,  in  which  it  was  shown  that  the  "scales"  were  not 
infective  for  monkeys.  These  authorities  believe  that  it  is  highly  prob- 
able, if  not  altogether  certain,  that  the  desquamating  epithelium  of 
measles  in  itself  does  not  carry  the  virus  of  the  disease.  This  conclu- 
sion is  warranted  hj  epidemiological  evidence. 

Measles  is  so  readily  communicable  that  clinicians  receive  the  im- 
pression that  the  virus  is  "volatile."  It  has  long  been  suspected  that 
the  virus  is  contained  in  the  expired  breath,  but  this  is  very  doubtful. 
In  fact,  it  may  now  be  stated  with  confidence  that  measles  is  not  air- 
borne, in  the  sense  in  which  this  term  is  usually  understood.  In  any 
case,  the  radius  of  danger  through  the  air  is  confined  to  the  immediate 
surroundings  of  the  patient — that  is,  within  the  danger  zone  of  droplet 
infection.  Droplet  infection  is  quite  possible,  as  the  virus  is  contained  in 
the  secretions  of  the  mouth  and  nose ;  furthermore,  it  evidently  requires 
an  exceedingly  minute  quantity  of  the  virus  to  reproduce  the  disease  in 
man,  who  is  exquisitely  susceptible  to  this  infection. 

Chapin  has  collected  important  evidence  indicating  that  the  infec- 
tion of  measles  is  not  air-borne.  Thus,  in  the  Pasteur  Hospital,  Paris, 
each  patient  is  cared  for  in  a  separate  room  opening  into  a  common 
hall.  Trained  nurses  exercise  strict  medical  asepsis.  In  2%  years  after 
this  hospital  was  opened  in  1900  many  cases  of  smallpox,  diiDhtheria, 
scarlet  fever,  and  126  cases  of  measles  were  cared  for.  In  no  instance 
did  measles  spread  within  the  hospital.  xA.t  the  Children's  Hospital  in 
Paris  (Hopital  des  Infants  Malades),  instead  of  being  in  separate 
rooms,  the  beds  are  separated  only  by  partitions.  Strict  asepsis  is  ob- 
served. Of  5,017  cases  there  were  only  7  cross-infections,  6  of  measles 
and  1  of  diphtheria.  Dr.  Moizard  thinks  that  this  experience  proves 
that  even  measles  is  not  air-borne,  for  the  few  cases  of  this  disease 
which  did  arise  were  not  all  in  cubicles  adjoining  those  occupied  by 
measles  patients.  Grancher  in  another  Paris  hospital  had  two  wards 
in  which  there  were  no  partitions,  but  only  wire  screens  around 
the  beds,  simply  as  a  reminder  for  the  nurses.  Of  6,511  patients 
treated  from  1890-1900,  115  contracted  measles,  7  scarlet  fever,  and 
1  diphtheria.  Grancher  insists  that  measles  is  probably  not  an 
air-borne  disease.  Adjacent  patients  do  not  necessarily  infect  one  an- 
other. At  various  English  hospitals  similar  methods  have  beeen 
tried  with  success.  These  various  hospital  experiences  indicate  that 
the  danger  of  aerial  infection  in  measles  is  much  less  than  is  generally 
supposed. 

The  infection  of  measles  is  usually  transmitted  more  or  less  directly 
from  person  to  person  by  means  of  the  excretions  from  the  mouth  and 
nose,  and  most  often  during  the  early  stages  of  the  disease.     Measles 


158  DISCHARGES    FROM    MOUTH    AND    NOSE 

may  be  transmitted  by  third  persons  or  by  fomites,  though  such  in- 
stances are  rather  exceptional. 

Prevention. — The  suppression  of  measles  is  one  of  the  most  diffi- 
cult problems  we  have  to  face,  for  the  reason  that  the  disease  is  one 
of  the  most  highly  communicable  of  all  infections,  and  for  the  further 
reason  that  it  is  most  contagious  during  the  preeruptive  stage.  To 
the  student  of  j^reventive  medicine  the  problem  of  measles  is  very 
similar  to  that  of  smallpox,  and  the  final  control  will  probably  have 
to  await  a  specific  prophylactic  measure.  Improved  sanitation,  better 
hygiene,  and  the  general  advance  of  civilization,  which  have  made  such 
a  marked  impression  upon  typhus  fever,  relapsing  fever,  typhoid  fever, 
and  other  "filth"  diseases,  have  no  influence  whatever  upon  such  infec- 
tions as  measles  or  smallpox. 

Measles  is  such  a  common  disease  that  parents  are  prone  to  take 
little  pains  to  avoid  the  infection;  they  even  sometimes  purposely  ex- 
pose their  children.  This  is  a  mistaken  attitude.  Special  care  should 
be  exercised  especially  during  the  first  five  years  of  life,  as  over  90 
per  cent,  of  the  fatal  cases  occur  in  this  period.  While  it  may  be  al- 
most hopeless  to  lessen  the  morbidity  in  measles,  it  is  quite  possible 
to  materially  decrease  the  mortality  by  simply  delaying  the  age  inci- 
dence. 

Clinical  experience  plainly  indicates  that  few  people  die  of  measles 
if  properly  cared  for.  The  mortality  may,  therefore,  be  decreased  by 
careful  nursing  and  protection,  especially  from  pneumonia,  which  is 
one  of  the  most  dangerous  complications.  Newman  sums  up  the  mat- 
ter of  prophylaxis  when  he  states  that  "the  prevention  and  control  of 
measles,  like  that  of  whooping-cough  and  tuberculosis,  is  largely  in  the 
hands  of  the  public  themselves." 

In  the  present  state  of  our  knowledge  the  prophylaxis  of  measles 
rests  almost  entirely  upon  one  measure — isolation.  Chapin  believes 
that  isolation  has  been  a  failure  in  measles.  This  is  because  of  the 
unrecognized  but  infectious  preeruptive  stage.  "No  amount  of  isolation 
after  the  disease  is  recognized  can  atone  for  the  harm  done  before  the 
diagnosis  is  made."  Isolation,  however,  accomplishes  one  worthy  ob- 
ject, viz.,  the  prevention  of  further  damage.  Isolation,  as  carried  out 
in  our  large  cities,  has  had  no  apparent  efEect  upon  the  prevalence  of 
the  disease.  In  Aberdeen  restrictive  measures  apparently  protected 
only  7  to  10  per  cent,  of  the  population. 

Despite  its  limitations,  isolation  is  quite  worth  while.  Cases  should 
be  at  once  reported  to  the  health  officer,  the  house  placarded,  and  visit- 
ing prohibited.  Quarantine  should  not  be  raised  nor  should  the  child 
be  permitted  to  return  to  school  until  the  manifestations  of  the  disease 
have  disappeared.  Measles  may  be  treated  in  the  household,  but  it  is 
difficult  under  ordinary  circumstances  to  prevent  the  spread  of  the  dis- 


MEASLES  159 

ease  to  tlie  other  children.  If  the  case  is  treated  at  home,  the  children 
who  have  not  had  the  disease  should  be  sent  away. 

Mild  atypical  and  unrecognized  cases  of  measles  occur,  but  are  far 
less  numerous  than  such  cases  in  scarlet  fever,  diphtheria,  and  typhoid. 
Clinical  evidence  points  to  the  fact  that  "carriers"  of  measles  are  not 
common.  The  disease  is  usually  spread  directly  from  person  to  person, 
occasionally  indirectly  through  a  third  person,  or  by  fomites.  Physi- 
cians may  convey  the  infection  to  healthy  children.  I  am  convinced 
that  I  carried  the  disease  to  my  own  son.  When  measles  is  conveyed 
by  a  third  person  or  by  fomites  it  is  by  means  of  contamination  with 
the  fresh  buccal,  nasal,  or  bronchial  secretions  upon  the  hands,  hand- 
kerchief, or  some  other  object  that  comes  in  contact  with  the  mouth  or 
nostrils  of  a  susceptible  child.  Physicians  may  readily  avoid  this  dan- 
ger by  wearing  a  gown  and  carefully  washing  the  hands,  face,  and 
hair,  and  waiting  a  reasonable  time  before  visiting  healthy  children. 

Terminal  disinfection  is  of  comparatively  little  value  in  preventing 
the  spread  of  measles.  After  the  patient  is  released  from  isolation  a 
general  disinfection  with  formaldehyde  may  be  practiced,  especially  if 
healthy  children  are  soon  to  occupy  the  playroom  or  bedroom.  How- 
ever, if  from  2  to  3  weeks  have  elapsed,  there  is  practically  no  danger 
in  a  well-ventilated,  sunny,  and  clean  room.  All  bedding,  towels,  hand- 
kerchiefs, and  other  fabrics  that  have  been  exposed  should  be  boiled 
or  otherwise  disinfected. 

The  question  of  closing  the  schools  in  order  to  prevent  the  spread 
of  measles  requires  consideration.  If  the  school  is  closed  at  the  begin- 
ning of  an  outbreak  and  the  disease  continues  to  spread  after  two  weeks, 
little  more  will  be  gained  in  keeping  the  school  closed,  for  it  must  then 
be  evident  that  other  factors  are  at  work  in  spreading  the  infection. 
As  the  disease  is  mainly  spread  in  the  preemptive  stage,  it  is  sufficient 
to  examine  the  children  each  morning  before  they  enter  school  for  symp- 
toms of  a  cold,  infection  of  the  eyes,  running  at  the  nose,  cough,  sore 
throat,  fever,  etc.  All  such  cases  should  be  sent  home  to  await  further 
developments.     If  these  measures  are  taken  the  school  may  be  kept  open. 

McVail  suggests  that  when  a  child  develops  measles  all  the  children 
exposed  may  be  allowed  to  continue  at  school  8  or  10  days,  and  then 
excluded  for  a  week  to  ten  days,  when  those  who  do  not  develop  the  dis- 
ease may  be  allowed  to  return.  This  is  a  rational  plan  used  in  certain 
districts  in  England.  When  measles  breaks  out  in  an  orphan  asylum,  a 
public  institution,  or  an  encampment,  the  only  chance  of  checking  the 
spread  of  the  disease  is  through  the  early  recognition  of  first  symptoms 
and  isolation. 


160  DISCHARGES    FROM    MOUTH    AND    NOSE 


SCARLET  FEVER 

Scarlet  fever  is  an  acute  febrile  infection  characterized  by  a  diffuse 
eruption  which  ai)i)ears  during  the  first  day  or  two  of  the  fever,  and 
sore  throat  of  variable  intensity.  The  seasonal  prevalence  of  scarlet 
fever  resembles  that  of  diphtheria.  The  disease  increases  in  the  fall 
of  tlie  year,  due,  in  part,  to  the  gathering  of  children  in  the  schools. 
The  period  of  incubation  is  from  1  to  7  days;  usually  3  to  4.  In  a 
few  instances,  in  which  individuals  have  been  inoculated  with  the  blood 
of  scarlet  fever  patients,  3  to  4  days  elapsed  before  the  onset  of  symp- 
toms. Scarlet  fever  is  rare  in  the  tropics;  when  introduced  it  soon 
dies  out.  There  is  probably  always  more  or  less  scarlet  fever  in  any 
thickly  settled  district  in  the  temperate  zone.  The  infection  is  kept 
alive  largely  through  the  mild  and  unrecognized  cases.  Scarlet  fever 
varies  greatly  in  intensity  in  different  outbreaks.  In  some  epidemics 
the  death  rate  is  30  per  cent.;  in  others  it  is  practically  nil. 

Landsteiner,  Levaditi  and  Prasek  ^  apparently  succeeded  in  transfer- 
ring scarlet  fever  to  chimpanzees  and  also  to  monkeys.  The  animals 
were  inoculated  both  by  ai)plying  throat  swabs  from  scarlet  fever  patients 
to  the  pharynx  of  the  animals,  and  also  by  injecting  the  animals  with 
blood  from  scarlet  fever  patients.  While  the  nature  of  the  virus  is  still 
unknown,  it  seems  to  be  present  in  the  tonsils,  tongue,  blood,  lymph 
nodes,  and  pericardial  fluid. 

The  cause  of  scarlet  fever  is  not  known.  Streptococci  are  almost 
constantly  found  in  the  throat  and  blood  of  scarlet  fever  cases.  Klein 
in  1885  was  the  first  to  advocate  the  Streptococcus  scarlatina;  as  the 
specific  cause  of  scarlet  fever.  Kurth  assigns  an  etiological  factor  to 
the  "Streptococcus  conglomeratus."  It  is  said  to  produce  a  rash  in 
animals  and  men  who  are  injected  with  it.  The  chief  reasons  for  con- 
sidering streptococci  as  the  cause  of  scarlet  fever  are  that  they  are  con- 
stantly found  in  the  throat  of  scarlet  fever  patients;  that  frequently 
they  can  be  isolated  from  the  blood  of  scarlet  fever  patients  during  life, 
and  almost  constantly  after  death;  the  cause  of  the  complications  and 
death  in  the  majority  of  cases  of  scarlet  fever  is  due  to  the  strepto- 
coccus. It  is  probable,  however,  that  the  streptococcus  plays  a  secondary 
role  in  scarlet  fever  as  it  does  in  smallpox;  the  disease  itself  may  be 
due  to  a  protozoon-like  body  described  by  ilallory,  which  lowers  the 
resistance  of  the  organism  to  streptococcal  invasion. 

Modes  of  Transmission. — It  is  taken  for  granted  that  the  virus  of 
scarlet  fever  is  contained  in  the  secretions  from  the  nose,  throat,  and 
respiratory  tract.  The  virus  probably  enters  by  the  mouth  and  respira- 
tory passages.     Scarlet  fever  is  not  contagious  during  the  period   of 

^  Annales  de  I'lnst.  Pasteur,  Oct.,   1911,   XXV,  No.   10,  p.   754. 


SCAELET    FEVER  161 

incubation;  little,  if  any,  during  the  period  of  invasion.  It  is  most 
contagious  during  the  jDeriod  of  eruption.  Scarlet  fever  is  readily 
communicable,  but  less  so  than  measles  or  smallpox ;  it  ranks  about  with 
diphtheria. 

It  has  long  been  accepted  and  taught  by  the  medical  profession 
that  the  desquamation  is  the  most  infectious  stage  of  scarlet  fever, 
and  it  is  now  very  difficult  to  unteach  the  public  this  erroneous  view. 
It  is  now  known  that  desquamating  patients  may,  as  a  rule,  be  safely 
released  from  quarantine  in  the  6th  week  of  their  attack  of  scarlet 
fever,  provided  they  have  no  mucous  complications  or  other  sequelae. 
Convalescents  may  be  a  source  of  danger  to  others  even  after  desquama- 
tion has  ceased.  This  fact  has  been  emj^hasized  from  a  study  of  the 
so-called  "return  cases."  Thus  convalescents  are  released  from  hos- 
pital and  permitted  to  return  home;  soon  another  case  appears  in  one 
of  the  members  of  the  household,  who  in  turn  comes  to  the  hospital. 
Neech  in  a  study  of  15,000  cases  found  that  the  percentage  of  return 
cases  was  1.86  in  those  cases  who  submitted  to  an  average  period  of 
isolation  of  -±9  da3's  or  under.  With  an  average  period  of  50  to  56 
days  the  percentage  was  1.12;  where  the  isolation  extended  to  between 
57  and  65  da3's  the  percentage  of  return  cases  was  1.  McCullom  states 
that  in  the  South  Department  of  the  City  Hospital,  Boston,  the  chil- 
dren are  kept  50  days,  and  no  patient  is  released  who  has  a  discharge 
from  the  nose  or  an  abnormal  condition  of  the  throat.  Of  3,000  pa- 
tients discharged  from  the  scarlet  fever  ward,  1.7  per  cent,  of  return 
eases  occurred.  McCullom  is  inclined  to  regard  the  infection  as  com- 
ing from  mild  and  unrecognized  cases  of  the  disease  rather  than  from 
the  discharged  case. 

There  is  no  accurate  means  of  determining  just  how  long  a  child 
remains  infective  after  scarlet  fever.  The  period  of  detention  varies 
very  much.  Fifty  days  may  be  taken  as  a  safe  average.  In  'New  Ha- 
ven and  Seattle  cases  are  dismissed  after  desquamation;  in  North 
Dakota  5  days  after  desquamation;  in  Ohio  and  South  Dakota  10  days 
after  desquamation.  In  various  cities  and  states  the  period  of  isola- 
tion varies  from  3  weeks  to  8  weeks  unless  the  physician  certifies  that 
desquamation  has  ceased.  In  Milwaukee,  Paterson,  and  Pittsburg  it 
is  never  maintained  longer  than  30  days,  even  if  desquamation  con- 
tinues. Owing  to  our  lack  of  knowledge  on  the  subject,  the  period 
of  isolation  must  remain  more  or  less  guesswork.  An  unduly  long 
detention  is  a  hardship  upon  the  patient  and  the  family;  on  the  other 
hand,  a  scant  period  is  hazardous  to  the  community.  Cases  with  rhinor- 
rhea,  otorrhea,  throat  trouble,  or  discharging  abscesses  must  receive  spe- 
cial care,  as  the  secretions  from  these  parts  are  now  known  to  remain 
infective  for  a  long  time. 

Many  cases  of  walking  scarlet  fever  present  little  further  evidence 


162  DISCHARGES    FROM    MOUTH    AND    NOSE 

than  a  passing  sore  throat.  These  cases  doubtless  spread  the  disease, 
especially  in  schools.  Third  persons  may  carry  the  disease  perhaps  on 
their  clothing  and  perhaps  also  as  carriers.  Toys,  cups,  spoons,  ther- 
mometers, handkerchiefs,  and  other  oljjects  contaminated  by  the  secre- 
tions of  tlie  mouth  j)lay  tlie  same  role  here  that  they  do  in  diphtheria. 
Scarlet  fever  is  not  air-borne;  at  least  the  radius  of  infection  is  limited 
to  droplet  infection. 

MiLK-BOHNE  Scarlet  Fever. — Milk  is  a  rather  frequent  vehicle  for 
scarlet  fever  infection.  The  milk  is  practically  always  contaminated 
from  human  sources.  There  is,  however,  some  suspicion  that  strepto- 
coccal diseases  of  the  cow  may  in  some  instances  be  identical  with  scarlet 
fever.  This  is  doubtful.  It  is  known,  however,  that  such  diseases  of  the 
udders  of  the  cows  may  cause  outbreaks  of  an  infection  resembling 
scarlet  fever.  Trask  collected  51  scarlet  fever  epidemics  reported  as 
spread  by  milk.  Twenty-five  of  tliese  occurred  in  the  United  States  and 
26  in  Great  Britain.  In  35  of  the  epidemics  a  case  of  scarlet  fever  was 
found  at  the  producing  farm,  the  distributing  dairy,  or  milkshop  at  such 
a  time  as  to  have  been  the  possible  source  of  infection;  in  3  of  tlie  out- 
breaks the  bottles  returned  from  infected  households  and  refilled  without 
previous  sterilization  were  given  as  the  source  of  infection;  in  3  of  the 
outbreaks  scarlet  fever  persons  handled  the  milk  or  milk  utensils,  and 
in  12  of  the  outbreaks  the  cows  were  milked  by  persons  having  scarlet 
fever;  in  one  epidemic  the  same  person  nursed  the  sick  and  handled  the 
milk;  in  2  of  the  outbreaks  the  source  of  infection  was  supposed  to  be 
due  to  disease  of  the  cow.  A  milk-borne  outbreak  in  Washington  was 
traced  to  a  convalescent  with  a  discharging  ulcer  on  the  finger.  Milk- 
borne  outbreaks  of  scarlet  fever  are  sometimes  very  extensive. 

An  unusually  extensive  milk-borne  outbreak  of  scarlet  fever  occurred 
in  Boston  during  April  and  May,  1910.  A  total  of  842  cases  were 
reported  from  Boston  and  the  surrounding  towns  of  Chelsea,  Winthrop, 
Cambridge,  Somerville,  ]\Ialden,  and  Everett.  Investigation  showed 
that  most  of  the  cases  occurred  on  the  route  of  a  large  milk  contractor. 
Of  the  409  cases  in  Boston,  2SG,  or  nearly  70  per  cent.,  were  on  the 
route  of  this  dealer;  while  123,  or  30  ])er  cent.,  used  other  milk.  Of 
the  155  cases  that  occurred  in  Cambridge,  126,  or  over  80  per  cent., 
were  on  the  route  of  the  same  dealer.  About  the  same  proportion  of 
the  cases  in  the  other  cities  used  the  milk  of  this  dealer.  The  cases 
appeared  suddenly  April  25th,  and  the  outbreak  ceased  May  7th.  The 
epidemic  reached  its  highest  mark  on  April  29th,  when  128  cases  were 
reported.  The  indications  were  plain  that  the  outbreak  was  the  result 
of  more  than  a  single  infection.  The  milk  was  pasteurized  at  60°  C. 
for  30  minutes  on  April  27th,  and  three  days  following  there  was  a 
notable  and  sharp  decline  in  the  number  of  cases.  The  source  of  the 
infection    could    not   be    traced,    although    it   probably    consisted    of    a 


SCAKLET    FEVER  163 

"missed"  case  oii  one  of  the  250  dairy  farms  from  which  the  dealer  ob- 
tained this  particular  supply  of  milk. 

Immunity. — One  attack  of  scarlet  fever  usually  protects  against 
subsequent  attacks.  In  rare  instances  second  attacks  may  occur  after 
an  interval  of  several  years.  Children  under  10  are  most  susceptible. 
Sucklings  .are  rarely  attacked,  though  susceptible.  After  the  10th  year 
the  resistance  to  the  disease  increases.  Ninety  per  cent,  of  the  fatal 
eases  occur  in  children  under  10  years  old.  The  reason  why  infants  at 
the  breast  are  less  likely  to  take  the  disease  may  be  on  account  of  the 
diminished  chances  of  the  infection  entering  the  mouth.  The  immunity 
acquired  in  later  life  may  in  part  be  due  to  previous  unrecognized  mild 
attacks. 

Prophylaxis. — Prophylaxis  in  scarlet  fever  must  necessarily  be  in 
excess  of  the  requirements,  awaiting  more  precise  knowledge  of  its 
cause  and  modes  of  transmission.  The  essential  features  of  prevention 
consist  in  isolation  and  disinfection.  It  is  important  to  recognize  the 
mild  cases  in  schools  through  an  efficient  medical  inspection.  The 
answer  to  the  question  whether  schools  should  be  closed  when  scarlet 
fever  breaks  out  varies  with  the  circumstances.  In  country  districts 
this  is  advisable,  as  the  children  may  be  kept  separate,  but  in  the  cities 
little  is  gained.  There  is  no  objection  to  treating  a  case  of  scarlet  fever 
in  the  household,  provided  a  suitable  room  and  trained  attendant  may  be 
had.  The  infection  may  be  confined  to  the  sick  room,  but  it  is  preferable 
to  take  no  chances  and  send  the  susceptible  individuals  out  of  the 
house.  The  nurse  should  use  the  precautions  described  for  dijDhtheria, 
smallpox,  or  measles.  The  physician  should  wear  a  gown  and  thor- 
oughly disinfect  his  hands  and  other  exposed  parts  after  the  visit.  Spe- 
cial care  must  be  taken  with  the  thermometer  and  other  instruments. 
The  physician  may  find  the  necessary  precautions  and  disinfection  to 
be  irksome,  but  they  should  not  be  shirked  in  Justice  to  his  other  pa- 
tients and  the  community. 

The  discharges  from  the  mouth,  nose,  and  respiratory  passages, 
etc.,  should  be  collected  upon  suitable  fabrics  and  burned.  Bed  and 
body  clothing,  dishes,  and  other  exposed  objects  must  be  disinfected. 
Care  must  be  taken  concerning  remnants  of  food  from  the  sick  room. 
Scarlet  fever  is  not  as  highly  contagious  as  measles,  but  the  meas- 
ures employed  should  be  practically  the  same  until  at  least  we  have 
more  definite  knowledge  concerning  the  channels  of  entrance  and  exit 
of  the  virus  and  its  modes  of  transmission.  The  virus  of  scarlet  fever 
is  more  resistant  than  that  of  measles.  It  clings  persistently  to  cloth- 
ing and  various  objects.  A  terminal  disinfection  with  formaldehyde  gas 
may  be  practiced^  although  little  seems  to  be  gained  thereby.  A  thorough 
cleansing  of  all  surfaces,  with  a  good  sunning  and  airing  of  the  room,  is 
always  in  order.     All  fabrics  and  other  objects  that  have  been  exposed 


1G4  DISCHAROES    FROM    MOUTH    AND    NOSE 

should  be  disinfected.  Tlie  virus  is  killed  with  agents  tliat  destroy 
non-spore-bearing  l)acteri;i.  In  Glasgow  a  sanitary  wash-house  has  been 
established,  where  the  clothing  of  scarlet  fever  cases  may  be  disin- 
fected and  washed.  This  is  a  commendable  example  that  might  be  fol- 
lowed with  advantage  by  other  cities. 

Specific  Prophylaxis. — Gabritschewsky  first  proposed  the  use  of 
streptococcus  vaccines  as  a  propliylaxis  against  scarlet  fever.  He  used  a 
concentrated  bouillon  culture  of  the  streptococcus  isolated  from  a  person 
ill  with  scarlet  fever.  The  culture  is  killed  by  heating  to  60°  C,  and  0.5 
per  cent,  carbolic  acid  added.  Gabritschewsky  uses  0.5  c.  c.  of  the  concen- 
trated bouillon  culture  in  children  2  to  10  years  old.  For  those  younger 
half  this  amount,  and  adults  twice  this  amount,  is  used.  The  injec- 
tions are  given  subcutaneously  in  the  abdomen,  thigh,  back,  or  arm. 
Another  method  of  dosage  is  to  use  0.1  c.  c.  for  each  year  of  the 
child's  age  with  0.25  c.  c.  as  the  minimum  and  1  c.  c.  as  the  maximum. 
Three  doses  are  given  in  periods  of  7  or  10  days,  the  dosage  increasing 
at  each  injection  li/^  to  2  times  the  previous  dose. 

The  only  cases  in  which  the  vaccines  are  withheld  are:  (1)  in  those 
having  a  high  temperature,  although  even  these  have  received  the 
prophylactic  without  evident  untoward  results;  (2)  in  very  young  in- 
fants or  patients  who,  from  some  cause  or  other,  are  greatly  exhausted; 
and  (3)   in  those  having  nephritis. 

The  claim  is  made  that  after  3  injections  of  the  vaccine,  and  usu- 
ally after  2,  a  complete  immunity  is  established  against  scarlet  fever. 
The  immunity  does  not  appear  until  5  to  7  days  after  the  last  dose. 
The  duration  and  degree  of  the  immunity  is  problematical,  as  the  vac- 
cines have  been  in  use  so  short  a  time.  It  appears  that  the  immunity 
probably  remaias  at  least  lYo  years. 

The  usual  reactions,  both  local  and  general,  follow  these  injections, 
but  in  10-15  per  cent,  of  the  persons  injected  quite  a  different  reaction 
occurs.  Twenty-four  hours  after  the  injection  there  appears  on  the 
chest  and  abdomen,  sometimes  extending  over  the  rest  of  the  body,  a 
punctate  erythema  very  much  like  the  eruption  of  scarlet  fever,  but  not 
followed  by  any  desquamation.  The  eruption  lasts  1-3  days,  and  may 
be  accompanied  by  sore  throat,  some  swelling  of  the  lymph  glands, 
and  often  a  so-called  strawberry  tongue.  Rarely  a  rather  severe 
reaction  with  high  fever,  a  little  albumin  in  the  urine,  and 
marked  prostration  occurs,  but  it  rapidly  disappears  without  permanent 
harm. 

The  reactions  following  the  second  injection  are  usually  much  less 
than  after  the  first;  often  none  at  all;  and  after  the  third  injection 
there  are  rarely  any  unpleasant  features.  The  longer  the  intervals  be- 
tween the  injections  the  more  frequently  will  there  be  a  reaction  to  the 
second  and  third  injections.     The  interval  of  a  week  is  considered  the 


SCARLET    FEVER  165 

most  satisfactory.  Richard  M.  Smith  ^  has  collected  over  50,000  in- 
stances in  which  the  killed  streptococcus  cultures  have  been  injected 
with  only  1  fatality,  which  was  a  child  23/2  years  old  who  had  a  severe 
nephritis  and  died  on  the  third  day  after  the  injection. 

The  method  has  been  extensively  tried  in  Russia  with  favorable  re- 
sults, so  far  as  one  may  judge  from  the  published  reports.  Thus  Smir- 
noff used  the  vaccines  in  13  small  communities  in  Russia  where  the 
sanitary  conditions  were  very  poor  and  the  conditions  favorable  for  the 
spread  of  scarlet  fever.  In  one  village  there  were  34  unvaccinated 
children,  of  whom  24,  or  70.6  per  cent.,  had  scarlet  fever;  48  vacci- 
nated children,  of  whom  4,  or  8.3  per  cent.,  had  scarlet  fever.  Of 
these  4,  3  came  down  within  a  week  after  the  first  inoculation,  the 
other  one  5  days  after  the  second  inoculation,  too  soon  for  immunity 
to  have  been  established.  The  results  in  the  other  villages  were  equally 
or  more  satisfactory.  Thus,  all  told,  Smirnoff  vaccinated  455  cases, 
only  a  part  of  whom  allowed  second  injections.  The  results  are  as 
follows : 

1  injection. — 285  cases — 5  cases  of  scarlet  fever 

2  "        —148      "    —2      "       "       "  « 

3  «        _  22      "    —no    "       "       "  « 

Of  the  7  cases  of  scarlet  fever  3  were  within  7  days  of  first  vac- 
cination, 2  were  within  7  days  of  second  vaccination. 

In  the  villages  without  vaccination  20  per  cent,  contracted  scarlet 
fever  and  11.1  per  cent.  died.  In  villages  with  vaccination  3.7  per 
cent,  contracted  scarlet  fever,  none  died. 

Yemelyanoff  used  the  prophylactic  in  an  epidemic  in  Krakow  in 
which  there  were  8  or  10  new  cases  reported  every  day.  Six  hundred 
and  ten  persons  were  inoculated;  of  these  not  a  single  one  contracted 
the  disease.  Often  it  was  possible  to  keep  the  schools  open  in  certain 
districts  where  inoculations  were  used,  even  though  the  children  came 
from  infected  houses. 

Equally  good  results  are  reported  by  a  number  of  other  Russian 
observers.  It  therefore  seems  that  in  the  streptococcus  vaccines  we 
have  a  useful  means  to  control  epidemics  of  scarlet  fever.  Their  use, 
with  proper  care,  is  attended  with  no  harmful  results,  and  they  de- 
serve a  wider  trial  in  this  country. 

Moser's  polyvalent  antistreptococcus  serum  has  been  used  in  the 
treatment  of  the  disease,  but  has  not  been  advocated  as  a  prophylactic. 

^Boston  Medical  and  Surgical  Journal,  CLXII,  8,  p.  242,  Feb.  24,  1910. 


13 


166  DISCHARGES    FROM    :\I01TH    AND    NOSE 

WHOOPING-COUGH 

Whooping-cough  occurs  in  epidemics,  which  vary  greatly  in  viru- 
lence, intensity,  and  mortality.  The  disease  is  more  frequent  and  se- 
vere in  cold  climates;  otherwise  uninfluenced  by  season  and  weather. 
The  cause  of  whooping-cough  is  a  small  bacillus,  described  by  Bordet 
and  Gengou.^  This  bacillus  is  found  most  readily  in  the  beginning  of 
the  disease,  in  that  part  of  the  expectoration  which  comes  from  the 
region  in  which  the  bacteria  are  most  active;  that  is,  in  the  products 
from  the  depths  of  the  bronchi  brought  up  during  the  paroxysms.  In 
this  exudate,  which  is  white,  thick,  and  rich  in  leukocytes,  the  bacilli 
exist  in  considerable  numbers  and  sometimes  in  almost  pure  culture. 

liode  of  Transmission. — Whooping-cough  is  usually  transmitted  di- 
rectly from  person  to  person  in  the  same  ways  that  diphtheria  and  other 
infections  contained  in  the  secretions  of  the  mouth  and  nose  are  spread; 
it  is  less  frequently  transmitted  by  indirect  contact  or  by  third  persons. 
Handkerchiefs,  toys,  drinking  cups,  roller  towels,  and  other  objects 
recently  contaminated  with  the  infective  secretions  may  act  as  directors. 
It  may  also  be  transmitted  by  droplet  infection,  although  in  the  ordinary 
sense  whooping-cough  is  not  air-borne. 

Jahn  and  others  called  attention  to  the  fact  that  domestic  animals 
may  be  affected  by  whooping-cough,  and  that  they  may  be  the  means  of 
transmitting  it  to  children.  It  is  most  frequently  observed  in  dogs,  but 
has  also  been  noted  in  cats.  Whooping-cough  may  be  reproduced  in 
puppies  by  dropping  a  pure  culture  into  the  nares;  once  started,  it  is 
readily  transmitted  from  puppy  to  puppy.  Klimenco  -  and  Fraenkel  ^ 
were  able  to  produce  what  seemed  like  typical  pertussis  in  monkeys,  and 
Inabo  *  showed  that  injection  of  the  bacillus  in  an  ape  gave  rise  to  a 
typical  whooping-cough  with  an  incubation  period  of  13  days.  ]\Iallory 
and  Horner  °  have  shown  that  the  bacilli  are  found  in  masses  in  the 
superficial  layer  of  the  trachea,  thereby  mechanically  parah'zing  the 
ciliae. 

Whooping-cough  is  apparently  not  contagious  during  the  period  of  in- 
cubation, but  is  communicable  from  the  appearance  of  the  early  symp- 
toms, and  is  most  contagious  during  the  early  stage.  It  may  be  trans- 
mitted in  the  late  stages  and  after  convalescence.  Wliile  the  virus  is 
known  to  be  in  the  secretions  from  the  respiratory  tract,  all  secretions 
from  the  mouth  and  nose  must  be  regarded  as  infective. 

Immunity. — There  is  no  natural  immunity  to  whooping-cough;  all 
are  susceptible.     The  greatest  susceptibility  is  between  6  months  to  5 

^  Ann.  de  J'Inst.  Pasieur,  Vol.  XX.  1906,  p.  731. 
^  Centralbl  f.  BakterioJ..  1908.  XLA^II,  64. 
^Munchen.  med.  Wochschr..  1908,  LY,  1683. 
*  Ztschr.  f.  Kinderh.,  June  15.  1912. 
^Jour.  Med.  Ees.,  Nov.,  1912,  XXVII,  2,  p.  115. 


WHOOPIXG-COUGH  167 

years.  After  5  years  the  susceptibility  decreases  with  age.  One  at- 
tack confers  a  definite  and  prolonged  immunity ;  second  attacks  are  rare. 

Prevention. — The  incubation  is  probably  1  to  2  weeks,  but  the  time 
is  indefinite,  owing  to  vagueness  of  the  onset  of  symptoms.  If  16  days 
have  passed  without  symptoms  the  danger  may  be  considered  as  having 
passed.  The  long-drawn-out  nature  of  the  disease,  the  difficulty  of 
diagnosis  in  the  early  stages  when  it  is  most  contagious,  and  the  fact 
that  patients  sometimes  continue  to  spread  the  infection  for  6  weeks 
after  apparent  recovery,  make  the  control  of  whooping-cough  an  ex- 
ceedingly difficult  problem.  Hence,  with  whooping-cough  we  have  the 
same  difficult  problem  that  confronts  us  in  the  prevention  of  measles. 

Whooping-cough  should  be  reported,  houses  placarded,  and  the  pa- 
tient isolated,  but  the  isolation  in  this  case  need  not  include  strict  con- 
finement to  a  room.  This,  in  fact,  may  be  an  unnecessary  hardship  to 
the  patient,  who  does  better  out  of  doors.  If  the  patient  is  permitted 
to  take  the  air,  he  must  avoid  contact  with  his  fellowmen  and  not  go 
to  school,  theater,  church,  public  assemblies,  nor  ride  in  street  cars  or 
public  vehicles.  Children  should  go  out  only  when  accompanied  by  an 
intelligent  caretaker  as  a  protection  to  others.  It  has  been  suggested 
that  children  with  whooping-cough  who  are  permitted  their  liberty 
should  be  plainly  labeled  with  a  red  cross  on  their  arm,  or  a  yellow 
flag  conspicuously  displayed  on  their  clothing,  to  serve  as  a  warning 
to  others. 

Patients  should  not  be  released  from  quarantine  until  the  spasmodic 
stage  is  over.  The  duration  of  isolation  varies  in  different  cities;  thus 
it  is  6  weeks  in  Montclair,  X.  J. ;  on  recovery  in  Providence ;  as  long 
as  the  cough  lasts  in  Boston.  In  Michigan  the  disease  is  considered 
infectious  3  weeks  before  the  whoop  and  -4  to  G  weeks  after  apparent 
recovery.  The  State  Board  of  Health  of  that  state  requires  disinfec- 
tion of  the  clothing  and  premises  before  the  patient  is  released,  and 
forbids  public   funerals   in  deaths   from   whooping-cough. 

Individual  prophylaxis  consists  in  avoiding  the  infection.  The  great- 
est care  in  this  regard  should  be  taken  with  children  before  the  age 
of  5  years.  Dogs,  cats,  and  other  domestic  animals  should  be  kept 
away  from  the  patient,  and  the  possibility  of  conveying  the  disease  in 
this  way  must  be  guarded  against  in  the  susceptible. 

The  control  of  whooping-cough  is  a  matter  which  is  largely  in  the 
hands '  of  the  public  itself.  The  dangerous  nature  of  this  infection 
should  be  emphasized,  and  people  taught  that  it  is  contagious  both  be- 
fore and  after  the  '''whoop."  Mild  cases  which  do  not  have  the  charac- 
teristic whoop  spread  the  disease;  this  is  especially  common  in  adults. 

Mortality. — The  dangerous  nature  of  whooping-cough  is  not  gen- 
erally realized.  Thus  in  Glasgow  the  annual  mortality  from  whooping- 
cough  for  10  years,  1855-1891,  was  13.5  per  thousand  inhabitants,  and 


1G8  DISCHARGES    FROM    MOUTH    AND    NOSE 

exceeded  that  from  any  other  acute  communicable  disease.  In  Eng- 
land and  Wales  in  1891  more  deaths  occurred  from  whooping-cough 
than  from  measles,  diphtheria,  scarlet  fever,  or  typhoid  fever.  In  our 
country  the  disease  ranks  high  as  a  cause  of  death  among  children. 
The  mortality  figures  would  be  still  higher  if  all  the  deaths  directly  or 
indirectly  due  to  it  were  completely  reported,  for  the  fatal  termination 
is  usually  due  to  complications  and  sequelae  which  occur  in  one-third 
to  one-fourth  of  all  cases.  As  a  result  of  these  complications  the  origi- 
nal disease  is  frequently  lost  sight  of  entirely  in  the  vital  statistics. 
According  to  Farr's  law — that  contagious  diseases  increase  as  density 
of  population  increases — the  death  rate  from  whooping-cough  in  our 
country  will  undoubtedly  increase  in  our  more  sparsely  settled  states 
with  increasing  population  and  rapidly  extending  lines  of  railroad  and 
other  facilities,  and  with  easy,  frequent,  and  rapid  movements  of  the 
people. 

MUMPS 

Mumps  usually  occurs  between  the  ages  of  5  to  15  years.  There  is 
decreased  susceptibility  both  before  and  after  this  time.  One  attack 
usually  confers  immunity,  but  second  attacks  are  by  no  means  rare, 
and  third  attacks  are  sometimes  reported.  The  disease  may  occur  as 
epidemics  in  institutions,  which  usually  develop  slowly  and  last  a  long 
time.  Mumps  is  contagious  before  the  symptoms  appear,  and  for  some 
time,  even  6  weeks,  after  symptoms  have  disappeared.  The  disease 
is  usually  spread  by  direct  contact;  rarely  by  indirect  contact  or  by  a 
third  person.  It  is  not  air-borne.  The  virus  is  contained  in  the  secre- 
tions from  the  mouth  and  perhaps  the  nose.  The  incubation  is  variously 
stated  at  from  4-25  days;  it  is  usually  prolonged. 

Mumps  is  required  to  be  reported  in  Maryland,  Grand  Rapids,  and 
Raleigh,  and  placarded  in  Cleveland.  Prevention  dei^ends  upon  the 
usual  practice  of  isolation  and  disinfection. 

LOBAR    PNEUMONIA 

Lobar  pneumonia  is  a  communicable  disease  which  should  be  classi- 
fied with  the  infectious  fevers.  If  pneumonia  were  a  new  disease  it 
would  be  regarded  as  "contagious,"  and  its  spread  would  be  guarded 
against  by  isolation  and  the  application  of  antiseptic  principles.  Many 
different  infections  are  caused  by  the  pneumococcus,  but  here  we  will 
consider  only  the  specific  self-limiting  disease  associated  with  massive 
involvements  of  one  or  more  lobes  of  the  lung,  known  as  lobar  or  croup- 
ous pneumonia.  The  pneumococcus  is  found  not  alone  in  the  local 
lung  lesions,  but  it  also  invades  the  blood. 


LOBAE    PNEUMONIA  169 

Pneumonia  is  one  of  the  most  prevalent  and  fatal  of  all  acute 
diseases.  As  a  cause  of  death  it  rivals  and  sometimes  exceeds  tuber- 
culosis. According  to  the  U.  S.  Census  of  1890,  over  9  per  cent,  of 
all  deaths  were  due  to  pneumonia,  and  in  1900  over  10.5  per  cent. 
Pneumonia  is  probably  on  the  increase,  owing  to  factors  favoring  the 
spread  of  the  infection  and  to  certain  devitalizing  influences  of  modern 
life  which  heighten  susceptibility  to  the  disease;  further,  more  persons 
are  now  saved  from  the  acute  and  fatal  infections  of  childhood  and  adoles- 
cence to  become  victims  of  pneumonia  later  in  life. 

Pneumonia  occurs  everywhere,  in  all  climates,  at  all  times  of  the 
year,  in  both  sexes,  and  at  all  ages;  it  is  more  frequent,  however,  dur- 
ing the  cold  months  of  the  year.  The  incidence  is  marked  at  both  ex- 
tremes of  life.  It  is  common  in  children  under  six  years;  between  the 
sixth  or  fifteenth  year  the  predisposition  is  less  marked,  but  for  each 
subsequent  decade  it  increases. 

Pneumonia  occurs  in  well-marked  epidemics.  Wells  gives  an  ex- 
haustive tabulation  of  the  epidemics  of  pneumonia  extending  back  to 
1440.^  Epidemics  of  pneumonia  have  occurred  in  all  parts  of  the 
world:  in  Alaska,  at  Erlangen,  Boston,  Ireland,  Italy,  France,  Switzer- 
land, and  on  board  ships.  The  disease  has  also  been  observed  to  spread 
in  hospitals  and  in  houses.  Epidemics  of  pneumonia  probably  only 
occur  when  the  organism  attains  an  increased  virulence  and  the  factors 
for  its  dissemination  are  favorable.  It  is  quite  proper  to  regard  pneu- 
monia as  pandemic. 

Modes  of  Transmission. — The  pneumococcus  leaves  the  mouth  main- 
ly in  the  discharges  from  the  mouth  and  nose,  and  enters  the  system 
through  the  same  channels.  The  infection  is  spread  directly  and  in- 
directly through  the  great  variety  of  ways  discussed  under  diphtheria 
and  tuberculosis.  Indirect  transmission  through  cups,  thermometers, 
handkerchiefs,  and  other  objects  contaminated  with  the  fresh  discharges 
occurs;  and  droplet  infection  also  comes  into  consideration. 

Resistance  of  the  Virus. — The  pneumococcus  is  a  frail  organism; 
it  does  not  multiply  in  nature  outside  of  the  body  and  indirect  trans- 
mission is  not  likely  except  with  fresh  infectious  material.  Even  upon 
artificial  culture  media  the  life  of  the  pneumococcus  is  brief;  it  must 
be  transplanted  every  2  or  3  days  in  order  to  keep  it  alive;  it  is  cus- 
tomary in  laboratories  to  pass  it  through  a  susceptible  animal,  such  as 
a  mouse  or  rabbit,  from  time  to  time,  in  order  to  maintain  its  viru- 
lence. 

The  pneumococcus  is  readily  destroyed  by  heat;  52°  C.  for  10  min- 
utes is  sufficient.  On  the  other  hand,  it  withstands  low  temperatures 
very  well.     The  ordinary  germicidal  agents  destroy  it  quickly  and  with 

V.  A.  M.  A.,  Feb.   23,   1889.     Med.  News,  Maj  20,  1905, 


170  DISCHARGES    FROM    MOUTH    AND    NOSE 

certainly.     It  may  live   lor  moiitlis  in  dried  sputum,  in  wliicli  it  also 
maintains  its  virulence. 

Immunity. — One  attack  of  pneumonia  does  not  leave  an  immunity. 
In  I  act.  one  attack  ])redisi)oses  to  subsequent  attacks,  as  is  the  case  with 
erysipelas  and  rlicuiiiatic  fever.  Man,  however,  must  possess  a  certain 
degree  of  resistance  to  the  ])neumococcus,  else  the  disease  would  he 
even  more  prevalent  than  it  is,  and  recovery  less  frequent. 

The  mechanism  of  the  immunity  to  this  infection  is  not  at  all  un- 
derstood. Phagocytosis  may  play  a  jirominent,  perhaps  a  dominant, 
role.  Protective  antibodies,  rather  feeble,  have  hcen  found  in  the  blood 
serum  of  immunized  animals,  and- also  in  the  blood  scrum  of  persons 
who  have  recovered  from  pneumonia.  The  pneumococcic  attack,  espe- 
cially the  crisis,  resembles  an  anaphylactic  reaction,  and,  while  the 
mechanism  of  immunity  in  this  infection  is  probably  complex,  the  best 
explanation  of  it  at  present  is  in  terms  of  anaphylaxis. 

Many  weakening  diseases  diminish  resistance  to  the  pneumococcus. 
Pneumonia  is  frequent  in  alcoholics,  and  is  commonly  brought  on  by 
exposure  to  cold,  to  trauma,  or  to  local  irritation.  It  is  a  frequent 
complication  of  typhoid  fever,  influenza,  Bright's  disease,  and  other 
debilitating  affections.  Old  age,  as  well  as  other  enfeebling  conditions, 
may  act  as  a  predisposing  cause  by  lowering  immunity.  Other  factors 
which  predispose  to  pneumonia  are  sudden  changes  in  temperature,  irri- 
tation caused  by  aspiration  of  foreign  substances,  or  the  inhalation  of 
dust  or  irritating  vapors. 

It  should  be  remembered  that  pneumonia,  like  other  communicable 
infections,  frequently  attacks  the  strong  and  robust. 

Prevention. — The  prevention  of  pneumonia  must  be  based  upon  gen- 
eral principles  guided  by  analogy  from  analogous  infections.  As  long 
as  we  are  ignorant  of  the  fundamental  factors  concerned  in  the  etiology 
and  pathogenesis  of  the  disease,  our  preventive  measures  must  lack 
precision. 

The  virulent  pneumococcus  should  not  be  lightly  regarded  as  a  nor- 
mal inhabitant  of  the  mouth,  throat,  and  nose.  Because  the  pneumo- 
coccus is  very  widely  spread  and  the  disease  is  ubiquitous,  and  because 
the  associated  factors  which  determine  infection  seem  complicated  and 
not  well  understood,  are  not  sufficient  excuses  for  a  supine  and  hope- 
less attitude.  The  problem  of  tuberculosis  has  been  attacked  with  vigor 
with  scarcely  better  understanding  of  the  fundamental  problems  at 
issue.  Each  case  of  pneumonia  should  be  regarded  as  a  focus  for  the 
spread  of  the  infection.  Ultimate  control  of  the  disease  will  probably 
have  to  await  the  discovery  of  a  specific  prophylactic  and  the  recognition 
of  dangerous  carriers.  Meanwhile  we  should  think  of  pneumonia  very 
much  as  we  think  of  whooping-cough  and  influenza,  as  an  infection 
which  is  spread  from  man  to  man  through  the  secretions  of  the  mouth 


LOBAE    PNEUMONIA  171 

and  nose.  It  is  true  that  the  pnemnococcus  is  frequently  found  in  the 
buccal  secretions  of  healthy  persons.  Sternberg  in  1880  first  demon- 
strated the  pneumococcus  in  his  own  saliva.  Netter  found  it  in  20 
per  cent,  of  the  persons  whom  he  examined,  and  the  New  York  Com- 
mission reported  its  presence  in  from  48  to  85  per  cent.  Pneumococci 
have  been  isolated  from  the  throat  in  50  out  of  80  normal  individuals, 
from  66  out  of  74  cases  of  lobar  and  lobular  pneumonia,  from  10  out 
of  15  "common  colds,"  and  from  14  out  of  31  cases  of  miscellaneous 
diseases;  in  other  words,  many  persons  are  pneumococcus  carriers. 
However,  there  are  many  different  strains  of  the  pneumococcus,  which 
vary  greatly  in  pathogenic  power.  We  therefore  do  not  know  how 
many  of  these  pneumococcus  carriers  are  dangerous  to  the  host  and 
also  to  his  fellowmen.  A  somewhat  analogous  situation  is  noted  in  the 
diphtheria-like  organisms  in  the  throats  of  about  1  per  cent,  of  all  healthy 
individuals.  It  is  probable  that  the  virulence  of  the  pneumococcus  is 
higher  in  pneumonia  than  in  the  above-mentioned  carriers,  although 
this  is  a  very  difficult  matter  to  determine.  The  findings  of  the  Medi- 
cal Commission  for  the  Investigation  of  Acute  Eespiratory  Diseases 
seem  to  make  prevention  a  less  hopeless  task  than  at  first  sight  ap- 
pears possible  from  the  widespread  distribution  of  the  pneumococcus. 
It  was  shown  that,  while  a  number  of  individuals  constantly  harbor 
virulent  strains  of  the  pneumococci  in  their  mouths,  the  majority  of 
people  do  so  only  from  time  to  time.  Individuals  who  come  in  con- 
tact with  pneumonia  patients  are  more  apt  to  harbor  the  pneumococ- 
cus than  those  not  so  exposed.  Patients  convalescent  from  pneumonia 
may  carry  virulent  organisms  in  their  respiratory  passages  for  weeks 
or  even  months. 

Pneumonia  should  be  added  to  the  list  of  diseases  requiring  com- 
pulsory notification.  Cases  should  be  isolated  at  least  in  the  same  sense 
that  tuberculosis  is  isolated — the  discharges  from  the  nose  and  throat 
should  be  burned  or  disinfected.  If  the  patient  is  treated  at  home,  the 
house  should  be  placarded  in  order  to  discourage  visiting  and  as  an 
educational  measure. 

There  is  no  specific  prophylaxis  for  pneumonia.  Prevention  con- 
sists in  avoiding  the  infection,  sustaining  the  tone  of  the  machine, 
care  and  cleanliness  of  the  upper  respiratory  passages,  avoiding  chills, 
exposure,  and  other  predisposing  causes,  and  especially  avoiding  living 
in  stuffy,  ill-ventilated  rooms  and  dusty  atmospheres. 

As  carriers  doubtless  play  an  important  role  in  disseminating  this 
infection,  the  education  of  the  public  concerning  certain  sanitary  habits 
should  be  actively  continued.  These  include  the  danger  of  spitting 
promiscuously  and  of  kissing;  the  proper  care  to  be  exercised  in  sneez- 
ing and  coughing;  the  peril  in  the  common  drinking  cup,  the  roller 
towel;  and  the  habit  of  placing  unnecessary  things  in  the  mouth. 


172  DISCHARGES    FEOM    MOUTH    AND    NOSE 

It  should  become  common  knowledge  that  anything  which  tends  to 
reduce  vitality  predisposes  to  pneumonia,  such  as  dissipation,  loss  of 
sleep,  overwork,  worry,  poor  or  insufficient  food,  lack  of  exercise,  al- 
cohol, colds,  or  excesses  of  all  kinds;  the  atonic  effect  of  living  in 
overheated  rooms,  and  the  injurious  effect  of  excessively  dried  and 
warmed  air,  and  sleeping  in  Avarmcd  rooms.  Cold  baths,  regulation  of 
temperature  and  ventilation,  sleeping  with  open  windows  or  in  the  open 
air,  are  useful  prophylactic  measures  for  pneumonia  as  well  as  tuber- 
culosis, "colds,"  and  a  large  group  of  diseases. 

Upon  the  Isthmus  of  Panama  pneumonia  was  unduly  prevalent 
owing  to  the  habit  of  the  perspiring  workmen  sleeping  exposed  to  the 
trade  winds.  According  to  Carter,  this  was  largely  controlled  by  sup- 
plying the  men  with  blankets.  In  Chicago,  Evans  believes  that  the 
prevalence  of  pneumonia  was  influenced  by  better  ventilation  of  the 
street  cars.  Allaying  street  dust  and  house  dust  removes  one  of  the 
predisposing  causes  of   pneumonia  and   other  respiratory  infections. 

Health  officers  may  assist  in  the  cause  by  disseminating  knowledge 
concerning  the  disease  and  by  enforcing  antispitting  regulations,  by 
proper  cleansing  and  oiling  of  streets,  by  requiring  a  stricter  compli- 
ance with  building  and  housing  laws,  and  by  the  regulation  of  the  ven- 
tilation and  conditions  of  the  air  in  theaters,  schools,  street  cars,  and 
public  buildings. 

INFLUENZA 

The  cause  of  influenza  is  assumed  to  be  a  small  bacillus  which  is 
constantly  associated  with  the  disease;  it  was  described  by  Pfeiffer  in 
1892  and  1893.^  Influenza  prevails  without  relation  to  climate,  wind, 
weather,  or  telluric  conditions.  It  occurs  sporadically,  in  epidemics 
and  in  great  pandemics.  In  1889  and  1890  influenza  spread  to  the 
four  quarters  of  the  globe,  and,  judged  by  the  morbidity  and  mortality, 
this  was  the  most  extensive  and  serious  pandemic  that  has  occurred  in 
modern  times.  These  worldwide  outbreaks  usually  spread  from  east 
to  west. 

Immunity. — 'Immunity  to  influenza  is  slight;  in  fact,  one  attack 
seems  to  predispose  to  subsequent  attacks;  second  and  third  attacks  are 
common  as  a  result  of  new  infections  or  reinfections.  Influenza  bacil- 
lus carriers  are  numerous.  Males  and  the  robust  individuals  in  a  com- 
munity seem  more  susceptible,  perhaps  on  account  of  greater  expo- 
sure. 

Modes  of  Transmission. — Influenza  is  spread  directly  from  person 
to  person.  It  is  highly  contagious  in  the  early  stages.  The  influenza 
bacillus  is  found  in  the  secretions  from  the  nose,  throat,  and  respira- 

^Deutsch.  med.  Wochenschr.,  2,  1892,  p.  28.     Zeitschr.  f.  Byg.,  XIII,  1893. 


COMMON    COLDS  173 

tory  tract.  The  bacillus  does  not  multiply  outside  the  body  and  has 
a  very  feeble  resistance.  It  grows  with  difficulty  upon  artificial  cul- 
ture media  and  soon  dies  out;  therefore  "contact"  infection  or  the  use 
of  handkercliiefs,  towels,  cups,  and  other  objects  contaminated  with 
the  fresh  secretions  are  the  common  modes  of  transmission.  Influenza 
is  kept  alive  in  interepidemic  years  in  carriers.  Lord  found  the  bacil- 
lus influenza  in  25  to  59  per  cent,  of  all  cases  with  cough  and  expectora- 
tion in  an  interepidemic  period  in  Boston. 

Prophylaxis. — Prophylaxis  is  practically  the  same  as  for  all  other 
infections  transferred  by  the  secretions  from  the  mouth  and  nose.  Iso- 
lation is  not  always  practicable,  but  patients  for  their  own  good  as  well 
as  the  protection  of  others  should  remain  in  bed  during  the  febrile 
stage.  This  one  measure  would  very  largely  diminish  the  prevalence  of 
influenza  as  well  as  common  colds.  The  infection  could  be  kept  out  of 
a  country  by  strict  maritime  quarantine,  provided  mild  cases  and  car- 
riers could  be  recognized;  this,  however,  is  not  practicable.  The  pub- 
lic has  not  sufficient  regard  for  influenza  to  .tolerate  aggressive  meas- 
ures. The  disease  may  frequently  be  avoided  by  individual  prophy- 
laxis. During  epidemics  individuals  should  avoid  theaters,  mass  meet- 
ings, closed  and  crowded  cars,  and  close  contact  with  their  fellowmen, 
especially  those  who  have  catarrhal  symptoms.  It  is  quite  worth  while 
to  isolate  the  first  case  of  influenza  in  a  household  in  order  to  prevent 
a  house  epidemic.  This  may  be  done  on  precisely  parallel  lines  to  those 
described  for  diphtheria.  Influenza  is  especially  dangerous  when  com- 
plicating pulmonary  tuberculosis,  and  care  should  be  taken  to  keep  it 
out  of  sanitaria.  Even  during  epidemics  influenza  may  successfully 
be  kept  out  of  institutions  by  an  intelligent  quarantine.  Once  within 
the  walls,  it  is  exceedingly  difficult  to  control.  Persons  who  continually 
carry  the  influenza  bacillus  in  their  nose,  throat,  or  respiratory  tract 
should  guard  against  exposure  to  wet  and  cold  on  account  of  the  dan- 
ger of  reinfection.  Influenza  is  another  one  of  those  diseases  the  con- 
trol of  which  rests  with  the  public.  Education,  therefore,  is  of  prime 
importance.  The  danger  from  the  use  of  the  common  drinking  cup, 
the  roller  towel,  kissing,  droplet  infection,  handkerchiefs,  pipes,  toys, 
soda-water  glasses,  spoons,  and  other  objects  recently  mouthed  should 
be  emphasized;  spitting  ordinances  enforced,  ventilation  and  overcrowd- 
ing of  street  cars  corrected,  and  dust  allayed. 

COMMON    COLDS 

More  people  probably  suffer  from  common  colds  than  from  any  other 
single  ailment.  Vital  statistics  give  no  hint  of  the  prevalence  and  im- 
portance of  these  minor  affections  because  the  mortality  is  nil  and  the 
morbidity  records  are  notoriously  imperfect  and  difficult  to  collect.   Could 


174  DISCHARGES    FROM    MOUTH    AND    NOSE 

the  sum  total  of  suffering,  inconveniences,  sequelae,  and  economic  loss 
resulting  from  common  colds  be  obtained,  it  would  at  once  promote 
these  infections  from  the  trivial  into  the  rank  of  tlie  serious  diseases. 

The  common  colds  here  considered  are  a  group  of  acute  infections 
of  the  mucous  membranes  of  the  nose,  pharynx,  tonsils,  larynx,  trachea, 
or  larger  bronchi.  A  common  cold  is  not  merely  a  congestion,  it  is 
an  infection. 

Congestion  and  inflammation  of  the  mucous  membrane  of  the  up- 
per respiratory  tract  frequently  occur  as  a  result  of  irritants  other 
than  bacteria.  Thus,  chemical  and  mechanical  irritants  will  produce  a 
congestion  or  inflammation;  an  increased  acidity  causes  a  flaring  up  of 
the  mucous  membranes,  especially  of  the  nose ;  and  many  other  local 
and  reflex  causes  lead  to  acute  or  chronic  catarrhal  conditions  of  these 
membranes,  which  may  become  exquisitely  sensitive  and  sometimes 
hypersusceptible.  In  the  absence  of  the  proper  bacteria,  however,  these 
conditions  do  not  develop  into  infectious  colds,  and  are,  therefore,  not 
communicable. 

The  popular  fallacy  of  colds  being  due  to  exposure  to  drafts,  sud- 
den changes  of  temperature,  and  chilling  of  the  body  clings  persistently 
in  both  the  professional  and  lay  mind.  These  are  predisposing  causes 
and  will  not  produce  a  cold  without  the  presence  of  the  specific  cause. 
The  bacteria  usually  found  associated  with  these  catarrhal  infections 
are :  staphylococci,  streptococci,  pneumococci,  influenza  bacillus,  the 
BaciUus  catarrhalis,  and  other  bacteria.  The  etiological  relationship 
between  these  organisms  and  the  disease  is  not  always  clear.  Many 
of  the  above-mentioned  bacteria  are  also  found  normally  upon  the 
mucous  membranes  of  the  nose,  mouth,  throat,  and  upper  resj)iratory 
passages;  reinfections  must,  therefore,  be  common,  and  predisposing 
factors  which  diminish  resistance  have  a  special  importance.  Common 
colds   frequently  attack  the  strong  and   robust  if  exposed. 

Colds  are  contracted  from  other  persons  having  colds,  just  as  diph- 
theria is  contracted  from  diphtheria.  Arctic  explorers  exposed  to  all 
the  conditions  ordinarily  supposed  to  produce  colds  do  not  suffer  from 
these  ailments  until  they  return  to  civilization  and  become  reinfected 
by  contact  with  their  fellowmen.  A  campaign  to  prevent  the  spread 
of  the  common  cold  would  have  much  collateral  good  in  aiding  the 
suppression  of  tuberculosis  and  causing  a  diminution  of  pneumonia  and 
other  infections.  Common  colds  occur  in  epidemics  and  have  all  the 
earmarks  of  a  contagious  disease.  Colds  are  apt  to  go  through  all  the 
members  of  a  household,  and  outbreaks  in  schools,  factories,  and  other 
places  where  people  are  closely  associated  frequently  occur  and  result 
in  considerable  loss  of  time  and  money. 

^^^lile  common  colds  are  never  fatal,  the  complications  and  sequelae 
jire  serious.    These  are :  rheumatic  fever,  pneumonia,  sinusitis,  nephritis, 


COMMON    COLDS  175 

and  a  depressed  vitality  which  favors  other  infections  and  hastens  the 
progress  of  organic  diseases. 

Common  colds  are  perhaps  most  contagions  during  the  early  stages. 
If  persons  would  isolate  themselves  by  remaining  in  bed  during  the 
first  three  days  of  a  cold,  they  would  not  only  benefit  themselves,  but 
would  largely  prevent  the  spread  of  the  infection.  The  contagiousness 
and  severity  of  colds  vary  greatly  in  different  epidemics  and  in  dif- 
ferent seasons  of  the  year,  depending  upon  the  particular  microorgan- 
ism involved  and  other  factors  not  well  imderstood. 

Prevention. — The  prevention  of  colds  consists,  first,  in  avoiding  the 
infection,  and,  secondly,  in  guarding  against  the  predisposing  causes. 
Contact  should  be  avoided  with  persons  who  have  colds,  especially  in 
street  cars,  offices,  and  other  poorly  ventilated  spaces  where  the  risk  of 
persons  coughing  or  sneezing  directly  in  one's  face  is  imminent.  Con- 
tact with  the  infection  may  further  be  guarded  against  by  a  careful 
self-education  in  sanitary  habits  and  cleanliness  based  Upon  the  mod- 
ern conception  of  contact  infection.  Colds,  like  other  diseases  con- 
veyed in  the  secretions  from  the  nose  and  mouth,  are  often  conveyed  by 
direct  and  indirect  contact  through  lack  of  hygienic  cleanliness  and 
a  disregard  of  sanitary  habits.  Kissing,  the  common  drinking  cup, 
the  roller  towel,  pipes,  toys,  pencils,  fingers,  food,  and  other  objects 
contaminated  with  the  fresh  secretions  will  transmit  the  disease. 

The  predisposing  causes  of  colds  include  a  number  of  conditions 
that  depress  vitality  and  thereby  diminish  resistance.  The  mechanism 
by  which  immunity  is  lessened  has  been  discussed  on  page  351.  The 
principal  predisposing  factors  in  catching  cold  are :  vitiated  air,  dust, 
drafts,  sudden  changes  of  temperature,  exposure  to  cold  and  wet,  over- 
work, loss  of  sleep  or  insufficient  rest,  improper  food,  and  other  con- 
ditions that  lower  the  general  vitality  of  the  body. 

A  special  word  concerning  drafts  is  necessary.  Drafts  in  them- 
selves cannot  produce  an  infectious  cold.  The  first  s3'mptom  of  the 
disease  is  a  chill,  which  is  not  the  cause,  but  the  effect,  of  the  infec- 
tion. It  is  a  common  belief  that  the  cold  is  caught  when  the  chill 
occurs.  The  rigor  frequently  consists  of  only  a  transient  chilliness, 
and  it  is  during  this  time  that  the  individual  thinks  he  feels  a  draft 
which  is  producing  his  cold. 

Drafts  have  no  appreciable  injurious  effect  upon  persons  in  good 
physical  tone.  They  are,  however,  injurious  to  infants,  the  aged,  and 
to  susceptible  individuals.  Drafts  are  particularly  apt  to  harm  persons 
accustomed  only  to  still,  warm  air.  "It  is  not  the  engine  drivers  and 
firemen  of  trains  that  catch  colds,  but  the  passengers  in  the  stuffy 
carriages."  Coddling  renders  one  susceptible  to  drafts,  partty  for  the 
reason  that  the  vasomotor  impulses  which  contract  the  blood  vessels  of 
the  skin  are  not  sent  out  by  the  nervous  mechanism,  and  consequently 


176  DISCHAEGES    FROM    MOUTH    AND    NOSE 

undue  cooling  of  the  part  blown  upon,  and  perhaps  of  the  blood  itself, 
takes  place.  Normally,  when  the  wind  blows  upon  the  skin  the  vaso- 
motor contraction  reduces  the  supply  of  blood  and  the  tendency  to 
cooling  is  further  met  by  a  stimulus  which  increases  heat  production. 
While  it  is  true  that  a  draft  can  no  more  cause  an  infectious  cold  than 
it  can  cause  diphtheria,  nevertheless,  it  is  true  that  a  draft  may  be  the 
predisposing  cause  by  which  immunity  is  lowered. 

It  is  a  mistake  to  think  that  the  skin  alone  is  involved  in  the  ques- 
tion of  drafts.  The  hardening  of  the  skin  as  a  prevention  of  colds  is, 
therefore,  a  misnomer.  The  good  effects  of  cold  baths,  exercise,  fresh 
air,  sunlight,  and  wholesome  food  do  not  consist  in  "hardening"  the 
skin,  but  in  improving  the  nutrition,  stimulating  the  metabolism,  help- 
ing the  control  of  the  nervous  system,  improving  the  tone  of  the  vaso- 
motor system,  strengthening  the  musculature,  and  enriching  the  blood. 

In  preventing  the  ill  effects  of  drafts,  therefore,  the  entire  organiza- 
tion of  the  body  must  be  considered,  and  not  the  skin  alone. 

Other  important  predisposing  factors  to  colds  are  mechanical  de- 
fects in  breathing,  or  the  filtering  power  of  the  upper  respiratory  pas- 
sages, also  local  pathological  conditions,  such  as  adenoids,  polypus, 
deviation  of  the  septum,  chronic  catarrhal  conditions,  all  of  which 
should  receive  appropriate  treatment. 

One  of  the  most  important  predisposing  factors  to  colds  is  breathing 
vitiated  and  dusty  air.  Good  ventilation,  therefore,  with  air  not  too 
dry  nor  too  warm,  and  the  allaying  of  dust  would  prevent  many  a 
cold.  The  bacteria  producing  colds  are  frequently  found  in  the  mouth, 
nose,  throat  and  teeth  of  persons  in  good  health.  Cleanliness  and  care  of 
these  parts  is,  therefore,  an  important  consideration  in  the  prevention 
of  common  colds. 

CEREBROSPINAL    FEVER 

Cerebrospinal  fever  is  an  infection  with  the  meningococcus  (Dtplo- 
coccus  intraceUitlaris  meningitidis,  "Weichselbaum).  The  essential  le- 
sions of  the  disease  are  chiefly  focused  upon  the  meninges  of  the  brain 
and  cord.  The  disease  occurs  both  in  localized  epidemics  and  sporadi- 
cally. 

The  meningococcus  is  a  frail  microorganism,  closely  resembling 
the  gonococcus.  Both  are  biscuit-shaped  cocci;  both  grow  feebly  on 
artificial  media.  They  are  readily  killed  by  drying,  sunlight,  heat, 
and  other  unfavorable  conditions.  They  live  a  strict  parasitic  exis- 
tence and  cause  diseases  peculiar  to  man,  with  lesions  which  resemble 
each  other,  both  as  far  as  the  character  of  the  inflammation  and  the 
distribution  of  the  cocci  within  and  without  the  cells  are  concerned. 
As  a  rule,  these  two  microorganisms  are  usually  distinguished  by  the 


CEREBROSPIXAL    FEVER  177 

source  from  "which  they  are  obtained.  Other^vise  the  differentiation  is 
difficult  and  depends  upon  careful  cultural  and  biological  studies. 

All  cases  of  meningitis  are  not  caused  by  the  meningococcus.  Spo- 
radic cases  may  be  due  to  the  pneumococcus,  streptococcus,  bacillus  of  in- 
fluenza, the  colon  bacillus,  the  typhoid  bacillus,  the  bacillus  of  bubonic 
plague,  and  of  glanders.  The  gonococcus  may  also  cause  meningitis 
as  a  secondary  complication.  The  epidemic  form  of  cerebrospinal  menin- 
gitis is  always  due  to  the  meningococcus.  Only  one  epidemic  so  far 
studied  bacteriologically  was  certainly  not  due  to  the  meningococcus; 
in  this  the  microorganism  responsible  seems  to  have  been  the  Strepto- 
coccus mucosus,  or  a  close  relative. 

The  first  epidemic  outbreak  of  meningitis  was  reported  by  Yieus- 
seux  in  Geneva  in  1805.  The  next  year  James  Jackson,  Thomas  Welch, 
and  J.  C.  Warren  investigated  an  outbreak  in  Massachusetts.  Since 
then  numerous  epidemics  have  occurred.  In  New  York  in  1904-05 
there  were   6,755   cases  and  3,455  deaths. 

The  epidemiology  of  cerebrospinal  fever  differs  from  that  of  infantile 
paralysis  in  several  respects.  The  seasonal  prevalence  of  infantile  paral- 
ysis follows  the  curve  of  the  summer  diarrheas  (July  to  September), 
while  cerebrospinal  fever  prevails  especially  in  the  fall  and  winter 
months.  The  seasonal  prevalence  of  cerebrospinal  fever  is  strikingly 
similar  to  that  of  pneumonia  and  influenza,  and  corresponds  to  a  num- 
ber of  diseases,  such  as  scarlet  fever,  measles,  diphtheria,  and  smallpox, 
in  which  the  principal  mode  of  infection  is  believed  to  be  through  the 
respiratory  tract,  and  which  are  supposed  to  be  spread  mainly  b}^  contact. 
The  epidemics  are  usually  localized.  Country  districts  are  more  afflicted 
than  cities.  Children  and  young  adults  are  most  susceptible.  Outbreaks 
sometimes  occur  in  camp  or  on  shipboard.  The  immunity  produced  by 
one  attack  is  not  lasting.  Councilman  reports  five  instances  in  which  the 
same  individual  is  reported  to  have  had  the  disease  twice. 

It  is  probable  that  the  meningococcus  enters  the  system  through  the 
mucous  membrane  of  the  nasopharynx.  From  this  position  it  may  reach 
the  meninges  directly  through  the  lymph  channels  or  indirectly  through 
the  circulation.  The  experiments  of  Flexner  in  the  monkey  indicate  that 
when  the  meningococcus  is  introduced  into  the  cerebral  cavity  it  escapes 
by  a  reversed  hinphatic  current,  so  that  under  these  circumstances  it  may 
be  found  in  the  mucous  membrane  of  the  nasophar}Tix.  Fliigge,  Weich- 
selbaum,  Scheurer,  and  others  have  found  the  meningococcus  present 
in  great  numbers  in  the  nose  and  pharynx  in  most  cases  of  the  dis- 
ease during  the  first  12  days  of  illness.  Park  states  that  after  the  1-ith 
day  they  cannot  usually  be  found.  The  admirable  monograph  of  Elser 
and  Huntoon  ^  includes  a  careful  study  of  210  cases  of  the  disease. 
The  most  striking  conclusion  by  these  authors  is  'the  essential  impor- 

"■  Journal  of  Medical  Research,  1909,  Vol.  XX,  pp.  377-536. 


178  DISCHARGES    FROM    MOUTH    AND    NOSE 

tance  of  meningococcus  carriers  in  the  tranpmission  of  epidemic  menin- 
gitis. Tiie  number  of  persons  who  become  such  carriers  during  an 
epidemic  of  meningitis  is  far  greater  than  the  number  of  cases  of  ac- 
tual meningitis.  Perhaps  70  per  cent,  of  liealthy  persons  exposed  may 
harbor  meningococci  in  the  respiratory  passages.  Apart  from  epidemics 
the  meningococcus  can  be  found  but  rarely  in  healthy  individuals,  but 
apparently  there  are  persons  who,  once  harboring  this  organism  in  the 
nasopharynx,  carry  it  permanently  and  thus  perpetuate  the  disease. 

Meyer,  Voltmann,  Furst,  and  Grieber  ^  studied  tlie  question  of  car- 
riers in  cerebrosj)inal  meningitis.  They  found  1.73  per  cent,  of  menin- 
gococcus carriers  in  over  9,111  healthy  soldiers  in  the  Munich  garri- 
son at  a  time  when  no  cerebrospinal  fever  was  present.  One  exam- 
ination was  made  from  each  soldier.  A  special  study  was  made  of 
1,911  healthy  persons  wlio  were  examined  many  times,  with  the  result 
that  2.-iG  per  cent,  were  found  to  be  meningococcus  carriers.  Of  the 
total  of  11,U"32  healthy  persons,  about  2  per  cent,  examined  contained 
the  meningococcus  in  their  throats.  Isolation  of  the  carriers  had  no 
influence  on  the  incidence  of  the  disease,  and  epidemiologically  they 
found  only  exceptional  relationship  between  the  carriers  and  the  sick. 
In  one  of  the  years  during  this  study  numerous  clinical  cases  occurred; 
in  another  year  none,  although  the  number  of  carriers  remained  the  same 
both  years.  The  authors  conclude  that  extreme  painstaking  cultural  de- 
tection of  meningococcus  carriers  is  unnecessary  in  combating  the  spread 
of  cerebrospinal  meningitis;  that  the  practical  benefits  do  not  justify 
the  care  and  time  necessary  for  such  work.  They  believe  that  the  chief 
foci,  aside  from  factors  not  understood  in  the  spread  of  this  disease, 
seem  to  be  the  sick  and  especially  the  mild  cases.  Great  care  should, 
therefore,  be  taken  to  isolate  the  mild  case  so  as  to  diminish  the  num- 
ber of  carriers.  On  the  other  hand,  in  the  epidemic  of  cerebrospinal 
meningitis  in  Texas  in  1912,  Thayer  examined  421  persons;  59.6  per 
cent,  were  healthy  carriers,  as  determined  by  the  examination  of  stained 
smears.  The  results  obtained  from  cultures  showed  53.75  per  cent, 
to  be  positive. 

It  is  now  believed  that  cerebrospinal  meningitis  is  transmitted  prin- 
cipally through  the  medium  of  healthy  carriers.  Only  a  small  percentage 
of  the  carriers  develop  the  disease.  The  occurrence  of  more  than  one 
case  in  families  is  common.  In  the  recent  Texas  epidemic  there  were 
many  instances  in  which  two  members  developed  the  disease,  and  in  a 
smaller  number  three,  four,  and  five  members  became  infected.  The 
disease  is  undoubtedly  transmitted  rather  directly  from  person  to 
person,  for  the  meningococcus  is  of  such  low  vitality  that  it  suc- 
cumbs quickly  to  dr^'ing,  sunlight,  and  other  injurious  influences.  On 
account  of  its  severity,  persons  suffering  from  the  disease  are  decidedly 
^Miinchener  Med.  Wochenschr.,  1910,  No.  30,  July  26. 


CEEEBEOSPIXAL    FEVEE  179 

limited  in  their  sphere  of  influence,  and,  as  only  a  very  small  propor- 
tion of  those  who  receive  the  microorganism  are  susceptible  to  it,  the 
perpetuation  and  spread  of  meningitis  must  depend  on  the  healthy  car- 
riers who  pass  the  meningococcus  on  from  one  to  another  until  a  sus- 
ceptible individual  is  infected  and  develops,  meningitis.  The  virulence 
of  the  organism  is  also  a  determining  factor. 

Prevention. — From  our  present  knowledge  preventive  measures  are 
clearly  indicated,  though  very  difficult  to  carry  out.  Epidemic  cerebro- 
spinal meningitis  is  a  good  example  of  a  group  of  diseases  in  which  a 
more  precise  knowledge  of  the  modes  of  transmission  of  the  disease 
makes  it  obvious  that  prevention  is  a  matter  of  extreme  practical  diffi- 
culty. Fliigge  estimates  that  healthy  carriers  of  this  disease  are  ten 
times  more  numerous  than  recognized  cases,  and,  therefore,  are  more 
than  ten  times  as  prolific  a  source  of  infection.  "Wliile  the  isolation 
of  the  known  cases  will  prevent  a  certain  number  of  secondary  cases, 
this  measure  alone  cannot  hope  to  control  the  disease.  It  is  obviously 
impractical  to  undertake  to  make  bacteriological  examinations  sufficient 
to  discover  all  the  carriers  in  a  community  of  any  considerable  size; 
moreover,  the  control  of  so  many  carriers  when  discovered  would  re- 
quire military  rule.  We  must  frankly  admit  that  when  cerebrospinal 
meningitis  has  once  become  epidemic  it  cannot  be  stamped  out  by  any 
known  means  of  practical  application. 

This  does  not  mean  that  we  should  assume  a  supine  attitude,  for, 
even  though  the  disease  cannot  be  satisfactorily  controlled,  a  certain 
number  of  secondary  cases  can  be  prevented.  Every  case  and  every  sus- 
pected case  should  at  once  be  reported  to  the  health  authorities  and 
the  patient  isolated.  The  virus  is  contained  especially  in  the  discharges 
of  the  mouth  and  nose,  and  these  secretions,  should  be  disinfected.  The 
house  should  be  placarded,  visiting  prohibited,  and  isolation  practiced. 
These  measures  will  help  diminish  the  number  of  carriers. 

Personal  prophylaxis  consists  in  avoiding  the  infection  so  far  as 
possible,  and  in  the  use  of  antiseptic  gargles  and  nasal  douches.  When 
the  disease  is  epidemic  people  should  keep  away  from  large  public  gath- 
erings, crowded  street  cars,  avoid  the  use  of  public  drinking  cups,  and 
the  like.  They  should  be  advised  to  exercise  more  than  the  usual  care 
as  to  personal  cleanliness.  The  closing  of  the  schools  may,  under  cer- 
tain circumstances,  be  justified.  Urotropin  in  moderate  doses  has  been 
suggested  as  a  possible,  though  quite  unproven,  prophylactic. 

"While  rigid  quarantine  is  not,  as  a  rule,  effective  in  controlling  this 
disease,  localized  outbreaks  in  institutions,  military  camps,  or  small 
towns  may  be  kept  from  spreading  by  a  strict  system  of  isolation,  even 
with  a  military  cordon. 

Antimeningitis  serum  is  useful  in  the  treatment  of  the  disease;  it 
is  not  practical  as  a  preventive.    It  must  be  introduced  into  the  subdural 


180  DISCHARGES    FROM    MOUTH    AND    NOSE 

space  by  lumbar  puncture.  The  scrum  should  be  provided  free  of  cost 
or  at  a  minimum  price  by  health  authorities.  Further,  boards  of  health 
should  provide  laboratory  facilities  for  the  bacteriological  diagnosis  of 
the  disease,  and  the  recognition  of  carriers. 

Sophian  and  Black  ^  recommend  an  active  immunization  induced  by 
inoculating  killed  cultures  of  the  meningococcus.  Tlie  cultures  are 
grown  on  2  per  cent,  glucose  agar,  and  after  18  hours'  growth 
are  washed  off  in  distilled  water,  shaken  for  20  minutes,  heated  at  50°  C. 
for  1  hour,  and  tested  for  sterility.  One  million  bacteria  are  injected 
at  the  first  dose,  7  days  later  the  same  number,  and  7  days  later  2,000,- 
000.  The  injection  of  the  dead  meningococcus  confers  a  considerable 
immunity,  and  may  prove  to  be  a  valuable  measure  for  personal  prophy- 
laxis. Chronic  carriers  should  be  inoculated  with  the  killed  cultures,  and 
their  sphere  of  activity  should  be  restricted.  Furthermore,  they  should 
be  impressed  with  the  danger  to  tlieir  fellowmen,  and  given  careful  in- 
structions concerning  spitting,  sneezing,  coughing;  the  care  of  fomites, 
such  as  handkerchiefs,  spoons,  cups,  etc. ;  and  the  importance  of  cleanli- 
ness of  the  teeth,  mouth,  nose,  and  throat. 

>  J.  A.  M.  A.,  Aug.  17,  1912,  LIX,  7,  p.  527. 


CHAPTER   IV 

INSECT-BORNE  DISEASES 

GENERAL    CONSIDERATIONS 

The  fact  that  disease  may  be  transmitted  through  the  bites  of  in- 
sects was  suspected  for  years,  but  it  was  not  until  1893  that  it  was 
demonstrated  as  a  new  principle  by  Theobald  Smith  in  the  case  of 
Texas  fever  of  cattle  and  the  tick.^  Since  then  many  diseases  have 
been  added  to  the  list,  which  is  constantly  growing.  We  now  know 
that  some  diseases  are  always  transmitted  through  insects  and  others 
occasionally.  A  thorough  comprehension  of  the  subject  is  necessary  for 
sanitarians  and  others  in  the  fight  against  disease  in  all  climates  and 
in  all  places. 

It  may  be  stated  as  a  general  law  that,  if  a  period  of  incubation 
in  the  insect  is  necessary,  it  indicates  that  the  parasite  probably  be- 
longs to  the  animal  kingdom  and  passes  part  of  its  life  cycle  within 
the  insect.  This  constitutes  the  so-called  extrinsic  period  of  incubation. 
Malaria  and  yellow  fever  are  examples  of  this  class,  which  is  spoken 
of  as  biological  transmission.  If,  on  the  other  hand,  insects  convey 
infection  at  once  without  a  period  of  incubation  in  the  insect,  the  trans- 
fer is  a  mechanical  one;  in  this  case  the  insect  does  not  play  the  part 
of  an  intermediate  host  in  the  true  biological  sense,  and  there  is  no 
cycle  of  development  of  the  parasite  within  the  insect.  These  cases 
are  almost  all  bacterial  infections. 

It  may  be  stated  as  a  general  rule  that  the  insect  hosts  are  not 
harmed  by  the  parasites  which  they  harbor  and  which  are  pathogenic 
for  man.  Thus,  the  malarial  protozoon  is  pathogenic  for  man,  but  a 
saprophyte  for  the  mosquito.  The  same  is  true  of  yellow  fever  and 
the  Stegomyia,  Texas  fever  and  the  tick,  plague  and  the  ilea,  sleeping 
sickness  and  the  tsetse  fly,  typhoid  and  the  house  fly,  typhus  fever  and 
the  louse,  etc. 

The  intermediate  host  in  the  zoological  sense  is  that  animal  which 
harbors  the  asexual  phase  of  the  life  cycle  of  the  parasite;  the  definitive 

^  The  other  names  associated  with  the  early  work  upon  insects  and  their  re- 
lation to  disease  are:  Manson,  Finlay,  Eoss,  Grassi,  and  the  U.  S.  Army  Com- 
mission— ^Eeed,  Carroll,  Lazear,  and  Agramonte. 

14  181 


182  INSECT-BORNE    DISEASES 

liost  is  the  animal  which  haii)ors  the  poxual  ])hasi\  Thus,  in  malaria 
man  is  the  intermediate  liost,  the  mosquito  the  definitive  host.  In 
jjopular  ])arUince,  the  insects  are  spoken  of  as  the  intermediate  liosts  in 
all  cases. 

Insects  transfer  infections  mechanically  in  a  variety  of  ways.  The 
mouth  parts,  legs,  or  outer  surfaces  of  the  body  may  be  smeared  with 
tlie  virus,  which  is  thus  simply  carried  to  the  lips,  fingers  or  food,  and 
thus  enter  the  susceptible  individual;  or  the  virus  may  remain  attached 
to  the  proboscis  of  a  biting  insect,  thus  transferring  the  infection  very 
much  as  a  hypodermic  syringe  would ;  or  the  virus  may  be  contained 
in  the  dejecta  of  the  insect  and  be  scratched  or  rubbed  into  the  wound 
made  by  the  bite;  or  the  virus  may  be  contained  in  the  digestive  tube 
or  the  body  cavity  and  be  released  when  the  insect  is  crushed. 

Insect-borne  infections  are  types  of  true  endemic  diseases,  as  they 
are  necessarily  limited  in  geographical  distribution  to  the  habitat  of 
the  insect  host. 

As  a  rule,  only  one  species,  or  at  most  a  single  genus,  acts  the  part 
of  a  host  for  any  particular  infection,  excepting  in  the  mechanical 
transference  of  infection  by  insects.  ]\Ialaria  is  confined  to  Anopheles, 
yellow  fever  to  Stegomyia,  Texas  fever  to  the  Margaropus  annular- 
tiLS,  sleeping  sickness  to  the  Glossina  palpaUs,  etc.  This  is  a  ques- 
tion of  specificity.  The  specific  nature  of  some  of  these  diseases 
may  be  due  to  the  fact  that  the  parasite  is  not  pathogenic  for  other 
hosts.  Thus,  yellow  fever  and  malaria  cannot  be  given  to  any  other 
animal  than  man,  even  though  large  amounts  of  the  infected  blood  be 
inoculated.  The  disease  may  be  specific,  in  the  sense  that  it  is  confined 
to  one  species,  because  the  insect  conveying  the  infection  refuses  to  bite 
other  than  its  own  host.  True  specificity  is  found  in  all  the  cases  of 
biological  transference,  whereas  mechanical  transference  of  infection 
may  take  place  through  widely  separated  genera. 

In  some  instances  the  virus  is  transmitted  hereditarily  through  the 
insect  from  one  molt  to  another,  and  even  from  one  generation  to  the 
next.  So  far  as  known,  however,  hereditary  transmission  takes  place  only 
in  those  "insects"  having  an  incomplete  metamorphosis,  such  as  the 
ticks.  Brues  suggests  that  the  hereditary  transmission  of  a  virus  is 
practically  impossible  in  insects  passing  through  complete  metamorphosis, 
owing  to  the  active  phagocytosis  during  the  pupal  stage. 

Protozoa,  bacteria,  and  even  parasitic  worms  may  be  transferred 
by  insects.  The  character  of  the  disease  cannot  be  predicated  from 
the  nature  of  the  insect  host.  Thus,  ticks  convey  Pirosoma  and  also 
spirochetes;  flies  convey  trypanosomes,  bacteria,  the  eggs  of  worms,  and 
a  variety  of  other  infections;  mosquitoes  are  concerned  in  the  transmis- 
sion of  the  Plasmodium,  a  protozoon,  filaria,  a  round  worm,  and  a 
filterable  virus    (yellow  fever). 


GENEEAL    CONSIDEEATIONS 


183 


Insect-borne  diseases  may  occur  in  great  epidemics,  as  yellow  fever, 
malaria,  dengue,  plague,  relapsing  fever,  etc.  When  this  occurs  it 
means  that  the  particular  insect  involved  prevails  in  enormous  num- 
bers in  the  epidemic  area. 

Ticks  and  mites  belong  to  the  lower  class  of  the  Arachnida  and 
are  not,  strictly  speaking,  insects  (insecta),  but  are  here  considered 
in  the   same  group   for  practical  convenience. 

All  the  parasitic  animals  which  live  upon  man  and  the  higher  ani- 
mals may  act  as  go-betweens  in  the  transportation  of  the  microorgan- 
isms of  disease.     Parasites  

which  live  upon  the  skin 
are  known  as  ectoparasites, 
in  contradistinction  to  en- 
doparasites,  which  live 
within  the  body.  The 
ectoparasites  may  be  tem- 
porary parasites,  as  the 
mosquito ;  or  permanent, 
as  the  tick,  which  spends 
all  but  its  earliest  and  last 
days  attached  to  the  skin 
of  its  host.  Between  these 
extremes  there  are  para- 
sites spending  more  or  less 
of  their  life  attached  to 
the  host;  thus,  the  bedbug 
and    flea     are     temporary,     whereas     lice     are     permanent     parasites. 

Many  of  the  insect-borne  diseases  were  formerly  known  as  "place 
diseases.''  Thus,  in  yellow  fever  it  was  realized  that  the  infection 
was  not  conveyed  directly  from  man  to  man,  but  it  was  believed  that 
the  house  or  place  became  infected,  and  it  was  thought  that  the  virus 
lived  in  the  soil,  upon  the  bedding,  or  on  the  clothing.  This  led  to 
the  notion  that  fomites  or  inanimate  objects  played  an  important  role 
in  the  transference  of  disease.  The  early  studies  in  bacteriology  gave 
countenance  to  this  view  until  our  knowledge  of  the  part  played  by  in- 
sects and  the  importance  of  "contacts"  has  placed  fomites  in  a  subordi- 
nate and  oftentimes  negligible  position. 

The  prevention  of  the  class  of  infections  belonging  to  the  insect- 
borne  diseases  depends  upon  a  knowledge  and  thorough  comprehension 
of  three  factors:  (1)  the  disease,  (2)  the  parasite,  and  (3)  the  insect. 
The  suppression  or  control  of  the  insect  depends  upon  a  thorough  knowl- 
edge of  its  biology.  Entomology,  therefore,  has  become  a  vitally  im- 
portant subject  so  far  as  preventive  medicine  is  concerned.  Without 
an  acquaintance  with  the  life  history  and  habits  of  the  insect  host  there 


\ 

y. 

y 

V 

j^ 

^"""^^ 

^ 

^^ 

r 

X 

3 

y 

■    '-vj 

'"j 

- 

Fig.  17. — A  South  African  Blood-Sucking  Fly 
(Pangonia),  Illustrating  Long  Proboscis  to 
Pierce  Heavy  Fur  of  Certain  Animals. 
(Brues.) 


184  INSECT-BORNE    DISEASES 

will  be  economic  loss,  wasted  energy,  and  disappointing  results.  The 
malaria  mosquito  is  active  at  night  and  breeds  in  tlie  swamps;  the 
yellow  fever  mosquito  is  active  by  day  and  breeds  about  houses.  Other 
mosquitoes  have  their  own  particular  breeding  and  hiding  places.  The 
su])pression  of  lice  depends  largely  upon  bodily  cleanliness,  the  suppres- 
sion of  the  bedbug  upon  house  cleanliness,  the  dangerous  fleas  come 
largely  from  association  with  other  animals,  the  flies  from  manure  and 
decomposing  organic  filth,  the  ticks  from  other  animals  and  from  the 
infested  ground  and  woods. 

For  the  control  of  the  insect-borne  diseases  it  is  not  always  neces- 
sary to  exterminate  the  particular  insect  host.  In  fact,  the  extermina- 
tion of  a  particular  species,  much  more  a  genus,  is  practically  a  biologic 
impossibility.  A  material  reduction  in  the  numbers  of  the  insects  in 
a  particular  area  will   often  result  in   an  elimination   of  the   disease. 

The  geographical  distribution  of  the  disease  is  always  more  lim- 
ited than  the  geographic  distribution  of  the  insect  host.  Anopheles 
exist  in  many  places  where  there  is  little  or  no  malaria.  Stegomyia 
mosquitoes  are  numerous  in  the  Philippines,  but  the  infection  has  not 
yet  been  carried  there. 

In  the  migration  of  insect-borne  diseases  it  is  usually  the  human 
host  and  not  the  insect  that  acts  as  the  traveler.  Insects,  as  a  rule, 
do  not  go  great  distances  of  their  own  volition,  and  never  over  seas 
or  from  one  country  to  another,  unless  taken  in  the  conveyances  of 
man  or  upon  some  higher  animal.  When  yellow  fever  or  malaria  go 
from  one  country  to  another,  the  infection  is  translated  in  man.  The 
infected  mosquitoes  are  rarely  transported,  except  occasionally  upon 
wooden  sailing  vessels  with  water  barrels  that  afford  breeding  places. 

An  apparent  exception  to  this  statement  is  the  case  of  plague.  It 
is  the  rat  rather  than  man  that  spreads  plague  from  land  to  land.  In 
this  case,  however,  the  disease  is  primarily  an  infection  of  the  rat,  which 
carries  the  flea  along  and  man  is  secondarily  attacked.  Another  excep- 
tion is  the  house  and  stable  fly,  which  are  known  to  travel  a  mile  or 
more  upon  the  wing. 

An  effective  campaign  against  mosquitoes,  flies,  or  other  in- 
sect pests  requires  the  expenditure  of  time  and  money.  Further,  it 
requires  the  assistance  of  the  entomologist,  the  engineer,  and  the  prac- 
tical administrator.  When  the  campaign  involves  extensive  drainage 
or  filling-in  operations,  this  calls  for  the  services  of  an  engineer  who 
has  specialized  along  these  lines.  To  attack  the  problem  without  a 
complete  knowledge  obtained  from  a  careful  study  of  the  habits  and 
breeding  places  of  the  particular  species  of  insect  will  probably  result 
in  economic  waste.  Thus,  in  New  Orleans,  during  the  yellow  fever 
campaign  of  1905,  much  time  and  effort  was  saved  by  knowledge  of 
the  fact  that  the  Stegomyia  mosquitoes  did  not  breed  in  the  street  gut^ 


GENERAL    CONSIDERATIONS  185 

ters  of  New  Orleans.  The  habits  and  habitat  of  some  species  may  vary 
in  different  localities,  and  a  careful  study  of  the  local  conditions  is 
important  to  insure  success.  In  the  organization  of  a  mosquito  cam- 
paign the  several  branches  of  the  work  may  be  allotted  to  special  divi- 
sions, each  consisting  of  a  foreman  and  crew.  These  men  become 
skilled  in  their  particular  duties,  and  efficiency  is  thereby  greatly  pro- 
moted. One  division  should  have  charge  of  the  oiling,  another  of  the 
fumigation,  another  should  seek  to  destroy  the  natural  breeding  places, 
another  should  attend  to  the  screening,  etc.  In  fly  suppression  one 
division  should  look  after  the  storing  and  handling  of  horse  manure, 
another  to  garbage  and  organic  refuse,  and  so  on.  All  the  work  must 
be  centralized  under  the  direction  of  one  person  with  executive  ability 
and  a  thorough  understanding  of  the  problem. 

The  suppression  of  insects  and  household  vermin  is  essentially  a 
question  of  cleanliness.  The  most  effective  measures  are  those  which 
strike  at  the  breeding  places,  and  these  will  be  considered  in  detail  un- 
der mosquitoes,  flies,  ticks,  lice,  fleas,  and  bedbugs.  Next  to  the  sup- 
pression of  their  breeding  places,  the  most  important  measure  in  a 
household  is  to  starve  out  these  pests.  Food  must  be  so  protected 
that  insects,  mice,  and  rats  cannot  gain  access  to  it.  Floors  and  other 
surfaces  must  be  kept  clean,  so  that  they  do  not  have  the  least  film  of 
organic  dirt  upon  which  insects  feed.  There  should  be  no  cracks  or 
crevices  to  collect  dust  and  dirt,  which  offer  comfort  for  insect  life. 
Cleanliness  and  incessant  care  must  not  only  be  exercised  in  the  house- 
hold itself,  particularly  the  kitchen,  pantry,  dining  room,  cellar,  attic, 
and  bathroom,  but  must  also  include  the  back  yard  and  surroundings  of 
the  house.  Old  cans  and  broken  bottles,  rubbish,  garbage,  and  general 
untidiness  around  the  household  afford  breeding  places,  hiding  places,  or 
food  for  vermin. 

All  the  blood-sucking  parasites  must  be  regarded  as  dangerous.  If 
they  do  not  play  the  role  of  an  intermediate  host  in  the  biological 
sense,  they  may  occasionally  transfer  infections  in  a  mechanical  way, 
or  the  little  wounds  may  allow  the  entrance  of  such  infections  as  ery- 
sipelas, the  pus  cocci,  anthrax,  tetanus,  and  other  microorganisms.  Fur- 
ther, all  blood-sucking  parasites  are  potentially  dangerous,  in  that 
new  diseases  may  be  established  as  the  old  ones  must  have  been 
established  at  one  time  through  the  triple  alliance  of  host,  insect,  and 
parasite. 

Science  has  demonstrated  the  danger  from  insects.  Experience  long 
ago  decided  that  a  healthy  home  must  be  free  of  insects  and  vermin  of 
all  kinds — it  remains  for  the  future  to  extend  this  kind  of  cleanliness 
to  municipal  housekeeping  and  rural  sanitation. 

The  principal  insect-borne  diseases,  their  causes,  and  the  insect  re- 
sponsible in  each  case  are  stated  in  the  following  table; 


MOSQUITOES 


Mau^uia  (Lavoran,  ISSO,  the 
parasite) (Ronald  Ross.  1895-8, 
relation  to  the  mosquito) 


Plasmodium  malaria:  (Laveran)    Anopheles 
Plasmodium     vivax     (Grassi    & 

Feletti)  | 

Plasmodium  falciparum  (Welch) 
Plasmodium       immaculalum 

(Grassi) 


Yellow    Fever    (Reed,     Carroll,  A  filterable  virus 
Lazcar  and  Agramonte,  1900-2)  i 


Stegomyia  calopus 


FiL.\RL\sis      (Dcniarquay,      1863)\ F ilaria  bancrofti 
(Manson — also  James) 


Culex   fatigans.    Anopheles    niger- 
rimus  and  others 


Dengpe  (Graham,  1903)  (Ashburn  A  filterable  virus 
and  Craig,  1907)  | 


[Culex  fatigans 


DiSTOXiLVSi9-BiLH.\RZiosis  (Bilharz,  Schistosoma  ■ha:matobium 
1851)  (Katsurada,  1904)  {Schistosoma  japonicum 


Anopheles  maculipennis  (?) 


FLIES 

Nag.\na  (Bruce,  1894) 

Trypanosoma  brucei 

Tsetse  fly  (a  biting  fly)  — (jto«s»no 
morsitans 

Sleeping  Sickness  (Button,  1901, 
and  Todd) 

Trypanosoma  gambiense 

Tsetse  fly — Glossina  palpalia 

Pappataci      Feveb — 3-day     feverj 
(Adriatic)  (Doerr,  1909) 


Phlebotomus     pappatasix — a     dip- 
terous biting  gnat 


'Pink  Eye' 


A   little  fly  or  midge  belonging  to 
the  genus  Hippelales 


PmcLENT  Ophth-^lmia  of  Egypt, 
etc. 

Flies,  el  al. 

PouoMYELJTi8(Rosenau  and  Brues, 
1912) 

A  filterable  virus    coccal    forms 
(Flexner  and  Noguchi,  1913) 

Stomoxys  calcitrans — ^The  stable  fly 

Typhoid,'Cholera.  Dysentery,  etc. 
Contagious     ophthalmia,      ery- 
sipelas,   anthrax,    glanders    and 
other  skin    infections,    smallpox 
and  other  exanthems,  etc. 

Mtisca   domestica   and   other   flies 
(Mechanical  transmission) 

TICKS 


Texas  FE^'ER  (of  cattle)  (Th.  Smith  Pyrosoma   bigeminum,  now  Ba- Margaropus  annulatus 
&  Kilborne,  1893)  besia  bigemina 


Rocky  Mountain  Spotted  Fevtesi 
(Ricketts,  1906) 


<Dermacentor    occidentalis    (now 

I      venustus) 


Atric.vnTickFea-er  (Dutton,  1905)  Spirochafa  duttoni 


lOrnithodoros  savignyi 


Relapsing FE\'ER(Obermcier,  1875)  Spirochceta  obermeieri 
(Ph.  Ross  and  Milne,  1904)         i 


\OrnithodoTos     moubata     or     Argas 
I      persicus 


PlROPL-VSMA  Canis 


Piroplasma  canis 


L\  Spirillose  des  Poules   (NLvr- 
CHOITC  &  Salembeni,  1903) 


(Ticks  are  not  true  Insecta.) 


SpirochcUa  gallinarum 


Argas  miniattis 


BEDBUG 

Relapsing  FtvER  (Obermeier,  1873) 

Spirochceta  obermeieri 

Cimex      lectularius,      Ornilhodoros 
moubata,     Argas    persicus    and 
perhaps  other  biting  insects,  as 
fleas  and  lice 

Kala-.\zak 

Trypanosoma  leishmanii 

Cimex  lectularius 

Cimex  rotundatus 


186 


IXSECTICIDES 


187 


DISRASE 

CAUSE 

INSECT 

Plague 

FLEA 

Bacillus  pestis 

LoemoTpsylla    cheopis     and    other 
fleas 

LOUSE 

Ttphoid    Fever     (XicoUe,     1909)  (?) 
(Ricketts      &      Wilder,      1910) 
(.■^derson  &  Goldberger,  1910) 

Pediculus  vestimenti 
Also,  Pediculus  capilis 

A  number  of  other  diseases  are  suspected;  thus,  barbiero  fever 
(Conorhinus  megistu^) ;  pellagra  (Simulium) ;  hookworm  (Mu^ca 
domestica),  etc. 

INSECTICIDES 

Practically  all  the  germicidal  agents  are  also  insecticides.  There 
are  some  exceptions  to  this  statement,  notably  formaldehyde,  which  is 
one  of  our  most  potent  germicides,  but  has  little  or  no  effect  upon  in- 
sect life  in  its  gaseous  state. 

The  action  of  insecticides  may  be  considered  under  three  classes: 
(1)  those  that  act  as  general  protoplasmic  poisons,  such  as  strong  acids 
or  alkalies,  hydrocyanic  acid,  sulphur  dioxid,  etc.;  (2)  those  that  suf- 
focate the  insects,  such  as  oily  substances,  and  (3)  those  that  act  upon 
the  nervous  structures,  such  as  chloroform,  ether,  and  other  general 
anesthetics. 

Another  classification  considers  insecticides  under  four  groups:  (1) 
those  used  by  contact  in  liquid  form  or  in  solution;  (2)  those  used 
by  contact  in  dry  or  powdered  form;  (3)  those  used  by  contact  in 
vapor  form;  (-i)  those  used  by  mixing  with  food  and  which  are 
poisonous  when  ingested.  Insects  differ  markedly  in  their  power  of 
resisting  insecticides.  Those  with  well-developed  chitinous  protection, 
such  as  bedbugs  and  roaches,  are  more  difficult  to  kill  than  flies,  fleas, 
and  mosquitoes. 

The  most  practical  of  the  insecticides  for  the  destruction  of  the 
winged  insects  in  an  enclosed  space  are  those  that  may  be  used  in  the 
gaseous  state.  Of  these,  sulphur  dioxid,  hydrocyanic  acid  gas,  carbon 
bisulphid,  or  carbon  tetrachlorid  are  most  commonly  employed  and  are 
most  reliable.  The  uses  and  limitations  of  these  and  other  insecticidal 
agents  will  now  be  considered  in  detail. 

Preparation  of  the  Room  for  Fumigation. — It  is  more  important  to 
tightly  seal  a  room  in  which  insects  are  to  be  destroyed  than  where 
only  a  germicidal  action  of  the  gas  is  looked  for.  Insects  may  escape 
through   minute   openings,   and  they  may  hide   in   nooks   and   corners 


188 


INSECT-BORNE    DISEASES 


where  the  gas  permeates  slowly  and  feebly,  or  may  take  cover  under 
the  folds  of  crumpled  paper  or  folded  fabrics,  and  thus  escape  the  in- 
secticidal  action  of  the  gas.  Self-preservation  tempts  mosquitoes  and 
other  insects  as  well  as  rats  and  mice  to  seek  the  light  when  in  the 
presence  of  an  irritating  gas.  It  is,  therefore,  convenient  to  darken 
the  place  to  bq  treated,  leaving  one  source  of  light.  The  dead  vermin 
may  then  be  readily  collected  about  this  place. 

Strips  of  paper  should  be  pasted  over  doors  and  windows.     Cracks 

and  crevices  may  be 
caulked  with  tow- 
els, waste,  or  other 
suitable  substance. 
Ventilators,  f  i  r  e- 
places,  hot-air  reg- 
isters, and  all  open- 
ings into  the  room 
must  be  covered, 
otherwise  both  the 
gas  and  the  insects 
will  escape.  Closets 
and  small  doors 
should  be  opened 
and  all  the  drawers, 
lockers,  and  similar 
places  exposed  in 
such  a  way  that  the 
gas  may  have  free 
access  to  remote 
corners.  Furniture 
should  be  moved 
away  from  the 
walls.  Fabrics, 
paintings,  instru- 
ments, bright  metal 
work,  or  other  ob- 
jects liable  to  injury  may  be  removed  or  covered,  especially  when  sulphur 
is  used. 

The  Relative  Efficiency  of  Insecticides. — McClintock,  Hamilton,  and 
Lowe  ^  have  tested  a  number  of  insecticidal  substances,  the  values  of 
which  are  shown  in  Table  4,  which  gives  a  list  of  the  substances 
tested  and  the  species  of  insects  used  in  the  experiments,  together  with 
the  quantity  of  each  substance  which,  when  properly  transformed  into 
vapors,  was  sufficient  to  kill  the  species  indicated.  The  coefficient  eol- 
Wour.  Am.  Pub.  Health  Assn.,  Vol.  II,  No.  4,  Apr.,  1911,  p.  227. 


FiQ.    18. — Example   of   Sealing    DooBa  for   Purpose   of 
Fumigation. 


INSECTICIDES 


189 


umn  Bhows  the  inverse  ratio  between  this  quantity  and  8  grams,  the 
weight  of  sulphur  which,  when  burned,  kills  the  bedbug  in  the  800,000 
c.  c.  of  inclosed  space. 

The  efficient  dilution  of  the  vapors  of  any  substance  may  be  ob- 
tained from  this  coefficient  by  multiplying  by   100,000. 

For  example,  if  one  wishes  to  use  carbon  disulphid,  by  consulting 
No.  28  in  the  table  it  is  shown  that  24  grams  were  required  to  kill 
bedbugs,  while  only  8  grams  were  required  of  sulphur.  It  is  therefore 
only  one-third  as  strong  and  its  coefficient  is  0.3-[-.  Its  efficient  dilu- 
tion is  33,000. 

TABLE  4 

INSECTICIDES 

Time  of  exposure — Varied  as  conditions  required. 

Column   1 — Quantity  used  to  kill  the  specified  insect. 

Column  2 — Coefficient  of  efficiency  compared  with  the  efficiency  of  sulphur   dioxid  on  bedbugs 


Substance 


Bedbug 


Cockroach 


Housefly 


Clothes 
Moth 


Mosquito 


1  Sulphur  Dioxid  as  Sulphur.  .  . 

2  P j-ridin 

3  Pyridin  Bases  (Merck) 

4  QuinoLLn 

5  Creosote  Oil 

6  Carbolic  Acid 

7  Naphthalene 

8  Kerosene 

9  Anilin  Oil 

10  Cedar  Oil 

11  Citronella  OU 

12  Cloves  Oil 

13  Peppermint  Oil 

14  Pennyroyal  Oil 

15  Australene 

16  Turpentine  (Oregon  Fir) 

17  Oil  Pinus  Palustris 

18  Oil  Turpentine 

19  Turpentine  (Mich.  Wood)..  .  . 

20  Benzaldehyde 

21  Nitrobenzol 

22  Ammonia  28% 

23  Alcohol,  Ethyl 

24  Alcohol,  Methyl 

25  Acetone 

26  Chloroform .' 

27  Ether  (Ethyl  Oxide) 

28  Carbon  Disulphid 

29  Carbon  Tetrachlorid 

30  Chloretone 

31  Camphor 

32*Nicotin,  80%  Sol 

33  Hydrocyanic  Acid,   as  Potas- 

sium Cyanid 

34  Paraform 

SSJFormaldehyde  40%  Sol 

36  Stramonium  Leaves 

37  Sabadilla  Seeds 

38  Chrysanthemum  Flowers .  .  .  . 


4  + 

8 

8  + 
16  + 

6.3  + 
11.5  + 

4  + 

4  + 

4  + 

8  + 

8  + 
36  + 
16  + 
20  + 
16  + 

4  + 

8  + 
36  + 
80  + 
80  + 
40  + 
40  + 


1 

1 

1.6 

1 

2 

1 

1 

0.5 

1.3 

0.7 

2 

2 

2 

1 

1 

0.2 

0.5 

0.4 

0.5 

2 

1 

0.2 

0.1 

0.1 

0.2 

0.2 


4 
4 
4 
8 
4  + 


16  + 

6.3  + 
11.5 

4  + 

4  + 

4  + 

8  + 

8  + 
36  + 
16  + 
20  + 
24  + 

4  + 

8 
36  + 
80  + 
80  + 
40  + 
40  + 


24 
40 

4  + 
8  + 
25 

6.3 

8  + 
54  + 
10 

8  + 
80  + 


0.3 
0.2 
2 
1 

4 

1.3 
1 

0.1 
0.8 


0.1 


36 
40  + 

4  + 
8 
25 

6.3 

8  + 
54  + 
10 

8  + 
80  + 


2 

2 

2 

1 

2 

1 

1 

0.5 

1.3 

0.7 

2 

2 

2 

1 

1 

0.2 

0.5 


0.4 

0.3 

2 

1 

0.2 

0.1 

0.1 

0.2 

0.2 


0.2 
0.2 
2 
1 

4 

1.3 

1 

0.1 

0.8 


3.2 

2 

1.6 


0.1 


2 

4  + 

6.3 

8 

2 

2 

4 

4 

3.2 
36  + 

4 
20 
16 

2 

1.6 
20  + 
80  + 
80  + 
40  + 
16  + 

15  + 
4 

40  + 
4 
4 
6 

2 

4 

16  + 
10  + 
16 

2.6 


2.5 

4 
5 


4 
1 
4 
2 

1.3 
1 
4 
4 
2 
2 

2.5 
0.2 
2 

0.4 
0.5 
4 
5 

0.4 
0.1 
0.1 
0.2 
0.5 
0.5 
2 

0.2 
2 
2 
20 

4 

2 

0.5 

0.8 

0.5 

3 


2.6 

1.6 

1.6 

2 

1 

8 

4 

4 

6.3 

2 

4 

2 

4  + 

4 

8 
16  + 

4 
20 
16 

2 

1.6 
36  + 
80  + 
80  + 
40  + 
16  + 


2 
40  + 

4 

4 
25 


16  + 

10  + 

16  + 

4 


3 

5 

5 

4 

8 

1 

2 

2 

1.3 

4 

2 

4 

2 

2 

1 

0.5 

2 

0.4 

0.5 

4 

5 

0.2 

0.1 

0.1 

0.2 

0.5 


3.2 
1.6 


4 
1 

4  + 
4 
1 
1 
1 
2 
1 
2 
8 
2 
10 


1 

1 
20 
80 

80  + 
14  + 
16  + 


4 

0.2 

2 

2 
40 


1 

0.5 

0.8 

0.5 

2 


2.5 
5 


4 
1 
4 
0.8 


0.4 
0.1 
0.1 
0.2 
0.5 


20 
0.2 


4 
100 


The   +  sign  after  a  number  indicates  that  this  quantity  was  the  largest  used  and  that  it  was 

insufficient. 
*   Coefficient  of  nicotin  based  on  100%  alkaloid. 
%  Quantity  of  formaldehyde  to  be  an  efficient  germicide  is  13J^  c.  c.  or  a  coefficient  of  0.625. 


100  INSECT-BORNE    DISEASES 

The  best  methods  of  generating  gases  for  fumigating  purposes  are 
considered  below.  For  further  information  concerning  these  substances, 
with  special  reference  to  tlieir  germicidal  action,  see  Section  XII. 

To  insure  success  the  gas  used  to  fumigate  a  room  should  be  liber- 
ated in  a  large  volume  in  a  short  time.  If  the  gas  is  evolved  slowly 
much  of  it  will  be  lost  before  the  room  can  become  charged  with  a 
sufficient  amount  to  kill  the  insects. 

The  amount  of  gas  and  the  time  of  exposure  stated  in  each  case 
are  the  minimum.  When  large,  leaky,  or  irregularly  shaped  spaces  are 
to  be  fumigated,  the  amount  of  gas  should  be  increased  and  the  time 
of  exposure  prolonged.  It  is  also  advisable  to  generate  the  fumes 
in  as  many  different  places  as  practicable,  as  this  favors  rapid  diffu- 
sion. 

Sulphur. — Sulphur  is  one  of  the  most  valuable  insecticides  we  pos- 
sess. It  may  be  used  either  as  a  gas — SOo — or  in  its  powdered  form 
— flowers  of  sulphur. 

Sulphur  dioxid  is  destructive  to  all  forms  of  life.  It  will  kill 
mosquitoes,  flies,  fleas,  roaches,  bedbugs,  and  all  kinds  of  vermin,  in- 
cluding rats  and  mice.  While  sulphur  dioxid  is  one  of  the  most  de- 
pendable insecticides  it  is  a  rather  feeble  germicide.  It  is  limited 
in  practice  on  account  of  its  destructive  and  corrosive  action.  This 
destructive  action  results  from  the  sulphurous  acid  and  sulphuric 
acid  produce'd  in  the  presence  of  moisture.  Fortunately  the  dry  gas 
is  quite  as  poisonous  to  mosquitoes,  flies,  rats,  mice,  etc.,  as  the  moist 
gas.  Dry  sulphur  dioxid,  however,  has  absolutely  no  germicidal  value. 
Dry  sulphur  dioxid  does  not  tarnish  metals,  does  not  rot  fabrics,  and 
does  not  bleach  pigments.  Fumigation  with  SO,  may,  therefore,  be  done 
with  little  damage  to  property  on  dry  days.  Metal  work,  fabrics,  and 
pigments  that  cannot  be  removed  from  the  room  may  be  protected  from 
the  sulphur  fumes  by  simple  mechanical  devices. 

Sulphur  dioxid  may  be  produced  either  by  burning  sulphur  or  by 
liberating  liquefied  sulphur  dioxid.  The  methods  of  generating  the 
gas  will  be  found  on  page  997.  One  pound  of  sulphur  burned  for 
each  thousand  cubic  feet  of  air  space  or  two  pounds  of  liquefied  sul- 
phur dioxid  and  an  exposure  of  two  hours  is  sufficient  to  kill  mos- 
quitoes, flies,  and  other  insects  in  a  small  tight  space.  Three  to  four 
hours  are  ample  for  rats  and  mice.  If  the  space  is  large  or  leaky  the 
amount  of  gas  should  be  increased  and  the  time  of  exposure  prolonged. 
Sulphur  dioxid  has  surprising  power  of  penetration  through  clothing 
and  fabrics.  In  very  dilute  proportions  it  will  in  one  hour's  time  kill 
mosquitoes  even  when  hidden  in  eight  layers  of  toweling.  It  has  ab- 
solutely no  power  of  penetration  when  used  as  a  germicide.  This  sub- 
stance, which  has  so  long  been  disparaged  as  a  disinfectant  because  it 
fails  to  kill  spores  and  many  spore-free  bacteria  under  certain  condi- 


INSECTICIDES  191 

tions,  must  now  be  considered  as  holding  first  rank  as  an  insecticide. 
For  consideration  of  sulphur  dioxid  as  a  germicide  see  page  997. 

Flowers  of  Sulphur. — Sulphur  in  its  dry,  powdered  state  is  use- 
ful against  a  number  of  parasites.  In  this  form,  however,  it  has  little 
use  as  an  insecticide  in  preventive  medicine,  not  being  efficacious  against 
bedbugs,  ants,  roaches,  or  fleas. 

It  may  be  applied  in  several  ways,  the  simplest  of  which  is  to 
sprinkle  the  dry  sulphur  about  the  places  where  insects  are  found. 
Flowers  of  sulphur  may  also  be  combined  advantageously  with  other 
insecticides,  such  as  kerosene  emulsion,  resin  wash,  or  soap  Avash.  It 
should  first  be  mixed  into  a  paste  and  then  added  to  the  spray  tank 
in  the  proportion  of  about  1  or  2  pounds  to  50  gallons.  It  is  particu- 
larly efficacious  for  the  destruction  of  the  mites  and  rust  of  plants 
and  fruits. 

Sulphur  in  the  form  of  an  ointment  is  particularly  obnoxious  to 
ticks  and  other  ectoparasites.  The  itch-mite  (Sarcojites  scahiei)  is 
very  susceptible  to  the  flowers  of  sulphur,  which  is,  therefore,  one  of 
the  ingredients  of  almost  all  ointments  used  in  this  skin  affection. 

Sulphur  dips  are  used  to  destroy  the  mites  on  domestic  animals. 
These  dips  ordinarily  contain  1  part  of  lime  to  3  parts  of  sulphur  or 
tobacco.  It  is  common  experience  that,  while  these  sulphur  dips  may 
be  depended  upon  to  destroy  the  mites,  they  do  not  destroy  the  eggs, 
hence  the  treatment  should  be  repeated  in  about  10  days,  which  per- 
mits time  for  the  eggs  to  hatch  and  develop  into  adults. 

Formaldehyde. — Formaldehyde,  while  holding  the  front  rank  as  a 
germicide,  is  a  feeble  insecticide.  The  gas  seems  to  have  no  effect 
whatever  upon  roaches,  bedbugs,  and  insects  of  this  class  even  after 
prolonged  exposure  to  very  high  percentages.  As  a  differential  poison 
formaldehyde  gas  is  a  very  remarkable  substance.  It  destroys  bacteria 
almost  instantly,  but,  while  it  is  irritating  to  the  higher  forms  of  ani- 
mal life,  it  is  not  very  toxic.  I  have  repeatedly  found  that  roaches  and 
other  insects  with  strong  chitinous  protection  seem  unharmed  after 
12  hours'  exposure  to  formaldehyde  gas  in  very  strong  atmospheres 
of  the  gas,  in  air-tight  disinfecting  chambers.  Mosquitoes  may  live  in 
a  weak  atmosphere  of  the  gas  over  night.  It  will  kill  them,  however,  if 
the  gas  is  brought  in  direct  contact  with  them  in  the  strength  and  time 
prescribed  for  bacterial  disinfection. 

When  a  weak  insecticidal  gas  is  used  it  is  much  more  difficult  to 
obtain  direct  contact  between  the  gas  and  the  insects  than  between 
the  gas  and  germs,  because  the  sense  of  self-preservation  aids  the  for- 
mer in  escaping  from  the  effects  of  the  irritating  substance.  Mos- 
quitoes and  other  insects  hide  in  the  folds  of  towels,  bed  clothing, 
hangings,  fabrics,  and  out-of-the-way  places  where  the  formaldehyde 
gas  does  not  permeate  in  sufficient  strength  to  kill  them.     The  gas  is 


192  INSECT-BORNE    DISEASES 

polymerized  and  deposited  as  paraforni  on  the  surface  of  fabrics  which 
prevent  its  penetration,  and  hirge  quantities  arc  lost  by  being  absorbed 
by  the  organic  matter  of  woolen  fabrics.  Mosquitoes  have  a  lively  in- 
stinct in  finding  cracks  or  chinks  where  fresh  air  may  enter  a  room 
or  other  places  where  the  gas  is  so  diluted  that  tliey  escape  destruc- 
tion. Therefore,  formaldeliyde  gas,  as  well  as  other  culicidcs,  cannot 
be  trusted  to  kill  all  the  mosquitoes  in  a  room  which  cannot  be  tightly 
sealed.  On  account  of  its  feeble  action,  formaldehyde  is  not  recom- 
mended as  reliable. 

For  the  l)est  methods  of  evolving  formaldehyde  gas,  the  quantities 
to  be  used,  and  other  details  of  the  process,  see  page  993. 

Formaldehyde  gas  in  watery  solution,  known  as  formalin,  is  use- 
ful for  the  destruction  of  flies.  Small  quantities  of  dilute  formalin 
(4  per  cent.)  placed  in  saucers  about  the  room  attract  flies.  They 
drink  the  fluid,  wliich  soon  kills  them. 

Pyrethrum. — Pyrethrum  is  a  popular  and  much  used  insecticide  be- 
cause it  is  comparatively  cheap  and  non-poisonous  to  man  and  the 
higher  animals.  It  is  also  non-corrosive,  but  unfortunately  it  is  not 
very  powerful  for  the  destruction  of  roaches,  ants,  bedbugs,  flies,  fleas, 
mosquitoes,  etc.     It  has  no  germicidal  action. 

Pyrethrum,  also  sold  under  the  names  of  Buhach  or  Persian  insect 
powder,  or  simply  "insect  powder,"  is  the  flowers  of  the  Chrysanthemum 
roseum  and  the  Chrysanthemum  carneum,  both  hardy  perennials  and 
resembling  camomile  in  appearance.  According  to  Kalbrunner,  4  grains 
of  the  pure  powder  sprinkled  on  a  fly  in  a  vial  should  stupefy  it  in 
one  minute,  and  kill  it  in  2  or  3  minutes.  .  It  acts  on  insects  exter- 
nally through  their  breathing  pores.  When  brought  in  direct  con- 
tact with  them  it  is  fatal  to  many  forms  of  biting  and  sucking  in- 
sects, such  as  roaches,  flies,  and  ants.  It  may  be  used  either  as  a  dry 
powder  or  by  its  l)urning  fumes.  As  a  dry  powder  it  may  be  used 
pure  or  mixed  with  flour,  in  which  form  it  should  be  puffed  about  the 
room,  especially  into  cracks. 

When  pyrethrum  powder  is  ignited  it  smolders,  giving  off  fumes 
which  stun,  but  do  not  always  kill,  mosquitoes.^  It  is  not,  therefore, 
a  dependable  insecticide.  This  uncertainty  and  the  price  of  pyrethrum 
restrict  its  field  of  usefulness. 

Pyrethrum  fumes  do  not  corrode  metals  or  act  injuriously  upon 
fabrics  and  pigments.  However,  a  slight  brown  deposit  is  occasionally 
left  on  exposed  surfaces  which  may  stain  linen  a  yellowish  color.  This 
deposit  or  stain  is  readily  washed  out,  or  soon  fades. 

Pyrethrum  powder  has  been  used  very  much  in  those  cases  where 
sulphur  is  prohibited  on  account  of  the  danger  of  damage  to  paintings, 

*  Tobacco  smoke  and  other  substances  which  produce  dense  fumes,  particu- 
larly those  containing  pyroligneous  products,  will  kill  mosquitoes. 


INSECTICIDES  193 

fabrics,  tapestries,  metal  work,  musical  instruments,  upholstered  furni- 
ture^ and  the  like.  It  is  used  in  the  proportion  of  2  pounds  per  1,000 
cubic  feet  of  air  space,  the  exposure  being  for  not  less  than  4  hours. 
As  its  insecticidal  effect  is  uncertain,  it  is  necessary  carefully  to  sweep 
up  and  burn  all  the  mosquitoes  that  have  been  stunned  and  are  ap- 
parently dead  after  the  fumigation.  Most  of  these  mosquitoes  will  be 
found  on  the  window  sill  or  on  the  floor  close  to  the  window,  where 
they  are  attracted  by  the  light  in  their  efforts  to  find  an  exit  to  es- 
cape the  fumes.  Advantage  should  be  taken  of  this  tendency  of  the 
mosquito  to  seek  the  light  by  darkening  all  but  one  window. 

Sheets  of  paper  containing  some  sticky  preparation  may  be  placed 
upon  the  floor  and  upon  the  window  sill  in  order  to  catch  the  mos- 
quitoes. A  satisfactory  adhesive  preparation  may  be  made  by  dissolv- 
ing, by  the  aid  of  heat,  65  parts  of  colophony  resin  in  35  parts  of 
castor  oil.     This  simplifies  the  collection  and  disposal  of  the  insects. 

Pyrethrum  powder  should  be  distributed  in  pots  or  pans  and  set  on 
fire  with  a  little  alcohol,  which  should  first  be  sprinkled  over  it.  The 
quantity  apportioned  to  any  one  pot  or  pan  should  not  exceed  1% 
inches  in  depth,  if  the  exposure  is  to  be  for  4  hours.  The  pots  and 
pans  should  be  set  on  bricks  to  prevent  scorching  the  floor. 

Much  of  the  pyrethrum  upon  the  market  is  impure,  which  further 
weakens  what  is  a  feeble  insecticide  at  best. 

Phenol-camphor  (Mini's  CuUcide). — Camphophenique  or  phenol- 
camphor  is  prepared  by  rubbing  up  equal  weights  of  phenol  crystals  and 
camphor.  It  may  be  more  conveniently  prepared  by  first  liquefying  the 
phenol  by  gentle  heat  and  then  pouring  it  over  the  camphor.  The  cam- 
phor and  phenol  combine  to  form  a  new  chemical  compound,  which  re- 
mains fluid  at  ordinary  temperatures.  This  preparation  was  first  used 
on  a  considerable  scale  during  the  yellow  fever  epidemic  in  New  Or- 
leans toward  the  close  of  1905  at  the  suggestion  of  Mr.  Mim,  the  city 
chemist.  At  this  time  I  took  the  opportunity  of  making  a  number  of 
tests  with  Dr.  Metz  concerning  the  culicidal  value  of  this  substance. 
The  effect  of  the  fumes  on  mosquitoes  was  later  studied  by  Berry  and 
Francis.  When  phenol-camphor  is  moderately  heated  it  gives  off  dense 
fumes,  which  rise  rapidly  and  diffuse  slowly,  and  after  30  to  60  min- 
utes, depending  upon  the  amount  employed  and  the  temperature  of  the 
air,  the  fumes  condense  and  are  deposited  as  a  slight  moisture  on  all 
exposed  surfaces.  As  a  culicide  phenol-camphor  may  be  compared  to 
pyrethrum;  the  fumes  stun  the  mosquitoes,  but  do  not  invariably  kill 
them.  The  fumes  are  somewhat  irritating  to  the  mucous  membranes, 
especially  the  eyes;  they  may  cause  dizziness,  headache,  cloudy  urine, 
and  other  mild  symptoms  of  phenol  poisoning  in  susceptible  individuals 
much  exposed  to  their  inhalation.  The  fumes  of  phenol-camphor  do 
not  tarnish  metals,   rot   fabrics,  or  bleach  pigments.     They,  however. 


194  INSECT-BORNE    DISEASES 

have  the  disagreeable  property  of  softening  the  varnish  of  surfaces  on 
which  tliey  condense.  On  account  of  its  slight  power  of  diffusion,  rela- 
tively high  cost,  and  uncertainty  of  action,  it  cannot  take  the  place  of 
sulphur  except  in  the  parlor,  pilot  house,  and  other  compartments  where 
sulphur  is  prohibited  on  account  of  the  damage  it  produces.  Compared 
with  pyrcthrum,  phenol-camphor  is  less  expensive,  more  certain,  and 
not  so  objectionable  to  the  housekeeper.  Its  use  involves  a  little  more 
care  and  intelligence  than  that  required  for  the  simple  burning  of  py- 
rethrum.  If  it  is  overheated  it  will  take  fire,  and  no  culicidal  action 
is  produced.  Goldberger  concludes  that,  for  use  on  a  large  scale,  as 
in  times  of  epidemics,  in  the  hands  of  trained  fumigators,  phenol-cam- 
phor is,  on  the  whole,  to  be  preferred  to  pyrethrum,  being  more  easily 
transportable  on  account  of  the  small  bulk  required,  and  because  the 
fumes  condense  quickly  and  the  room  may,  if  desired,  be  entered  in  an 
hour  and  the  apparatus  removed,  thus  making  it  possible  to  fumigate 
a  larger  number  of  rooms  in  a  given  time  with  less  labor  than  in  the 
case  of  either  sulphur  or  pyrethrum. 

Phenol-camphor  is  used  in  the  proportion  of  4  ounces  to  every  thou- 
sand cubic  feet  of  air  space,  and  with  an  exposure  of  2  hours.  In  this 
proportion  and  time  the  film  of  condensation  is  slight  and  is  rapidly  dis- 
sipated after  the  doors  and  windows  are  opened.  The  preparation  of 
the  room  is  the  same  as  that  described  above.  The  phenol-camphor  ap- 
portioned to  the  room  to  be  fumigated  should  be  distributed  in  agate- 
ware basins,  not  more  than  8  to  10  ounces  to  any  one  basin.  Each 
basin  is  set  over  an  alcohol  lamp  at  such  an  elevation  and  in  such  a 
manner  as  will  permit  a  rapid  evolution  of  the  fumes.  Care  must  be 
taken  not  to  heat  the  basin  so  quickly  as  to  cause  the  liquid  to  become 
overheated  and  take  fire.  This  point  must  first  be  determined  experi- 
mentally for  each  type  of  lamp  used.  One  of  the  small  brass  alcohol 
vapor  lamps  to  be  found  on  the  market  serves  excellently.  As  a  safe- 
guard against  accidents  the  lamp  should  stand  in  a  pan  containing  about 
one-half  inch  of  water.  The  basin  containing  the  phenol-camphor  may 
be  set  upon  a  section  of  galvanized  iron  stove-pipe,  at  one  end  of  which 
sectors  are  cut  out  so  as  to  form  legs  of  a  length  equal  to  the  height 
of  the  lamp;  just  below  the  upper  margin  of  the  pipe  a  series  of  holes 
are  punched  so  as  to  provide  for  draft.  The  stove-pipe  should  be  of 
such  a  length  as  to  support  the  basin  containing  the  phenol-camphor 
about  10  inches  above  the  flame.  This  ingenious  and  simple  device, 
suggested  by  Berry  and  Francis,  acts  as  a  chimney,  protects  the  flame, 
is  relatively  cheap,  and  has  proven  satisfactory. 

Hydrocyanic  Acid  Gas. — Hydroc^^anic  acid  gas  is  extremely  poison- 
ous to  all  forms  of  life.  It  kills  roaches,  bedbugs,  mosquitoes,  fleas, 
flies,  rats,  mice,  and  other  vermin  with  great  certainty  and  very  quickly. 
It  is  much  less  poisonous  to  the  higher  forms  of  vegetable  life,  al- 


IIS^SECTICIDES  195 

though  it  has  a  certain  amount  of  germicidal  power.  Hj'drocyanic  acid 
gas  is  much  used  in  greenhouses  for  the  destruction  of  insect  pests  and 
for  scale  and  other  parasites  of  fruit  trees.  The  gas  has  a  distinct 
place  in  the  disinfection  of  granaries,  stahles,  ships,  barns,  outhouses, 
railroad  cars,  and  other  uninhabited  structures  infested  with  "vermin. 
It  is  also  extensively  used  in  flouring  mills  against  weevils,  in  rail- 
road cars  against  bedbugs,  and  in  tobacco  warehouses  against  insects  in 
general.  It  should  be  used  in  the  household  onlv  with  the  greatest 
precaution,  as  the  least  carelessness  with  it  would  jDrobably  mean  the 
loss  of  human  life.  It  has  the  marked  advantage  that  it  does  not  harm 
metals,  fabrics,  or  j)igments,  and  may  be  used  in  the  most  expensive 
drawing  rooms. 

Hydrocyanic  acid  gas  is  lighter  than  air  and  has  an  agreeable 
aromatic  odor  quite  familiar  in  the  flavoring  essence  of  bitter  almonds. 
The  best  method  of  generating  it  for  the  purj^ose  of  fumigation  is  by 
the  action  of  dilute  sulphuric  acid  upon  potassium  cyanid,  in  the  fol- 
lowing proportions : 

Potassium  cyanid   1.0     part 

Sulphuric   acid    1.5     parts 

Water    2.25  parts 

The  first  step  is  to  dilute  the  acid,  which  is  done  by  adding  the 
acid  to  water  in  a  vitrified  clay  jar  or  receptacle  capable  of  withstand- 
ing the  heat.  The  whole  amount  of  cyanid  must  be  put  into  the  acid  at 
once.  As  the  evolution  of  the  gas  is  very  rapid,  the  operator  should 
be  ready  to  leave  the  spot  immediately.  As  pointed  out  by  Fulton,  it 
is  convenient  to  tie  the  cyanid  up  in  a  bag  made  of  cheese  cloth  or  tissue 
paper,  which  is  lowered  into  the  acid  by  a  cord  passing  outside  of  the 
room.  The  amount  of  gas  used  for  plant  fumigation,  expressed  in  terms 
of  cyanid,  is  about  1  ounce  per  100  cubic  feet;  about  the  same  quantity 
is  effective  as  an  insecticide  in  rooms  and  confined  spaces.  Hydrocyanic 
acid  gas  is  quite  as  effective  as  sulphur  dioxid,  is  not  destructive,  is 
reasonably  cheap,  and  is  certain  in  its  action,  but  its  poisonous  nature 
is  such  a  serious  drawback  that  it  has  a  limited  place  as  an  insecticide 
in  the  disinfection  of  houses. 

BisulpMd  of  Carbon. — Bisulphid  of  carbon  (CSo)  is  a  very  efficient 
insecticide,  but  a  dangerous  one,  on  account  of  its  inflammable  and  ex- 
plosive nature.  It  quickly  kills  mosquitoes,  roaches,  flies,  ants,  and 
insects  of  all  kinds,  as  well  as  rats,  mice,  and  squirrels.  Wlien  pure  it 
is  a  mobile,  colorless  liquid  with  an  agreeable  ethereal  odor,  but  often 
it  has  a  more  or  less  fetid  odor  from  the  presence  of  other  volatile 
compounds.  The  liquid  must  be  kept  in  well-stoppered  bottles  in  a  cool 
place,  and  away  from  the  light  and  fire.     It  evaporates  rapidly  at  ordi- 


19G  INSECT-BOENE    DISEASES 

nary  temperatures,  so  that  in  using  this  substance  in  a  confined  space  it 
is  sufficient  to  pour  it  into  open  pans.  Carbon  bisulphid  is  very  in- 
flammable— more  so  tlian  ether — and  burns  witli  a  pale  blue  flame 
yielding  sulphur  dioxid  and  carbon  dioxid  or  monoxid.  In  its  use 
every  precaution  must  be  taken  to  see  that  there  is  no  fire,  lighted 
cigar,  etc.,  in  or  about  the  field  of  operation.  On  account  of  its  poison- 
ous nature,  if  used  in  a  house  or  other  inhabited  structure,  the  rooms 
must  be  thoroughly  aired  after  its  use. 

According  to  Hinds,  shallow  tin  pans  or  plates  make  good  evaporat- 
ing dishes  for  carbon  bisulphid.  The  larger  the  evaporating  area  the 
better.  About  one  square  foot  of  evaporating  surface  is  used  to  every 
25  square  feet  of  floor  area,  and  one-half  to  one  pound  of  the  liquid 
carbon  bisulphid  is  used  for  each  square  foot  of  evaporating  surface. 
These  figures,  of  course,  are  only  suggestive  and  approximate.  The 
pans  should  be  placed  as  high  in  the  room  as  possible,  since  the  vapor 
is  so  heavy  that  it  settles  rapidly.  Care  should  be  taken  when  placing 
the  pans  to  see  that  they  are  nearly  level  so  as  to  hold  the  liquid,  though 
ordinarily  no  particular  harm  will  be  done  if  some  of  it  is  spilled.  It 
should  not  be  found  necessary  to  lose  time  in  adjusting  such  things  after 
the  operation  has  begun. 

Carbon  bisulphid  is  being  extensively  used  in  California  in  the 
plague  campaign.  A  piece  of  waste  the  size  of  an  orange  is  saturated 
with  the  liquid  and  the  wet  ball  placed  in  the  mouth  of  the  squirrel 
hole.  Wet  clay  is  then  stamped  into  the  warren  so  that  the  gas  which 
is  generating  may  have  no  opportunity  to  escape.  All  of  the  holes  of 
the  burrows  are  treated  in  this  way.  In  some  instances  the  ball  is 
placed  deeply  in  the  hole  and  then  ignited.  This  is  more  or  less  dan- 
gerous, as  an  explosion  occurs,  and,  while  the  gas  is  thus  disseminated 
to  all  parts  of  the  warren,  its  action  only  covers  a  limited  period  of 
time,  and  is,  therefore,  not  as  certain  as  simply  allowing  the  carbon 
bisulphid  to  evaporate.  It  not  only  kills  the  squirrels,  but  also  the 
fleas  on  them.  Carbon  tetrachlorid  may  be  used  in  place  of  carbon 
bisulphid.    It  is  just  as  poisonous  but  neither  inflammable  nor  explosive. 

Petroleum. — Petroleum,  kerosene,  or  coal  oil  is  a  very  valuable  in- 
secticide, but  of  limited  application,  as  it  must  be  used  in  liquid  form. 
As  a  remedy  for  mosquitoes  it  is  applied  in  the  proportion  of  al)0ut  1 
ounce  to  15  square  feet  of  water  surface.  It  should  form  a  uniform 
film  over  the  surface,  and  will  then  destroy  the  larva3  and  pupae  of 
the  mosquito  and  the  adult  females  coming  to  the  water  to  lay  their 
eggs.  The  oil  must  be  renewed  every  week  or  two,  depending  upon 
the  temperature  and  other  conditions.  A  light  grade  of  fuel  oil  is 
best  for  this  purpose  (see  page  203). 

Petroleum  is  also  useful  against  roaches,  bedbugs,  fleas,  lice,  and 
other  insect  vermin  when  used  by  direct  application  or  by  spraying. 


INSECTICIDES  197 

either  in  the  form  of  the  pure  oil  or  as  an  emulsion.  Petroleum  is 
very  efficient  against  fleas.  Frequent  application  to  the  floor  or  other 
places  will  keep  away  ants^  and  by  direct  application  to  the  breeding, 
feeding,  and  traveling  places  it  is  a  useful  remedy  against  household 
vermin  in  general.  By  direct  application  to  the  head  or  other  parts 
affected,  coal  oil  is  the  cheapest  and  most  effective  remedy  for  lice. 

Emulsion  of  crude  petroleum  for.  application  to  the  skin  of  animals 
or  to  trees,  or  other  plants,  or  for  general  insecticidal  purposes  is  made 
from  the  formula  of  T.  M.  Price: 

Crude   petroleum    2  gallons 

Water    %  gallon 

Hard  soap %  pound 

Dissolve  the  soap  in  the  water  with  the  aid  of  heat.  To  this  add 
the  crude  petroleum;  mix  with  a  spray  pump  or  shake  vigorously  and 
dilute  with  the  desired  amount  of  water.  The  emulsion  of  crude  petro- 
leum made  according  to  this  modified  formula  remains  fluid,  and  can 
be  easily  poured.  It  will  stand  indefinitely  without  any  tendency 
toward  separation  of  the  oil  and  water,  and  can  be  diluted  in  any  pro- 
portion with  cold  soft  water. 

Arsenic. — The  arsenical  compounds,  according  to  Marlatt,^  have  sup- 
planted practically  all  other  substances  as  a  food  poison  for  biting  in- 
sects. The  two  arsenicals  in  most  common  use  obtainable  everywhere 
are  arsenate  of  lead  and  Paris  green.  Scheele's  green  and  arsenite  of 
copper  are  less  known  and  less  easily  obtainable,  but  in  some  respects 
are  better  than  Paris  green.  The  use  of  powdered  white  arsenic  is  not 
recommended  on  account  of  its  corrosive  action,  as  well  as  the  fact  that 
it  is  ai)t  to  be  mistaken  for  harmless  substances. 

The  arsenical  poisons  may  be  applied  in  one  of  three  ways:  (1)  in 
suspension,  as  poisoned  waters,  mainly  in  the  form  of  sprays;  (2)  as  a 
dry  powder  blown  or  dusted  about  the  infested  areas;  or  (3)  as 
poisoned  bait. 

It  must  be  remembered  that  the  arsenicals  are  very  jDoisonous,  and 
should  be  so  labeled,  and  care  taken  to  prevent  accidents. 

Paris  geeen  is  a  definite  chemical  compound  of  arsenic,  copper, 
and  acetic  acid  (acetoarsenite  of  copper),  and  should  have  a  nearly 
uniform  composition.  It  is  rather  a  coarse  powder,  or,  more  properly 
speaking,  crystal,  and  settles  rapidly  in  water,  which  is  its  greatest  fault 
so  far  as  the  making  of  suspensions  of  this  substance  is  concerned.  The 
cost  of  Paris  green  is  about  20  cents  per  pound. 

ScHEELE^s  GREEN  is  similar  to  Paris  green  in  color  and  differs  from 
it  only  in  lacking  acetic  acid;  in  other  words,  it  is  simply  arsenite  of 

^Farmers'  Bulletin  No.  19,  U.  S.  Dept.  of  Agriculture. 
15 


198  INSECT-BOEXE    DISEASES 

copper.  It  is  a  finer  powder  than  Paris  green,  and,  tlierefore,  is  more 
easily  kept  in  suspension,  and  has  the  additional  advantage  of  costing 
only  half  as  much  per  pound. 

Arsexite  of  lead  is  prepared  by  combining,  approxiinately,  3  parts 
of  the  arsenite  of  soda  with  7  parts  of  the  acetate  of  lead  (white  sugar 
of  lead)  in  water.  These  substances,  when  pulverized,  unite  readily 
and  form  a  white  precipitate,  which  is  more  easily  kept  suspended  in 
water  than  any  of  the  other  arsenical  poisons.  Bought  at  wholesale,  the 
acetate  of  lead  costs  about  7I/2  cents  a  pound,  and  the  arsenite  of  soda 
costs  about  7  cents  a  pound.  Its  use  is  advised  where  excessive  strengths 
are  not  desirable,  and  upon  delicate  plants,  wliere  otherwise  scalding  is 
likely  to  result. 

An  average  of  one  pound  of  either  Paris  green  or  Scheele's  green,  or 
London  purple  to  150  gallons  of  water  is  a  good  strength  for  general 
purposes  in  using  the  wet  method.  The  powder  should  first  be  made 
up  into  a  thin  paste  in  a  small  quantity  of  water,  and,  if  the  suspen- 
sion is  to  be  used  upon  plants,  vegetables,  or  about  foliage,  an  equal 
amount  of  quicklime  should  be  added  to  take  up  the  free  arsenic  and 
remove  or  lessen  the  danger  of  scalding. 

For  the  distribution  of  dry  poison  the  arsenicals  are  diluted  with 
10  parts  of  flour,  lime,  or  dry  gypsum. 

The  following  mixtures  are  used  in  the  form  of  sprays,  to  destroy 
insects  and  fungi  upon  plants.^  The  arsenate  of  lead  mixture  has  been 
much  used  in  Massachusetts  with  success  against  the  gipsy  moth  and 
other  destructive  insects  upon  trees  and  plants.  These  mixtures  are 
equally  useful  as  insecticides  wherever  sprays  or  local  applications  are 
practicable. 

AKSENATE    OF    LEAD 

Arsenate  of  soda   (5  per  cent,  strength),  4  ounces. 
Acetate  of  lead,  11  ounces. 
Water,  100  gallons. 

Put  the  arsenate  of  soda  in  2  quarts  of  water  in  a  wooden  pail,  and 
the  acetate  of  lead  in  four  quarts  of  w^ater  in  another  wooden  pail. 
When  both  are  dissolved,  mix  with  the  rest  of  the  water.  Warm  water 
in  the  pails  will  hasten  the  process.  For  the  elm-leaf  beetle  use  10 
instead  of  100  gallons  of  water. 

A  number  of  ready-made  arsenates  of  lead  are  now  on  the  market, 
and,  except  when  very  large  amounts  are  needed,  it  will  prol)ably  prove 
cheaper  to  buy  the  prepared  material  than  to  make  it.  With  this 
ready-made  material  take  3  pounds  to  50  gallons  of  water  for  codling 
moth,  and  5  pounds  to  50  gallons  to  the  elm-leaf  beetle  and  on  potatoes. 

'From  BuUetin  No.  123,  April,  1908,  of  the  Massachusetts  Agricultural 
Experiment  Station  by  Stone  and  Ferald. 


INSECTICIDES  199 

AESENITE    OF    LIME 
White  arsenic,  2  pounds. 
Sal-soda,  8  pounds. 
Water,  2  gallons. 

Boil  till  the  arsenic  all  dissolves — about  45  minutes.  Make  up  the 
water  lost  by  boiling  and  place  in  an  earthen  dish.  For  use  take  one 
pint  of  this  stock,  2  pounds  freshly  slaked  lime,  and  45  gallons  water, 
and  spray. 

KEEOSENE    EMULSION 

Hard  soap,  shaved  fine,  %  pound. 
Water,  1  gallon. 
Kerosene,  2  gallons. 

Dissolve  the  soap  in  the  water,  which  should  be  boiling;  remove 
from  the  fire  and  pour  it  into  the  kerosene  while  hot.  Churn  this  with 
a  spray  pumj^  till  it  changes  to  a  creamy,  then  to  a  soft,  butter-like, 
mass.  Keep  this  as  a  stock,  using  one  part  in  nine  of  water  for  soft- 
bodied  insects,  such  as  plant  lice,  or  stronger  in  certain  cases. 

EESIN-LIME    MIXTURE 
Pulverized  resin,  5  pounds. 
Concentrated  lye,  1  pound. 
Fish  or  other  animal  oil,  1  j)int. 
Water,  5  gallons. 

Place  the  oil,  resin  and  one  gallon  of  hot  water  in  an  iron  kettle 
and  heat  till  the  resin  softens;  then  add  the  lye  and  stir  thoroughly; 
now  add  4  gallons  of  hot  water  and  boil  till  a  little  will  mix  with  cold 
water  and  give  a  clear,  amber-colored  liquid;  add  water  to  make  up  5 
gallons.    Keep  this  as  a  stock  solution.     For  use  take: 

Stock  solution,  1  gallon. 
Water,  16  gallons. 
Milk  of  lime,  3  gallons. 
Paris  green,  ^  pound. 

BOEDEAUX    MIXTUEE 
Copper  sulphate   (blue  vitriol),  4  pounds. 
Lime  (unslaked),  4  pounds. 
Water,  25  to  50  gallons. 

Dissolve  the  copper  in  hot  or  cold  water,  using  a  wood  or  earthen 
vessel.     Slake  the  lime  in  a  tub,  adding  the  water  cautiously  and  only 


200  INSECT-BOKNE    DISEASES 

in  sufficient  amount  to  insure  tliorougli  slaking.  After  thoroughly 
slaking,  more  water  can  be  added  and  stirred  in  until  it  has  the  con- 
sistency of  thick  cream.  When  l)(ith  are  cold,  dilute  each  to  the  re- 
quired strength  and  pour  both  together  in  a  separate  receptacle  and 
thoroughly  mix.  Before  using,  strain  through  a  fine  mesh  sieve  or  a 
gunny  cloth;  the  mixture  is  then  ready  for  use. 

If  the  amount  of  lime  in  the  Bordeaux  mixture  is  insufficient  there 
is  danger  of  Imrning  tender  foliage.  In  order  to  obviate  this,  the  mix- 
ture can  be  tested  witli  a  knife  blade  or  with  ferrocyanid  of  potassium 
(1  oz.  to  5  or  G  oz.  of  water).  If  the  amount  of  the  lime  is  insufficient, 
copper  will  be  deposited  on  the  knife  blade,  while  a  deep  brownish-red 
color  will  be  imparted  to  the  mixture  when  ferrocyanid  of  potassium 
is  added.  Lime  should  be  added  until  neither  reaction  occurs.  A  slight 
excess  of  lime,  however,  is  desirable,  and  it  is  seldom  one  has  to  apply 
these  tests. 

The  Bordeaux  mixture  is  a  good  fungicide,  but  is  less  useful  as  an 
insecticide. 

MOSQUITOES 

Mosquitoes  differ  markedly  in  their  habits.  Some  species  may  be 
classed  as  domestic  aninuils  l)ecause  they  are  commonly  or  almost  ex- 
clusively found  in  or  close  to  human  hal)itations.  This  is  notably  the 
case  with  Stegomyia  calopiis,  the  yellow  fever  moscpiito;  Culcx  pungens, 
the  intermediary  for  Filarta  hancroftli  (filariasis)  ;  and  Culex  faligans, 
the  carrier  of  dengue  fever.  The  sylvan -or  wild  mosquitoes,  of  which 
the  Culex  sollicitans,  the  common  salt  marsh  mosquito  of  our  Atlantic 
coast,  is  a  well-known  example,  are  seldom  met  with  in  human  habita- 
tions. A  third  or  semi-domestic  class  may  be  encountered  either  in 
or  near  houses,  or  in  fields  or  swamps.  This  class  includes  the  malarial 
mosquitoes  belonging  to  the  genus  Anopheles. 

The  adult  mosquito  may  be  carried  to  considerable  distances  by 
winds;  but  of  its  OM-n  volition  it  does  not  ordinarily  travel  outside  of 
a  radius  of  half  a  mile  from  its  Ijreeding  phice.  Most  species  do  not 
fly  nearly  so  far.  This  moans  that  the  destruction  of  all  lireeding  places 
within  a  comi)aratively  small  radius  of  a  habitation  will  rid  it  of  all 
but  those  mosquitoes  which  are  blown  in  by  the  winds  from  more  or 
less  distant  marshes,  or  which  are  brought  in  the  vessels  and  vehicles 
of  trade  and  travel. 

life  History  and  Habits. — Mosquitoes  pass  through  four  stages: 
(1)  the  egg  or  eml)ryo,  (■.^)  the  larva,  (3)  the  pupa,  and  (4)  the  imago 
or  adult  winged  insect.  The  Qg^,  larval,  and  ])upal  stages  are  aquatic. 
Mosquitoes  never  breed  in  damp  grass,  weeds,  or  bushes,  as  is  popularly 
supposed,  but  the  winged   insects  frequently   rest  and  hide  in  vegeta- 


MOSQUITOES  201 

tion.  The  different  species  of  mosquitoes  not  only  differ  markedly  in 
their  habits,  but  differ  considerably  in  the  character  of  their  breeding 
places.  The  domestic  species,  such  as  the  yellow  fever  mosquito  and 
Culex  pun  gens,  may  be  found  breeding  in  any  collection  of  water 
in  or  about  houses.  Thus,  they  have  been  found  in  discarded  tin  cans, 
bottles,  and  broken  crockery  on  the  garbage  heap ;  in  buckets,  tubs,  bar- 
rels, cisterns,  and  wells ;  in  baptismal  fonts ;  in  flower  pots  and  sagging 
roof  gutters;  in  street  and  roadside  puddles,  gutters,  and  ditches;  in 
cesspools  and  sewers. 

The  semi-domestic  mosquitoes,  to  which  the  malarial-bearing  insects 
belong,  may  occasionally  be  found  breeding  in  tin  cans,  barrels,  hoof 
prints,  post  holes,  and  hollows  in  trees  or  tree  stumps,  but  they  usually 
prefer  grass-bordered  pools,  slowly  flowing  ditches,  the  margins  of  lakes 
and  streams,  even  such  as  are  stocked  with  fish,  provided  the  margins 
are  shallow  or  are  more  or  less  choked  Avith  reeds  and  water  plants  so 
that  the  fish  cannot  reach  them.  The  sylvan  or  wild  mosquitoes  select 
breeding  places  of  mu£h  the  same  character  as  do  the  semi-domestic 
species,  with  which  they  are  not  infrequently  found  associated,  except 
that  such  breeding  places  are  more  or  less  remote  from  human  habita- 
tions, in  woods,  swamps,  and  fresh  or  salt  (brackish)  coastal  marshes. 

Male  mosquitoes  are  vegetarians.  The  females  of  many  spe- 
cies have  developed  a  taste  for  blood,  and,  indeed,  blood  has  become 
indispensable  to  nearly  all  for  the  full  development  of  their  eggs.  This 
is  the  case  with  Stegomijia  calopus.  Eemembering  how  all-important 
the  generative  instinct  is,  we  can  now  well  understand  why  the  yellow 
fever  mosquito,  for  example,  will,  when  disturbed,  return  again  and 
again  in  an  endeavor  to  obtain  her  fill  of  this  life-giving  iluid. 

The  mosquito  lays  her  eggs  upon  the  surface  of  the  water,  and 
these,  depending  upon  the  species,  either  fioat  separately  on  their  sides 
(Stegomyia  calopus  and  Anopheles),  or  adhere  together  in  irregular, 
raft-like  masses  (Culex).  In  a  day  or  two,  under  ordinary  conditions, 
the  eggs  hatch  out  into  larvse  or  "wiggle-tails."  Although  the  larva 
is  an  aquatic  animal,  it  is  a  true  air-breather.  The  larva  of  Anopheles 
ordinarily  rests  and  feeds  at  the  surface,  where  it  lies  in  an  almost 
horizontal  position,  its  tail  and  dorsal  bristles  touching  the  surface 
film,  while  it  breathes  through  a  breathing  siphon,  which  is  very  short 
and  insignificant  in  appearance. 

The  larvse  of  the  other  species  move  about  more  or  less,  actively 
searching  for  food,  but  at  intervals  of  a  minute  or  two  they  may  be 
seen  to  come  to  the  surface  for  air,  where  they  hang,  head  down,  at- 
tached by  their  more  or  less  prominent  conical  breathing  tubes  to  the 
surface  film.  The  mosquito  remains  in  the  larval  stage  about  a  week 
and  is  then  transformed  into  a  comma-shaped  creature  known  as  the 
pupa. 


203  INSECT-BOKNE    DISEASES 

The  pupa  has  no  mouth  and  does  not  feed.  It  remains  quietly  at 
the  surface  except  when  disturbed.  It  breathes  through  a  pair  of  trum- 
pet-shaped tubes,  whicli  project  from  the  dorsum  of  the  thorax.  The 
pupal  stage  usually  lasts  two  or  three  days,  and  is  terminated  by  the 
emergence  of  the  adult  winged  insect  (imago)  from  its  pupal  case 
through  a  rent  in  the  region  of  the  breathing  tubes. 

The  time  from  the  laying  of  the  egg  to  the  winged  insect  may,  there- 
fore, be  as  short  as  nine  days.  The  time  depends  upon  the  tempera- 
ture and  the  abundance  of  the  food  supply.  Warmth  favors  and  cold 
retards;  therefore,  mosquitoes  are  most  abundant  during  the  summer, 
late  spring,  and  early  fall  months  in  our  climate.  In  the  tropics  the 
wild  species  become  more   al)undant  during  the  wet  season. 

The  way  in  which  mosquitoes  manage  to  pass  through  the  rigors  of 
the  winter  probably  varies  with  the  different  species.  Some,  like  the 
malarial  Anopheles,  hide  in  sheltered  cellars  or  dark  nooks,  or  hibernate 
in  other  out-of-the-way  places.  Other  species  survive  through  the  power 
of  the  larva  or  egg  to  resist  cold,  for  the  larvae  or  eggs  of  some  species 
will  hatch  even  after  they  have  been  frozen. 

THE  DESTRUCTION  OF  MOSQUITOES 

The  life  of  a  mosquito  may  be  divided  into  an  aquatic  and  an  aerial 
stage,  the  former  including  the  egg,  larva,  and  pupa,  and  the  latter 
the  adult  winged  insect.  Accordingly,  the  measures  aimed  at  the  de- 
struction of  the  mosquito  naturally  fall  into  two  classes:  (a)  those  di- 
rected against  the  larva  and  pupa — the  aquatic  stages — and  (b)  those 
directed  against  the  winged  insect. 

For  the  extermination  of  mosquitoes  the  most  effective  measures 
are  those  which  aim  to  destroy  their  breeding  places,  and  thus  prevent 
their  multiplication.  For  the  best  results  both  individual  and  com- 
munal effort  are  necessary,  but  the  importance  of  individual  effort  alone 
cannot  be  too  much  emphasized.  The  individual,  b}'  attacking  the  prob- 
lem on  his  own  premises,  grounds,  or  estate,  can  not  only  do  much  to 
rid  his  own  immediate  neighborhood  of  mosquitoes,  and  thereby  in- 
crease his  own  comfort  and  guard  against  disease,  but  the  example  thus 
set  will  perhaps  stimulate  his  less  enterprising  neighbor. 

To  insure  success  it  is  important  to  know  the  habits  and  breeding 
places  of  the  particular  species  that  it  is  desired  to  suppress. 

Natural  Breeding  Places. — Xatural  collections  of  water  which  may 
serve  as  breeding  places  are  best  dealt  with  by  filling  in  or  by  draining. 
In  this  way  they  are  disposed  of  once  for  all.  For  filling,  inorganic 
refuse,  such  as  cinders  and  ashes,  may  be  employed,  or  sufficient  earth 
may  be  dug  from  a  nearby  knoll  or  hill,  care  being  observed  that  in  so 
doing  a  depression  capable  of  holding  w^ater  is  not  made.     Low  marshy 


MOSQUITOES  203 

lands  adjacent  to  rivers,  lakes,  or  the  sea  may  be  filled  by  pumping  silt 
or  sand. 

When  filling  is  not  practicable,  good  and  permanent  results  may 
be  obtained  by  drainage.  As  a  rule,  the  draining  of  ponds,  pools,  or 
marshes  is  the  simpler  and  cheaper  method.  By  the  draining  of  marshes 
is  meant  the  draining  of  the  pools  of  stagnant  water,  or  in  the  case  of 
coastal  marshes  the  draining  of  the  stagnant  fishless  pools  that  are  be- 
yond the  reach  of  the  ordinary  tides;  it  does  not  necessarily  include  the 
draining  of  the  water-soaked  soil  itself.  The  underdraining  of  wide 
acreages  of  our  arable  land  in  the  Middle  West  has  been  very  effective 
in  suppressing  the  malarial  mosquito.  Marshy  lands  may  be  drained 
simply  by  means  of  ditches.  These  must  be  dug  of  sufficient  depth  to 
completel}"  empty  the  joools  under  treatment  and  have  sufficient  fall  to 
prevent  stagnation  in  the  course  of  the  ditch  itself.  Where  a  sufficient 
fall  is  not  obtainable  fishless  pools  may  be  connected  with  those  con- 
taining fish  or  with  a  neighboring  stream,  so  that  the  fish  may  freely 
enter.  Mosquito  breeding  places  in  the  pools  in  coastal  marshes  may 
be  suppressed  by  connecting  them  with  tide  water,  so  that  they  may 
be  freely  scoured  by  the  daily  tides.  Ditches  should  have  straight  sides 
and  must  be  inspected  at  frequent  intervals,  and  care  must  be  taken  to 
see  that  they  do  not  become  choked. 

Fish  are  among  the  most  effective  of  the  natural  enemies  of  the 
mosquito.  The  fish  may  be  admitted  to  ponds  and  pools  in  the  man- 
ner just  described,  or  the  ponds,  pools,  ornamental  lakes,  and  fountains 
may  be  directly  stocked  with  minnows  or  gold  fish.  The  margins  of 
pools,  rivers,  and  other  bodies  of  water  must  be  kept  free  of  reeds 
and  water  plants,  so  as  to  permit  the  fish  to  reach  the  edges — a  favorite 
breeding  place  for  mosquitoes.  One  of  the  very  best  means  of  clear- 
ing the  land  of  the  numerous  small  natural  collections  of  water  is  to 
place  it  under  cultivation. 

When  radical  measures,  such  as  filling  in  or  draining,  are  not  prac- 
ticable, resort  may  then  be  had  to  coal  oil.  Coal  oil  upon  the  surface 
of  the  water  acts  mainly  by  suffocating  the  larvge  and  pupse.  A  light 
qualit}^  of  oil  should  be  used,  and  it  may  be  poured  upon  the  surface 
from  an  ordinary  sprinkling  pot,  or  the  surface  may  be  sprayed  with 
a  hose.  Along  the  banks  of  ponds,  lakes,  and  slowly  moving  streams 
with  shallow  margins  containing  vegetation,  which  offer  favorite  breed- 
ing places  for  the  mosquito,  the  oil  may  be  applied  with  a  mop.  This 
practice  is  laborious,  but  effective.  Sufficient  oil  should  be  used  to 
cover  the  entire  surface  with  a  thin  film.  As  the  oil  is  volatile,  it  may 
disappear  within  a  few  days.  Furthermore,  the  film,  which  should  be 
intact  to  be  effective,  may  be  broken  by  winds.  A  strong  wind  will  blow 
all  of  the  oil  to  one  side,  thereby  entirely  defeating  the  object  desired. 
It  is,  therefore,  imj)ortant  to  repeat  the  oiling  regularly  at  intervals 


204  INSECT-BORNE    DISEASES 

of  not  more  than  one  week,  and  as  often  in  addition  as  necessary. 
Oiling,  though  fairly  effective  when  properly  carried  out,  is  only  a  tem- 
porary expedient,  and  in  the  end  is  rather  expensive.  (See  also  page  206.) 

No  body  of  water  is  too  small  for  a  mosquito  nursery.  They  breed 
in  puddles  by  the  roadside;  in  water  that  accumulates  in  furrows  in 
gardens  or  fields,  especially  in  clayey  soil ;  in  street  gutters  and  house 
gutters;  in  holes  in  rocks;  in  hollows  in  trees,  and  anywhere  that  half 
a  pint  of  water  is  allowed  to  stand. 

Artificial  Breeding  Places. — The  permanent  elimination  of  artificial 
breeding  ]*lace.s  for  iiiu.<(]uitoes  in  a  city  depends  first  of  all  upon  provid- 
ing a  good  quality  and  sufficient  quantity  of  portable  water  by  means  of  a 
modern  closed  system.  This  will  permanently  do  away  with  the  neces- 
sity of  cisterns,  barrels,  and  tubs  for  the  storage  of  water  about  the 
premises.  When  domestic  storage  is  a  necessity,  care  must  be  taken  to 
prevent  the  mosquito  from  gaining  access  to  the  water.  The  water  bar- 
rels should  be  provided  with  tightly  fitting  covers.  Burlap,  sheeting,  or 
several  thicknesses  of  cheese-cloth,  or,  better,  wire  acreening  held  in 
place  by  a  well-fitting  hoop,  serve  this  purpose  very  well.  Wooden 
covers  are  unsatisfactory,  for  they  rarely  fit  accurately  enough  to  keep 
out  the  mosquito,  and  this  defect  is  enhanced  by  the  warping  of  the 
wood,  which  usually  makes  an  old  cover  worse  than  useless.  More 
satisfactory  than  the  wooden  cover  is  one  made  of  light  galvanized 
sheet  iron,  the  central  portion  of  which  may  "be  made  of  wire  gauze.  The 
rim  of  the  barrel  should  be  trimmed  to  remove  any  irregularities  that 
might  prevent  the  cover  from  fitting  evenly  all  around.  Whatever  the 
form  of  the  cover  employed,  it  should  not  be  removed  except  for  cleaning 
or  refilling  the  barrel.  The  water  should  be  drawn  from  a  spigot. 
Where  the  water  is  very  turbid  and  must  undergo  sedimentation  before 
being  used,  several  barrels  should  be  provided  for  its  storage  and  the 
water  used  from  each  barrel  in  turn.  In  such  a  case  the  spigot  should 
be  placed  about  a  foot  from  the  bottom,  so  that  the  sediment  need  not 
be  disturbed  as  the  water  is  drawn  off  for  use.  Wells  should  be  pro- 
vided with  tight  covers  and  the  water  drawn  by  pumps. 

Cisterns  and  tanks  should  also  be  provided  with  accurately  fitting 
covers,  and  should  be  inspected  frequently  for  seams  and  cracks  result- 
ing from  warping  and  shrinking  of  the  wood.  To  guard  against  this 
loophole,  wire  gauze  should  be  used  to  screen  the  joint  between  the  tank 
and  its  cover.  The  gauze  should  include  about  one  foot  of  the  tank 
and  overlap  well  upon  the  cover.  The  inlet  to  the  tank  or  cistern 
should  be  provided  with  a  cap  of  copper  meshed  wire  gauze  which  may 
be  protected  by  another  and  coarser  meshed  cap  of  stout  wire,  to  pre- 
vent its  choking  with  leaves,  etc.  As  an  additional  precaution,  the  in- 
let pipe  should  be  long  and  extend  well  below  the  water  level.  In  cases 
of  emergency,  as  in  times  of  epidemics  of  yellow  fever  or  dengue,  where 


MOSQUITOES  205 

the  permanent  measures  for  preventing  mosqnito  breeding  have  been 
neglected,  the  surface  of  the  water  in  barrels,  tanks,  and  cisterns  may 
be ,  covered  with  some  neutral  non-volatile  oil  which  does  not  impart  a 
taste  to  the  water. 

Cesspools  and  privy  vaults  should  be  done  aAvay  with  and  replaced 
with  dry  earth  closets  or  a  water  carriage  cistern.  Where  this  has  not 
been  done  they  may  be  frequently  and  copiously  oiled. 

Among  the  artificial  breeding  places  for  mosquitoes  may  be  men- 
tioned chicken-pens  in  poultry  yards;  water  cups  on  the  frames  of 
grindstones;  baptismal  fonts;  tin  cans  or  broken  bottles  in  back  yards; 
the  catch  basins  of  sewers;  the  water  that  stands  in  sagging  house  gut- 
ters; tlower-pots,  and  similar  places. 

Screening. — Mosquito  screens  are  the  obvious  and  most  effective 
single  measure  for  personal  prophylaxis  where  disease-carrying  mosqui- 
toes exist.  In  order  to  be  effective  the  screening  must  be  intelligently 
carried  out  with  careful  attention  to  details.  The  screen  itself  must 
be  sufficiently  close  to  keep  out  the  mosquitoes.  Some  of  them  are  able 
to  squeeze  through  surprisingly  narrow  chinks.  I  was  able  to  demon- 
strate, in  the  experimental  work  at  Vera  Cruz,  that  the  stegomyia  mos- 
quito can  pass  a  metal  wire  screen  containing  16  strands  or  15  meshes  to 
the  inch,  but  cannot  pass  one  containing  20  strands  or  19  meshes  to  the 
inch.  When  the  screen  consists  of  a  fabric  which  is  apt  to  pull  out  of 
shape  so  that  some  of  the  meshes  are  larger  than  others,  it  is  advisable 
to  use  a  net  woven  closer  than  20  strands  to  the  inch.  Experience  in 
malarial  and  yellow  fever  districts  has  taught  this  lesson,  so  that  it  is 
customary  in  those  countries  to  use  a  rather  closely  woven  material  re- 
sembling nainsook.  Metal  screens  made  of  iron  wire  are  cheapest  only 
when  first  cost  is  considered.  They  hardly  last  a  season  unless  painted, 
in  which  case  the  size  of  the  mesh  is  considerably  reduced  and  inter- 
feres with  ventilation,  a  serious  objection  in  hot  weather  or  a  tropical 
climate.  Mesh  made  of  galvanized  iron  wire  has  a  greater  durability. 
Screens  made  of  brass  or  bronze  are  expensive,  but  cheap  in  the  long 
run,  as  they  are  found  to  last  almost  indefinitely. 

The  screening  should  include  the  entire  house,  or  at  least  those 
parts  that  are  occupied.  In  the  tropics  it  is  better  to  screen  the  gal- 
leries than  each  individual  window.  In  any  case,  frequent  and  repeated 
inspection  should  be  made  to  discover  breaks  in  the  screen  or  openings 
due  to  warping  of  the  woodwork.  In  screening  care  must  be  exercised 
not  to  overlook  fireplaces,  ventilators,  and  other  openings.  The  door 
should  be  guarded  by  a  screened  vestibule  of  such  a  depth  as  to  make 
it  impossible  for  a  person  to  hold  both  doors  open  at  the  same  time. 
The  screen  door  should  open  outward  and,  if  possible,  should  be  exposed 
to  the  direct  sunlight  during  the  day  without  vines  or  nearby  vegeta- 
tion of  any  kind  to  protect  and  lodge  the  mosquitoes.    During  the  night 


206  L\Sl-:("r-lU)lJ.\K    DI.SEASKS 

the  floor  sliould  not  bo  in  an  artificial  li<rht,  which  attracts  many  mos- 
quitoes. An  electric  fan  directed  outward  is  a  very  cjcod  device  to  pre- 
vent mosquitoes  flyin^^  through  the  doorway.  In  ailditinn.  a  whisk- 
broom  or  feather  duster  should  hang  in  the  vestil)iile  to  brush  olf  the 
insects  that  may  rest  upon  the  clothing.  A  screened  house  is  safe  only 
to  careful  and  intelligent  people. 

In  addition  to  screening  the  house,  mosquito  bars  over  the  bed  will 
be  found  necessary  in  mosquito-infected  places.  It  is  best  to  suspend  the 
mosquito  bar  from  the  ceiling  and  carefully  gather  the  l)ottom  together 
so  as  to  keep  the  insects  out  during  the  day  time.  At  night  the  bar 
should  be  carefully  tucked  in  around  the  bed  so  as  to  leave  no  openings. 
Mosquitoes  have  no  trouble  in  i)iting  through  the  meshes  of  the  Inir, 
provided  a  restless  sleeper  comes  close  enough  to  it. 

Persons  who  are  required  to  go  out  at  night  in  a  malarious  district, 
or  who  must  expose  themselves  during  yellow  fever  times,  may  screen 
themselves  effectively  with  a  veil  of  mosquito  netting  hanging  from  a 
broad-brimmed  hat  to  the  shoulders  and  chest.  The  hands  and  wrists 
may  be  protected  witli  gloves,  and  the  ankles  w'ith  leggings  or  other 
suitaljlo  mechanical  device. 

Miscellaneous  Measures. — Spirits  of  camphor,  oil  of  pennyroyal,  and 
other  volatile  substances,  such  as  oil  of  peppermint,  lemon  juice,  or 
vinegar.  n;bl)ed  upon  the  face  and  hands,  or  a  few  drops  on  the  pillow 
at  night,  will  keep  mosquitoes  away  only  for  a  time.  Oil  of  citronella 
is  one  of  the  best  known  sul)stances  to  be  used  in  this  way.  Ordinarily 
a  few  drops  on  a  bath  towel  hung  over  the  head  of  the  bed  will  keep 
the  common  house  mosquitoes  away.  When  they  are  very  abundant  and 
persist,  a  few  drops  rubbed  on  the  face  and  hands  will  suffice.  All  these 
substances  soon  lose  their  efficiency ;  none  of  them  last  until  morning. 

In  Panama  a  larvicide  is  being  used  which  is  made  as  follows:  150 
gallons  of  carbolic  acid  is  heated  in  a  tank  to  a  temperature  of  212°  F., 
then  150  pounds  of  powdered  or  finely  broken  resin  is  poured  in.  The 
mixture  is  kept  at  a  temperature  of  212°  F.  Thirty  pounds  of  caustic 
soda  is  then  added,  and  the  solution  is  kept  at  the  same  temperature 
until  a  perfectly  dark  emulsion  without  sediment  is  formed.  The  mix- 
ture is  thoroughly  stirred  from  the  time  the  resin  is  used  until  the  end. 
One  part  of  this  emulsion  to  10,000  parts  of  water  is  said  to  kill  Ano- 
pheles larvae  in  less  than  half  an  hour,  while  1  part  to  5.000  parts  of 
water  will  kill  them  in  from  5  to  10  minutes. 

The  Panama  larvicide  is  mixed  with  5  parts  of  water  and  sprayed 
upon  pools  or  along  the  banks  of  streams.  This  larvicide  added  to  5 
parts  of  crude  petroleum  favors  its  spread  upon  the  surface  of  the  w-ater. 
A  good  method  is  to  place  the  mixture  in  a  barrel  and  permit  it  to 
drip  i;pon  the  surface  of  the  stream  or  pond  to  be  treated. 

Other  larvicides  that  may  be  used  in  water  not  used  for  drinking 


MOSQUITOES  207 

purposes  are:  sulphuric,  hydrochloric,  and  other  acids,  potassium  per- 
manganate, sulphate  of  copper,  sulphate  of  iron,  bichlorid  of  mercury, 
carbolic  acid,  anilin  products,  or  coal  tar.  They  must  be  used  in  rela- 
tively large  amounts  to  be  effective,  and  frequently  renewed  according 
to  circumstances. 

The   diseases   known   to    be    conveyed   by   mosquitoes   are :    malaria 

{Anoplieles  spp.),  yellow  fever  {Stegomyia  calopus),  filariasis  {Culex 
fatigans),  dengue  {Culex  fatigans),  and  doubtless  other  infections. 

MALARIA 

Malaria  is  one  of  the  most  prevalent  of  all  preventable  diseases ;  it  is 
the  scourge  of  the  tropics.  The  cause  of  this  infection  was  one  of  the 
first  to  be  discovered  (Laveran,  1880),  and  its  mode  of  transmission 
was  one  of  the  most  brilliant  discoveries  in  sanitary  science  (Eoss, 
1895).  Despite  the  fact  that  we  have  more  exact  knowledge  of  malaria, 
considering  the  difficulties  of  the  subject,  than  perhaps  any  other  dis- 
ease, despite  the  fact  that  we  have  accurate  means  of  diagnosis  and  a 
ready  cure,  and  despite  the  fact  that  we  have  assured  measures  of  pre- 
vention, malaria  counts  its  victims  by  the  hundreds  of  thousands  annu- 
ally. In  geographic  distribution  malaria  extends  from  the  Arctic  circle 
to  the  Equator,  but  becomes  more  virulent  the  warmer  the  climate. 

At  least  three  separate  malarial  parasites  of  man  are  known,  namely : 
(1)  Plasmodium  malarice  (Laveran),  quartan  fever;  (2)  Plasmodium 
vivax  (G-rassi  and  Filetti),  tertian  fever;  and  (3)  Plasmodium  falci- 
parum (Welch),  estivoautumnal  or  tropical  malaria.  These  are  closely 
allied  hematocytozoa  or  blood  parasites.  They  produce  diseases  with 
well-defined  clinical  differences,  but  having  the  same  etiology  and  mode 
of  transference,  so  that,  as  far  as  prevention  is  concerned,  they  may 
be  regarded  as  one  infection. 

Many  species  of  animals  have  a  malarial-like  infection  closely  re- 
sembling malaria  in  man;  for  example,  Texas  fever  of  cattle,  piroplas- 
mosis  of  dogs  and  sheep,  proteosoma  of  birds,  etc.  So  far  as  is  known, 
no  other  animal  than  the  Anopheles  mosquito  is  subject  to  the  malarial 
parasites  pathogenic  for  man.  Both  man  and  the  mosquito  are  neces- 
sary to  complete  the  life  cycle  of  the  plasmodium.  Man  is  the  inter- 
mediate host  harboring  the  asexual  phase,  and  the  mosquito  is  the  defi- 
nitive host  harboring  the  sexual  phase  of  the  life  cycle  of  the  plas- 
modium. 

Mosquito  Transmission. — It  is  now  definitely  known  that  in  nature 
malaria  is  transmitted  only  by  the  sting  of  the  Anopheles  mosquito.^ 
Experimentally,   the  infection  may  be  transferred   by  injecting  blood 

^  The  genus  Anopheles  has  recently  been  divided  into   several   genera. 


208  IXSECT-BOPiME    DISEASES 

(containiniT  the  parasites)  of  one  person  into  the  system  of  another. 
Nearly  2,000  years  ago  Varro  and  ColunibeUa  mentioned  the  possibility 
that  the  disease  was  transmitted  by  mosquitoes.  In  Africa  some  savage 
tribes  call  malaria  the  "mosquito  disease."  In  1848  Nott,  of  New  Or- 
leans, considered  the  matter  proven  from  biological  analogies.  In  1883 
King,  of  Washington,  vigorously  advocated  the  mosquito  theory  based 
upon  philosophical  deductions  but  no  proof.  In  1884  Laveran  suggested 
mosquito  transmission  as  probable.  In  1894  Manson  elaborated  the 
mosquito  theory  and  inspired  Eoss,  of  the  Indian  Army  Medical  Service, 
who  in  1895  demonstrated  that  the  crescents  of  estivoautumnal  malaria 
underwent  changes  in  the  mosquito.  In  189G  Bignanii  advocated  the 
theory  and  compan'd  it  to  the  transmission  of  Texas  fever  by  the  tick. 
In  1897  Ross  published  further  convincing  observations  upon  the  de- 
velopment of  the  estivoautumnal  parasite  in  the  mosquito.  In  1898  !Mc- 
Collum  observed  an  important  missing  link  in  the  life  cycle  by  observ- 
ing the  tlagellum  of  the  microgametocyte  (male)  fertilize  the  macro- 
gametocyte  (female)  with  the  formation  of  the  vermicule.  These  ob- 
servations were  made  upon  Halteridum  or  malaria  of  birds;  later  he  saw 
the  same  phenomenon  in  estivoautumnal  malaria.  The  life  cycle  of  the 
malarial  parasite  has  been  confirmed  l\v  Daniels,  Koch,  Grassi,  Big- 
nami,  Celli,  Manneberg,  Schaudinn,  and  others. 

Further  evidence  that  malaria  is  transmitted  by  the  mosquito  was 
furnished  by  Sambon  and  Low,  of  the  London  School  of  Tropical  Medi- 
cine, and  Dr.  Terzi,  who  lived  during  the  three  most  malarial  months  of 
1900  in  Ostia,  a  very  malarial  locality  of  the  Roman  Campagna.  These 
observers  escaped  infection  simply  by  keeping  within  their  well-screened 
hut  from  before  sundown  until  after  sunrise.  The  final  proof  was  fur- 
nished in  1900  by  Dr.  P.  Thurber  Manson  and  Mv.  George  Warren,  who 
were  bitten  by  infected  mosquitoes  forwarded  from  Italy  in  cages  to 
London. 

The  Malarial  Mosquito. — Of  the  fifty  or  more  species  of  the  genus 
Anopheles  sixteen  are  known  to  transmit  malaria.  In  Europe  Anopheles 
maculipennis,  in  tropical  America  A.  argyrotarsus  or  albipes,  in  tem- 
perate America,  A.  quadrimaculatus,  which  is  probably  the  same  as  A. 
■maculipennis,  in  India  A.  sinensis,  in  Africa  A.  costalis,  are  the  chief 
culprits. 

The  Anopheles  mosquitoes  are  brownish  and  rather  large.  They  may 
be  distinguished  by  the  fact  that  the  palpi  in  both  the  male  and  the 
female  are  at  least  as  long  as  the  proboscis.  Only  the  female  transmits 
the  infection.  It  sits  more  or  less  at  right  angles  upon  the  wall,  the 
head,  thorax,  and  abdomen  being  in  a  straight  line.  Contrary  to  the 
yellow  fever  mosquito,  the  malarial  mosquito  is  nocturnal  in  its  habits 
and  breeds  chiefly  in  the  open  ponds,  puddles,  and  natural  collections 
of  water  in  the  woods,  fields,  and  swamps. 


MOSQUITOES 


209 


Fig.  19. — Anopheles  Punctipenis. 


The  mosquito  becomes  infected  upon  drinking  the  blood  containing 
the  micro-. and  macrogametocytes.  It  requires  about  twelve  days  before 
the  sporozoites  appear  in  the 
salivary  glands  of  the  insect.  It 
cannot,  therefore,  transmit  the 
infection  to  another  person  until 
the  lapse  of  this  extrinsic  period 
of  incubation.  The  infected  mos- 
quito may  live  a  long  time  and 
infect  more  than  one  person  suc- 
cessively. The  malarial  parasite 
seems  to  be  a  harmless  sapro- 
phyte for  the  mosquito. 

Immunity. — A    person    who 
once    has    had   malaria    is    more 
apt   to   have   subsequent   attacks. 
Ordinarily  there  is  an  increased 
susceptibility  rather  than  an  im- 
munity.     However,   repeated   in- 
fections,  especially   during   early 
life,  leave  a  very  pronounced  re- 
sistance.    In  malarious  regions  many   children  carry  the  parasites  in 
their    circulating    blood    without    any    manifestations    of    the    disease. 
These  carriers  are  important  factors  in  spreading  the  infection  in  en- 
demic areas,  and  must  be  taken  into  account  in  preventive  measures. 

There  is  no  true  racial  immunity  in  this  disease.  Occasionally  a 
congenital  immunity  seems  to  be  transmitted;  this  must  be  rare.  Prac- 
tically all  persons  who  receive  the  infection  for  the  first  time  are  sus- 
ceptible. The  freedom  from  malaria  which  some  persons  seem  to  enjoy 
may  be  accounted  for  partly  by  the  fact  that  mosquitoes  seldom  bite 
such  persons.  It  is  well  known  that  on  account  of  the  odors,  or  what 
not,  mosquitoes  do  not  bother  certain  individuals.  No  doubt  the  in- 
fection of  a  small  number  of  parasites  is  often  overcome  largely  through 
a  vigorous  phagocytosis. 

Individual  resistance  varies  in  different  individuals  and  in  the  same 
individual  at  different  times.  The  parasite  may  remain  latent  in  the 
spleen  and  other  organs  for  years.  Exposure,  overeating,  fasting,  over- 
work, or  worry,  or  anything  that  lowers  the  vitality  of  such  individuals 
predisposes  to  an  attack  of  malaria.  The  disease  often  breaks  out  in 
persons  in  good  health  leaving  a  malarial  region  for  a  health  resort, 
whether  mountain  or  seashore.  I  was  enabled  to  confirm  this  observa- 
tion upon  the  returning  transports  from  Cuba  following  the  Spanish- 
American  war,  when  many  cases  of  malaria  broke  out  among  the  troops 
previously  in  good  health  upon   reaching  the  cold  winds   about   Cape 


210  IXSECT-BORXE    DISEASES 

Hatteras.     Personal  prophylaxis,  therefore,  involves  careful  attention  to 
personal  hygiene. 

Prevention. — The  successful  suppression  of  malaria  requires  a  com- 
bined attack  upon  the  mosquito  and  the  parasite  in  the  human  host. 
Ultimate  success  rests  upon  the  suppression  of  the  mosquito.  This, 
however,  is  a  difficult  and  expensive  undertaking  in  the  case  of  the 
Anopheles.  Immediate  relief  is  most  quickly  gained  by  measures  directed 
against  the  infection  in  man.  Screening  and  quinin  prophylaxis,  while 
practical,  are  only  temporary  measures; 

Measures  Directed  Against  the  Mosquito. — If  the  breeding  of 
the  Anopheles  mosquito  could  be  stopped  malaria  would  cease.  Mosquito 
suppression  is  fundamental  and  radical.  The  best  way  to  abolish  the 
breeding  places  of  malaria  mosquitoes  is  to  fill  up  low  places  or  to  dry 
the  surface  of  the  land  with  drains.  These  two  measures  hold  first 
place  as  permanent  work.  The  underdraining  of  large  areas  of  our 
arable  land  of  the  Middle  West  with  tiled  drain  has  been  very  effective 
in  supjjressing  malaria.  Open  ditches  properly  constructed  and  cared 
for  are  likewise  effective.  In  the  tropics  the  ditches  should  be  lined 
with  cement,  on  account  of  the  lux:uriant  vegetation  which  soon  interferes 
with  their  efficiency  or  may  actually  convert  them  into  breeding  places. 
The  open  ditches  are  much  the  cheapest  in  first  cost,  but  not  when 
maintenance  is  reckoned.  The  draining  of  swampy  lands  is  an  engineer- 
ing problem  in  which  the  economic  factor  looms  large.  One  of  the  very 
best  means  of  destroying  the  breeding  places  of  the  malaria  mosquito 
is  to  clear  the  land  and  to  keep  it  in  cultivation. 

"When  drainage  is  not  practical,  the  number  of  mosquitoes  may  be 
kept  down  by  introducing  fish  into  the  pools,  streams,  ditches,  and 
other  collections  of  water.  Upon  limited  water  surfaces  the  larvae  may 
be  killed  with  a  film  of  coal  oil. 

Large  open  spaces  cause  the  destruction  of  a  number  of  mosquitoes, 
as  they  cannot  live  long  in  the  hot  sun ;  therefore,  clearing  the  brush 
and  high  grass,  which  furnish  shelter  to  the  insects,  aids  in  keeping  away 
wild  mosquitoes  around  dwelling  houses. 

The  use  of  screens  and  culicides  has  already  been  referred  to. 

Personal  Prophylaxis. — Persons  visiting  or  residing  in  a  malari- 
ous region  should  be  particularly  careful  not  to  expose  themselves  at 
night  time.  The  experience  of  Sambon  and  Low  on  the  Roman  Cam- 
pagna  is  instructive  and  should  be  imitated.  The  location  of  the  resi- 
dence is  important.  In  a  city  it  should  be  a  reasonably  safe  distance 
from  the  native  quarter,  because  the  infection  is  there  most  concentrated. 
The  dwelling  should,  if  possible,  face  the  trade  winds.  A  row  of  tall 
trees  will  partly  screen  the  house  from  the  swamp,  but  the  trees  must 
not  be  too  close,  else  they  will  furnish  shelter  for  the  insects.  The 
house  should  be  on  high  land  if  practicable,  as  it  is  an  old  observation 


MOSQUITOES  211 

that  the  malarial  mosquito  does  not  fly  high.  People  living  upon  the 
second  floor  are  less  apt  to  contract  the  infection  than  those  who  sleep 
on  the  ground  floor.  If  it  is  necessary  to  go  out  in  the  night  time,  one 
may  protect  himself  by  the  use  of  gloves  and  mosquito  netting  hang- 
ing from  the  helmet  to  the  shoulders.  Care  must  be  taken  to  guard 
the  ankles  against  mosquito  bites.  As  all  these  measures  require  much 
time  and  attention  to  details,  they  are  usually  not  sufficient  in  actual 
practice.     Therefore,  quinin  prophylaxis  is  much  used. 

QuiNiN  Prophylaxis. — Theoretically  the  administration  of  quinin 
to  healthy  individuals  for  the  prevention  of  malaria  is  not  an  ideal 
method  of  prophylaxis,  for  it  does  not  prevent  infection,  but  only  de- 
stroys the  parasites  in  the  blood  during  the  period  of  incubation.  It 
should  be  remembered  that  quinin  kills  only  the  young  and  tender  forms 
of  the  Plasmodium,  and  has  no  influence  upon  the  crescents.  Quinin 
prophylaxis  is  indicated  in  proportion  to  the  difficulty  of  pursuing  more 
permanent  methods.  It  is  especially  valuable  where  screens  and  bars  are 
not  available,  as  in  camping,  marching,  traveling,  or  where  the  occupa- 
tion takes  one  out  at  night.  When  residents  of  non-malarial  countries 
go  into  malarial  localities,  especiallv  in  the  rural  districts,  for  short 
periods  of  time,  quinin  is  a  valuable  preventive. 

To  be  effective  as  a  preventive  of  malaria,  quinin  must  be  taken  in 
sufficient  doses  during  the  entire  malarial  season.  The  expense  of  pub- 
lic prophylaxis  with  quinin  on  a  large  scale  is  enormous;  in  fact,  in 
some  instances  prohibitive.  The  daily  ingestion  of  2.5  grains  would 
require  the  annual  use  of  no  less  than  59.4  tons  per  million  people. 
The  size  of  the  dose  and  the  interval  at  which  the  prophylactic  is  ad- 
ministered are  of  the  utmost  importance.  Koch  advised  one  gram  of 
quinin  every  sixth  or  seventh  day,  or  every  seventh  and  eighth  day,  or 
eighth  and  ninth,  or  ninth  and  tenth  day,  according  to  the  danger  of 
the  infection.  This  manifestly  leaves  several  intervening  days  in  which 
there  is  no  quinin  in  the  circulation.  In  localities,  therefore,  where 
estivoautumnal  malaria  is  prevalent,  a  shorter  interval  should  be  pre- 
ferred on  account  of  the  shorter  period  of  incubation  of  this  form  of 
malaria. 

Ziemann  gives  a  gram  of  quinin  sulphate  every  four  days.  The  al- 
kaloid is  administered  in  solution  with  5  drops  of  hydrochloric  acid 
early  in  the  morning  or  about  one  and  one-half  to  two  hours  after  a 
meal.  A  convenient  rule  is  to  give  a  dose  on  the  first  of  the  month 
and  thereafter  on  each  day  of  the  month  divisible  by  4.  By  this  method 
the  alkaloid  is  probably  constantly  in  the  circulating  blood. 

Plehn  advises  one-half  a  gram  of  quinin  every  fifth  evening. 

The  administration  of  small  doses  of  quinin  daily  is  the  oldest  method 
of  giving  quinin  as  a  prophylactic.  From  II/2  to  6  grains  have  been  given 
daily.     In  Italy  0.04  gram   (about  2-3  grain)    daily  is  the  universally 


21S  INSECT-BORNE    DISEASES 

adopted  dose,  and  accomplishes  good  results.  The  Italian  government 
undertakes  the  sale  of  quinin  at  a  low  price.  This  is  a  beneficent  public 
health  measure  comparable  to  the  free  distribution  of  antitoxin  and  vac- 
cine virus. 

On  the  Isthmus  of  Panama  good  results  have  been  obtained  by  the 
use  of  moderate  doses,  3  to  6  grains  per  day.  When  the  disease  in- 
creases in  prevalence  or  virulence  the  amount  is  raised  to  8  or  10  grains 
per  day,  then  dropping  off  to  4  or  5. 

The  particular  metliod  of  election  in  giving  quinin  prophylaxis  should 
be  chosen  according  to  the  experience  of  the  region. 

An  objection  to  the  use  of  quinin  as  a  prophylactic  has  recently  been 
raised  by  Stitt,  who  claims  that  the  malarial  parasites  gradually  become 
immune  to  the  effects  of  the  alkaloid,  and  that  when  the  disease  subse- 
quently breaks  out  in  one  who  has  used  quinin  as  a  prophylactic  it  is 
not  readily  amenable  to  treatment.  Ehrlich  has  shown  experimentally 
that  trypanosomes  may  be  immunized  in  this  sense  to  trypanrot,  and 
that  other  microparasites  belonging  to  the  animal  kingdom  may  similarly 
be  accustomed  to  unusual  amounts  of  substances  ordinarily  very  toxic. 

Quinin  prophylaxis  has  advantages  that  commend  it  as  a  prompt  and 
practical  measure.  It  is  at  best,  however,  only  tentative,  and  does  not 
take  the  place  of  mosquito  suppression. 

YELLOW  FEVER 

The  prevention  of  yellow  fever  rests  entirely  upon  the  fact  that  it 
is  communicated  through  the  bite  of  an  infected  mosquito — the  Stego- 
myia  calopus}  The  mosquito  becomes  infected  by  sucking  the  blood  of 
yellow  fever  patients  during  the  first  three  days  of  the  fever.  All  the 
experimental  evidence  thus  far  shows  that  the  infection  is  absent  from 
the  blood  after  the  third  day,  and  that  mosquitoes  do  not  become  in- 
fective after  this  period.  The  importance  of  this  fact  in  preventing  the 
spread  of  the  disease  is  evident.  The  mosquito,  after  drinking  the  in- 
fected blood,  is  not  able  to  transfer  the  infection  to  another  person  until 
about  twelve  days-  have  elapsed;  that  is,  it  requires  about  twelve  days 
for  the  yellow  fever  parasite,  whatever  it  may  be,  to  undergo  its  cycle 
of  development  in  the  mosquito.  The  mosquito  once  infected  remains 
so  during  the  rest  of  its  life,  which  may  be  many  months.  Only  the 
female  mosquito  transmits  the  infection ;  the  male  Stegomyia  calopus  is 
a  vegetarian;  its  proboscis  is  too  soft  to  penetrate  the  skin.     A  single 

*  This  mosquito  was  first  called  Culex  fasciatus,  which  was  changed  to 
Stegomyia  fasciatus,  and  then  to  Stegomyia  calopus,  and  recently  expressed  as 
A'edes  calopus  by  Coquillett. 

■  This  constitutes  the  extrinsic  period  of  incubation,  in  contradistinction  to 
the  intrinsic  period  of  incubation,  that  is,  the  time  between  the  mosquito  bite 
and  the  onset  of  symptoms,  which  is  from  2  to  5  and  sometimes  6  days  in  this 
disease. 


MOSQUITOES  213 

sting  of  a  single  infected  mosquito  is  sufQeient  to  produce  the  disease. 
An  infected  mosquito  may  infect  more  than  one  person  at  different 
times. 

Tlie  prevention  and  control  of  yellow  fever  are  based  upon  a  series 
of  epoch-making  investigations  and  discoveries  (1900-1902)  by  a  com- 
mission composed  of  Walter  Eeed,  James  Carrol;,  Aristides  Agramonte, 
and  Jesse  W.  Lazear,  medical  officers  of  the  United  States  army.  These 
experiments  have  been  fully  confirmed,  and  in  some  respects  amplified, 
by  independent  workers,  namely,  Guiteras  of  Cuba  (1901)  ;  Barreto,  de 
Barros,  and  Eodrigues,  of  Brazil  (1903)  ;  Eoss  (1902) ;  Parker,  Beyer, 
and  Pothier  (1903)  ;  Eosenau,  Parker,  Francis,  and  Beyer  (1904)  ; 
Eosenau  and  Goldberger  (1906),  of  America;  Marchoux,  Salimbeni,  and 
Simond  (1903);  Marchoux  and  Simond  (1906),  of  France;  and  Otto 
and  Neumann  (1905),  of  Germany. 

The  cause  of  yellow  fever  is  unknown.  The  virus  is  ultramicroscopic, 
that  is,  passes  the  close-grained  pores  of  the  finest  porcelain  filter. 
While  in  nature  the  disease  is  transmitted  only  through  the  bite  of  an 
infected  Stegomyia,  the  disease  may  be  transferred  experimentally  by 
taking  some  of  the  blood  from  a  patient  during  the  first  three  days  of 
the  fever  and  injecting  it  into  a  susceptible  individual.  So  far  as  is 
known,  yellow  fever  is  peculiar  to  man,  for  all  other  animals  tested  have 
failed  to  react.  At  one  time  it  was  generally  believed  that  yellow  fever 
infection  was  conveyed  by  fomites.  This  has  been  disproved,  and  we  now 
know  that  there  is  no  danger  from  soiled  clothing  or  other  inanimate 
things,  even  though  stained  with  the  black  vomit  and  other  discharges. 

The  diagnosis  of  yellow  fever  rests  upon  clinical  evidence  and  is  fre- 
quently difficult  to  make,  especially  in  the  early  stages.  It  is,  therefore, 
important  to  screen  all  cases'  of  fever  in  a  yellow  fever  campaign  until 
the  nature  of  the  illness  is  established. 

Immunity. — There  is  no  natural  immunity  to  yellow  fever.  All  per- 
sons receiving  the  infection  for  the  first  time  seem  to  be  susceptible. 
Contrary  to  the  usual  statement,  there  is  no  racial  immunity  in  this  dis- 
ease, for  negroes,  Chinese,  Indians,  and  other  races  take  the  disease. 
One  attack  of  yellow  fever  affords  protection  against  a  subsequent  attack. 
The  acquired  immunity  in  this  disease  is  one  of  the  strongest  known 
and  lasts  throughout  the  lifetime  of  the  individual.  Two  attacks  of 
yellow  fever  are  almost  unknown.  I  reported  a  supposed  instance  in  a 
Spaniard  in  Havana,  but  the  diagnosis  of  tlie  first  attack  was  not  con- 
clusive. 

In  endemic  areas  children  may  have  yellow  fever,  which  leaves  them 
immune  for  life.  The  disease  often  runs  a  mild  and  unrecognized  course 
in  children,  and  this  fact  explains  the  supposed  natural  immunity  of 
natives  in  endemic  foci. 

The  Yellow  Fever  Mosquito. — The  yellow  fever  mosquito  has  a  wide 
16 


214 


INSECT-BORNE    DISEASES 


distribution  ranging  from  38  degrees  south  to  38  degrees  north  latitude. 
They  are  found  in  the  East  and  West  Indies.  China,  Sumatra,  Java.  In- 
dia, Philippine  Islands,  Japan,  Hawaiian  Islands,  in  tlic  SDutlnM-n  part  of 
Italy,  Africa.  Spain,  South  America,  etc.  They  usually  ])refer  the  low- 
lands. I  have  found  them 
as  far  up  llie  mountains 
as  Orizaba  in  Mexico,  4,- 
200  feet  above  sea  level. 
In  tlie  United  States  they 
are  very  prevalent  south 
of  the  Potomac  along  the 
gulf  coast,  but  are  absent 
or  rare  in  the  higher 
elevations  of  Georgia  or 
A  1  a  b  a  ni  a  ,  which  are, 
therefore,  non-infectable 
regions. 

The  yellow  fever  mos- 
quito is  a  domestic  in- 
sect. It  breeds  by  pref- 
erence in  any  standing 
water  about  the  house- 
hold, such  as  cisterns, 
rain  barrels,  or  any  col- 
lection of  water  in 
buckets,  bottles,  old  cans, 
etc.  The  yellow  fever 
mosquito  does  not  breed 
in  the  fields,  woods,  and 
swamps,  which  are  the 
favorite  resorts  of  the 
malarial  mosquito.  The 
Stegomyia  mosquitoes  do  not  fly  far  of  their  own  volition,  but  sliow  a 
cat-like  tendency  to  remain  about  their  place  of  birth  or  adoption.  All 
these  facts  have  an  evident  bearing  upon  preventive  measures.  A 
thorough  knowledge  of  the  biology  of  the  mosquito  is  essential  to  the 
success  of  a  yellow  fever  campaign. 

It  is  important  to  remember  that  the  yellow  fever  mosquito  is  chietly 
active  during  the  day  time.  It  cannot,  however,  distinguish  between 
artificial  light  and  sunlight.  I  have  watched  Stegomyia  mosquitoes  bite 
me  by  electric  light  at  eleven  o'clock  at  night.  However,  as  a  rule, 
they  rest  at  night,  which,  therefore,  diminishes  the  risk  of  exposure 
at  that  time.  The  Stegomyia  mosquito,  however,  cannot  survive  for 
long  in  the  direct  rays  of  a  tropical  sun.     There  is,  therefore,  little 


Fig.  20. — Stegomyia  Calopus  (female). 


MOSQUITOES 


215 


danger  in  visiting  a  community  where  yellow  fever  is  epidemic  dur- 
ing the  day  time,  provided  the  person  keeps  out  of  houses.  The  ex- 
periences during  the  last  yellow  fever  epidemic  at  New  Orleans,  1905, 
showed  that  the  radius  of  activity  of  an  infected  Stegomyia  is  con- 
tracted. It  may  possibly  at  times  fly  across  the  street,  but  it  is  evident 
that  it  neither  flies  far  nor  is  it  ordinarily  transported  to  any  great  dis- 
tance on  railroad  cars,  although  it  may  be  carried  over  seas  on  ships. 

The  yellow  fever  mosquito 
may  pass  a  screen  composed 
of  16  strands  or  15  meshes  to 
the  inch,  but  cannot  pass  one 
containing  20  meshes  or  19 
strands  to  the  inch.  Effective 
screens  must,  therefore,  be  at 
least  this  fine. 

Stegomyia  calopus  is  a 
grayish  mosquito  of  average 
size  with  beautiful  glistening 
silver-white  markings.  These 
markings  are  lyre-shaped  on 
the  back  of  the  thorax;  silver- 
white  spots  are  seen  on  the 
side  of  the  thorax.  White  lines 
are  apparent  at  each  tarsal 
joint  and   also   on  the   palpi; 

the  scutellum  is  white.  In  the  female  the  palpi  are  much  shorter  than 
the  proboscis,  which  at  once  distinguishes  it  from  Anopheles. 

Egg. — The  female  lays  her  eggs  on  the  surface  of  the  water  or  just 
above  the  water  line.  The  eggs  do  not  adhere  to  one  another,  and  hence 
do  not  form  the  compact  boat-shaped  mass  characteristic  of  the  culex, 
but  float  on  their  sides  more  or  less  singly.  At  the  moment  of  laying 
the  eggs  are  a  cream  color,  but  rapidly  become  jet  black.  They  are 
somewhat  cigar-shaped,  and  measure  on  the  average  about  0.55  mm.  in 
length  and  0.16  mm.  in  width  at  the  broadest  part.  The  eggs  show 
marked  powers  of  resistance  to  unfavorable  influences.  They  may  be 
kept  dry  for  six  and  one-half  months,  and  still  retain  their  vitality,  and 
hatch  out  when  put  back  into  the  water.  Freezing  does  not  kill  them. 
The  egg  probably  plays  an  important  role  in  the  hibernation  of  the 
yellow  fever-  mosquito.  The  winged  insect  may  also  survive  a  short 
winter.  Under  the  most  favorable  conditions  as  to  temperature  (30°  C.) 
Stegomyia  eggs  hatch  out  in  about  36  hours  after  they  are  laid.  Under 
20°  C.  they  will  not  hatch  at  all. 

Larva. — The  egg  hatches  the  larva  ("wiggle-tail"),  which  has  a 
black  barrel-shaped  respiratory  siphon.    This  distinguishes  it  from  Culex 


Fig.  21. — Head  of  Stegomyia  Calopus  (male). 


216 


INSECT-BORXE    DISEASES 


Fig.  22. — Eggs  of  Stegomtia  Calopus. 

pxpiens,  its  common  mess  mate,  in  which  the  air  tube  is  brown,  longer, 
and  more  slender.  Although  the  larva  lives  in  the  water,  it  is  strictly 
an  air-breather  and  must  come  to  the  surface  for  air.  It  thrusts  its 
breathing  tube  up  into  the  surface  film  and  remains  suspended,  head 
down,  at  an  angle  of  somewhat  less  than  -15  degrees,  which  distinguishes 
it  from  Anopheles  larvae,  which  lie  horizontal.  A  film  of  oil  on  the 
surface  of  the  water  is  sufficient  to  obstruct  the  air  tube  and  thus  cause 


Fig.  23. — Larva  of  Stegomtta  Calopus. 
Respiratory  Syphon  of  Culex  to  the  Right. 


MOSQUITOES 


217 


the  death  of  the  larva  by  suffocation.  The  larva  is  very  timid,  so  that 
a  slight  jar  or  agitation  or  a  sudden  shadow  will  cause  it  to  wriggle 
rapidly  to  the  bottom,  where,  indeed,  it  may  very  commonly  be  observed 
to  feed.  The  duration  of  the  larval  stage  is  never  less  than  6  to  7 
days,  and  depends  upon  the  food  supply  and  temperature.  Under  fa- 
vorable conditions  it  may  be  prolonged  for  weeks.  Freezing  for  short 
periods  does  not  appear  to  injure  it. 


Fig.  24. — Pupa  of  Stegomtia  Calopus. 


Pupa. — The  larva  changes  into  the  pupa.  The  pupa  is  not  provided 
with  a  mouth  and  does  not  feed.  It  is  an  air-breather  and  spends  most 
of  its  time  at  the  surface  of  the  water.  The  pupal  stage  lasts  at  least 
36  hours,  during  which  time  metamorphosis  occurs  into  the  imago  or 
perfect  winged  insect. 

Imago. — Under  the  most  favorable  conditions  it  is  at  least  9  days 
from  the  time  the  Stegomyia  lays  its  egg  to  the  appearance  of  the 
imago.  Under  natural  conditions  the  length  of  life  of  the  adult  female 
probably  varies  greatly.  Guiteras  succeeded  in  keeping  a  presumably 
infected  one  alive  for  154  days  during  the  fall  and  winter  temperature 
in  Havana.  Deprived  of  water,  it  does  not  usually  survive  longer  than 
3I/2  to  4  days,  and  only  very  exceptionally  5  days.  This  fact  has  a 
bearing  on  the  possibility  of  transporting  the  mosquito  in  band-boxes, 
trunks,  and  other  containers. 

"Aerial"  Conveyance, — It  is  notorious  that  yellow  fever  is  usually 
ponveyed  but  a  short  distance  "^aerially" — perhaps  across  the  street,  or. 


218  INSECT-BORXE    DISEASES 

more  often,  to  a  neighboring  house  in  the  rear.  This  represents  a  dis- 
tance of  some  75  yards,  which  is  about  as  far  as  we  may  expect  it  to 
be  thus  conveyed,  from  our  knowledge  of  the  habits  and  flight  of  the 
Stegomyia  mosquito.  The  longest  distance  recorded  in  recent  years  of 
aerial  conveyance  is  one  of  225  meters  (Melier)  and  one  of  456  feet 
(Carter).  These  are  entirely  exceptional.  My  experience  in  the  deten- 
tion of  hundreds  of  susceptible  immigrants  in  quarantine  for  days  in 
Havana  harbor  showed  that  infected  Stegomyiae  do  not  travel  a  short 
distance  across  the  water.  Tliis  observation  is  in  confirmation  of  others, 
that  vessels  moored  within  1,200  feet  of  the  shore  are  entirely  safe  so 
far  as  yellow  fever  is  concerned,  provided,  of  course,  personal  intercourse 
is  interdicted  or  supervised. 

Prevention. — The  prevention  or  suppression  of  yellow  fever  may  be 
attacked  in  either  one  of  its  two  hosts,  man  or  insect.  If  every  person 
developing  yellow  fever  were  immediately  isolated  from  the  Stegomyia 
mosquito,  the  disease  would  inevitably  cease.  The  elimination  of  the 
Stegomyia  mosquito  would  give  the  same  happy  result.  Usually  both 
methods  of  attack  are  employed.  It  would  seem  easier  to  control  the 
human  hOst  simply  by  screening  during  the  first  three  or  four  days 
of  the  fever.  Practically  this  method  has  been  found  insufficient,  be- 
cause the  disease  is  difficult  to  diagnose  in  the  early  stage,  and  the 
mild  cases  escape  attention.  The  essence  of  yellow  fever  prevention, 
therefore,  consists  in :  ( 1 )  screening  cases  of  yellow  fever  and  all  sus- 
pected cases  of  yellow  fever;  (2)  destruction  of  infected  insects;  (3) 
the  suppression  of  stegomyiae  through  the  control  of  their  breeding 
places.  It  was  a  combination  of  these  three  methods  which  was  first  so 
brilliantly  carried  out  by  Gorgas  in  Havana  in  1901,  and  later  in 
Panama ;  by  White  in  Xew  Orleans,  1905 ;  by  Liceaga  for  Vera  Cruz, 
and  recently  by  Oswaldo  Cruz  in  Eio  de  Janeiro,  1909. 

Yellow  fever  patients  should  be  isolated  only  in  the  sense  of  separat- 
ing them  from  Stegomyia  calopus.  This  may  be  done  by  proper 
screening.  It  is  not  necessary  to  remove  the  patient  to  a  hospital,  al- 
though this  is  desirable,  for  the  reason  that  a  special  hospital  is  more 
carefully  guarded  than  is  practicable  in  a  private  house,  and  the  trained 
assistants  are  an  additional  safeguard.  As  soon  as  the  patient  is  re- 
moved, the  mosquitoes  in  the  house  and  the  surroimding  houses  should 
at  once  be  destroyed.  Yellow  fever  patients  must  be  moved  with  caution, 
for  the  reason  that  undue  excitement  or  exertion  seems  to  increase  the 
severity  of  the  disease. 

The  insecticides  best  suited  for  the  destruction  of  mosquitoes  are: 
sulphur  dioxid,  hydrocyanic  acid  gas,  pyrethrum  powder,  tobacco  smoke. 
Mini's  culicide  (camphor  and  phenol)  (see  page  187).  At  first  glance 
it  might  appear  to  be  a  hopeless  task  to  attempt  to  eradicate  the  yel- 
low fever  mosquito  in  a  large  city,  but  that  this  is  possible  was  demon- 


MOSQUITOES  219 

strated  in  Xew  Orleans  in  1905,  when,  after  several  months  of  a 
vigorous  campaign,  it  was  dilficult  to  find  a  Stegomyia  mosquito. 
The  measures  consisted  mainly  in  screening  the  water  cisterns  and 
eliminating  all  standing  collections  of  water  in  and  about  the  house- 
hold. 

Historical  Note. — Dr.  Charles  J.  Finlay  studied  the  relation  of  the 
mosquito  to  yellow  fever  as  far  hack  as  1882  and  1883.  The  first  in- 
sects used  iDy  the  United  States  Army  Commission  to  bring  about  the 
demonstration  of  the  new  doctrine  were  received  from  the  hands  of  Dr. 
Finlay.  Finlay  believed  that  the  cause  of  the  disease  was  a  micrococcus 
and  considered  that  the  insects  were  capable  of  transmitting  the  dis- 
ease a  few  days  after  they  had  stung  a  yellow  fever  patient.  Stern- 
berg's studies  upon  yellow  fever  are  published  by  the  Government  as 
a  report  of  the  United  States  Marine  Hospital  Service  on  the  Etiology 
and  Prevention  of  Yellow  Fever,  1890.  Carter's  observations  at  Orville, 
Mississippi,  upon  the  extrinsic  period  of  incubation  were  published  in 
the  Medical  Record,  June  15,  1901. 

The  work  of  the  United  States  Army  Commission  appeared  in  the 
following  publications : 

"The  Etiology  of  Yellow  Fever — a  Preliminary  jSTote,"  Proceedings 
of  the  28th  Annual  Meeting  of  the  Am.  Pub.  Health  Assn.,  Oct.  22-26, 
1900;  also  Philadelphia  Med.  Jour.,  Oct.  27,   1900. 

-  "The  Etiology  of  Yellow  Fever— An  Additional  Note,"  J.  A.  M.  A., 
Feb.  16,  1901. 

"Experimental  Yellow  Fever,"  Am.  Med.  Jour.,  July  6,  1901. 

"Etiology  of  Yellow  Fever — Supplemental  Note,"  Am.  Med.  Jour., 
Feb.  22,  1902. 

On  account  of  their  historical  interest  and  accuracy,  the  conclusions 
of  the  United  States  Army  Commission  are  here  given : 

1.  The  mosquito — C.  fasciatus — serves  as  the  intermediate  host 
for  the  parasite  of  yellow  fever. 

2.  Yellow  fever  is  transmitted  to  the  non-immune  individual  by 
means  of  the  bite  of  the  mosquito  that  has  previously  fed  on  the  blood 
of  those  sick  with  this  disease. 

3.  An  interval  of  about  12  days  or  more  after  contamination  ap- 
pears to  be  necessary  before  the  mosquito  is  capable  of  conveying  the 
infection. 

4.  The  bite  of  the  mosquito  at  an  earlier  period  after  contamina- 
tion does  not  appear  to  confer  any  immunity  against  a  subsequent  at- 
tack. 

5.  Yellow  fever  can  also  be  experimentally  produced  by  the  sub- 
cutaneous injection  of  blood  taken  from  the  general  circulation  during 
the  first  and  second  days  of  the  disease. 

6.  An  attack  of  yellow  fever  produced  by  the  bite  of  the  mosquito 


230  INSECT-BORNE    DISEASES 

confers  immunity  against  the  subsequent  injection  of  the  blood  of  an 
individual  suffering  from  the  non-experimental  form  of  this  disease. 

7.  The  period  of  incubation  in  thirteen  cases  of  cxj)c'rimental  yel- 
low fever  has  varied  from  forty-one  hours  to  five  days  and  seventeen 
hours. 

8.  Yellow  fever  is  not  conveyed  by  fomites,  and  hence  disinfection 
of  articles  of  clothing,  bedding,  or  merchandise,  supposedly  contami- 
nated by  contact  with  those  sick  with  this  disease,  is  unnecessary. 

9.  A  house  may  be  said  to  be  infected  with  yellow  fever  only  when 
there  are  present  within  its  walls  contaminated  mosquitoes  capable  of 
conveying  the  parasite  of  this  disease. 

10.  The  spread  of  the  yellow  fever  can  be  most  effectually  con- 
trolled by  measures  directed  to  the  destruction  of  mosquitoes  and  the 
protection  of  the  sick  against  the  bites  of  these  insects. 

11.  While  the  mode  of  proj)agation  of  yellow  fever  has  now  been 
definitely  determined,  the  specific  cause  of  this  disease  remains  to  be 
discovered. 

Prevention  of  Malaria  and  Yellow  Fever  Contrasted. — For  the  pre- 
vention of  malaria  the  same  principles  guide  us  that  have  been  set 
forth  for  the  prevention  of  yellow  fever.  In  practical  application,  how- 
ever, our  methods  of  attack  differ,  owing  to  differences  in  the  habits  of 
the  two  mosquitoes,  and  owing  to  differences  in  the  two  diseases.  The 
malarial  problem  is  much  more  difficult,  because  it  is  harder  to  get  rid 
of  Anopheles  than  of  Stegomyia.  The  breeding  places  of  the  yellow 
fever  mosquito  are  practically  confined  to  artificial  containers  in  the 
neighborhood  of  human  habitations,  while  those  of  anopheles  are  found 
in  marshes,  pools,  or  streams,  and  often  in  collections  of  water  in  the 
grass  or  brush.  The  breeding  places  of  the  malarial  mosquito  cover  a 
much  larger  area,  frequently  the  whole  country,  and  are  rather  hard 
to  find  and  difficult  to  destroy;  also  this  insect  travels  much  further 
from  its  breeding  place  than  the  Stegomyia,  probably  from  three  to  four 
times  as  far.  Compared  to  yellow  fever,  the  control  of  the  malarial 
human  host  presents  special  difficulties.  In  yellow  fever  man  is  infec- 
tive to  the  Stegomyia  only  a  few  days;  in  malaria  the  parasites  continue 
in  the  circulating  blood  a  very  long  time.  In  the  case  of  malaria,  then, 
we  have  to  deal  with  chronic  carriers,  which,  fortunately  for  us,  does 
not  occur  in  yellow  fever.  For  malaria  we  have  quinin  as  a  prophylac- 
tic, whereas  no  known  drug  will  prevent  yellow  fever. 

DENGUE 

All  who  visit  the  tropics  or  subtropical  countries  where  dengue  pre- 
vails are  very  apt  sooner  or  later  to  contract  this  infection.  So  far  as 
known,  few  persons  have  ever  died  of  dengue.     Although  the  mortality 


MOSQUITOES  221 

is  practically  nil,  the  disease  is  a  painful  affection  and  sometimes  leaves 
the  body  in  a  weakened  condition  for  long  periods  of  time.  In  its 
epidemiology  and  symptomatology  the  disease  strikingly  parallels  yellow 
fever,  which  adds  to  its  importance.  Outbreaks  of  dengue  often  precede 
and  may  be  coincident  with  those  of  yellow  fever.  In  the  tropics  influ- 
enza and  dengue  are  also  frequently  confused.  Dengue  also  has  some 
resemblance  to  the  three-day  fever  or  pappataci  fever  of  Herzegovina, 
which  is  transmitted  by  the  bite  of  the  Phlehotomus  pappatasii,  a  biting 

fly- 

There  is  no  definite  immunity  produced  by  an  attack  of  dengue. 
Persons  often  give  a  history  of  an  attack  in  each  outbreak.  The  cause 
of  the  disease  is  not  known. 

Graham  studied  dengue  in  Beirut,  Syria,  and  described  a  protozoon 
inhabiting  the  red  blood  corpuscles  and  closely  resembling  the  Plasmo- 
dium of  malaria  except  for  the  absence  of  pigment.^  Graham  believed 
that  this  organism  underwent  a  developmental  stage  within  the  mos- 
quito (Culex  fatigans).  He  claimed  to  have  observed  the  spores  of  this 
organism  "in  among  the  cells  of  the  salivary  glands"  after  48  hours  in 
mosquitoes  which  had  bitten  a  dengue  patient  upon  the  fourth  day  of 
the  disease.  Graham  produced  a  very  severe  case  of  fever  resembling 
dengue  by  inoculating  a  man  subcutaneously  with  peptonized  normal 
salt  solution  containing  the  salivary  glands  of  a  mosquito  which  had 
bitten  a  dengue  patient  24  hours  before.  Graham's  observations  con- 
cerning the  parasite  in  the  blood  and  in  the  mosquito  have  not  been 
confirmed,  although  the  subject  has  been  studied  by  several  experienced 
microscopists.  Carpenter  and  Sutton,-  however,  obtained  two  positive 
results  out  of  four  experimental  cases  of  mosquito  inoculation.  The 
period  of  incubation  in  one  of  these,  however,  was  two  weeks,  and  the 
subjects  were  not  sufficiently  controlled  to  exclude  the  bites  of  other  mos- 
quitoes. Agramonte '  studied  an  epidemic  in  Habana  which  was  ac- 
companied by  a  plague  of  Culex  fatigans.  He  attempted  to  transmit 
the  disease  by  mosquitoes,  trying  various  species  at  various  intervals 
after  the  insects  had  fed  upon  dengue  patients,  but  did  not  succeed  in 
producing  the  disease  in  this  way.  Guiteras  and  Finlay  *  endeavored 
to  transmit  the  disease  with  Culex  pipiens,  but  with  negative  results. 
Guiteras,  Finlay,  Agramonte,  and  others  who  have  worked  upon  this 
subject  state  that  their  faith  remains  unshaken  that  the  mosquito  acts  as 
the  vector  of  dengue,  despite  the  negative  results  of  their  experiments. 

Ashbum  and  Craig  ^  in  1907  studied  the  disease  in  Manila  and 
showed  that  the  virus  is  contained  in  the  blood  during  the  febrile  stage. 

^Jour.  Trap.  Med.,  1903,  Vol.  VI,  p.  209. 

'■'Jour.  A.  M.  A.,  1905,  XLIV. 

^New  Yorlc  Med.  Jour.,  1906,  LXXXIV. 

*Rev.  Med.  Trop.,  1906,  Vol.  VII,  p.  53. 

^Philippine  Jour,  of  Sci.,  Vol.  II,  No.  2,  Section  B,  May  1,  1907. 


222  INSECT-BOILXE    DISEASES 

The  intravenous  inoculation  of  filtered  dengue  blood  into  healthy  men 
is  followed  by  a  typical  attack  of  the  disease.  The  cause  of  the  disease 
is,  therefore,  probably  ultramicroscopic.  They  transmitted  the  infec- 
tion by  the  mosquito,  Ciilcx  fatigans,  and  concluded  that  this  is  probably 
the  most  common  method  of  transmission.  The  period  of  incubation 
in  the  experimental  cases  averaged  3  days  and  14  hours.  They  con- 
cluded from  their  studies  that  dengue  is  "not  a  contagious  disease,  and 
is  infectious  in  the  same  manner  as  are  yellow  fever  and  malaria." 

All  our  preventive  measures  are  now  based  upon  the  supposition  that 
dengue  is  a  mosquito-borne  infection.  At  times  dengue  appears  to  be 
one  of  the  most  contagious  of  all  diseases,  for  it  spreads  like  wildfire 
and  spares  practically  no  one  in  the  community.  An  instance  showing 
the  non-contagiousness  of  dengue  is  given  by  Persons,  U.  S.  N. :  A 
squad  of  marines  from  the  U.  S.  S.  Baltimore  were  given  shore  leave 
at  Cavite.  Twenty  of  the  24  marines  who  had  been  ashore  came  down 
with  the  disease  after  returning  to  the  ship,  while  there  was  a  total  ab- 
sence of  infection  among  those  who  had  remained  aboard.  Observations 
made  at  the  Xaval  Hospital  at  Canacao  demonstrated  that  in  the  mos- 
quito-free wards  the  disease  did  not  spread,  whereas  when  the  hospital 
was  located  at  Cavite  it  was  noted  that  practically  every  case  admitted 
became  infected  with  dengue  while  under  treatment  for  the  original 
complaint  (Stitt). 

FILAIUASIS 

The  filaria  is  a  long,  slender  filiform  threadworm  with  a  curved  or 
spiral  tail.  The  adult  worms  live  in  the  connective  tissue,  lymphatics, 
and  body  cavities.  The  embryos  or  larva  are  found  in  great  numbers 
in  the  blood.  In  several  species  of  which  the  life  history  is  known  mos- 
quitoes act  as  the  intermediate  host.  The  most  important  filariae  of  man 
are:  (1)  Filaria  bancroftii,  the  larva  of  which  is  known  as  Filaria 
nociurna,  appearing  in  the  blood  at  night  and  occurring  especially  in 
Australia  and  the  tropics;  (2)  Filaria  loa,  the  larva  of  which  is 
known  as  Filaria  diurna,  occurring  in  the  blood  by  day  and  prevalent  in 
West  Africa  and  India;  (3)  the  Filaria  perstans,  the  larva  of  which  is 
known  as  Filaria  perstans,  which  persists  in  the  blood  both  day  and 
night,  and  occurs  especially  in  West  Africa  and  a  number  of  other  places. 
None  of  these  young  worms  do  any  appreciable  injury  in  the  blood;  of 
the  adult  worms,  only  one.  namely,  Filaria  hancrofti,  can  be  viewed 
as  serious,  while  the  second  species,  Filaria  loa,  is  more  or  less  trouble- 
some. According  to  Manson,  we  are  hardly  justified  at  present  in  as- 
suming that  all  the  other  species  are  entirely  without  effect  upon  their 
hosts.  These  parasites  infect  man  throughout  the  tropical  and  sub- 
tropical belt.  In  the  United  States  the  infection,  while  not  very  preva- 
lent, is  endemic  as  far  north  as  Charleston. 


FLIES  223 

According  to  Manson,  Culex  faiigans,  and  according  to  James 
the  Anopheles  nigerrinus,  are  the  intermediate  hosts.  When  fed  on 
the  blood  of  a  filarial-infested  individual,  it  is  found  that  the  filarial 
larvge  soon  escape  from  their  shields  in  the  thickened  blood  within  the 
stomach  of  the  mosquito.  They  pierce  the  stomach  wall,  enter  the 
thoracic  muscles  of  the  insect,  pass  through  a  metamorphosis  which 
takes  from  16  to  20  daj's  (longer  or  shorter,  according  to  atmospheric 
temperature)  ;  they  now  quit  the  thorax  and  a  few  find  their  way  to 
the  abdomen;  the  vast  majority,  however,  pass  forward  through  the 
prothorax  and  neck,  and,  entering  the  head,  coil  themselves  up  close  to 
the  base  of  the  proboscis  and  beneath  the  pharynx  and  under  surface  of 
the  cephalic  ganglia.  This  account  is  taken  from  Manson,  to  whose  per- 
sonal interest  in  this  disease  we  are  indebted  for  the  advances  in  our 
knowledge  of  the  entire  subject  of  filariasis.  The  wonderful  prepara- 
tions of  Low  may  be  seen  at  the  London  School  of  Tropical  Medicine, 
showing  the  Filana  nodurna  in  the  head  and  proboscis  of  the  mosquito 
ready  to  come  out  when  the  proboscis  of  the  insect  pierces  its  victim. 
The  fact  that  the  mosquito  is  the  intermediate  host  in  conveying  the 
infection  of  Filaria  rests  upon  these  observations  and  not  upon  experi- 
ments which  demonstrate  the  actual  transference  of  the  disease.  Whether 
the  worm  may  obtain  an  entrance  by  any  other  channel  or  medium 
would,  according  to  Manson,  be  hard  to  prove  and  rash  to  deny.  Our 
correct  preventive  measures  are  based  upon  the  theory  that  this  is  an 
insect-borne  disease,  although  other  possible  modes  of  transference  must 
not  be  neglected.  Prophylaxis,  therefore,  depends  upon  the  suppression 
of  the  mosquito  and  the  prevention  of  the  infective  mosquito-bite.  As 
it  is  not  definitely  known  how  many  species  of  mosquitoes  convey  the 
infection,  the  preventive  measures  must  be  along  general  lines;  a  com- 
bination of  those  described  under  malaria  and  yellow  fever,  as  well  as 
general  sanitation  and  personal  hygiene. 

FLIES 

The  true  flies  have  but  two  wings,  that  is,  they  belong  to  the  order 
Diptera.  They  comprise  an  enormous  number  of  species.  Not  only 
have  the  flies  a  superiority  in  point  of  numbers,  but  entomologists  are 
concluding  that  they  probably  stand  at  the  head  of  the  insect  system 
in  point  of  evolution;  that  is,  they  are  the  most  highly  specialized  of 
all  insects.  Contrary  to  popular  opinion,  flies  are  poor  scavengers.  Most 
flies  prefer  the  sunshine,  but  species  vary  greatly  in  their  habits  and 
breeding  places.  However,  surprisingly  little  is  known  of  the  life  his- 
tory and  habits  of  most  flies.  The  subject  lacks  attraction — especially 
the  maggots  or  larval  stage.  The  life  history  of  the  house  fly  in  general 
was,  down  to  1873,  mentioned  in  only  three  European  works,  and  few 


224 


INSECT-BOENE    DISEASES 


Fig.  25. — House  Fly  {Musca  domestica). 
Showing  Proboscis  in  the  Act  of 
Eating  Sugar. 


exact  facts  were  given.  Dr.  A.  S.  Packard,  then  of  Salem,  Mass., 
studied  the  house  fly  and  gave  descriptions  of  all  its  stages,  showing  that 
the  growth  of  a  generation  from  the  egg  to  the  adult  occupies  from  10 
to  14  days.  In  1895  Howard  further  traced  the  life  history  and  indi- 
cated that  120  eggs  are  laid  hy  a  single  female,  and  that  a  generation 
is  produced  every  10  days  at  the  summer  temperatures  of  Washington. 

There  may  be,  therefore.  12  gen- 
erations in  a  summer.  If  each 
female  lays  only  120  eggs  (1,- 
000  have  been  noted),  we  have 
the  po.ssil)ility  of  countless  mil- 
lions coming  from  a  single  fly 
during  a  single  season.  Allow- 
ing 1,000  flies  to  the  ounce,  it 
bas  been  estimated  that  the  total 
product  of  a  single  fly  in  40 
days  would  equal  810  ])Ounds, 
provided  only  one-half  of  them 
survived ;  hence,  the  logical  time 
to  begin  fly  suppression  is  in  the  early  spring.  Flies  transmit  disease 
in  one  of  several  ways.  The  biting  flies,  such  as  the  tsetse  flies,  which 
transmit  sleeping  sickness,  inoculate  the  trypanosome  directly  into  the 
system  by  piercing  the  skin  with  their  mouth  parts.  The  common 
house  fly  does  not  bite.  Biting  flies,  such  as  the  Stomoxys  calcitrans, 
abound  in  the  United  States  in  stables,  houses,  and  also  in  nature. 
They  have  recently  been 
implicated  as  go-betweens 
in  poliomyelitis,  and  also 
in  anthrax,  relapsing 
fever,  horse  sickness 
(Pferdesterbe),  and  epi- 
thelioma of  fowls.  Other 
blood-sucking  genera, 
such  as  Tahanus,  Chry- 
sops,  Hcematohia,  etc., 
are  of  common  occur- 
rence, but  are  not  known  to  carry  any  infection  regularly,  although  they 
might  readily  do  so. 

The  following  brief  account  of  the  common  house  fly  may  be  taken 
as  a  type  of  the  life  history  and  habits  of  flies  in  general.  Eemedies 
and  preventive  measures  depend  upon  the  peculiarities  in  the  life  his- 
tory and  habits  of  each  particular  genus  and  species. 

Life  History  of  the  Musca  Domestica. — A  few  adults  live  over  the 
winter  in  cellars,  barns,  attics,  and  out-of-the-way  places,  and  as  soon 


Fig.  26. — Eggs  of  House  Fly  as  Laid  in  a  Mass. 


FLIES  225 

as  warm  weather  sets  in  they  lay  their  eggs  in  manure  or  organic 
refuse.  In  6  to  8  hours  the  eggs  hatch  into  larvae  (maggots),  which 
grow  rapidly  and  are  fully  developed  in  4  or  5  days.     Each  larva  then 


Fig.  27. — Eggs  of  House  Fly.    Some  have  hatched. 

becomes  a  pupa  in  a  hard  brown  case — the  puparium.  In  5  days  more 
the  pupal  case  opens  and  the  adult  fly  appears  for  a  season  of  activity 
covering  several  weeks.     Most  of  them  die  in  the  early  autumn,  in  great 


Fig.  28. — Larv^  of  House  Fly. 


part  due  to  a  fungus  disease,  caused  by  Emptisa  muscce,  which  becomes 
prevalent  among  the  flies  at  this  season  of  the  year.  A  few  are  left  and 
hibernate  to  continue  the  species.  Hence,  it  takes  about  10  days  from 
egg  to  imago.     It  is,  therefore,  important  to  remove  manure,  garbage, 


22G 


INSECT-BORXE    DISEASES 


Fig.  29. — Puparium  of  House  Fly. 


and  other  organic  refuse  at  least  as  often  as  this  in  order  to  prevent 
the  development  of  the  winged  insects. 

The  chief  breeding  place  of  common  house  flies  is  in  horse  manure. 
They  also  have  been  found  to  breed  in  human  excrement,  fermenting 

vegetable  and  putrefying  animal 
matter,  in  the  bedding  in  poultry 
pens,  in  refuse  hog  hair,  in  tal- 
low vats,  in  carcasses  of  varicms 
animals,  and  in  garbage  and  or- 
ganic material  of  all  kinds.  All 
of  which  means  that  if  we  allow 
the  accumulation  of  filth  we  will 
have   hou>('   i]\e<. 

Life  History  of  Stomoxys  Cal_ 
citrans. — Stomoxys  calcitrans,  the 
biting  staljle  tly,  is  very  similar 
to  the  house  fly  in  its  life  history 
and  in  appearance  during  the 
preparatory  stages,  but  develops 
more  slowly,  requiring  nearly  a 
month  to  undergo  a  complete  life 
cvde.  The  eggs  are  laid  like  those  of  the  house  fly  in  horse  "manure, 
but  more  frequently  in  fermenting  heaps  of  grass,  cow-dung,  brewers 
refuse  ("spent  hops"),  etc.  The  adult  flies  are  much  like  the  house 
fly,  but  have  a  sharp,  needle-like  proboscis.  They  feed  exclusively  on. 
mammalian  blood  and  are 
a  great  annoyance  to 
horses  and  cattle  in  late 
summer  and  autumn. 
They  bite  persons  less 
frequently,  but  are  of  im- 
portance on  account  of 
their  relation  to  polio- 
myelitis, anthrax,  etc. 
The  stable  fly  can  best  be 
controlled  by  eliminating 
its  breeding  places. 

Flies  as  Mechanical 
Carriers  of  Infection. — 
Leidy  in  18G4  attributed 

the  spread  of  gangrene  in  hospitals  during  the  Civil  ^Ya^  to  the  agency 
of  the  house  fly.  Shortly  thereafter  it  was  discovered  that  the  bite  of 
the  gad-fly  may  transmit  anthrax  from  cattle  to  man.  Later  it  was 
found  that  purulent  ophthalmia  of  the  Egyptians  is  carried  by  the  house 


Fig.  30. — Stable  Fly  (^Stomoxys  calcitrans).     (Brues. 


FLIES 


^21 


Fig.  31. — Head  show- 
ing Proboscis, 
Stomoxys  Calci- 
TKANS.      (Brues.) 


fly,  and  the  spread  of  an  infectious  conjunctivitis  known  as  "pink  eye" 
in  the  South  has  heen  shown  by  Hubbard  to  be  facilitated  by  little 
midges  of  the  genus  Hippelates.  Eeference  has  already  been  made  to 
the  bite  of  the  tsetse  flies  in  spreading  nagana,  sleeping  sickness,  and 
other  trypanosomatic  infections.  Eeeently  the  stable  fly  has  been  shown 
to  be  able  to  transmit  various  infections  in  a  mechanical  way. 

It  is  now  known  that  typhoid  fever  and  other  intestinal  infections 
may  be  transmitted  by  the  common  house  fly.  Celli 
in  1888  fed  flies  with  pure  cultures  of  typhoid, 
and  showed  that  the  virulent  bacilli  were  passed 
in  the  dejecta.  Kober  in  1895  was  one  of  the  first 
to  call  special  attention  to  the  danger  of  contami- 
nating food  supplies  by  flies  coming  from  the  ex- 
creta of  typhoid  patients.  The  United  States 
Army  Commission — Keed,  Vaughan,  and  Shake- 
speare— studied  the  presence  of  typhoid  fever  in 
our  camps  during  the  Spanish- American  war  in  the 
summer  of  1898.  They  concluded  that  flies  un- 
doubtedly serve  as  carriers  of  the  infection.  '"Flies 
swarm  over  infected  fecal  matter  in  the  pits  and  then  deposit  it  and 
feed  upon  the  food  prepared  for  the  soldiers  at  the  mess  tents.  In  some 
instances,  where  lime  had  recently  been  sprinkled  over  the  contents  of 
the  pits,  flies  with  their  feet  whitened  with  lime  were  seen  walking  over 
the  food."  Vaughan  subsequently  stated  that  he  considered  that  about 
15  per  cent,  of  the  cases  of  typhoid  in  the  camps  were  caused  by  fly 

transmission. 

Alice  Hamilton  ^  iso- 
lated typhoid  bacilli  from 
5  out  of  18  house  flies 
captured  in  Chicago  in 
the  privies  and  fence 
near  a  sick  room.  It  has 
been  shown  experi- 
mentally that  living,  ty- 
phoid bacilli  may  re- 
main in  or  upon  the 
bodies  of  flies  for  as  long  as  23  days  after  infection. 

Howard  studied  fly  abundance  in  relation  to  the  origin  and  preva- 
lence of  typhoid  fever  in  the  District  of  Columbia  in  the  summer  of 
1908.^  No  particular  correlation  between  the  prevalence  of  the  flies  and 
the  prevalence  of  the  disease  could  be  made  out. 


^ 

^^^= 

_,. — ' 

— -"^..^ 

•-''■''■■''' 

X 

xC 

— ""^ 

"^^v^^'^---^ 

-~-^_--^ 

^ 

^H 

\/ 

^^^ 

~..,. 

Fig.  32. — Wing  of  Stable  Fly   (Stomoxys  calcitrans). 


^Jour.  A.   M.  A.,   1903,  40,   p.   576. 

^Rosenau,  Lumsden,  and  Kastle:    Report  No.  3,  1908,  P.  H.  and  M.   H.  S., 
Hygienic  Laboratory  Bull.   No.  52. 


228 


INSECT-BORNE    DISEASES 


Flies  undoubtedly  spread  the  infection  of  typhoid  fever,  hut  the  im- 
portance of  the  role  they  jjlay  in  this  regard  varies  considerably  with 
circumstances.  In  camps,  unsewered  towns,  and  overcrowded  places  in 
poor  sanitary  condition  the  danger  from  flies  may  ho  considerable,  but 
even  under  the  worst  conditions  it  is  doul)tful  whether  flies  ever  play 
the  major  role  or  are  responsible  for  the  bulk  of  typhoid  fever,  as  has 
leen  stated.  In  a  well-sewered  city,  such  as  Washington,  we  concluded 
that  the  flies  are  probably  responsible  but  for  an  occasional  case  of  the 
disease.  It  is  very  difficult  in  any  particular  instance  to  know  quantita- 
tively just  how  much  of  the  infection  is  conveyed  by  flies  and  how 
much  by  contacts.  The  danger  of  flies  is  great  enough  without  the  need 
of  exaggeration,  and  their  suppression  fully  justifies  the  best  energies 
of  the  health  officer.  It  is  perhaps  a  mistake  to  call  the  common  house 
fly  the  "ty})hoid  fly,"  not  alone  for  the  reason  that  tlie  disease  is  spread 
in  many  other  ways,  but  for  the  reason  that  the  fly  is  responsible  for 

the  spread  of  many  infec- 
tions other  than  typhoid 
fever.  Flies  undoubtedly 
play  the  same  role  in 
dysentery,  cholera,  and 
all  other  intestinal  infec- 
tions that  they  do  in 
typlioid  fever.  Tizzoni 
and  Cattani  in  1896  dem- 
onstrated active  cholera 
organisms  in  the  dejecta 
of  flies  caught  in  the 
cholera  colonies  of 
Bologna,  Italy.  These 
observations  were  subsequently  verified  and  extended  by  Simonds,  Offel- 
man,  McEae,  and  others. 

It  is  now  quite  evident  that  flies  lighting  upon  a  case  of  smallpox, 
measles,  scarlet  fever,  and  other  exanthematous  disease  may  very  readily 
transmit  these  infections  to  another  person.  I  have  actually  seen  mag- 
gots breeding  in  the  open  lesions  of  a  case  of  smallpox  treated  in  the 
open  air  at  Eagle  Pass,  Texas. 

Flies  may,  in  the  same  mechanical  wa}^  transmit  the  infection  of 
erysipelas,  anthrax,  glanders,  and  other  skin  infections.  It  is  known 
that  flies  may  ingest  tuberculous  sputum  and  excrete  tubercle  bacilli 
which  may  remain  virulent  as  long  as  15  days.  Flies  have  also  been 
associated  with  leprosy  and  many  other  diseases. 

Esten  and  Mason  ^  counted  the  bacterial  population  of  415  flies  and 
found  that  the  number  of  bacteria  on  a  single  fly  may  range  all  the 
^Store's  Agricultural  Experiment  Station,  Bull.  No.  51,  April,  1908. 


Fig.    33. — The    "Little    House    Fly"    (Homulomyia 
canicularis   i  ).     (Hewitt.) 


PLIES 


329 


way  from  550  to  6,600^000.  Early  in  the  fly  season  the  numbers  of 
bacteria  on  flies  are  comparatively  small,  while  later  the  numbers  are 
comparatively  very  large.  The  places  where  flies  live  also  determine 
largely  the  number  of  bacteria  they  carry.  The  average  of  the  415  flies 
was  about  one  and  one-quarter  million  bacteria.  The  method  of  the  ex- 
periment was  to  introduce  the  flies  into  a  sterile  bottle  and  pour  into  the 
bottle  a  known  quantity  of  sterilized  water,  then  shake  the  bottle  to 
wash  the  bacteria  from  the  body  of  the  fly.  The  numbers,  therefore, 
only  represent  those  carried  on  the  outside  and  not  those  in  the  intestinal 
tract.  The  experiments  of  Esten  and  Mason  were  designed  to  simulate 
the  number  of  microorganisms  that  would  come  from  a  fly  in  falling 
into  milk. 

Torrey  ^  found  that  a  single  fly  may  carry  from  570  to  4,400,000 
bacteria  upon  its  surface,  and  from  16,000  to  38,000,000  in  its  intes- 
tinal-tract.    The  prevailing  types  are  Streptococctis  equiniis  fecalis  and 


Fig.  34. — Wing  op  House  Fly,  Showing  How  It  Carries  Dust  Particles. 


salivarius,  which  are  also  found  in  the  breeding  and  feeding  places  of 
the  house  fly.  Torrey  also  obtained  three  cultures  of  B.  paratypliosus, 
which  is  especially  significant. 

Even  though  flies  breed  in  manure,  and  the  larvae  teem  with  bacteria, 
the  adult  winged  insect,  when  newly  hatched,  contains  fewer  micro- 
organisms. This  cleansing  is  due  to  the  active  phagocytosis  which  takes 
place  during  metamorphosis  from  pupa  to  imago.  The  bacteria  in  the 
intestinal  tract  of  the  newly  hatched  imago  are  mostly  extruded  soon 
after  emergence  from  the  puparium. 

Bacot,^  however,  has  shown  that  certain  species  of  bacilli  ingested 
during  the  larval  period  of  Musca  domestica  can  retain  their  existence 
while  their  host  is  undergoing  the  process  of  metamorphosis,  and  con- 
tinue their  existence  in  the  gut  of  the  adult  fly,  but  that  their  number 
diminishes  suddenly  after  emergence.     In  a  subsequent  work   Bacot^ 

^J.  A.  M.  A.,  May  11,  1912,  LVIII,  No.   19,  p.   1445. 
'  Trans.  Ento.  Soc,  London,  1911,  Part  II,  p.  497. 
""  Parasitology,  IV,  I,  Mar.,  1911,  p.  68. 
17 


230  INSECT-BORNE    DISEASES 

demonstrated  that  Bacillus  pyocyaneus  may  thus  survive.  Faichnie  * 
shows  how  B.  typhosus  may  also  persist.  Ledingliam  confirms  tlu'se  con- 
clusions, and  states  that  he  has  recently  isolated  B.  typhosus  from  pupa, 
the  larva>  of  which  have  fed  on  tliis  organism. 

Graham-Smith  -  recovered  B.  anthracis  from  blow  flies  bred  from 
larvae  fed  on  meat  infected  with  tlie  organism,  but  failed  to  recover 
B.  typhosus  and  B.  entpritidis. 

Among  the  list  of  diseases  of  wiiich  there  is  more  or  less  evidence 
that  the  infection  may  be  conveyed  by  files  are:  typhoid,  cholera,  dysen- 
tery, diarrhea  in  infants,  anthrax,  yaws,  erysipelas,  ophthalmia,  diph- 
theria, smallpox,  plague,  tropical  sore,  parasitic  worms,  sleeping  sick- 
ness, poliomyelitis,  relapsing  fever,  and  several  infections  of  the  lower 
animals. 

An  interesting  light  was  thrown  on  the  possible  modes  of  dissemina- 
tion of  the  eggs  and  larvae  of  hookworms  by  Galli-Valerio  (1905).  He 
phiced  eggs  and  larva?  of  Ankylostouia  duodenaUs  in  a  bottle  with  flies, 
and  on  washing  found  many  eggs  and  encapsulated  larvae  which  had 
adhered  to  their  bodies,  but  none  in  the  flies'  intestines. 

Flies  may  transmit  the  virus  of  disease  mechanically,  either  through 
their  dejecta  or  upon  their  mouth  parts,  legs,  and  other  surfaces  of  the 
body.  The  flies  may  carry  the  infection  directly  to  our  lips  or  indirectly 
to  our  fond  or  to  any  surface  upon  which  they  light. 

Suppression. — The  suppression  of  the  common  house  fly  may  be  ac- 
complished by  striking  at  their  breeding  places.  In  a  city  this  does  not 
present  very  great  difficulty.  It  resolves  itself  simply  into  a  matter  of 
cleanliness — organic  cleanliness  of  our  environment.  The  chief  breed- 
ing places  are  in  horse  manure  and  garbage.  These  should  be  given 
first  attention.  One  neglected  stable  will  furnish  a  plague  of  flies  for 
an  entire  neighborhood.  Their  suppression  in  a  well  ordered  city  for- 
tunately is  neither  expensive  nor  difficult,  but  it  requires  a  well-trained 
and  capable  corps  of  inspectors  with  sufficient  autliority  to  enforce  the 
regulations.  The  suppression  of  flies  by  voluntary  effort  through  the 
slow  process  of  education  cannot  be  relied  upon. 

In  cities  stable  manure  should  be  placed  in  properly  covered  recep- 
tacles and  removed  at  least  once  a  week.  Tliis  one  measure  obviates  the 
use  of  kerosene,  chlorid  of  lime.  Paris  green,  or  arsenate  of  lead,  all  of 
which  are  expensive  and  uncertain  unless  used  frequently  and  in  lib- 
eral amounts ;  further,  they  decrease  the  fertilizing  value  of  the  manure. 

Garbage  should  be  kept  in  water-tight  cans  with  good  covers  and 
removed  frequently,  especially  in  the  warm  weather.  Eefuse  on  city 
lots,  in  back  yards,  in  alleys,  about  wharves,  markets,  and  similar  places 
where  organic  matter  collects  should  be  regularly  and  faithfully  taken 

^  Jour.  Boy.  Army  Med.  Corps,  XIII,  1909. 

^'Eepts.  to  Local  Gov.  Bd.,  New  Series,  No.  53,  1911. 


PLIES 


231 


Fig.    35.— The    Hodge    Fly    Thap 
ON  A  Garbage  Can. 


away.  Householders,  provision  merchants,  storekeepers,  and  others 
should  be  held  responsible  for  the  cleanliness  and  tidiness  of  their  prem- 
ises, and  those  who  violate  these 
simple  and  primitive  hygienic  re- 
quirements should  have  their  places 
cleaned  up  for  them  at  their  own 
expense.  The  orders  of  the  Health 
Department  of  the  District  of  Co- 
lumbia, published  May  3,  1906,  are 
excellent,  and,  if  carried  out,  would 
be  very  effective.  These  orders  may 
be  briefly  condensed  as  follows : 

All  stalls  in  which  animals  are 
kept  shall  have  the  surface  of  the 
ground  covered  with  a  water-tight 
floor.  Every  person  occupying  a 
building  where  domestic  animals  are 
kept  shall  maintain,  in  connection 
therewith,  a  bin  or  pit  for  the  recep- 
tion of  manure,  and,  pending  the 
removal  from  the  premises  of  the 
manure  from  the  animal  or  animals,  shall  place  such  manure  in  said 
bin  or  pit.  This  bin  shall  be  so  constructed  as  to  exclude  rain  water, 
and  shall  in  all  other  respects  be  water-tight,  except  as  it  may  be  con- 
nected with  the  public  sewer.  It  shall  be  provided  with  a  suitable  cover 
and  constructed  so  as  to  prevent  the  ingress  and  egress  of  flies.  No 
person  owning  a  stable  shall  keep  any  manure  or  permit  any  manure 
to  be  kept  in  or  upon  any  portion  of  the  premises  other  than  the  bin 
or  pit  described,  nor  shall  he  allow  any  such  bin  or  pit  to  be  overfilled 
or  needlessly  uncovered.  Horse  manure  may  be  kept  tightly  rammed 
into  well-covered  barrels  for  the  purpose  of  removal  in  such  barrels. 
Every  person  keeping  manure  in  any  of  the  more  densely  populated 
parts  of  the  District  shall  cause  all  such  manure  to  be  removed  from 
the  premises  at  least  twice  every  week  between  June  1  and  October  31, 
and  at  least  once  every  week  between  Kovember  1  and  May  31.  No 
person  shall  remove  or  transport  any  manure  over  any  public  highway 
in  any  of  the  more  densely  populated  parts  of  the  District  except  in  a 
tight  vehicle,  which,  if  not  closed,  must  be  effectually  covered  with 
canvas,  so  as  to  prevent  the  manure  from  being  dropped.  No  person 
shall  deposit  manure  removed  from  the  bins  or  pits  within  any  of  the 
more  densely  populated  parts  of  the  District  without  a  permit  from 
the  health  officer.  Any  person  violating  any  of  these  provisions  shall, 
upon  conviction  thereof,  be  punished  by  a  fine  of  not  more  than  $40 
for  each  offense. 


232  INSECT-BORNE    DISEASES 

In  addition  to  this  ordinance,  others  have  been  issued  by  the 
health  department  of  the  District  of  Columbia  which  provide  against 
the  contamination  of  exposed  food  by  flies  and  by  dust.  The  ordinances 
are  excellently  worded  so  as  to  cover  all  possible  cases.  They  provide 
for  the  registration  of  all  stores,  markets,  cafes,  lunch  rooms,  or  any 
other  places  where  food  or  beverage  is  manufactured,  prepared,  stored, 
offered  for  sale,  or  sold. 

Where  it  is  not  practicable  to  remove  manure,  it  may  be  kept  cov- 
ered in  a  dark  place,  which  discourages  the  visitation  and  breeding  of 
flies,  and  in  addition  should  be  carefully  screened.  Flies  may  be  de- 
stroyed with  sulphur  dioxid,  carbon  bisulphid,  hydrocyanic  acid  gas, 
petroleum,  chlorinated  lime,  Paris  green,  and  other  insecticides.  Kero- 
sene (petroleum)  poured  upon  manure,  garbage,  and  other  fly-breeding 
places  is  effective ;  it  kills  the  larvae.  Lime  is  not  effective ;  chlorinated 
lime  is  good,  but  is  not  practical,  for,  like  all  other  substances  used 
for  this  purpose,  it  needs  frequent  application  and  in  generous  amounts. 

Flies  are  thirsty  insects  and  will  be  attracted  to  a  saucer  of  water 
containing  a  little  formalin  (4  per  cent.).  This  simple  measure  will 
kill  many  of  them  in  a  room.  The  salts  of  barium,  cobalt,  and  other 
poisons,  such  as  arsenic,  potassium  bichromate,  or  quassia  infusion,  may 
be  used  instead  of  formalin,  and  are  better  bait  if  sweetened.  Sticky 
fly-paper,  fly  traps,  electric  fans,  and  other  well-known  measures  will 
help  dispose  of  a  certain  number  of  flies,  but  all  these  measures  are 
tentative,  and  attack  the  problem  at  the  wrong  end. 

The  fly  has  a  number  of  natural  enemies:  various  fungi,  especially 
one  belonging  to  the  Entomoplitliorece,  which  destroys  flies  in  the  autumn. 
Flies  also  harbor  protozoa  and  nematodes  as  parasites,  which,  however, 
seem  to  do  them  little  harm.  The  little  bright  red  objects  often 
seen  attached  to  flies  are  mites,  which  are  usually  only  temporary  ecto- 
parasites stealing  a  free  ride.  When  spider  webs  are  not  disturbed  they 
catch,  and  the  spiders  devour,  a  large  number  of  flies.  The  house  centi- 
pede (Scutigera)  also  sometimes  catches  and  eats  flies,  as  do  the  com- 
mon garden  toad,  some  lizards,  and  a  few  insectivorous  birds. 

Flies  and  similar  dipterous  insects  are  responsible  for  the  trans- 
mission of  a  large  number  of  diseases,  most  of  which  are  discussed  else- 
where. It  now  remains  to  consider  sleeping  sickness,  transmitted  by 
the  tsetse  fly  {Glossina  palpalis),  and  pappataci  fever,  transmitted  by 
a  biting  dipterous  insect  (Phlehotomus  pappatasii).  For  convenience 
a  general  consideration  of  the  trypanosomes  is  inserted  in  this  chapter. 

SLEEPING   SICKNESS 

Sleeping  sickness  was  limited  to  tropical  Africa,  especially  in  the 
Congo,  on  the  shores  of  Victoria  Nyanza,  and  about  the  head  waters 


FLIES 


233 


of  the  ISTile,  'but  is  gradually  spreading.  Many  thousands  have  perished 
from  this  infection,  caused  by  Trypanosoma  gamMense  and  transmit- 
ted by  the  tsetse  fly  (Glossina  palpalis).  The  disease  is  characterized 
by  two  stages:  in  the  first  there  are  irregular  fever,  glandular  enlarge- 
ments, an  erythematous  rash,  and  localized  edemas.  In  the  second 
there  are  slowly  increasing  lethargy  and  other  morbid,  nervous  symp- 
toms. After  a  chronic  course  sleeping  sickness  usually  terminates  in 
death;  few  cases  recover.  Many  instances  of  fatal  homesickness  in  the 
negroes  during  the  slave  trade  are  now  believed  to  have  been  this 
disease. 

The  Trypanosoma  gamhiense  was  discovered  by  Button  in  1901  dur- 
ing the  first  or  febrile  stage  of  sleeping  sickness,  and  subsequently 
studied  by  Button  and  Todd,  who  did  not  at  first  suspect  the  relation 
of  the  trypanosome  to  sleeping  sickness.  This  was  shown  by  Castellane 
in  1903.  The  trypanosomes  are  found  in  the  cerebrospinal  fluid,  in 
the  enlarged  lymphatic  glands,  and  also  in  the  circulating  blood.  It 
seems  that  when  the  trypanosomes  are  inoculated  through  the  skin  by 
the  tsetse  fly  they  are  temporarily  blocked  by  the  lymphatic  glands. 
From  here  small  numbers  of  them  pass  into  the  circulation  and  thus 
to  other  parts  of  the  body.  They  are  always  in  the  fluids;  never  in  the 
cells  or  tissues.  Novy  and  McNeal  in  1903  accomplished  the  remarkable 
feat  of  growing  trypanosomes  in  the  water  of  condensation  of  blood 
agar  tubes.  Pure  cultures  show  marked  differences  between  the  Trypano- 
soma lewisi  of  the  rat  and  the  Trypanosoma  grussei  of  horses  and  other 
domestic  animals.  So  far  no  one  has  succeeded  in  cultivating  the  Try- 
panosoma gamhiense  in 
artiflcial    culture    media. 

The  relation  of  the 
tsetse  fly  to  the  transmis- 
sion of  this  disease  rests 
upon  satisfactory  evi- 
dence. Button  and 
Todd,  as  well  as  others, 
find  these  fiies  abundant 
wherever  sleeping  sick- 
ness exists.  Wherever 
the  Glossina  palpalis  is 
absent  sleeping  sickness 
never  spreads,  as  Koch 
observed;  while,  on  the 
other  hand,  if  a  case  is  brought  to  a  locality  where  the  tsetse  fly  pre- 
vails, it  soon  spreads.  It  is  probable  that  the  transmission  by  the  tsetse 
fly  is  not  of  the  simple  mechanical  type,  but  that  the  parasite  undergoes 
a  sexual  evolution  within  the  insect.     Flies  seena  to  lose  their  power  of 


Fig.  36. — Tsetse  Fly    (Glossina  palpalis). 


234  INSECT-BORNE    DISEASES 

transmission  soon  after  feeding  on  an  infected  animal,  and  Bruce  con- 
siders it  thoroughly  im])ossible  tluit  mechanical  transuiission  alone  could 
e.\])lain  the  situation.  Kleine's  cxjx'riiiicnt  on  monkeys,  confirmed  by 
Bruce,  siiowed  that  tlie  Hies  may  convey  the  disease  '^1  days  after  one 
feeding  upon  a  monkey  infected  with  sleeping  sickness.  In  another 
experiment  by  Taute,  which  is  i-epoi'ted  l)y  Kleine,  infection  was  })ro- 
duced  on  each  of  the  first  three  days  after  feeding.  From  the  fourth 
to  the  tenth  day  no  infection  resulted.  The  flies  then  became  infective 
again  and  pr()(Uu'ed  the  disease  from  the  eleventh  to  t]:e  forty-fourth 
day.  Kleine  '  concludes  that  the  period  of  development  or  intrinsic 
period  of  incubation  in  the  fly  is  about  20  days  or  a  little  loss.  Flies 
remain  infective  at  least  75  days.  Not  all  flies  which  drink  lihiod  con- 
taining trypanosomes  become  infective.  The  proportion  is  about  1  in 
20.  Of  the  flies  caught  in  nature  in  endemic  areas,  from  2  to  10  in  one 
tliousand  are  capable  of  transmitting  the  disease  to  animals.  Novy  has 
emphasized,  and  Minchini  has  corroborated  the  fact,  that  tsetse  flies 
may  harbor  non-pathogenic  as  well  as  pathogenic  trypanosomes,  a  fact 
which  impairs  the  value  of  a  great  deal  of  the  microscopic  work  which 
has  been  done.  As  a  means  of  avoiding  the  accident  of  dealing  with 
naturally  infected  flies,  it  is  best  to  use  those  which  have  been  bred 
and  raised  in  the  laboratory. 

Prevention. — The  prevention  of  sleeping  sickness  in  the  present  state 
of  our  knowledge  depends  first  upon  isolation  of  the  sick,  protecting 
both  the  sick  and  the  well  against  fly  bites,  and  the  suppression  of  the 
flies  themselves.  The  sick  should  be  isolated  in  a  location  where  GIos- 
sina  paJpalis  is  absent,  or  in  a  w^ell-screened  and  carefully  managed 
hospital.  It  is  especially  important  to  isolate  all  those  who  carry  the 
infection  in  the  early  stages  of  the  disease,  whether  they  feel  sick  or 
not.  It  is  not  sufficient  simply  to  isolate  those  who  have  enlarged 
glands,  but  careful  blood  examinations  must  be  made.  The  trypano- 
somes have  been  found  in  the  circulating  blood  of  persons  with  normal 
lymph  glands. 

All  persons  taken  to  the  hospital  and  detention  station  are  given  a 
thorough  treatment  with  atoxyl  (a  combination  of  arscnious  acid  and 
anilin  oil).  Atoxyl  is  one-tenth  as  toxic  and  contains  about  three  times 
as  much  arsenic  as  arsenious  acid  alone.  The  dose  is  from  %  to  3 
grains  (0.05-0.2  grams)  subcutaneously. 

The  extermination  of  the  tsetse  fly  seems  a  hopeless  task.  The 
larvae  remain  in  the  body  of  the  mother  fly  until  fully  developed  and 
are  then  dropped  on  jnoist  soil,  in  which  they  burrow  to  undergo  trans- 
formation to  the  adult  state;  therefore,  clearing  of  the  land  in  limited 
locations  largely  diminishes  the  number  of  flies.  Clearing  the  brush 
exposes  the  earth  to  the  sun,  and  the  surface  becomes  dry  and  hard,  so 

^  Bull,  of  the  Sleeping  Sickness  Bureau,  No.   7,  1909, 


FLIES 


235 


that  flies  die  during  the  pupal  period.  This  measure  has  limited  possi- 
bilitieSj  but  is  useful,  as  Shirata  points  out,  around  ports^  in  the  neigh- 
borhood of  villages,  wharves,  and  other  places. 

The  tsetse  fly  may  also  be  fought  by  suppressing  its  food  supply.    It 
must  obtain  the  blood  of  some  vertebrate  animal  every  two  or  three  days. 


1.  Culicoides  milnei,  Austen. 

3.  Culicoides  grahamii,  Austen. 

5.  Simulium  latipes,  Mg. 

7.  Simulium  wellmanni,  Rouband. 


•Various  Gnats 


2.  Culicoides  brucei,  Austen. 

4.  Phlebotomus  duboscqi,  Neven -Lem.aire 

6.  Simulium  damnosum,  Theob. 

8.  Simulium  griseicollis,  Becker. 


Simulium  is  implicated  in  pellagra;   Phlebotomus  in  pappataci  fever. 


The  German  Commission  has  shown  that  on  the  banks  of  the  Victoria 
Nyanza  the  tsetse  fly  lives  largely  upon  crocodile  blood.  This  fact  was 
discovered  by  the  interesting  observation  that  the  flies  frequently  con- 
tain parasites  peculiar  to  the  crocodile's  blood.  Koch  believes  that  the 
disease  may  be  successfully  controlled  by  destruction  of  the  crocodiles, 
a  theory  which  later  research  has  rendered,  very  unlikely. 


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FLEAS  237 

Todd  and  Wolbach  ^  suggest  a  systematic  examination  of  the  natives 
in  the  endemic  area  by  gland  palpation  and  gland  puncture.  The  lat- 
ter consists  in  withdrawing  a  drop  of  fluid  from  one  of  the  enlarged 
lymphatic  glands  by  means  of  a  hypodermic  syringe.  The  little  drop 
of  bloody  fluid  thus  obtained  is  examined  as  a  fresh  preparation  under 
the  microscope  for  trypanosomes.  By  this  method  these  investigators 
found  at  least  0.8  per  cent,  of  the  population  of  the  Gambia  to  harbor 
trypanosomes.  If  all  the  infected  individiials  could  be  collected  in  vil- 
lages for  observation^  treatment,  and  isolation,  it  would  do  much  to 
limit  the  disease. 

Trypanosomes  are  the  cause  of  numerous  other  diseases  in  animals, 
as  will  be  seen  by  reference  to  the  table  on  page  236.  So  far  as  known, 
sleeping  sickness  is  the  only  important  disease  of  man  produced  by 
trypanosomes.  Kala-azar,  however,  is  produced  by  a  flagellated  proto- 
zoon  parasite  which  probably  belongs  to  the  trypanosomes. 

Practically  all  animals  are  susceptible  to  almost  all  trypanosomes. 
The  trypanosomes  which  infect  man  may  readily  be  transmitted  to  mon- 
keys, guinea-pigs,  rabbits,  etc. 

PAPPATACI    FEVER 

Doerr  and  Euss  -  and  also  Doerr,  Franz,  and  Taussig  originally  de- 
scribed a  three-day  fever  which  occurs  on  the  shores  of  the  Adriatic, 
the  cause  of  which  is  not  known,  but  which  is  of  special  interest  for 
the  reason  that  it  has  been  demonstrated  to  be  transmitted  through  the 
bite  of  a  dipterous  insect  commonly  called  a  gnat — Phlehotomus  pap- 
patasid. 

FLEAS 

Fleas  are  flat,  wingless  insects  related  to  the  Diptera.  They  pass 
through  a  complete  metamorphosis :  embryo,  larva,  pupa,  and  imago. 
The  adult  female  flea  deposits  her  eggs  among  the  hair  or  fur  of  the 
host  animal,  but,  unlike  the  eggs  of  many  ectoparasites,  they  are  not 
fastened  to  the  hairs  and  therefore  fall  freely  to  the  ground.  The  eggs 
are  oval,  whitish,  and  smooth  and  about  half  a  millimeter  long.  The 
larvas  escape  from  the  eggs  in  2  to  5  days.  They  are  able  to  break  the 
egg  shell  by  a  slender  process  on  the  top  of  the  head  which  disappears 
after  the  first  molt.  The  larva  is  a  slender,  legless,  cylindrical  creature, 
whitish  or  yellowish  in  color,  with  a  head  and  13  segments.  There  are  a 
few  scattered  hairs  or  bristles  on  the  body,  and  at  the  tip  is  a  pair  of  cor- 
neus  processes.     At  the  front  of  the  head  is  a  pair  of  biting  jaws  or 

^Annals  of  Tropical  Medicine  and  Parasitology,  Vol.  V,  No.  2,  Aug.,  1911, 
p.  245. 

^  ScMffs  und  Tropen  Myg.,  1909,  Vot  XIII,  No.  22,  p.  693. 


238 


INSECT-BOENE    DISEASES 


mandibles.  The  lan'ae  feed  on  almost  any  kind  of  refuse.  They  have 
been  reared  on  the  sweepings  from  rooms.  There  is  always  some  or- 
ganic matter  in  such  dust,  and  this  is  doubtless  their  nourishment.  In 
houses  the  larvae  usually  crawl  into  cracks  or  in  carpets,  where  they  feed 


FiQ.  38. — The  Indian  Rat  Flea  (Lcemopsylla  cheopis  Rothsc). 

and  grow.  Those  that  infest  wild  animals  probably  feed  on  the  refuse 
in  the  nests  or  retreats  of  these  animals.  It  will  be  noticed  that,  con- 
trary to  the  mosquito,  the  larval  and  pupal  stages  of  the  flea  are  not 
aquatic.  They  remain  in  the  larval  stage  from  a  week  to  ten  days, 
sometimes  two  weeks,  molting  the  skin  three  times  in  this  interval. 
Then  they  spin  flat,  white,  silken  cocoons  in  which  they  transform  to 
the  pupal  stage.  In  from  5  to  8  days  the  adult  flea  emerges  from  the 
cocoon.  The  period  of  their  transformation  is  affected  by  the  tempera- 
ture and  moisture.  In  warm,  damp  weather  a  generation  may  develop 
in  ten  da3's  or  two  weeks,  but  usually  about  18  days  to  three  weeks 
elapse  from  the  egg  to  the  adult.  Although  some  moisture  is  neces- 
sary for  their  development,  an  excess  is  apt  to  destroy  the  larva?. 

The  leaping  ability  of  adult  fleas  is  familiar  to  all.  This,  however, 
has  been  greatly  exaggerated.  The  British  Plague  Commission  de- 
termined that  fleas  jump  3  to  5  inches,  never  over  6.  jSTo  part  of  the 
leg  is  particularly  enlarged,  so  that  tlie  jump  is  made  by  the  entire 
leg,  as  in  the  leaf-hopper  insect,  and  not  by  the  femur  of  the  hind  leg, 
as  in  the  grass-hopper.  Fleas  do  not  vary  much  in  size.  They  are 
mostly  about  2  to  3  millimeters  long.  The  adult  insect  has  a  hard, 
strongly  chitinized  body.  The  mouth  parts  resemble  somewhat  those 
of  the  mosquito.  Both  the  male  and  the  female  flea  are  capable  of 
piercing  the  skin  to  obtain  blood  and  thus  transmit  infection.  Fleas, 
as  a  rule,  prefer  certain  hosts,  but  are  not  as  particular  in  this  regard 
as  are  many  parasites.  Those  species  which  are  best  known  are  found 
to  attack  several  hosts,  including  man.     This  is  one  reason  that  makes 


FLEAS 


239 


them  dangerous  parasites,  so  far  as  plague  and  other  infections  are 
concerned.  Over  300  species  are  described.  Formerly  all  fleas  were 
classified  in  the  single  family  PulicidEe,  genus  PuJex;  now  they  are  ar- 
ranged in  many  genera  and  these  genera  grouped  into  families.^ 


m 

pill 

^mH 

^^K     .■         ^rr^if                             ^ 

^^^ 

BPlMfc.' jtowMK  "^x  »^- 

Vv  ? 

\N 

■\ 

Fig.  39. — The  Common  Rat  Flea  of  Europe   and  Noeth  Amebica     (Ceratophylliis 

fasciatus  Bosc). 

Pulex  serraticeps  or  Ctenocephalm  cants  occurs  all  over  the  world, 
infesting  cats  and  dogs,  also  many  other  animals.  They  are  fre- 
quently brought  into  houses  upon  domestic  animals,  and  thus  become 
troublesome  to  man.  Pulex  irritans  is  the  human  flea,  sometimes  called 
the  "house  flea"  or  "common  flea." 


Fig.  40. — The  Human  Flea  (Pulex  irritans  Linn.). 


The  fleas  concerned  in  the  transmission  of  plague  are  Loemopsylla 
cheopis,  the  Indian  rat  flea,  and  CeratopJiyllus  fasciatus,  the  common 
rat  flea  of  Europe  and  North  America.  Plague  may  also  be  transmitted 
by  Ctenocephalus  felis,  the  cat  flea;  Pulex  irritans,  the  human  flea; 
Ceratophylhis  acutus,  the  squirrel  flea,  and  doubtless  other  genera  and 
species. 

*  Banks:  "The  Rat  and  Its  Relation  to  the  Public  Health,"  P.  H.  and  M. 
H.  S.,  p.   69, 


240  INSECT-BOKNE    DISEASES 

In  addition  fleas  act  as  intermediate  hosts  for  certain  tapeworms 
{Dipylidium  coninum),  and  doubtless  are  the  mechanical  or  biological 
carriers  of  other  infections.  Xicolle  incriminates  the  flea  in  typhus 
fever. 

Pulicides. — Adult  fleas  succumb  to  the  agents  applicable  to  in- 
sects in  general.  Mitzmain  ^  has  shown  that  water  is  of  little  value  in 
the  destruction  of  mature  fleas.  Glycerin  is  also  practically  inert  as  a 
pulicide,  but  tincture  of  green  soap  is  very  quick  and  effective.  This 
action  cannot  be  due  to  the  alcohol  in  the  soap,  for  alcohol  in  the 
strength  of  70  per  cent,  and  absolute  is  uncertain  in  its  action  and 
practically  inefficient.  Kerosene  (coal  oil)  is  a  very  efficient  flea  de- 
stroyer. Formalin,  phenol,  mercuric  bichlorid,  and  tricresol  in  the 
strength  used  as  disinfectants  are  of  little  value  in  killing  fleas.  Pow- 
dered sulphur  seems  to  be  of  no  value. 

Of  gases,  bisulphid  of  carbon  (CSj),  hydrocyanic  acid  gas  (HCN), 
and  sulphur  dioxid  (SO,)  are  highly  efficient  in  the  strengths  recom- 
mended for  general  insecticidal  purposes.  Chloroform  or  ether  first 
anesthetizes  fleas,  and  if  continued  kills  them.  This  is  important  for 
the  safe  handling  of  rats,  squirrels,  and  other  plague  animals.  The 
host  may  be  chloroformed  and  the  fleas  and  other  ectoparasites  re- 
moved with  a  comb.  The  anesthetic  may  be  controlled  by  practice  so 
that  the  host  will  recover  and  the  fleas  die,  or  both  recover,  or  both  die, 
as  may  be  desired. 

In  flea-infected  houses  the  larvge.  living  in  the  cracks  of  the  floor, 
etc.,  may  be  easily  controlled  by  sprinkling  a  thin  coating  of  flake  naph- 
thalene on  the  floor  and  then  leaving  the  room  tightly  closed  over  night. 
In  the  morning  the  naphthalene  may  be  swept  up  and  what  remains 
used  again. 

RELATION  OF  PLAGUE  TO  RATS  AND  FLEAS 

Plague  is  primarily  a  disease  of  the  rat  and  secondarily  of  man. 
This  fact  is  now  firmly  established  not  only  by  the  recent  experiences, 
but  especially  through  the  admirable  studies  of  the  Indian  Plague  Com- 
mission,- which  established  beyond  doubt  the  fact  that  plague  may  be 
and  generally  is  transmitted  from  rat  to  rat  and  from  rat  to  man 
through  the  agency  of  the  flea — Locmopsylla  cheopis — and  sometimes  by 
CeratopJiyllus  fasciatus,  et  al.  During  some  plague  epidemics  it  has  been 
noted  that  the  rats  die  in  great  numbers  before  and  during  the  out- 
break. It  is  now  known  that  this  epizootic  in  the  rat  is  true  plague. 
In  nature,  rats  suffer  both  with  acute  and  chronic  plague. 

In  the  laborator}',  rats  may  be  infected  with  plague  by  ingestion,  by 

'  Public  Health  Beports,  July  29.  1910,  Vol.  XXV.  No.  30,  p.  1039. 

'Journal  of  Hygiene,  Vol.  VI,  No.  4;  Vol.  VII,  Nos.  3,  6;  Vol.  VIII,  No.  2. 


EELATION  OF  PLAGUE  TO  EATS  AKD  FLEAS   241 


application  of  the  virus  to  rtmcous  or  cutaneous  surfaces,  or  by  sub- 
cutaneous inoculation.  In  nature,  rats  may  become  infected  by  any  of 
these  means  or  through  flea  bites. 

Eats  are  great  travelers,  and  have  carried  the  plague  to  all  quarters 
of  the  globe.  A  more  complete  discussion  of  the  rat  and  its  relation 
to  plague  and  other  diseases  will  be  found  on  page  242. 

Within  the  past  few  years  it  has  been  discovered  that,  while  the 
rat  is  the  great  medium  for  the  spread  of  plague,  the  disease  is  probably 
preserved  from  extinction  in  Thibet  by  another  rodent,  the  marmot 
(Arctomys  hohac).  In  California  the  infection  has  gotten  into  the 
ground  squirrels  (Citellus  heecheyi),  in  which  the  disease  will  doubt- 
less be  kept  alive  for  many  years  to  come.  To  realize  the  full  impor- 
tance of  these  discoveries,  it  is  only  necessary  to  call  to  mind  that,  in 
order  to  eradicate  plague  forever  from  the  surface  of  the  globe,  a  war- 


FiG.  41. — A  SQuraREL  Flea  (Hoplopsyllus  anomalus  Baker.). 

fare  against  the  rat  alone  is  not  sufficient,  but  must  include  the  ro- 
dents mentioned  and  perhaps  others. 

Simond  in  1897  advanced  the  theory  that  plague  was  carried  by 
fleas.  This  theory  was  developed  by  J.  Ashburton  Thompson  and  others 
and  conclusively  proved  by  the  Indian  Plague  Commission.  The  exact 
method  by  which  the  flea  transmits  the  infection  from  animal  to  ani- 
mal is  not  definitely  understood.  The  mouth  parts  appear  not  to  re- 
main infected.  It  is  possible  that  the  salivary  secretions  contain  the 
microorganisms.  It  is  known  that  the  plague  bacilli  may  live  in  the 
digestive  tract  and  be  passed  in  live  and  virulent  numbers  in  the  de- 
jecta. It  is  easy  to  understand  how  some  of  the  infected  dejecta  may 
be  rubbed  or  scratched  into  the  little  wound  produced  by  the  flea  bite. 
Wlien  it  was  found  that  the  common  rat  flea  of  Europe,  the  Cej-atophyl- 
lus  fasciatus,  does  not  readily  bite  man,  considerable  doubt  Avas  thrown 
upon  the  part  played  by  the  flea  in  plague  transmission.  These  nega- 
tive results,  however,  are  offset  by  the  convincing  positive  proofs  of  the 
British  Plague  Commission  in  India,  and  by  McCoy  and  Mitzmain  in 


242  INSECT-BORNE    DISEASES 

San  Francisco,  who  showed  tliat  under  certain  conditions  the  rat  flea 
will  bite  man,  es])eciallj  if  the  natural  food  siipi)ly  is  limited,  and  that 
these  fleas  may  feed  on  a  man's  hand  even  in  the  presence  of  a  rat. 

Eaybaud  ^  calls  attention  to  the  fact  that  the  rat  flea  {Ceratophyllus 
fasciatus)  is  able  to  hibernate  for  a  month  or  45  days  without  nourish- 
ment, and  that  virulent  plague  germs  may  persist  unharmed  in  its 
stomach  during  this  length  of  time  and  even  longer.  This  fact  may 
be  of  importance  for  the  transmission  of  plague  to  a  distance. 

It  should  be  remembered  that,  according  to  the  observations  of  Nut- 
tall  and  Yersin,  flies  and  possibly  other  insects  may  also  occasionally 
convey  the  infection.  Walker  -  considers,  as  the  result  of  experiments, 
that  bedbugs  and  other  biting  insects  play  an  important  role  in  the 
transmission  of  plague. 

RATS  AND   OTHER   RODENTS 

Eats,  mice,  squirrels,  and  other  rodents  have  become  a  serious  prob- 
lem in  preventive  medicine,  and  their  habits  and  methods  of  suppression 
may  be  considered  conveniently  at  this  place.  Plague  being  primarily 
a  disease  of  rats,  the  prevention  and  suppression  of  this  infection  re- 
solve themselves  into  a  war  upon  these  rodents.  For  the  control  of  plague 
it  is,  therefore,  necessary  to  have  a  knowledge  of  the  life  history  and 
mctliods  of  attacking  the  problem  in  the  lower  animals.  In  addition  to 
plague,  rats  are  the  great  reservoir  of  trichinosis.  They  are  responsible 
for  the  transmission  of  certain  tapeworms  and  other  parasites.  They 
arc  subject  to  leprosy,  cancer,  and  numerous  other  diseases,  some  of 
which  concern  man. 

Rodents  comprise  more  than  one-third  of  all  living  species  of  mam- 
mals, and  exceed  any  other  mammalian  order  in  the  number  of  in- 
dividuals. They  have  no  canine  teeth,  but  strongly  developed  incisors. 
Only  the  front  of  the  incisors  is  covered  with  enamel,  which  keeps 
them  sharp  and  chisel-like,  owing  to  the  more  rapid  wearing  away  of 
the  softer  dentine.  The  incisor  teeth  continue  to  grow  throughout  the 
life  of  the  animal.  The  most  extensive  family  of  rodents  is  the  Muridce, 
which  includes  the  true  rats  and  mice,  typified  by  the  genus  Mils. 
Trouessart,  in  his  "Catalogus  mammalium,"  enumerates  250  species  of 
Mws  described  before  1905.  Since  that  date  a  number  of  new  forms 
have  been  described. 

The  genus  Mus  is  characterized  by  narrow,  ungrooved  incisors ;  three 
small-rooted  molars;  soft  fur  mixed  with  hairs,  sometimes  with  spines; 
a  rudimentary  pollex  (thumb)  having  a  short  nail  instead  of  a  claw; 
a  long  tail  bearing   rings   or   overlapping  scales   and   often   naked   or 

^Presse  Medicale,  March  8,  1911,  No.  20. 
'Walker:   Indian  Med.  Gas..  1910,  No.  3.  p.  93. 


EATS    ATiD    OTHER    EODENTS  243 

nearly  so.     The  ears  are  rather  large,  the  eyes  bright  and  prominent, 
and  the  muzzle  somewhat  pointed. 

The  distinction  between  rats  and  mice  is  arbitrary  and  based  on 
size.  Of  the  many  species  of  the  genus  Mus  only  three  or  four  have 
developed  the  ability  to  adapt  themselves  to  such  a  variety  of  condi- 
tions as  to  become  cosmopolitan.  Four  have  found  lodgment  in  Amer- 
ica:  . 

The  common  house  mouse,  Mus  musculus. 
The  English  black  rat,  Mus  rattus. 
The  Egyptian  or  roof  rat,  Mus  alexandrinus. 
The  brown  rat,  TIfws  norvegicus. 

The  black  rat  and  the  roof  rat  differ  from  each  other  mostly  in 
color,  and  some  zoologists'  regard  them  as  races  of  the  same  species. 
The  brown  rat  is  also  known  as  the  gray  rat,  barn  rat,  wharf  rat,  sewer 
rat,  and  Norway  rat. 

The  black  rat  {Mus  rattus)  has  been  known  in  Europe  since  the 
twelfth  century,  and  from  there  has  been  carried  to  America.  The. 
brown  rat  (Mu^  norvegicus)  came  later,  and,  as  it  is  more  destructive, 
larger,  and  more  ferocious,  it  is  rapidly  driving  the  black  rat  before  it. 
The  brown  rat  differs  somewhat  in  habits  from  the  black  rat,  especially 
in  that  it  burrows,  which  protects  it  against  its  enemies  and  renders  its 
suppression  more  difficult. 

The  house  mouse  holds  its  own  everywhere  against  the  brown  or 
Norway  rat,  as  it  is  able  to  get  into  holes  too  small  for  the  rat  to  fol- 
low. Albinism  and  melinism  occur  in  all  species;  pied  forms  are  com- 
mon. The  white  rat  of  the  laboratory  is  an  albino  form  of  either  Mv^ 
rattus  or  Mus  norvegicus. 

Breeding"  and  Prevalence. — The  brown  rat  is  more  prolific  than 
either  the  roof  rat  or  the  black  rat.  The  brown  rat  reproduces  from 
three  to  five  times  a  year,  each  time  bringing  forth  from  six  to  nine, 
and  sometimes  as  many  as  22  or  23,  young.  They  breed  more  rapidly 
in  temperate  and  equable  climates  than  in  those  of  great  variability. 
The  number  of  rats  is  only  limited  by  the  food  supply  and  opportu- 
nities to  nest.  Few  people  have  any  conception  of  the  enormous  num- 
bers of  rats  in  cities  and  on  farms.  Although  few  are  seen  in  the  day 
time,  at  night  they  fairly  swarm  along  river  fronts  and  wharves,  as 
well  as  in  sewers,  stables,  warehouses,  markets,  and  other  places  where 
food  may  be  found.  A  few  instances  will  illustrate  the  prolific  habits 
and  give  an  idea  of  the  destructive  tendency  of  rats. 

In  1901  an  estate  near  Chichester,  England,  was  badly  infested  with 
rats;^  31,981  were  killed  by  traps,  poisons,  and  ferrets,  while  it  is  esti- 

^  The  Field,  London,  Vol.  C,  p.  545,  1902. 


244  INSECT-BORNE    DISEASES 

mated  that  tenants,  at  the  threshing,  destroyed  fully  5,000  more.  Even 
then  the  property  was  by  no  means  free  from  rats. 

During  the  phigue  of  rats  on  the  island  of  Jamaica,  in  1833.  the 
number  killed  on  a  single  plantation  in  a  year  was  38,000.^  The  in- 
jury to  sugar  cane  on  the  island  caused  by  the  animals  was  at  that  time 
estimated  at  half  a  million  dollars  a  year. 

The  report  of  the  Indian  Famine  Commission  in  1881  affords  one 
of  the  best  illustrations  of  the  number  of  rats  that  may  infest  a  coun- 
try. An  extraordinary  number  of  the  animals  at  tliat  time  inhabited 
the  Southern  Deccan  and  Mahratta  districts  of  India.-  The  autumn 
crop  of  1878  and  the  spring  crop  of  1879  were  both  below  the  average, 
and  a  large  portion  of  each  was  destroyed  by  rats.  The  resulting 
scarcity  of  food  led  to  the  payment  of  rewards  for  the  destruction  of 
the  pests,  and  over  12,000,000  were  killed. 

Migration. — The  migrations  of  rats  have  often  been  recorded.  The 
brown  rat  is  known  in  Europe  quite  generally  as  the  migratory  rat; 
the  Germans  call  it  the  Wanderrattc.  Pallas  relates  that  in  the  autumn 
of  1772  they  arrived  from  the  East  at  Astrakhan,  southeastern  Russia, 
in  such  great  numbers  and  so  suddenly  that  nothing  could  be  done  to 
oppose  them.  They  crossed  the  Volga  in  immense  troops.  The  cause 
of  this  general  migration  was  attributed  to  an  earthquake,  but,  since 
similar  movements  of  the  same  species  often  occur  without  earthquakes, 
it  is  probable  that  only  the  food  supply  of  the  animals  was  involved 
in  the  migration  which  first  brought  the  brown  rat  to  Europe. 

Seasonal  movements  of  rats  from  houses  and  barns  to  the  open 
fields  take  place  in  the  spring,  when  green  and  succulent  plant  food  is 
ready  for  them.  The  return  movement  takes  place  in  the  autumn. 
This  seasonal  migration  is  nota])le  even  in  large  cities.  In  1903  a 
multitude  of  migrating  rats  spread  over  several  counties  of  western 
Illinois.  They  traveled  in  great  armies  and  invaded  the  farms  and 
villages  of  Rock  Island  and  Mercer  counties,  and  caused  heavy  losses 
during  the  winter  and  summer  of  1904.  In  one  month  Mr.  Montgom- 
ery of  Mercer  county  killed  3,435  rats  on  his  farm.  He  caught  most  of 
them  in  traps. 

In  England  a  general  movement  of  rats  inland  from  the  coast  oc- 
curs every  October.  This  is  known  to  be  closely  connected  with  the 
closing  of  the  herring  season.  During  the  fishing  the  rodents  swarm 
to  the  coast  attracted  by  the  offal  left  in  cleaning  the  herring,  and 
when  this  food  fails  the  animals  troop  back  to  the  farms  and  villages. 

An  invasion  of  rats  (Mus  rattus)  in  the  Bermuda  Islands  occurred 
about  the  year  1615.  Within  two  years  they  had  increased  so  alarmingly 
that  none  of  the  islands  was  free  from  them.     The  rodents  "devoured 

^New  England  Farmer,  Vol.  XII,  p.  315,  1834. 
^British  Med.  Jour.,  Sept.  16,  1905,  p.  623. 


EATS    AND    OTHEE    EODEIs^TS  245 

everytliing  that  came  in  their  way — fruits,  plants,  and  even  trees" — so 
that  for  a  year  or  two  the  people  were  nearly  destitute  of  food.  A  law 
was  passed  requiring  every  man  in  the  island  to  keep  12  traps.  In 
spite  of  all  efforts  the  animals  continued  to  increase  imtil  they  finally 
disappeared,  so  suddenly  that  it  is  sttpposed  they  must  have  been  vic- 
tims of  a  pestilence. 

While  stationed  upon  Angel  Island  in  San  Francisco  harbor  I  ob- 
served several  migrations  of  rats  between  the  army  post  and  the  quar- 
antine station,  which  were  about  a  mile  apart  and  separated  by  an  in- 
tervening ridge.  Everyone  is  familiar  with  the  sudden  invasion  of 
stores,  factories,  and  other  structures  with  these  rodent  pests,  which 
causes  considerable  economic  loss. 

On  Vessels. — Eats  are  found  on  all  vessels;  they  are  great  travelers. 
It  is  through  this  seagoing  tendency  that  the  rat  has  become  cosmo- 
politan. Eats  get  on  board  vessels  readily  as  they  lie  at  their  dock; 
sometimes  they  are  carried  on  board  in  the  cargo. 

It  is  very  important  to  prevent  the  introduction  of  rats  on  vessels 
at  plague-infected  ports;  it  is  also  important  to  prevent  the  passage  of 
rats  from  ship  to  shore,  particularly  if  the  vessel  is  from  a  plague  port. 
In  order  to  accomplish  this,  it  is  necessary  to  exercise  particular  care. 
In  extreme  cases  the  ship  should  not  approach  the  dock,  but  the  cargo 
should  be  handled  l)y  means  of  lighters.  When  the  ship  lies  at  its 
moorings  in  a  stream  or  in  the  open  bay  rats  may  get  on  board  by 
swimming,  and  climbing  in  through  the  hawse  pipe.  Eats  rarely  swim 
more  than  one-C[uarter  to  one-third  of  a  mile.  If  the  vessel  ties  up  at 
the  dock,  inverted  funnels  should  be  placed  on  the  hawsers.  The  gang- 
planks should  be  watched  during  the  day  and  always  taken  up  at  night. 
Vessels  from  plague  ports  should  always  be  treated  with  sulphur  dioxid, 
preferably  when  empty,  and  always  before  leaving,  and  also  en  route, 
to  kill  the  rats  that  may  be  on  board.  A  wise  measure  in  international 
sanitation  would  be  to  require  all  vessels,  whether  trading  at  plague 
ports  or  not,  to  fumigate  for  rats  no  less  than  three  or  four  times  a  year. 

Food. — Eats  are  not  strictly  herbivorous,  as  might  be  inferred  from 
their  dentition;  they  are  practically  omnivorous.  Their  bill  of  fare  in- 
cludes grains  and  seeds  of  every  kind ;  flour,  meal,  and  all  food  products 
made  from  them;  garden  vegetables,  mushrooms,  bark  of  growing  trees, 
bulbs,  roots,  stems,  leaves,  and  flowers  of  herbaceous  plants;  eggs,  chick- 
ens, ducklings,  squabs,  and  young  rabbits;  milk,  butter,  and  cheese; 
fresh  meat  and  carrion;  fish,  frogs,  mollusks,  and  crustaceans;  they  are 
also  cannibals.  This  great  variety  of  food  explains  the  ease  with  which 
rats  maintain  themselves  in  almost  any  environment. 

Habits. — The  roof  rat   {Mus  aUxandrin-us)   and  the  black  rat   {Mus 

rattus)   are  more  expert  climbers  than  the  brown  rat,  which  is  larger 

and  clumsier.     In  buildings  the  brown  rat  keeps  mainlv  to  the  cellar 
18 


246  INSECT-BORNE    DISEASES 

and  lower  parts,  where  it  commonly  live?  in  burrows.  From  these  re- 
treats it  makes  niglitly  excursions  in  search  of  food.  The  roof  rat  and 
the  black  rat  live  in  the  walls  or  in  tlie  space  between  ceilings  and  roofs. 
Rats  readily  climb  trees  to  obtain  fruit.  In  tlie  tropics  the  roof  rat 
and  the  black  rat  habitually  nest  in  trees.  In  the  open  rats  seem  to 
have  defective  vision;  by  daylight  they  move  slowly  and  uncertainly; 
on  the  contrary,  at  the  side  of  the  room  and  in  contact  with  the  wall 
they  run  with  great  celerity.  This  fact  suggests  that  the  vihrissce 
(whiskers)  serve  as  feelers,  and  that  the  sense  of  touch  in  them  is  ex- 
tremely delicate.  The  animals  alwa}^?  prefer  narrow  places  as  highways 
— another  circumstance  which  may  l^e  made  use  of  in  placing  tra])S. 

The  ferocity  of  rats  has  been  grossly  exaggerated.  The  stories  of 
their  attacks  upon  human  beings,  sleeping  infants  especiall}^  have  but 
slight  foundation.  Ordinarily  the  probal)iIity  of  being  bitten  l)y  rats  is 
remote,  and  the  bite  is  not  usually  poisonous.  Miyake  ^  has  described 
a  "rat-bite  disease"  called  Sodoku  in  Japan. 

Plague  in  Rats. —  It  is  now  known  that  rats  are  more  or  less  respon- 
sible for  cases  of  human  plague,  and  in  addition  are  the  most  frequent 
medium  by  which  plague  is  carried  from  one  locality  to  another.  They 
also  convey  the  plague  infection  to  other  rodents,  such  as  ground  squir- 
rels. 

The  clinical  manifestations  of  plague  in  rats  are  of  little  importance. 
It  is  generally  said  that  a  plague-infected  rat  staggers  about  with  a 
drunken  gait,  loses  fear  of  its  natural  enemies,  and  is  readily  captured. 
Rats  experimentally  infected  show  no  marked  manifestations  of  illness 
until  shortly  before  death,  when  they  become  quiet,  crouch  in  the  cor- 
ner of  the  cage,  and  try  to  hide.  It  is  rather  surprising  that  compara- 
tively few  plague  rats  are  found  dead  in  endemic  centers.  In  the  San 
Francisco  campaign  McCoy  estimates  that  certainly  not  more  than  20 
per  cent,  of  the  infected  rodents  were  found  dead,  the  remainder  being 
trapped.  This  is  probably  due  to  the  fact  that  plague  in  rats  is  of 
several  days'  duration,  and  during  this  period  there  are  good  chances  of 
catching  the  sick  rodent  in  a  trap,  while  the  chance  of  finding  the  body 
after  death  is  handicapped  by  obvious  circumstances. 

Rats  suffer  both  with  acute  plague  and  chronic  plague,  the  lesions 
of  which  differ. 

The  diagnosis  of  plague  in  rats  may  he  made  maeroscopically.  The 
Indian  Plague  Commission,  which  had  the  opportunity  of  examining  an 
enormous  number  of  plague  rats  in  Bombay  and  elsewhere  in  India,  state 
that  "the  results  of  tests  carried  out  for  the  purpose  of  comparison 
make  it  manifest  that  the  naked  eye  is  markedly  superior  to  the  micro- 
scopic method  as  an  aid  in  diagnosis,  and  as  the  result  of  our  experi- 

^  Mitt.  a.  d.  Grensgeh.  d.  Med.  u.  Chir.,  1902;  also  Proescher,  Internat. 
Clinics,  IV,  25th  Series,  p.  77. 


EATS  AND  OTHER  EODENTS  247 

ence  we  are  prepared  to  make  a  diagnosis  of  plague  on  the  strength  of 
the  maeroscopical  appearance  alone,  even  though  the  other  results  of 
cutaneous  inoculation  and  culture  are  negative  and  the  animals  show 
signs  of  putrefaction."  The  experience  of  McCoy  and  others  in  the 
Federal  Plague  Laboratory  in  San  Francisco  leads  to  the  same  conclu- 
sion. It  should  be  remembered,  however,  that  occasionally  plague  oc- 
curs in  rats  without  gross  lesions.  This  has  been  observed  by  Dunbar 
and  Ivister  and  also  by  McCoy.  In  any  critical  case  the  bacteriological 
confirmation  is  essential. 

Acute  plague  in  rats  is  characterized  by  engorgement  of  the  subcu- 
taneous blood  vessels  and  a  diffuse  pink  color  of  the  subcutaneous 
structures  and  muscles.  The  diagnosis  may  often  be  inferred  at  the 
first  incision.  The  lymphatic  glands  of  the  neck,  axilla,  groin,  or  pel- 
vis are  enlarged  and  frequently  surrounded  by  a  hemorrhagic  exudate 
and  edema.  The  liver  is  granular  with  focal  necroses,  the  spleen  en- 
larged and  friable,  and  j^leural  effusions  are  common. 

Chronic  plague  in  rats  has  been  encountered  in  a  considerable  num- 
ber of  cases  among  Mus  rattus  in  the  Punjab  villages  of  Kasel  and 
Dhand.  It  has  not  been  foimd  in  California.  In  the  chronic  disease 
the  lesions  consist  of  purulent  or  caseous  foci,  usually  of  the  visceral 
type;  that  is,  they  occur  as  splenic  nodules  and  abscesses,  or  mesenteric 
abscesses.  Sometimes  the  abscesses  are  situated  in  the  regions  of  the 
peripheral  lymph  glands.  Plague  bacilli  are  either  absent  or  very 
scanty  upon  microscopic  examination  in  these  abscesses,  but  they  may 
be  recovered  by  cultural  methods  or  more  surely  by  inoculating  the 
material  into  susceptil^le  animals.  There  is  no  evidence  to  show  that 
chronic  rat  plague  has  anything  to  do  with  the  recurrence  of  acute 
plague  among  the  rats. 

Eats  may  be  infected  by  the  ingestion  of  infective  material  or  the 
application  of  virulent  plague  bacilli  to  a  mucous  or  cutaneous  surface, 
or  by  subcutaneous  injection  of  the  microorganism.  The  infection  may 
also  be  transferred  from  rat  to  rat  through  the  agency  of  the  flea.  In 
nature  the  mode  of  transference  probably  takes  jolace  through  all  of 
these  methods,  but  commonly  through  the  flea. 

Contrary  to  the  general  impression,  the  wild  rat  has  a  considerable 
resistance  to  plague  infection.  The  Indian  Plague  Commission  found 
that  59  per  cent,  were  immune  when  inoculated  by  the  subcutaneous 
method  from  the  spleen  of  infected  rats.  A  series  of  experiments  con- 
ducted in  the  Federal  laboratory  in  San  Francisco  also  showed  a  high 
grade  of  immunity,  especially  among  the  large  rats.  About  15  per 
cent,  of  small  rats  and  about  50  per  cent.  of. large  rats  Avere  found  to 
be  immune  when  inoculated  with  highly  virulent  material.  The  experi- 
ments demonstrated  that  this  immunity  is  not  acquired  through  a  prior 
attack  of  the  disease,  but  must  be  a  natural  immunity. 


248  INSECT-BOKNE    DISEASES 

The  natural  subsidence  of  plague  among  rats  in  any  community  is  a 
point  about  which  much  more  evidence  must  be  obtained  before  we  can 
speak  with  any  degree  of  autliority.  It  may  be  due  to  a  lack  of  suscep- 
tible material,  ])0ssil)ly  to  a  loss  of  virulence  of  the  organism,  but  it 
seems  more  probable  that  it  is  due  to  a  change  in  the  number  or  rela- 
tions of  the  ectoparasites  of  the  rat. 

Rat  Leprosy. — ^Leprosy  occurs  spontaneously  among  rats  and  bears  a 
close  reseiubhuu-e  to  llie  disease  in  man,  but  it  seems  that  the  rat  lep- 
rosy is  not  communicable  to  man.  For  a  further  discussion  of  rat  lep- 
rosy see  page  393. 

Trichinosis. — The  three  most  important  hosts  for  the  TrichineUa 
spiralis  are  man,  swine,  and  rats.  The  infection  is  spread  by  one  ani- 
mal eating  the  flesh  of  another.  It  is.  therefore,  evident  that  if  the 
disease  occurred  only  in  hogs  and  man  it  would  soon  die  out.  Rats,  on 
account  of  their  habits,  may  then  be  viewed  as  the  great  reservoir  for 
the  parasites  and  for  the  disease  it  causes.  Hence,  a  well-directed  pub- 
lic health  cam])aign  against  trichinosis  should  consider  the  eradication 
of  rats,  especially  around  slaughter  houses,  butcher  shops,  hog  pens, 
and  similar  places. 

Trichinosis  is  very  common  among  rats;  they  become  infected  by 
eating  each  other,  by  eating  scraps  of  pork  found  on  the  offal  pile  of 
slaughter  houses,  butcher  shops,  or  in  swill.  Swine  become  infected  by 
eating  rats  and  infected  offal.  Man  becomes  infected  almost  exclusively 
by  eating  pork  or  boar  meat  that  has  not  been  thoroughly  cooked. 

Other  Parasites. — IJats  and  mice  may  harbor  eleven  species  of  in- 
ternal parasites  which  also  occur  in  man.  Seven  of  these  are  of  academic 
importance  only.  Those  which  concern  us  principally,  in  addition  to 
the  TrichineUa  spiralis,  are  the  Tlymenolepis  diminuta  and  Lamhlia 
duodenalis.  Rats  also  harbor  the  Ci/sticercas  celliilosa',  and  are  suscep- 
tible to  experimental  infections  with  Trypanosoma  gamhiense,  the  cause 
of  sleeping  sickness. 

Eats  have  also  been  accused  of  dragging  typhoid  from  the  sewers 
to  our  food.  The  connection  is  close  and  the  possiljility  apparent.  A 
recent  outbreak  of  typhoid  fever  in  an  asylum  has,  in  fact,  been  traced 
to  this  source  by  Dr.  ]\Iills.'' 

Economic  Importance. — The  destruction  of  food,  merchandise,  and 
property  by  rats  is  so  great  that  this  alone  would  justify  active  measures 
of  suppression,  even  though  they  were  not  responsible  for  plague,  trichi- 
nosis, and  other  infections.  Rats  destroy  grain  while  growing;  invade 
stores,  destroy  flowers,  laces,  silks,  carpets;  eat  fruits,  vegetables,  meat, 
etc.,  in  the  market;  destroy  by  pollution  ten  times  as  much  as  they  eat; 
cause  conflagration  by  dragging  matches  into  their  holes;  gnaw  lead 
pipes  and  floors  of  houses  ;•  ruin  artificial  ponds  and  embankments  by 

^Brit.  Med.  Jour.,  January  21,  1911. 


EATS  AND  OTHEE  EODENTS  249 

burrowing ;  destroy  eggs  and  young  poultry ;  damage  foundations, 
floors,  doors,  piers;  in  short,  they  have  become  the  worst  mammalian 
pest  among  us.  It  is  estimated  that  in  the  United  States  alone  the 
losses  due  to  rat  depredations  vary  from  $35,000,000  to  $50,000,000 
annually. 

Suppression. — The  extermination  of  the  rat  is  hopeless;  they  are 
very  intelligent  and  cautious.  Extermination  seems  a  biological  im- 
possibility, for  killing  off  large  numbers  gives  the  survivors  an  easier 
living.  Millions  of  rats  have  been  killed  in  India,  Japan,  San  Fran- 
cisco, and  other  places  during  the  recent  plague  measures  without  mak- 
ing an  appreciable  impress  upon  the  numbers  remaining.  They  may  be 
exterminated  and  kept  out  of  a  limited  area,  such  as  a  ship,  a  granary, 
a  stable,  a  warehouse,  a  market,  or  local  compound.  In  the  well-built 
residential  sections  of  a  city,  with  concrete  walks,  asphalt  streets,  stone 
cellars,  and  few  stables,  there  are  very  few  rats.  In  10  years  of  resi- 
dence in  such  a  district  in  Washington  I  never  saw  or  heard  of  one  in 
the  neighborhood. 

The  measures  for  the  repression  and  destruction  of  rats  will  be 
considered  under:  (1)  rat-proof  buildings,  (2)  keeping  food  from  rats, 
(3)  natural  enemies,  (4)  traps,  (5)  poisons,  (6)  domestic  animals,  (7) 
shooting,   (8)   fumigation,  and   (9)    bacterial  viruses. 

Eat-pkoof  Buildings. — This  is  a  measure  of  first  importance  in 
the  fight  against  rats.  Eats  can  only  gain  entrance  to  a  cement  struc- 
ture properly  constructed  through  neglect  or  ignorance.  They  come  in 
through  drain  pipes  if  left  open;  through  doors,  especially  from  alleys; 
and  through  basement  windows.  Once  in,  they  intrench  themselves  in 
out-of-the-way  places,  nest  behind  rubbish,  and  are  difficult  to  dislodge. 
The  lower  parts  of  the  outer  doors  of  public  structures,  such  as  markets 
and  wharves,  should  be  reinforced  with  metal  to  keep  the  rats  from 
gnawing  through.  Basement  windows  should  be  screened  and  doors 
provided  with  springs  to  keep  them  closed. 

A  rat-proof  dwelling  must  have  concrete  footings  and  the  walls  of  a 
wooden  house  should  have  one  foot  of  concrete  between  the  sheathing 
and  lathing.  All  water  and  drain  pipes  should  be  surrounded  with  ce- 
ment. Eat  holes  may  be  closed  with  a  mixture  of  cement,  sand,  and 
broken  glass,  or  sharp  bits  of  crockery  and  stone. 

Aside  from  dwellings,  the  chief  refuges  for  rats  in  cities  are  sewers, 
wharves,  stables,  provision  houses,  markets,  out-buildings,  and  uninhab- 
ited structures.  Modern  sewers  are  highways  and  not  nesting  places  for 
rats.  They  find  a  safe  retreat  from  nearly  all  enemies  under  wooden 
sidewalks.  In  the  country  it  is  important  to  build  corn  cribs,  barns,  and 
granaries  rat-proof  with  the  liberal  use  of  cement,  iron  sheeting,  or 
galvanized  iron  netting. 

Keeping  Food  from  Eats. — Well-fed  rats  mature  quickly,  breed 


250  INSECT-BOKNP]    DISEASES 

often,  and  liave  large  litters.  A  scarcity  of  food  helps  all  other  sup- 
pressive measures.  Garbage  and  od'al  must  l)e  disposed  of  so  tliat  rats 
cannot  get  at  such  stuff.  Well-covered  garbage  cans  should  l)e  required 
and  the  garl)age  frequently  removed  and  ])urned.  To  dei)osit  it  upon 
the  ground  anywhere  only  invites  and  nourishes  rats  and  other  vermin. 
Slaughter  houses  are  centers  of  rat  propagation.  The  offal  is  best  dis- 
posed of  by  burning.  Care  should  also  be  taken  as  to  the  disposal  of 
remnants  of  lunches  in  office  buildings  and  the  disposal  of  organic  waste 
generally.    Produce  in  provision  stores  may  be  protected  with  wire  cages. 

Natural  Enemies. — The  natural  enemies  of  the  rat  are  the  larger 
hawks,  owls,  skunks,  foxes,  coyotes,  weasels,  minks,  dogs,  cats,  and  fer- 
rets. The  persistent  killing  off  of  the  carnivorous  birds  and  mammals 
that  prey  upon  rats  has  ])een  an  important  factor  in  the  increase  of 
these  rodents  in  the  United  States.  "Rats  actually  destroy  more  eggs, 
chickens,  and  game  than  all  tlie  wild  animals  eomljined. 

Traps. — There  are  many  kinds  of  traps,  such  as  the  guillotine,  s])ring 
trap,  the  cage  trap,  the  barrel  and  pit  trap.  One  of  the  best  is  the  old- 
fashioned  wire  cage  trap.  The  rats  get  in  l)ut  cannot  get  out.  In  ]jlac- 
ing  the  trap  it  is  advisable  to  leave  a  rat  in  as  a  decoy.  The  trap  should 
be  placed  along  runways,  or  the  entrance  to  the  trap  may  be  arranged  so 
that  the  rats  first  have  to  go  through  a  pipe,  as  they  like  to  explore 
dark  passages.  It  requires  ingenuity  to  successfully  trap  rats.  They 
are  very  wary  and  avoid  man-smell.  To  guard  against  this  the  traps 
may  be  burned  and  then  smeared  with  the  bait,  always  handling  them 
with  tongs  or  properly  prepared  gloves.  Cheese,  bacon,  grain,  and  bread 
are  the  best  baits. 

Poisons. — Poisons  are  objectionable  in  dwellings,  ov.dng  to  the  odor 
of  the  dead  rats.  They  are  of  service  in  granaries,  stables,  wharves, 
and  similar  places.  Most  rat  poisons  are  dangerous  to  children  as  well 
as  to  chickens  and  other  domestic  animals,  and,  therefore,  the  greatest 
care  must  be  exercised  in  their  use.  It  requires  experience  in  laying  out 
poisons;  the  old  rats  are  very  smart  and  will  refuse  the  bait  unless 
artfully  concealed  and  judiciously  placed. 

The  principal  poisons  used  for  rats  are  l)arium  carbonate,  strychnin, 
arsenic,  and  phosphorus.  In  several  states  the  law  requires  that  notice 
of  intention  to  lay  poison  must  lie  given  to  persons  living  in  the  neigh- 
borhood. Poisons  for  rats  should  never  be  placed  in  open  or  unsheltered 
places.  For  poisoning  rats  in  buildings  and  yards  occupied  by  poultry 
the  following  procedure  is  recommended :  I'wo  wooden  boxes  should 
be  used,  one  considerably  larger  than  the  other,  and  each  having  two 
or  more  holes  in  the  sides  large  enough  to  admit  rats.  The  poisoned 
bait  should  be  placed  in  the  bottom  and  near  the  middle  of  the  smaller 
box,  and  the  larger  box  should  then  be  inverted  over  the  other.  Rats 
thus  have  free  access  to  the  bait,  but  fowls  are  excluded. 


EATS  AND  OTHEE  EODENTS  251 

The  cheapest  and  most  effective  poison  is  barium  carbonate.  This 
may  be  made  into  a  dough  with  four  parts  of  meal  or  flour  to  one  part 
of  barium  carbonate.  A  good  plan  is  to  spread  the  barium  carbonate 
upon  fish,  on  toasted  bread  (moistened),  or  upon  ordinary  bread  and 
butter. 

Strychnin  is  effective  and  may  be  used  by  inserting  the  dry  crystals 
in  a  piece  of  meat,  cheese,  or  sausage,  which  is  placed  in  the  runways. 

Arsenic  is  popular;  the  powdered  white  arsenic  (arsenious  acid) 
may  be  used  as  described  for  strychnin  or  barium;  or  a  stiff  dough 
may  be  made  by  mixing  twelve  parts  by  weight  of  corn  meal  and  one 
part  of  arsenic  with  whites  of  egg.  An  old  English  formula  is  one 
pound  of  oatmeal,  one  pound  of  brown  sugar,  and  a  spoonful  of  arsenic. 

Phosphorus  is  an  effective  and  attractive  bait.  The  yellow  phosphorus 
in  the  proportion  of  one  to  four  per  cent,  may  be  mixed  with  glucose 
or  other  suitable  material.  The  use  of  phosphorus  is  very  dangerous  on 
account  of  fire.  Eats  poisoned  with  phosphorus  may  die  on  the  prem- 
ises and  decompose,  contrary  to  the  statements  sometimes  made  in  the 
advertisements. 

The  following  formula  is  recommended  as  a  poisonous  bait  for  rats, 
mice,  squirrels,  etc. : 

Strychnin    1  oz. 

Cyanid  of  potassium 2  oz. 

Eggs    1  doz. 

Honey 1  pint 

Wheat  or  barley 30  lbs. 

Stir  eggs  well,  then  mix  in  honey  and  again  stir.  Then  put  in  dry 
powdered  strychnin  and  cyanid  and  stir  until  well  mixed.  Put  wheat 
in  large  box  or  can  and  pour  in  the  mixture  of  poison  and  stir  until 
it  is  well  distributed  over  the  wheat.  Stir  two  or  three  times  during 
twenty-four  hours,  then  spread  out  and  dry.  Before  putting  it  out  for 
squirrels  add  oil  of  rhodium,  1  drachm. 

Domestic  Animals. — A  well-trained  dog  may  be  relied  upon  to 
keep  the  farm  premises  reasonably  free  of  rats.  Small  Irish,  Scotch, 
and  fox  terriers  make  the  best  ratters;  the  ordinary  cur  and  the  larger 
breeds  of  dogs  seldom  develop  the  necessary  qualities  for  ratters. 

However  valuable  cats  may  be  as  mousers,  few  of  them  learn  to 
catch  rats.  The  ordinary  house  cat  is  too  well  fed  and  too  lazy  to  un- 
dertake the  capture  of  an  animal  as  formidable  as  the  brown  rat.  Koch 
has  advised  the  breeding  and  distribution  of  cats  capable  and  willing  to 
attack  rats. 

Shooting. — Many  rats  may  be  shot  as  they  come  out  to  forage  about 
sundown.     This  method  is  particularly  effective  in   a  large  building 


252  INSECT-BOKNE    DISEASP^S 

which  is  suddenly  overrun  with  the  rodents.  The  shooting  of  a  numher 
of  them  upon  two  or  three  successive  niglits  discourages  the  remainder, 
who  leave  for  some  other  happier  hunting  ground. 

Fumigation. — Kats  may  he  killed  with  certainty  in  any  inclosed 
structure  by  the  use  of  sulphur  dioxid,  carbon  bisulphid,  hydrocyanic 
acid  gas,  or  carbon  monoxid.  The  methods  of  evolving  these  substances 
have  been  described  in  Section  XII.  Sulphur  dioxid  is  particularly 
useful  to  destroy  rats  on  board  ships,  in  cellars,  stables,  sewers,  and 
places  where  they  abound  and  which  are  not  injured  by  the  corrosive 
action  of  the  sulphur  fumes.  Enormous  numbers  of  rats  are  frequently 
killed  when  ships  are  fumigated  with  sulphur  dioxid.  I  have  seen  buck- 
ets full  thrown  overboard  from  comparatively  small  vessels.  Hobdy 
counted  310  on  a  lumber-carrying  schooner  of  only  260  tons  burden. 
The  S.S.  Minnehalia,  a  new  vessel  only  nine  months  in  commission 
fumigated  in  London  in  May,  1901,  yielded  a  bag  of  1,700  rats. 

For  the  destruction  of  rats  upon  vessels  the  sulphur  dioxid  may  be 
produced  by  the  pot  method,  if  the  hold  is  empty,  or  may  be  generated 
in  a  Kinyoun-Francis  or  a  Clayton  furnace,  or  may  be  liberated  from 
its  compressed  liquefied  state.  No  less  than  three  pounds  of  sulphur 
should  be  burned  for  each  1,000  cubic  feet  of  space,  and  the  exposure 
should  not  be  less  than  5  hours  (see  page  997). 

Carbon  Monoxid. — Carbon  monoxid  is  an  exceedingly  poisonous  gas. 
From  the  fact  that  it  has  no  odor  it  is  even  more  hazardous  in  practice 
than  hydrocyanic  acid.  Carbon  monoxid  is  fatal  to  all  forms  of  mam- 
malian life,  but  has  no  germicidal  properties  whatever.  It  has  been 
used  in  Hamburg  ^  and  other  ports  for  the  destruction  of  rats  on  ships. 

Carl)on  monoxid  is  a  colorless,  odorless  gas,  lighter  than  air.  It 
forms  a  stable  compound  with  the  hemoglobin  of  the  blood — carl)on 
monoxid-hemoglobin.  For  the  toxic  action  of  this  gas  and  its  other 
properties  see  page  637.  The  particular  advantages  of  carbon  monoxid 
for  the  destruction  of  rats  on  hoard  ship  are  that  it  may  be  generated 
cheaply,  is  quickly  effective,  and  does  no  injury  to  cargo  or  vessel.  The 
disadvantages  are  that  it  is  poisonous  and  inflammable.  The  addition 
of  a  little  sulphur  dioxid  to  the  gas  makes  its  presence  known  and  tends 
to  prevent  accidents.  After  exposure  the  hold  must  be  thoroughly  ven- 
tilated, and  it  is  customary  to  lower  a  mouse  in  a  cage  for  10  minutes 
to  be  sure  that  it  is  safe  for  a  man  to  enter.  Divers'  helmets  should 
also  be  kept  in  readiness  so  that  the  hold  may  be  entered  in  case  of 
need. 

A  gas  generator  has  been  made  by  Pintch  which  furnishes  a  mix- 
ture consisting  of  CO,  5  per  cent.,  CO2,  18  per  cent.,  N",  77  per  cent. 
These  gases  are  generated  by  the  incomplete  combustion  of  coke.     The 

*Nocht*and  Giemsa:  Arbeiten  a.  d.  kaiserlichen  Gesundheitsampte,  Bd.  20, 
Ersten  Heft,  1904,  p.  91. 


EATS  AND  OTHEK  EODENTS  253 

mixture  of  gases  is  pumped  into  the  hold  of  the  vessel  or  other  com- 
partments where  it  is  desired.  The  hold  should  be  kept  tightly  closed 
from  7  to  8  hours. 

The  Bacterial  Eat  Viruses. — Eats  are  notoriously  resistant  to 
bacterial  infection.^  Even  plague  usually  fails  markedly  to  diminish 
their  prevalence.  An  epizootic  of  bacterial  nature,  therefore,  cannot  be 
classed  with  the  natural  enemies  of  the  rat.  We  are  not  surprised,  then, 
to  learn  that  the  bacterial  rat  viruses  have  signally  failed  to  accomplish 
their  mission. 

These  bacterial  viruses  belong  to  the  colon-typhoid  group  of  organ- 
isms. They  are  either  identical  with  or  closely  related  to  the  original 
bacillus  of  mouse  typhoid  {B.  typhi  murium)  discovered  by  Loeffler,  or 
the  paratyphoid  bacillus,  type  B,  which  is  frequently  the  cause  of  meat 
poisoning,  or  the  Bacillus  enteritidis  of  Gaertner,  which  has  been  asso- 
ciated with  gastrointestinal  disorders. 

The  claim  that  these  rat  viruses  are  harmless  to  man  needs  revision, 
in  view  of  the  instances  of  sickness  and  death  reported  by  various  ob- 
servers. The  pathogenicity  for  man  depends  upon  the  virulence  of  the 
culture,  the  amount  ingested,  the  nature  of  the  medium  in  which  it 
grows,  and  many  other  factors. 

Danysz  virus  (B.  typhi  murium)  is  pathogenic  for  rats  under  labora- 
tory conditions,  but  has  feeble  powers  of  propagating  itself  from  rat  to 
rat.  It  rapidly  loses  its  virulence,  especially  when  exposed  to  light 
and  air.  The  result  depends  largely  upon  the  amount  ingested.  The 
other  viruses  have  proven  even  less  satisfactory. 

Under  natural  conditions  these  rat  viruses  may  be  likened  to  a 
chemical  poison,  with  the  great  disadvantage  that  they  rapidly  lose  their 
virulence  and  arc  comparatively  expensive.  They  also  have  the  further 
disadvantage  that  chemical  poisons  do  not  possess  of  rendering  animals 
immune  by  the  ingestion  of  amounts  that  are  insufficient  to  kill  or  by 
the  ingestion  of  cultures  that  have  lost  their  virulence. 

Squirrels. — In  August,  1903,  a  blacksmith  died  of  plague  probably 
contracted  from  a  squirrel  in  Contra  Costa  County,  California.  In 
1904  Currie  demonstrated  the  susceptibility  of  the  ground  squirrel  to 
bubonic  plague.  In  1908  McCoy  and  Wherry  discovered  natural  plague 
in  ground  squirrels.  It  was  then  learned  that  thousands  of  squirrels 
had  died  of  some  disease  during  1904,  1905,  and  1906.  This  epizootic 
was  doubtless  plague.  It  is  now  realized  that  plague  has  become  en- 
demic in  California,  in  the  squirrel.  It  is  also  believed  that  the 
disease  has  been  kept  alive  in  the  endemic  foci  of  Tibet  in  an- 
other rodent,  the  marmot  (Arctomys  hohac).     The  eradication  of  plague 

^ ' '  The  Inefficiency  of  Bacterial  Viruses  in  the  Extermination  of  Eats, "  M.  J. 
Eosenau.  "The  Eat  and  Its  Eelation  to  the  Public  Health,"  Bulletin  of  the 
P,  H,  &  M.  H.  S.,  1910, 


254  INSECT-BOKNE    DISEASES 

must,  therefore,  consider  these  and  perhaps  other  susceptible  wild 
animals. 

California  is  overrun  with  three  species  of  ground  squirrels.  The 
commonest  is  the  CiicUus  heecheyi.  Thev  live  in  colonies  in  burrows 
or  warrens.  The  booby  owl  is.  a  frequent  companion  occupying  the  same 
burrow,  and  they  probably  spread  the  infection  by  carrying  fleas.  Squir- 
rels become  infected  through  fleas  from  each  other  and  from  rats.  The 
squirrel  flea  (Ceratopliijllus  acidus)  attacks  num  just  as  the  rat  flea 
does.  The  infection  may  also  be  conveyed  to  man  through  sciiiincl  bites, 
as  in  the  case  of  the  child  in  Los  Angeles  studied  by  Stimson.  Squir- 
rels make  good  food  for  man,  but  since  the  danger  has  been  realized 
the  shooting  or  trapping  of  them  for  food  purposes  is  now  forbidden 
in  California. 

Plague  in  the  squirrel  may  be  recognized  '  by  the  gross  anatomical 
lesions  in  the  lymphatic  glands,  the  liver,  and  lungs.  The  pneumonic 
form  of  the  disease  is  common  in  the  squirrel.  Many  cases  are  subacute 
or  clironic.  Smear  preparations  from  squirrels  dead  of  plague  are 
frequently  negative  for  plague-like  bacilli.  The  diagnosis  may,  there- 
fore, be  made  more  surely  by  animal  experimentation.  Subcutaneous 
inoculation  is  surer  than  the  cutaneous  method,  as  the  latter  often 
fails  on  account  of  the  comparatively  few  plague  bacilli  present  in  squir- 
rel lesions. 

Squirrels  may  be  destroyed  by  various  means.  One  of  the  most 
successful  is  to  saturate  cotton  waste  the  size  of  an  orange  with  carbon 
bisulphid  and  place  it  in  the  warren;  then  close  the  opening  with  wet 
clay.  Poisoned  bait,  such  as  strychnin,  phosphorus,  or  cyanid  of  potas- 
sium, is  effective.  Traps  are  not  very  successful,  as  the  squirrel  is 
wary.  Natural  enemies,  such  as  the  coyote,  wolf,  badger,  skunk,  moun- 
tain lion,  the  cobra  snake,  and  red-tailed  hawk  should  be  encouraged.^ 

PLAGUE 

In  considering  the  prevention  of  plague  it  is  necessary  to  recog- 
nize that  the  different  types  of  the  disease  are  spread  in  different 
ways.  At  least  three  clinical  types  are  now  recognized:  (1)  bubonic, 
(2)  pneumonic,  and  (3)  septicemic.^  In  the  bubonic  and  septicemic 
types  of  the  disease  the  plague  bacillus  is  locked  up  in  the  glands, 
blood,  and  other  tissues  and  organs  of  the  body,  and  are  not  eliminated 

'McCoy:    Jour,  of  Infect.  Dis.,  Nov.  26,  1909,  Vol.  V,  No.  5. 

^  In  this  chapter  material  has  been  freely  drawn  from  ' '  The  Rat  and  Its 
Relation  to  the  Public  Health,"  Public  Health  and  Marine  Hospital  Service, 
1910,  particularly  articles  by  Lantz,  McXJoy,  Brinckerhoft",  Banks,  Stiles.  Rucker, 
Creel,  Holdy,  Kerr,  and  Rosenan.  This  book  may  bo  obtained  by  addressing  the 
Surgeon-General  or  the  Superintendent  of  Public   Documents,   Washington,  D.   C. 

^Occasionally  other  varieties  occur  in  which  the  chief  manifestations  are  in 
the  skin  and  subcutaneous  tissues,  or  in  the  intestines,  causing  diarrhea.  In  the 
latter  case  the  infection  is'  excreted  in  the  feces. 


EATS  AND  OTHEK  EODENTS  255 

in  the  usual  excretions.  These  forms  of  the  disease  are,  therefore,  not 
'^contagious,"  but  are  spread  mainly  through  the  agency  of  the  ilea. 
On  the  other  hand,  in  the  pneumonic  type  of  the  disease  plague  bacilli 
are  contained  in  enormous  numbers  in  the  sputum.  The  disease  is 
frequently  transmitted  directly  by  close  association  with  a  patient  hav- 
ing plague  pneumonia.  The  pneumonic  type  of  the  disease  does  not 
necessarily  follow  when  the  infection  is  taken  into  the  system  through 
the  respiratory  channel;  on  the  other  hand,  it  may  result  from  infection 
through  a  flea  bite. 

The  Bacillus  pestis  (Yersin,  1894)  has  more  than  fulfilled  Koch's 
laws.  Several  accidents  in  which  pure  cultures  have  been  inoculated 
into  man,  producing  all  the  symptoms  and  lesions  of  the  disease,  have 
added  to  the  proof  that  this  organism  is  the  cause  of  plague  (Vienna, 
1898,  Ann  Arbor,  1902,  and  also  in  laboratories  in  Eussia,  Berlin,  and 
Japan).  The  plague  bacillus  is  comparatively  easy  to  isolate  and  grows 
readily  on  artificial  culture  media,  and  has  characteristics  that  readily 
distinguish  it  from  all  other  species.  It  is  a  short  rod  with  rounded 
ends,  not  motile,  decolorized  by  Gram's  method,  and  grows  better  at 
30°  C.  than  at  blood  temperature. 

Eecognition  of  the  plague  bacillus  rests  upon  the  following  charac- 
teristics: (1)  Curious  involution  forms  upon  salt  agar  within  24  hours; 
(2)  stalactite  growth  in  liquid  media;  (3)  characteristic  lesions  pro- 
duced by  experimental  plague  in  guinea  pigs,  rabbits,  rats,  etc.  Kolle's 
method  consists  in  rubbing  the  material  containing  the  plague  bacillus 
upon  a  shaved  area  of  the  skin  of  a  guinea  pig.  The  plague  bacilli  pene- 
trate the  skin,  leaving  other  pathogenic  organisms  behind.  The  skin  of 
the  guinea  pig  thus  acts  as  a  differential  filter;  (4)  the  final  test  of  the 
identity  of  the  plague  l^acillus  is  the  fact  that  its  pathogenicity  may  be 
neutralized  by  the  use  of  antiplague  serum. 

The  Bacillus  pestis  does  not  live  a  saprophytic  existence  in  nature. 
It  is  readily  killed  by  drying,  sunlight,  heat,  and  the  usual  germicides. 
The  organism  does  not  live  long  in  the  soil  or  upon  the  floors  of  houses, 
as  was  once  commonly  supposed.  There  is,  therefore,  comparatively 
little  danger  from  these  sources. 

Immunity. — One  attack  of  plague  usually  protects  for  life.  Occa- 
sionally second  attacks  are  noted  in  the  same  person.  In  such  cases 
the  second  attack  is  usually  mild.  This  is  an  old  observation  and  led 
to  the  employment  of  persons  with  a  plague  history  or  a  plague  scar 
in  hospitals  and  laboratories. 

Artificial  immunity  of  either  an  active  or  passive  nature  may  be 
acquired  by  various  procedures.  The  passive  immunity  produced  by 
the  injection  of  antiplague  serum  lasts  only  about  three  to  four  weeks. 
The  active  immunity  produced  by  vaccination  of  cultures  may  be  de- 
pended upon  for  about  six  months. 


256  INSECT-BORNE    DISEASES 

Ilafflxine's  prophylactic  consists  of  a  killed  culture  of  the  pla^e 
bacillus,  which  is  injected  subcutaneously.  HafPkine  used  a  bouillon 
culture,  six  weeks  old,  grown  at  25-30°  C.  and  killed  at  65°  C,  for 
one  hour.  One-half  of  one  per  cent,  of  phenol  is  then  added.  From 
2  to  3.5  c.  c.  (this  was  later  increased  to  20  c.  c.)  of  this  vaccine  are 
injected  subcutaneously.  Ten  days  later  a  second  injection  of  a  still 
larger  amount  is  given. 

In  twelve  districts  in  India  224,228  persons  were  inoculated  with 
Haffkine's  prophylactic.  Of  these  3,399  took  the  disease.  Of  639,600 
not  inoculated  in  the  same  districts  49,430  were  attacked.  C.  J.  ^Martin 
concludes  that  the  chances  of  subsequent  infection  are  reduced  four- 
fifths,  and  the  chances  of  recovery  are  2.5  times  as  great  as  in  the  cases 
of  the  non-vaccinated. 

The  German  Plague  Commission  prepared  their  prophylactic  vac- 
cine from  a  fresh  virulent  agar  culture,  suspending  the  bacilli  in  salt 
solution  or  bouillon.  The  organisms  are  killed  at  65°  C.  for  one  to 
two  hours,  and  0.5  per  cent,  phenol  added.  The  amount  injected  rep- 
resents one  agar  culture. 

Lustig  and  Galliotti  extract  the  immunizing  substance  from  the 
bacterial  cell  (endotoxin)  with  weak  potassium  hydroxid.  This  nucleo- 
protein  is  collected  and  dried,  and  thus  permits  of  exact  dosage.  The 
amount  injected  is  two  to  three  milligrams  of  the  dry  extract  dis- 
solved in  water. 

Terni  and  Bandi  recommend  the  peritoneal  exudate  of  plague- 
infected  guinea  pigs,  sterilized  fractionally  at  50°  C.  and  the  addition 
of  0.5  per  cent,  of  phenol,  0.25  per  cent,  sodium  carbonate,  and  0.75 
per  cent,  sodium  chlorid. 

Shiga  prefers  a  combined  active  and  passive  immunity  produced 
with  killed  cultures  and  antipest  serum,  because  this  mixed  immu- 
nizing process  has  the  advantage  of  producing  milder  reactions. 

Kolle  and  Strong  started  out  from  the  principle  that  a  much  higher 
degree  of  immunity  is  produced  by  living  microorganisms  than  dead 
ones,  and  recommend  the  use  of  live  attenuated  cultures.  Strong  has 
a  strain,  an  entire  agar  culture  of  which  may  be  injected  into  man 
without  harm.  In  ^Manila  42  persons  were  given  a  preventive  inocula- 
tion with  this  culture. 

The  reactions  which  follow  vaccination  with  a  plague  culture, 
whether  alive  or  dead,  are  sometimes  marked.  The  symptoms  consist 
of  a  rise  in  temperature  to  39°  C,  malaise,  depression,  and  headache, 
and  swelling  and  pain  at  the  site  of  the  inoculation.  The  symptoms 
usually  pass  away  in  24  to  48  hours. 

The  production  of  an  active  acquired  immunity  has  a  distinct  prac- 
tical usefulness  in  the  prevention  of  the  disease,  although  it  cannot  take 
the  place  of  rat  and  flea  eradication.     It  has  been  used  on  a  large 


RATS  AND  OTHER  RODENTS  257 

scale  by  Haffkine  in  India,  and  to  a  lesser  extent  by  others  in  many 
parts  of  the  world  during  the  recent  plague  pandemic.  Those  who 
get  plague  after  Haffkinization  usually  have  a  mild  form  of  the  dis- 
ease, which,  in  the  experience  in  India,  rarely  results  in  death.  The 
active  immunization  of  the  community  in  the  face  of  an  epidemic 
is  a  valuable  addition  to  our  preventive  measures  against  plague. 
It  is  of  first  importance  in  jDrotectiug  small  communities,  on  ship- 
board, in  camps  and  barracks,  at  quarantine  stations,  in  plague  labora- 
tories, among  rat  brigades,  as  well  as  for  physicians,  nurses,  and  others 
who  are  exposed. 

Yersin's  serum  is  obtained  from  a  horse  that  has  received  repeated 
injections  of  plague  cultures;  at  first  killed  plague  cultures,  afterward 
living  bacilli,  are  used.  At  most  this  antitoxic  serum  is  weak,  and, 
while  it  has  a  certain  amount  of  protective  properties,  it  has  slight 
curative  power.  Very  large  quantities  must  be  administered  early  in 
the  disease  to  obtain  any  effect  at  all.  The  protection  lasts  only  a  few 
weeks,  three  to  four  at  most,  and  is,  therefore,  of  limited  practical  use. 

Endemic  Foci. — There  are  four  historic  endemic  foci  in  which  plague 
has  slumbered  for  ages.  One  is  on  the  eastern  slope  of  the  Himalayas, 
in  the  valley  of  the  Yiinnan.  The  great  epidemic  in  Hongkong  in  1894 
came  from  this  center.  A  second  endemic  focus  near,  and  perhaps  con- 
nected with  the  first  is  on  the  western  slope  of  the  Himalayas.  From 
here  the  infection  was  carried  to  Bombay  in  1896,  where  it  still  prevails. 
A  third  plague  focus  exists  from  about  the  center  of  Arabia  to  near  Meso- 
potamia. From  here  the  infection  was  dragged  to  Samarkand,  the  Black 
Sea,  and  Persia.  The  fourth  endemic  area  was  discovered  by  Koch  in 
1898  in  the  interior  of  Africa,  near  the  source  of  the-  White  Nile  in 
Uganda.  We  must  now  add  to  this  a  fifth  endemic  focus,  for  plague  has 
obtained  a  foothold  in  California  in  the  ground  squirrels,  which  will 
take  years  of  well-directed  energy  to  control.  The  disease  has  caused 
dreadful  havoc  in  India  since  1892.  In  1907  over  one  million  persons 
died  of  plague  in  that  country. 

Plague  is  kept  alive  in  the  endemic  foci  in  the  rat,  the  ground 
squirrel,  the  marmot,  the  brush  rat,  and  other  rodents.  The  campaign 
of  eradicating  plague  in  the  ground  squirrel  in  California  has  been 
directed  to  killing  as  large  a  number  of  these  animals  as  possible.  For 
this  purpose  carbon  disulphid,  sulphur  dioxid,  hydrocyanic  acid  gas, 
bait  poisoned  with  strychnin,  and  cyanid  of  potassium  are  used.  Natu- 
ral enemies,  such  as  the  coyote,  wolf,  fox,  badger,  snake,  mountain 
lion,  skunk,  and  red-tailed  hawk,  are  encouraged.  Trapping  has  not 
proven  successful,  as  the  squirrel  is  a  very  wary  animal.  Many  squir- 
rels may  be  shot,  but  those  killed  should  not  be  used  for  food. 

Management  of  a  Plague  Epidemic. — The  handling  of  a  plague 
epidemic  is  conducted  along  two  definite  lines  of  activity.     One  is  to 


258  INSECT-BORNE    DISEASES 

liml  and  care  for  the  luiinan  cases,  the  other  consists  in  a  warfare 
aijaiiist  rats.  The  organization  and  general  management  of  a  phigiie 
campaign  do  not  diil'cr  radically  from  similar  work  in  other  epidemics 
(see  page  319).  Cases  of  the  disease  must  be  sought  for  and  early 
diagnosis  coniirmcd;  all  deaths  from  no  matter  what  cause  must  be 
investigated,  and  the  body  examined  by  an  expert  before  burial  is  per- 
mitted. A  bacteriological  laboratory  is  a  sine  qua  non.  Cases  of  the 
disease  should  be  isohitcd  and  the  usual  disinfection  of  excreta  and 
surroundings  exercised.  Particular  care  must  be  taken  that  the  isola- 
tion wards  are  vermin-frco.  The  place  from  which  the  case  is  removed 
should  then  be  given  a  preliminary  disinfection  with  sulphur  dioxid 
or  other  substance  that  may  be  depended  upon  to  kill  rats  and  fleas, 
and  a  search  made  in  the  neighborhood  for  secondary  cases  both  in 
man  and  rodents. 

The  campaign  against  the  rat  is  expensive  and  dilTicult,  but  must 
be  vigorously  prosecuted  to  insure  success.  The  rat  warfare  may  be 
briefly  summarized  as  a  simultaneous  attack  upon  the  habitation  and 
food  supply  of  the  rat;  the  destruction  of  rat  burrows  and  nesting 
places;  the  separation  of  the  rat  from  his  food  supply  by  concreting  and 
screening  such  places  as  stables,  warehouses,  markets,  restaurants,  etc.; 
the  prevention  of  the  entry  of  the  rat  into  human  habitations  by  the 
use  of  concrete,  wire  netting,  or  other  barriers ;  and  the  use  of  poisons, 
traps,  etc.  For  further  con'^ideration  concerning  rats  and  their  eradi- 
cation see  page  242.  All  the  rats  that  are  caught  in  traps  or  found 
dead  are  brought  to  the  bacteriological  laboratory,  where  tliey  are  ex- 
amined and  careful  records  kept  concerning  the  species,  the  location, 
the  place  where  the  rat  was  caught,  the  character  of  the  infection,  etc. 
As  it  is  a  hopeless  task  to  exterminate  rats  from  a  large  city,  Ileiser 
has  jjroposed  a  practical  plan  which  proved  effective  in  j\Ianila.  A 
list  of  the  places  in  which  the  plague-infected  rats  were  found  was 
made.  Each  was  regarded  as  a  center  of  infection.  Eadiating  lines, 
usually  five  in  number,  were  prolonged  from  this  center,  evenly  placed 
like  the  spokes  of  a  wheel.  Rats  were  caught  along  these  lines  and 
examined.  Plague  rats  were  seldom  found  more  than  a  few  blocks 
away.  The  furthermost  points  at  which  the  infected  rats  were  found 
were  then  connected  with  a  line,  as  is  roughly  shown  in  the  diagram. 
Figs.  38  and  39.  The  place  inclosed  by  the  dotted  line  was  regarded  as  a 
section  of  infection.  The  entire  rat-catching  force  was  then  concen- 
trated along  the  border  of  the  infected  section,  that  is.  along  the  dotted 
line.  'I'hey  then  commenced  to  move  toward  tlie  center,  catching  the 
rats  as  they  closed  in.  Behind  them  ratproofing  was  carried  out.  One 
section  after  another  v/as  treated  in  this  way,  until  they  had  all  been 
wiped  out.  Once  weekly  thereafter  rats  were  caught  in  the  previously 
infected  sections  and  at  other  places,  especially  those  which  had  been 


EATS    AND    OTHER    RODENTS 


259 


infected  in  years  gone  by.  Since  the  above  system  was  adopted  plague 
has  disappeared  in  the  city  of  Manila,  and  at  a  cost  of  only  a  small 
fraction  of  that  of  a  general  rat  extermination  campaign. 

Quarantine. — Plague  infection  is  frequently  carried  over  seas  in 
vessels.  When  this  happens  it  is  more  apt  to  be  due  to  the  disease  in 
the  rat  than  man.  Maritime  quarantine,  therefore,  finds  its  greatest 
justification  in  keeping  out  plague.  To  be  successful,  measures  must 
be  directed  almost  entirely  against  the  rat,  although  a  keen  eye  must 


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be  kept  on  the  lookout  for  mild  cases  known  as  Pestis  minor,  or  walk- 
ing plague.  Rats  may  be  kept  down  on  board  a  vessel  by  the  frequent 
use  of  sulphur  dioxid.  All  vessels  trading  with  a  plague-infected  port 
should  have  each  cargo  compartment  fumigated  with  this  gas,  at  least 
when  it  is  empty,  at  the  port  of  departure.  The  vessel  must  be  again 
fumigated  with  sulphur  dioxid  on  arrival.  Both  at  the  infected  port 
and  at  the  port  of  arrival  care  must  be  taken  to  prevent  the  ingress 
and  egress  of  rats.  The  period  of  detention  of  the  personnel  for  a 
plague  ship  is  seven  days.  For  further  details  concerning  quarantine 
see  page  321. 


260 


INSECT-BORNE    DISEASES 


Prevention — Summary. — The  principles  and  many  of  the  details  for 
the  prevention  of  plague  have  been  stated  in  the  foregoing  pages,  and 
need  not  be  repeated. 

Personal  prophylaxis  consists  in  avoiding  the  infected  regions  and 
guarding  against  flea  bites.  Physicians  and  nurses  should  remember 
that  the  pneumonic  form  of  the  disease  is  higlily  "contagious"  in  the 
ordinary  sense  of  the  term.  Attendants  and  persons  who  come  in  con- 
tact with  such  cases  may  protect  themselves  with  Haffkine's  prophylac- 
tic or  Ycrsin's  serum.     Individual  measures  to  guard  against  droplet 


Fig.  43. — Isolated  Plague-infested  Center,  Manila,  P.  I. 


infection,  such  as  the  wearing  of  masks  or  veils  of  cheesecloth,  may 
be  resorted  to.  The  bubonic  and  septicemic  forms  of  the  disease  are 
not,  as  a  rule,  directly  communicable,  and,  therefore,  the  preventive 
measures  recommended  for  typhoid  fever  are  effective. 

The  ordinary  germicidal  solutions,  such  as  bichlorid  of  mercury, 
1-1,000,  carbolic  acid,  2i/^  per  cent.,  formalin,  10  per  cent.,  are  effec- 
tive against  the  Bacillus  pestis.  Of  the  gaseous  disinfectants  sulphur 
dioxid  is  preferred,  because  it  not  only  kills  the  frail  plague  bacillus, 
but  also  destroys  rats,  fleas,  etc. 

Cases  of  plague  should  be  isolated  in  a  well-screened  room  other- 
wise free  of  insects.     Fabrics  and  other  objects  which  become  contam- 


TICKS  261 

inated  with  the  discharges  should  be  thoroughly  disinfected  by  proper 
methods. 

It  is  important  to  have  prompt  reports  of  all  cases  of  suspected 
plague,  and  the  diagnosis  must  be  confirmed  by  bacteriological  meth- 
ods. In  all  plague  centers  there  should  be  a  special  hospital  and  also 
a  laboratory  where  diagnostic  work  may  be  carried  on;  this  is  an  es- 
sential part  of  the  equipment  for  a  successful  campaign.  A  traveling 
laboratory  organized  like  a  flying  squadron  for  quick  service  should 
be  provided  to  furnish  this  service  wherever  it  may  be  demanded. 

The  prevention  of  plague,  after  all,  is  reduced  to  warfare  against 
rats  and  fleas.  This  has  been  fully  discussed.  All  seaport  towns  hav- 
ing communication  with  plague  countries  would  do  well  to  examine 
for  plague  rats  caught  from  time  to  time  about  the  wharves.  This, 
in  fact,  should  be  one  of  the  routine  duties  of  the  port  sanitary  authori- 
ties. Plague  may  slumber  in  the  rats  for  years  before  human  cases 
occur.  Other  preventive  measures  are  obvious  from  the  nature  of  the 
infection  and  its  mode  of  transmission,  or  have  already  been  stated  in 
the  preceding  pages. 

TICKS 

Ticks  belong  to  the  family  Ixodidse,  and  the  diseases  which  they 
transmit  are  known  as  isodiasis.  Quite  a  number  of  different  species 
are  known  to  attack  man. 

Ticks,  or  wood  lice,  are  not  true  insecta,  but  belong  to  the  acarines 
which  include  the  mites,  and  are  closely  allied  to  spiders  and  itchmites 
(scabies).  Ticks  have  an  unsegmented  body  with  eight  legs  in  the 
adult  stage  and  six  legs  in  the  larval  stage.  In  some  of  their  habits 
they  resemble  bedbugs.  So  far  as  is  known,  they  take  no  vegetable 
food,  but  live  on  blood.  Ticks  are  ectoparasites  of  man  and  many 
animals.  They  frequently  hang  tenaciously  to  the  skin,  in  which 
they  partly  bury  themselves.  If  covered  with  oil  or  vaselin,  thus  clos- 
ing their  breathing  pores  situated  behind  the  fourth  pair  of  legs,  they 
may  be  induced  to  release  their  hold.  If  pulled  off  roughly  the  head 
(capitulum)  is  likely  to  break  off  and  remain  in  the  skin.  Sulphur 
in  some  form  is  useful  to  destroy  ticks  in  the  adult  stage.  Sulphur 
ointment  is  particularly  obnoxious  to  this  group  of  parasites.  Ar- 
senic and  crude  oil  also  act  as  poisons  to  the  tick,  and  may  be  used 
by  local  application. 

The  life  cycle  of  the  tick  consists  of  four  distinct  stages,  viz. :  egg 
(embryo),  larva,  nymph,  and  adult.  The  eggs  are  invariably  deposited 
on  the  ground  in  large  masses.  The  larvas  which  emerge  from  the 
eggs  are  minute  six-legged  creatures.  The  larvse  attach  themselves  to 
a  suitable  host,  upon  which  they  feed,  then  usually  drop  to  the  ground 
19 


262  IXSECT-BOENE    DISEASES 

and  molt,  becoming  nymphs.  The  nymphs  have  eight  legs.  The  nymph 
waits  until  it  can  attach  itself  to  a  liost.  engorges  blood,  usually  drops. 
molts  its  skin,  and  becomes  adult.  The  life  history  of  the  tick 
differs  from  the  mosquito  in  that  the  larval  and  pupal  stages  are  not 
aquatic. 

It  was  first  shown  by  Smith  and  Kilborne  that  in  the  case  of  Texas 
fever  the  microorganism  within  the  adult  tick  passes  into  the  egg  and 
is,  therefore,  transmitted  "hereditarily"  to  the  next  generation.  The 
infection  of  Eocky  Mountain  spotted  fever,  of  canine  piroplasmosis.  and 
probably  also  that  of  African  tick  fever,  is  also  transmitted  by  the  female 
to  the  next  generation.  Tick-borne  diseases  are  not  always  transmitted 
in  nature  in  this  way.  The  virus  may  be  transferred  directly  by  the 
larva,  the  nymph,  or  the  adult.  Thus  some  ticks  leave  their  host  re- 
peatedly, and  the  parasites  they  draw  from  one  animal  may  be  injected 
into  another  animal  either  during  the  same  or  at  a  subsequent  stage  in 
the  development  of  the  tick. 

Ticks  upon  domestic  stock  may  be  controlled  by  dipping,  spraying, 
or  by  hand  methods.  The  arsenical  dip  has  practically  displaced  all 
others  for  the  destruction  of  ticks  in  the  various  parts  of  the  world. 
Crude  oils  have  been  used  to  a  considerable  extent  in  some  cases.  They 
are  more  expensive  than  the  arsenical  dip,  and  dangerous  to  cattle 
under  some  conditions.  Serious  losses  have  followed  the  use  of  heavy 
oils  in  dry  regions,  or  where  it  has  been  necessary  to  drive  the  cattle 
any  considerable  distance  after  dipping. 

The  formula  for  the  arsenical  dip  is  as  follows: 

Sodium  carbonate    (sal.   soda) 24  lbs. 

Arsenic  trioxid    (white   arsenic) 8  lbs. 

Pine   tar    2  gals. 

Water sufficient   to   make  500  gals. 

Sometimes  dipping  is  not  practical.  Instead  of  driving  cattle  con- 
siderable distances  to  dipping  vats  it  will  be  found  sufficient  to  treat 
them  thoroughly  by  hand  methods.  The  procedure  consists  simply  in 
applying  the  arsenical  mixture  liberally  by  means  of  rags,  mops,  or 
brushes,  or  by  means  of  spray  pumps.  Crude  oil  may  be  used  by  hand 
instead  of  the  arsenical  solution.  For  most  tick-borne  diseases  cattle 
must  be  dipped  or  treated  weekly. 

The  following  diseases  transmitted  by  ticks  will  be  given  brief  con- 
sideration: Texas  fever  (Margarojnis  annulatus).  South  African  tick 
fever  {Ornithodoros  savignyi),  Eocky  Mountain  spotted  fever  {Derma- 
cenfor  venustus),  and  relapsing  fever  (Ornithodoros  moubata).  Al- 
though it  is  probable  that  the  latter  disease  is  also  transmitted  by  the 
Argas  persicus,  and  perhaps  other  biting  insects. 


TICKS  263 


TEXAS  FEVER 

Texas  fever  or  splenetic  fever  is  also  known  as  bovine  malaria,  tick 
fever,  and  hemoglobinuria.  The  disease  does  not  affect  man.  It  is 
confined  to  cattle,  and  is  of  very  great  economic  importance.  Texas 
fever  is  an  infection  which  should  be  understood  by  all  sanitarians,  on 
account  of  its  scientific  and  historic  importance.  The  cause  of  this  in- 
fection and  its  mode  of  transmission  were  ascertained  in  1893  by  Smith 
and  Kilborne.  The  discovery  that  the  tick  is  the  intermediate  host  of 
Texas  fever  opened  an  entirely  new  principle  in  the  sanitary  sciences. 

Texas  fever  is  caused  by  a  protozoon  parasite.  This  parasite  was 
first  named  Pyrosoma  higeminum  on  account  of  the  twin-like,  pear- 
shaped  forms  commonly  seen  in  the  red  corpuscles.  This  genus  was 
changed  by  Patton  in  1895  to  Piroplasma.  These  terms  having  been 
preoccupied,  the  present  name  of  the  parasite  is  Babesia  higemina.^ 


Si 

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Fig.  44. — The  Tkxas  Fever  Tick  (Margaropus  annalatus). 

The  contagium  is  carried  by  the  cattle  tick,  Boophilus  hovis,  now 
M.  annulatus.  The  tick  lives  upon  the  skin  and  feeds  upon  the  infected 
blood,  becomes  sexually  mature  at  the  last  molt;  the  female  drops  to 
the  ground  and  lays  about  2,000  eggs;  the  newly  hatched  larvae  attach 
themselves  to  the  skin  of  a  fresh  host,  which  they  infect.  This  explains 
the  long  extrinsic  period  of  incubation  in  this  disease,  40-60  days;  30 
days  of  which  are  required  for  the  development  of  the  larvae  and  the 
remainder  for  the  development  of  the  parasite  within  the  host. 

ROCKY  MOUNTAIN  SPOTTED  FEVER 

This  disease,  also  called  tick  fever  and  spotted  fever,  is  an  interest- 
ing infection  which  occurs  chiefly  in  the  Bitter  Root  Valley  of  Montana, 
centering  around  Missoula.     Cases  also  occur  in  the  neighboring  states 

^  These  various  names  are  given  for  the  reason  that  they  are  all  found  in  the 
literature. 


264: 


INSECT-BORNE    DISEASES 


of  Idaho  and  Wyoming.  The  symptoms  closely  resemble  those  of  ty- 
phus fever,  including  a  petechial  eruption.  Anderson  and  Goldberger 
have  shown  that  typhus  fever  of  Mexico,  called  tabardillo,  is  not  trans- 


FiG.  45. — Rocky  Mountain  Spotted  Fever  Tick.   (Dermacentor  venustus). 
1,  Adult  female,  unengorged,  dorsal  view;   2,  Adult  male,  dorsal  view;   3,  Adult  female, 
unengorged,  ventral  view;  4,  Adult  male,  ventral  view;  5,  Adult  female  in  act  of  de- 
positing eggs. 

missible  to  guinea  pigs,  while  Eicketts  and  also  King  independently 
demonstrated  that  some  of  the  infected  blood  of  a  case  of  Eocky  Moun- 
tain fever  injected  into  a  guinea  pig  will  reproduce  the  chief  features 
of  this  disease.     The  two  diseases  are,  therefore,  distinct. 


TICKS  265 

Wilson  and  Chowning  first  suggested  that  the  tick  acts  as  the  car- 
rier of  Eocky  Mountain  spotted  fever.  This  was  proven  by  Eicketts  in 
1906,  who  showed  tliat  the  particular  tick  is  Dermacentor  occiden- 
talis  (now  venustus).  The  infection  may  be  transmitted  by  the  larva, 
the  nymph,  and  both  the  adult  male  and  female  ticks.  The  infection 
is  also  transmitted  hereditarily  through  the  ticks  to  their  larvae.  The 
disease  has  been  transmitted  through  the  tick  from  man  to  monkey 
and  the  guinea  pig,  and  also  from  monkey  to  monkey  and  from  guinea 
pig  to  guinea  pig.  A  few  infected  ticks  have  actually  been  found  by 
Eicketts  in  nature. 

Mayer  ^  has  proved  by  experiment  that  different  species  of  ticks  col- 
lected from  various  regions  [Dermacentor  marginatus  (Utah),  Amtly- 
omma  americanus  linnceus  (Missouri),  and  Dermacentor  variabilis 
(Mass.)]  are  able  to  transmit  the  virus  of  Eocky  Mountain  spotted 
fever.  The  inference  is  that  the  disease  may  find  favorable  conditions 
for  its  existence  in  localities  other  than  those  to  which  it  is  now  limited. 

One  attack  of  the  disease  establishes  a  rather  high  degree  of  immu- 
nity to  subsequent  attacks.  The  blood  serum  of  recovered  cases  con- 
tains protective  properties  of  a  rather  high  degree  for  guinea  pigs. 
The  virus  is  not  filterable  through  a  Berkefeld  filter.  The  nature  of 
the  virus  is  not  known. 

The  prevention  of  Eocky  Mountain  spotted  fever  is  directed  en- 
tirely against  the  tick.  Ticks  are  to  be  avoided  in  the  infected  region. 
If  it  is  necessary  to  work  in  the  fields  and  woods  and  about  animals 
where  these  ticks  abound,  the  bites  should  at  once  be  cauterized  with 
strong  carbolic  acid.  A  vigorous  campaign  should  be  carried  on  by  the 
health  authorities  to  destroy  all  the  ticks  in  and  about  each  case  of 
the  disease. 

The  ultimate  control  of  Eocky  Mountain  spotted  fever  depends  upon 
the  suppression  of  the  Dermacentor  venustus.  This,  perhaps,  is  not  so 
hopeless  a  task  as  may  at  first  seem  likely.-  Henshaw  and  Birdseye  ^ 
found  twenty  species  of  five  hundred  mammals  examined  in  and  around 
Bitter  Eoot  Yalley  to  carry  ticks  either  in  the  immature  or  adult  stage. 
The  mammalian  hosts  of  fever  ticks  fall  naturally  into  two  groups : 
those  that  harbor  chiefly  adult  ticks  and  those  that  harbor  the  younger 
stages.  In  the  former  class  belong  mountain  goats,  bears,  coyotes,  badg- 
ers, woodchucks,  and  possibly  elk,  deer,  mountain  sheep,  rabbits,  and 
domestic  stock,  such  as  horses,  cattle,  and  sheep.  Those  of  the  second 
class  harboring  the  nymphs  and  larvae 'are  mainly  rodents  and  comprise 
ground   squirrels,    woodchucks,    chipmunks,    pine   squirrels,   mice,    and 

"^Jour.  Infect.  Bis.,  April   12,   1911. 

'^ Fortunately  the  Derm-acentor  venustus  is  the  only  tick  in  the  endemic  region 
which  attacks  man. 

^  U,  S.  Dept.  of  Agr.,  Bureau  of  Biol.  Survey,  Cir.  82. 


2r.6  INSECT-BORXE    DISEASES 

wood  rats.  These  smaller  animals  are  too  agile  to  permit  the  adult 
ticks  to  remain  upon  tliem. 

Unquestionably  the  great  bulk  of  fever  ticks  {Derma^enior  venus- 
tiis)  which  become  engorged  in  the  Bitter  Root  Valley  do  so  on  do- 
mestic stock — horses,  cattle,  sheep,  and  sometimes  dogs.  They  ob- 
tain the  ticks  from  the  pastures  and  other  uncultivated  land  infested 
by  wild  animals.  It  is  obvious,  therefore,  that,  if  the  domestic  ani- 
mals in  the  valley  are  rendered  tick-free  by  dipping,  spraying,  or  by 
some  other  equally  effective  method,  the  chances  of  the  infection  of 
human  beings  will  be  vastly  lessened.  Dipping  carried  on  upon  an  exten- 
sive scale  throughout  the  endemic  area  by  McClintic  has  given  surpris- 
ingly successful  results,  there  having  been  fewer  cases  of  the  disease 
this  season  in  the  Bitter  Eoot  Valley  than  for  any  year  of  record. 

Supplementary  measures  for  the  control  of  Eocky  Mountain  spot- 
ted fever  consist  in  the  reduction  of  the  number  of  rodents  and  the 
clearing  of  the  brush  land  along  the  edges  of  the  valley.^ 

]\IcClintic  infected  Rhesus  monkeys  and  guinea  pigs  with  spotted 
fever  and  treated  them  with  the  following  drugs:  salvarsan,  sodium 
cacod3-late,  and  urotropin.  The  results  obtained,  however,  do  not  in- 
dicate that  any  of  these  drugs  possess  any  value  whatever  either  as  a 
prophylactic  or  in  the  treatment  of  spotted  fever,  but,  on  the  contrary, 
their  administration  seems  on  the  whole  rather  to  intensify  the  severity 
of  the  disease  in  the  animals  compared  with  the  course  of  the  disease 
in  the  controls. - 

RELAPSING  FEVER 

Relapsing  fever,  also  called  famine  fever  and  seven-day  fever,  is 
found  upon  all  the  five  continents  of  the  globe.  Epidemics  of  this 
disease  have  been  reported,  especially  from  Ireland  and  Russia.  The 
infection  prevails  in  India,  w^here  Vandyke  Carter  of  Bombay  made  his 
classic  investigations.  Relapsing  fever  was  epidemic  in  jSTew  York  and 
Philadelphia  in  1869.  It  has  not  reappeared.  The  disease  has  receded 
from  civilization  where  cleanliness  is  observed. 

Obermeier  in  1868  discovered  the  spirillum  in  the  blood — Spirillum 
ohermeieri.  Carter  and  Koch  in  1878  showed  that  the  infection  may 
be  transferred  to  apes  by  the  inoculation  of  the  blood  of  a  patient. 
Miinch  and  Moczutkowski  transferred  the  disease  by  the  inoculation  of 
relapsing  fever  blood  to  healthy  individuals.  Koch  succeeded  in  dem- 
onstrating that  the  spirochetes  of  African  relapsing  fever  multiplied 
in  the  tick  (Ortiithodoros  mouhata),  and  that  the  bite  of  this  tick 
may  convey  the  disease  to  healthy  men.     The  African  relapsing  fever 

'Hunter.  W.  D.,  and  Bishopp,  F.  C:    "The  Rocky  Mountain  Spotted  Fever 
Tick,"  Bureau  of  Entomology  BuU.  No.   105.  U.  S.  Dept.   of  Agr. 
=^17.  S.  Pub.  Health  Beports,  Vol.  XXVII,  No.  20,  May  17,  1912. 


TICKS  367 

which  Koch  studied  in  East  Africa  shows  some  slight  diiJerences  from 
the  European  disease. 

Although'  Koch  and  also  Button  and  Todd  demonstrated  that  the 
African  relapsing  fever  may  be  transmitted  through  the  bite  of  a 
tick^  it  is  very  probable  that  in  Europe  and  other  countries  where  re- 
lapsing fever  occurs  the  disease  may  also  be  transmitted  by  the  Argas 
persicus.  In  fact,  other  insects,  as  bedbugs,  fleas,  biting  flies,  and  lice, 
may  convey  the  infection. 

Leishman  ^  has  demonstrated  that  the  Spirochceta  duttoni  may  be 
transmitted  hereditarily  in  the  tick.  He  has  obtained  positive  results 
in  the  second  generation,  the  bites  of  which  were  infective  for  mice 
and  monkeys.  Attempts  to  carry  the  infection  to  the  third  generation 
in  the  tick  have  so  far  failed.  Leishman  considers  the  hereditary  trans- 
mission of  the  infection  as  biological  evidence  that  the  spirochetes  be- 
long to  the  protozoa  rather  than  the  bacteria. 

Schuberg  and  Manteuf e  ^  found  that  a  temperature  of  22°  C.  is 
not  favorable  for  the  spirochete  in  the  Ornithodoros  mouhata.  This 
was  shown  by  experiments  upon  rats  in  which  the  infection  through 
the  bite  of  the  tick  disappeared  more  quickly  at  22°  C.  than  at  higher 
temperatures. 

One  attack  protects  against  subsequent  attacks.  Second  attacks 
among  negroes  in  Africa  in  after  years  are  very  light.  The  only  sus- 
ceptible animals  are  man,  the  apes,  mice,  and  rats. 

The  prevention  of  relapsing  fever  is  based  upon  personal  and  domes- 
tic cleanliness  and  the  avoidance  of  tick  and  other  bug  bites.  Personal 
prophylaxis  depends  upon  keeping  aloof  from  vermin-infested  places, 
especially  where  the  disease  prevails.  Manson  suggests  that  a  mosquito 
net,  a  bed  well  off  the  ground,  and  a  night  light  are  indispensable  in 
Africa,  where  the  nocturnal  habits  of  the  Ornithodoros  mouhata  ren- 
der the  hours  of  sleep  especially  dangerous. 

SOUTH  AFRICAN   TICK  FEVER 

This  is  a  febrile  disease  common  in  parts  of  Africa.  The  incubation 
is  from  five  to  ten  days  and  the  attack  lasts  from  two  days  to  a  week 
or  more,  with  abdominal  pains,  chills,  vomiting,  diarrhea.  Eelapses 
do  not  occur  as  in  relapsing  fever.  The  disease  is  caused  by  a  spirillum 
very  similar  to  the  Spirillum  ohermeieri,  but  shown  by  ISTovy  and  others 
to  have  slight  differences.  The  spirillum  was  demonstrated '  in  1905 
by  Button,  who  also  showed  that  the  infection  can  be  transferred  to 
monkeys  by  the  bites  of  young  ticks  at  their  first  feeding  after  hatching 
from  infected  parents.     Here   again  is   an  instance  of  the  hereditary 

"■Lancet,  Jan.  1,  1910,    Vol.  1,  p.  11. 

^  Zeitsclir.  f.  Immunitdtsforschung,  Orig.  Bd.  4,  1910,  p.  512,. 


268  INSECT-BORNE    DISEASES 

transmission  of  the  parasite  in  the  insect  host.  Button  accidentally 
inoculated  himself  through  a  wound  on  the  hand  at  an  autopsy  and 
developed  the  disease  which  caused  his  death. 

The  particular  tick  in  this  case  is  the  Ornithodoros  savignyi.  The 
prevention  of  the  disease  depends  entirely  upon  a  knowledge  of  the 
biology  of  the  tick  and  efforts  to  guard  against  its  bite,  to  prevent  in- 
fection of  the  ticks,  and  to  destroy  them,  as  far  as  possible,  in  the  in- 
fected regions. 

LICE 

The  insects  known  as  pediculi  or  lice  are  parasitic  during  their 
entire  life  on  warm-blooded  animals,  including  man.  They  are  de- 
graded, flat,  rather  elongate,  wingless  insects  with  a  small  head  and 
stout  legs  which  end  in  a  strong  claw,  opposable  to  a  projection  at 
the  tip  of  the  penultimate  joint.  The  mouth  parts  are  of  a  very  pe- 
culiar nature.  There  is  a  short  beak  or  proboscis  in  front.  Through 
this  beak  extends  a  slender  stylet  which  has  three  parts.  The  stylet 
is  used  to  pierce  the  skin  of  the  host  and  the  blood  is  thus  sucked  up 
through  the  proboscis.  Lice  usually  walk  sideways,  but  do  not  travel 
much  and  keep  fairly  close  to  one  host.  The  eggs  are  slightly  elongated 
and  fastened  to  the  hair  of  the  host  or  clothing.  They  hatch  in  about 
ten  to  fifteen  days,  the  young  coming  out  of  the  top  of  the  egg.  These 
young  do  not  differ  much  in  structure  from  the  adults,  but  are  paler 
in  color.  They  molt  their  skin  a  few  times,  probably  four,  before  they 
reach  the  matured  condition.  The  males  are  less  numerous  than  the 
females,  and  ordinarily  smaller.  There  are  several  generations  each 
year,  dependent,  doubtless,  on  the  temperature,  but  the  life  history  is 
not  thoroughly  known  for  any  species. 

It  is  the  blood-sucking  habits  of  lice  which  render  them  dangerous 
parasites  and  capable  of  transmitting  disease  from  one  host  to  another. 
Fortunately,  they  do  not  readily  change  hosts,  so  that  they  cannot  be 
considered  quite  as  dangerous  as  some  more  active  parasites.  There 
are  about  50  or  60  known  species  which  are  arranged  in  15  genera 
and  4  families.  It  is  Pediculus  vestimenti,  the  clothes  or  body  louse, 
which  is  mainly  responsible  for  the  transmission  of  typhus  fever. 

Three  species  of  lice  are  found  upon  man:  (1)  Pediculus  capitis 
(now  humanus),  the  ova  of  which  are  attached  to  the  hairs  and  can 
readily  be  seen  as  white  specks,  known  as  nits.  (2)  Pediculus  vesti- 
menti (or  corporis),  the  clothes  or  body  louse,  lives  on  the  cloth- 
ing, and  in  sucking  the  blood  causes  minute  hemorrhagic  specks,  com- 
monly about  the  neck,  back,  and  abdomen.  (3)  Pediculus  (or 
Phthirius)  pubis  or  crab  louse  is  found  in  the  parts  of  the  body  cov- 
ered with  short  hairs,  as  the  pubes;  more  rarely  the  axilla  and  eye- 
brows. 


LICE  269 

The  prevention  of  lousiness  is  almost  entirely  a  matter  of  personal 
cleanliness.  However,  the  most  scrupulous  individuals  may  become 
infested.  Lice  may  be  passed  directly  from  one  person  to  another,  or 
occasionally  may  be  carried  by  flies,  or  other  means.  Beds  in  hotels 
and  sleeping  cars  are  sources  of  infection. 

Human  lice  may  be  destroyed  with  kerosene,  turpentine,  carbolic 
acid  (1-50),  bichlorid  of  mercury  solutions,  tincture  of  cocculus  in- 
dicus,  and  other  well-known  insecticides.  It  is  comparatively  easy  to 
destroy  the  adult  insect,  but  the  eggs  are  resistant.  On  badly  infected 
heads,  therefore,  the  hair  should.be  cut  short.  To  free  the  hair  of  lice 
a  good  practice  is  to  use  equal  parts  of  kerosene  and  olive  oil.  Eub 
the  mixture  well  into  the  scalp,  then  cover  the  hair  with  a  piece  of 
muslin  and  fasten  it  about  the  head.  Care  must  be  exercised  to  avoid 
a  lighted  gas  jet  or  flame.  In  the  morning  wash  the  scalp  well  with 
soap  and  hot  water,  then  use  a  flne-toothed  comb  wet  in  vinegar  to 
remove  the  nits.     Eepeat  the  treatment  two  or  three  nights. 

In  the  case  of  the  body  louse  the  clothing  should  be  boiled,  baked, 
or  steamed.  Articles  injured  by  heat  may  be  subjected  to  sulphur 
fumes  or  dipped  in  carbolic  acid  solution.  Carbon  bisulphid  and  hydro- 
cyanic acid  are  also  effective. 

For  pubic  lice  white  precipitate  or  mercurial  ointment  should  be 
used  and  the  parts  thoroughly  washed  two  or  three  times  a  day  with 
soft  soap  and  water. 

The  principal  disease  known  to  be  transmitted  by  lice  is  typhus 
fever,  but  it  is  suspected  in  relapsing  fever  and  other  infections. 

TYPHUS  FEVER 

Typhus  fever  was  formerly  confused  with  typhoid  fever,  but  Ger- 
hard in  1829  was  the  first  to  insist  upon  the  non-identity  of  these  two 
diseases.  Previous  to  that  time  typhus  fever  was  the  prominent  and 
prevailing  disease,  while  typhoid  fever  was  of  secondary  interest.  Now 
the  situation  is  reversed;  typhoid  fever  has  become  pandemic,  while 
typhus  fever  has  receded  with  civilization  and  improvements  in  sani- 
tation. Epidemics  of  typhus  fever  are  now  rare,  except  in  a  few 
places,  notably  the  Grand  Plateau  of  Mexico,  where  the  disease  prevails 
extensively  and  with  a  high  mortality.  It  prevails  also  in  certain  por- 
tions of  Ireland,  in  some  provinces  of  France,  portions  of  Russia, 
particularly  Poland  and  the  east  sea  provinces,  and  at  times  in  Tunis, 
Algiers,  and  Egypt  in  JSTorthern  Africa;  in  Spain,  Hungary,  and  cer- 
tain provinces  of  the  Baltic  States. 

Typhus  fever  last  prevailed  in  epidemic  form  in  the  United  States 
in  ISlew  York  in  1881-82  and  again  in  1892-93,  and  in  Philadelphia  in 
1883,     Since  then,  except  for  a  few  sporadic  cases  at  our  seaports,  the 


270  INSECT-BORNE    DISEASES 

disease  has  been  thought  to  be  non-existent  in  the  United  States.  How- 
ever, Anderson  and  Goldberger  ^  have  recently  shown  that  the  symp- 
tom-complex known  as  "Brill's  disease"  is  in  reality  typhus  fever,  and 
that  the  typhus  fever  of  Europe  and  the  typhus  fever  or  "tabardillo" 
of  Mexico  are  the  same  disease.  It  is  now  evident  that  typhus  fever 
has  been  existent  in  New  York  a  great  many  years,  certainly  since 
1896,  when  Brill  first  observed  cases  of  what  was  known,  previous  to 
the  work  of  Anderson  and  Goldberger,  as  "BrilFs  disease.*'  The  disease 
in  New  York  is  generally  mild,  but  seems  to  be  on  the  increase;  there- 
fore, we  face  a  new  sanitary  problem  in  this  country. 

Typhus  fever,  when  prevalent  in  epidemic  form,  has  been  said  by 
the  older  writers  to  be  one  of  the  most  highly  contagious  of  febrile 
diseases,  doctors  and  nurses  and  others  in  close  contact  with  the  dis- 
ease being  almost  invariably  stricken.  The  sad  case  of  Ricketts,  who 
lost  his  life  in  endeavoring  to  unravel  this  pathological  puzzle  in  Mex- 
ico, is  still  fresh  in  mind. 

The  period  of  incubation  of  typhus  fever  is  from  five  to  twenty 
days,  with  an  average  of  twelve.  One  attack  apparently  confers  a  very 
definite  immunity,  second  attacks  being  very  unusual.  The  cause  of 
the  infection  is  unknown. 

Methods  of  prevention  have  been  given  a  sound  foundation  through 
the  recent  work  of  Xicolle  of  France,  Eicketts  and  Wilder  of  the  Uni- 
versity of  Chicago,  and  of  Anderson  and  Goldberger  of  the  U.  S.  Pub- 
lic Health  and  Marine  Hospital  Service.  It  is  now  clear  that  the  virus 
exists  in  the  circulating  blood  during  at  least  all  of  the  febrile  stage 
and  possibly  in  some  instances  for  thirty-six  hours  after  the  crisis. 

The  disease  may  be  transmitted  by  blood  inoculations  to  chimpan- 
zees and  probablv  to  all  the  lower  monkeys.  The  virus  as  it  exists  in 
the  circulating  blood  is  apparently  held  back  by  the  Berkefeld  filter. 
It  is  not  killed  by  freezing  for  eight  days,  but  is  deprived  of  virulence 
by  heating  at  55°  C.  for  15  minutes. 

Monkeys  that  recover  from  the  experimental  disease  show  a  definite 
immunity  to  subsequent  infection. 

Nicolle  in  1909  was  the  first  to  report  the  transmission  of  typhus 
fever  by  the  bite  of  the  body  louse  (PediciiJus  restimenti).  Since 
then  his  work  has  been  confirmed  by  Ricketts  and  Wilder  and  by  An- 
derson and  Goldberger.  These  latter  authors  have  recently  shown  that 
the  head  louse  (Pedicidits  capitis)  may  also  transmit  the  infection. 
The  role  of  the  body  louse  in  the  transmission  of  typhus  fever  will 
receive  ready  support  from  students  of  the  epidemiology'  of  typhus 
fever,  for  this  disease   presents   all  the  characteristics  of   insect-borne 

^Anderson,  John  F.,  and  Goldberger,  Joseph:  "The  relation  of  so-called 
Brill's  disease  to  tvphus  fever;  an  experimental  demonstration  of  their  identity." 
Public  Health  Eeports,  XXVII,  February  2.  1912. 


LICE  371 

disease.  Since  the  transmission  of  the  disease  by  the  body  louse  has 
been  shown,  we  can  understand  why  typhus  fever  prevails  in  epidemic 
form  only  in  overcrowded,  filthy,  unhygienic  surroundings,  and  the 
truth  is  readily  understood  of  the  oft-quoted  sentence  of  Hirsch,  that 
"the  history  of  typhus  is  the  history  of  human  wretchedness." 

The  disease  has  greatly  decreased  from  civilized  centers  with  dim- 
inution in  lousiness.  The  prevention  of  typhus  now  focuses  itself  upon 
the  eradication  of  the  body  louse.  Fortunately,  this  insect  does  not 
of  itself  travel  far,  but  it  may  be  carried  many  miles  upon  the  body 
or  in  the  clothing.  The  eradication  of  the  body  louse  is  largely  a 
question  of  personal  cleanliness,  and,  so  far  as  typhus  fever  is  con- 
cerned,  is  closely  interwoven  with  squalor,   ignorance,  and  poverty. 

'Now  that  we  know  how  the  disease  is  spread,  measures  may  be  in- 
telligently applied  for  its  prevention,  these  measures  being  primarily 
directed  to  the  destruction  of  the  Pediculus  vestimenti  and  its  eggs. 
When  a  case  of  typhus  fever  is  discovered  the  patient  should  be  re- 
moved to  a  vermin-free  room  or  hospital.  The  patient's  clothes  should 
be  removed  and  either  placed  in  boiling  water  or  a  1-500  solution  of 
bichlorid  of  mercury  for  the  destruction  of  lice  and  their  eggs.  The 
patient's  hair  should  be  clipped  and  he  should  then  be  given  a  thor- 
ough sponging  with  a  1-2,000  solution  of  bichlorid  of  mercury  for  the 
destruction  of  lice  eggs.  The  room  or  apartment  from  which  the  pa- 
tient was  removed  should  be  thoroughly  fumigated  by  the  burning  of 
sulphur  for  the  destruction  of  lice,  and  the  room  kept  sealed  for  at 
least  12  hours. 

The  fact  should  be  kept  constantly  in  mind  that  the  louse  is  neces- 
sary for  the  spread  of  typhus  fever,  just  as  the  mosquito  is  for  the 
spread  of  malaria,  and  our  efforts  toward  prophylaxis  should  be  con- 
ducted with  this  point  continuously  in  mind.  Even  with  the  knowledge 
of  the  mode  of  transmission  of  typhus  fever  individual  prophylaxis  is 
still  somewhat  difficult,  especially  where  infected  insects  abound  in 
thickly  populated  centers. 

Those  whose  duties — such  as  doctors  and  nurses — take  them  into 
an  infected  area  should  avoid  outer  clothing  which  is  liable  to  brush 
against  the  furniture,  bedding,  etc.  The  skirts  of  nurses  should  be 
sufficiently  short  to  avoid  touching  the  floor;  trousers  should  be  rolled 
above  the  shoe-tops  and  the  sleeves  above  the  elbows,  so  that  occasional 
vermin  which  may  lodge  on  the  hand  may  be  more  readily  detected. 
Eucalyptus  oil  has  been  recommended  for  smearing  the  neck,  wrists, 
and  ankles.  Personal  prophylaxis  may  also  be  assisted  through  the 
use  of  gloves,  veils,  netting,  and  similar  mechanical  devices.  The  cloth- 
ing worn  by  those  attending  cases  of  the  disease  where  lice  are  present 
should  be  frequently  changed  and  close  attention  given  to  personal 
cleanliness. 


272 


INSECT-BORNE    DISEASES 


BEDBUGS 


Cimex  leciularius  has  been  carried  by  man  to  all  parts  of  the  in- 
habited world.  It  has  become  a  true  domesticated  animal  and  has 
accommodated  itself  well  to  the  environment  of  human  habitations. 
The  bedbug  lias  no  wings  and  a  very  flat  body,  which  enables  it  to  hide 
in  tlie  narrowest  chinks  and  cracks  of  beds  and  wells.  It  may  subsist 
for  incredibly  long  periods  of  time  without  food.  It  is  nocturnal  in 
its  habits. 

The  pronounced  odor  of  this  insect  is  produced  by  certain  glands 
opening  on  the  back  of  the  abdomen  in  young  bugs  and  on  the  under 


Fig.  46. — The  Bedbug. 

a,  Adult  female,  gorged  with  blood;   b.  Same  from  below;  c,  Rudimentary  wing  pad; 

d,  Mouth  parts.     (Marlatt.) 

side  of  the  metasternum  in  the  adults.  The  odor  is  common  to  most 
members  of  the  group  to  which  this  insect  belongs.  It  is  useful  in 
plant  bugs,  protecting  them  from  their  enemies. 

The  bedbug  undergoes  an  incomplete  metamorphosis,  the  young  be- 
ing very  similar  to  their  parents  in  appearance,  structure,  and  habits. 
The  eggs  are  white,  oval  objects  having  a  little  projecting  rim  around 
one  edge,  and  are  laid  in  batches  of  from  six  to  fifty,  in  cracks  and 
crevices  where  the  bugs  go  for  concealment.  The  eggs  hatch  in  a 
week  or  ten  days  and  the  young  escape  by  pushing  the  lid  within  the 
projecting  rim  from  the  shell.  At  first  the  larvae  are  yellowish-white, 
nearly  transparent,  the  brown  color  of  the  more  mature  insect  increas- 
ing with  the  later  molts.  During  the  course  of  development  the  skin 
is  shed  five  times,  and  with  the  last  molt  the  minute  wing  pads,  char- 
acteristic of  the  adult  insect,  make  their  appearance.  Marlatt  found 
that  under  favorable  conditions  about  seven  weeks  elapse  from  the  egg 


BEDBUGS  2n 

to  the  adult  insect,  and  that  the  time  between  each  molt  averages  about 
eight  days.  Without  food  they  may  remain  unchanged  for  an  indefinite 
time.  Ordinarily  but  one  meal  is  taken  between  molts,  so  that  each 
bedbug  must  puncture  its  host  five  times  before  becoming  mature,  and 
at  least  once  afterward  before  it  can  develop  eggs. 

The  presence  of  bedbugs  in  a  house  is  not  necessarily  an  indication 
of  neglect  or  carelessness.  They  are  very  apt  to  get  into  trunks  and 
satchels  of  travelers  or  may  be  introduced  in  the  homes  upon  the  cloth- 
ing of  servants,  workmen,  or  visitors.  The  bedbug  is  quite  capable  of 
migrating  from  one  house  to  another.  Ships  are  almost  sure  to  be 
infested  with  them.  They  are  not  specially  limited  by  cold,  and  are 
known  to  occur  well  north.  They  thrive  particularly  in  old  houses 
which  are  full  of  cracks  and  crevices,  in  which  they  can  conceal  them- 
selves beyond  easy  reach.  The  biting  organ  of  the  bedbug  is  similar 
to  that  of  other  Hemipterous  insects.  The  skin  of  the  host  or  victim 
is  pierced  with  four  thread-like  hard  filaments  or  setae,  which  glide 
over  each  other  with  an  alternating  motion  and  thus  pierce  the  skin. 
The  blood  is  drawn  up  through  the  beak,  which  is  closely  applied  to 
the  point  of  puncture.  The  bite  of  the  bedbug  is  decidedly  poisonous 
to  some  individuals,  resulting  in  a  swelling  and  disagreeable  inflamma- 
tion. 

The  Suppression  of  Bedbugs. — On  account  of  its  habits  of  conceal- 
ment the  bedbug  is  usually  beyond  the  reach  of  the  ordinary  insect 
powders,  which  are  practically  of  no  avail  against  it.  If  iron  or  brass 
bedsteads  are  used,  the  eradication  of  the  insect  is  made  easier.  Large 
wooden  bedsteads  furnish  many  cracks  and  crevices  into  which  the  bugs 
can  force  their  flat  thin  bodies,  and  extermination  becomes  a  matter 
of  considerable  difficulty.  The  most  practical  way  of  eradicating  bed- 
bugs is  by  a  very  liberal  application  of  gasolene,  benzine,  kerosene,  or 
any  other  of  the  petroleum  oils.  These  must  be  introduced  into  all 
crevices  with  small  brushes  or  feathers,  or  by  injecting  with  small 
syringes;  a  saturated  solution  of  corrosive  sublimate  in  water  is  also 
of  value,  and  oil  of  turpentine  may  be  used  in  the  same  way.  The 
liberal  use  of  scalding  hot  water  or  soap  suds  wherever  it  may  be  em- 
ployed without  damage  to  furniture  is  also  an  effectual  method  of,  de- 
stroying both  eggs  and  active  bugs.  Fumigation  with  hydrocyanic  acid 
gas,  sulphur  dioxid,  or  carbon  bisulphid  are  alike  effective.  Crevices  in 
warm  parts  of  the  room  are  favorite  nesting  places,  as  under  picture 
mouldings,  or  over  door  frames. 

In  sleeping  cars  and  other  places  where  hydrocyanic  acid  gas  may 
be  used  without  fear  of  accidents,  this  is  the  most  efficacious  and  least 
destructive  method. 

The  bedbug  has  long  been  under  suspicion  as  an  intermediate  host 
in  the  transference  of  manv  communicable  infections.     There  is  more 


274  INSECT-BORNE    DISEASES 

than  a  suspicion  that  it  is  concerned  in  relapsing  fever,  in  kala-azar, 
and  it  has  been  accused  of  carrying  the  bacteria  of  tuberculosis,  leprosy, 
and  many  other  diseases. 

KALA-AZAR 

Kala-azar  is  a  tropical  infection  characterized  by  anemia  and  en- 
largement of  the  spleen.  It  is  caused  by  a  parasite  which  occurs  in 
great  numbers  in  the  spleen  and  which,  upon  culture  media,  develops 
into  a  flagellated  organism  resembling  the  trypanosomes..  The  trypano- 
somes  w^ere  discovered  by  Leishman  and  Donovan  in  the  spleen  and 
liver  and  the  epithelium  of  the  blood  vessels.  Manson  and  Low  found 
similar  bodies  in  the  ulcerous  mucous  membranes  of  the  intestines,  and 
Marchand  and  Ledingham  found  the  same  peculiar  bodies  in  the  cells 
of  the  bone  marrow^  and  lymphatic  glands.  Rogers  cultivated  the  para- 
sites from  the  spleen  of  patients  suffering  with  kala-azar  upon  agar 
streaked  with  fresh  human  blood.  Flagellate  forms  developed.  This 
was  confirmed  by  Christophers,  who  used  Xovy's  method  of  growing 
trypanosomes  upon  the  water  of  condensation  of  blood  agar  tubes. 
The  kala-azar  parasites  grow'n  in  artificial  culture  media  liave  a  cilium 
but  no  membrane. 

References. — The  literature  upon  insects  and  insect-borne  diseases 
is  very  widely  distributed.  Many  of  the  entomological  facts  contained 
in  this  chapter  have  been  taken  from  "The  Insect  Book"  by  L.  0. 
Howard  and  the  many  excellent  publications  of  Howard  and  his  col- 
leagues of  the  Bureau  of  Entomology,  Department  of  Agriculture. 
The  Government  publications  may  be  had  upon  application  to  the  Su- 
perintendent of  Documents,  Washington,  D.  C.  Many  of  the  facts 
concerning  the  prevention  and  destruction  of  mosquitoes  have  been 
taken  from  articles  in  the  Public  Health  Reports  of  the  Public  Health 
and  Marine  Hospital  Service.  In  the  chapter  upon  insecticides  free 
reference  has  been  made  to  my  own  book  upon  "Disinfection  and  Dis- 
infectants," as  well  as  my  other  writings  and  unpublished  work  in 
different  phases  of  this  subject. 


CHAPTEE   V 

MISCELLANEOUS    DISEASES 

INFANTILE    PARALYSIS 

(Acute  Anterior  Poliomyelitis) 

An  entirely  new  literature  upon  the  subject  of  infantile  paralysia 
is  now  being  constructed.  The  chief  contributors  to  this  recent  advance 
in  our  knowledge  have  been  Wickman  of  Sweden,  who,  in  1905-06,  gave 
us  a  new  symptomatology,  and  defined  clinical  types  not  before  recog- 
nized. Wickman  made  the  first  systematic  study  of  the  disease  from 
an  epidemiological  point  of  view,  and  found  evidence  that  it  was  con- 
tagious, though  usually  slightly  so.  He  directed  especial  attention 
to  several  factors  in  its  spread,  viz. :  routes  of  travel,  public  gath- 
erings of  children,  abortive  or  ambulant  cases,  and  healthy  inter- 
mediate carriers.  In  the  spring  of  1909  Landsteiner  and  Popper 
succeeded  in  transmitting  the  disease  to  two  monkeys  by  inoculating 
them  with  the  spinal  cord  of  a  child  who  had  died  of  infantile  paral}^- 
sis.  Later  in  the  year  Flexner  and  Lewis  obtained  the  same  results, 
and  further  transmitted  the  infection  from  monkey  to  monkey  through 
an  indefinite  number  of  passages.  To  Harwitz  and  Scheele  of  Nor- 
way we  are  indebted  for  formulating  the  pathologic  anatomy  of  the 
affection. 

Infantile  paralysis  is  now  properly  regarded  as  a  communicable  dis- 
ease. The  virus  is  filterable,  that  is,  "ultramicroscopic,^'  yet  coccae 
forms  have  been  described  by  jSToguchi  and  Flexner  in  artificial  cultures. 
(J.  A.  M.  A.,  Feb.  1,  1913,  LX,  5,  362.) 

It  appears  that  infantile  paralysis  is  becoming  more  and  more  com- 
mon and  more  widespread  of  late  years.  This  increase  cannot  be  ac- 
counted for  by  the  fact  that  the  disease  is  now  better  known  and  more 
readily  recognized.  Bergenholtz,  in  1881,  described  the  first  out- 
break with  sufficient  accuracy  to  accept  infantile  paralysis  as  a  new 
disease.  Since  that  time  the  number  of  outbreaks  and  the  number  of 
cases  have  progressively  increased,  as  shown  in  the  following  table : 

275 


276  MISCELLAXEOUS    DISEASES 

Av.  Xo.  of  Cases 

Cases  Outbreaks  per  Outbreak 

1880-1884 23  2  11.5 

1885-1889 93  7  13. 

1890-189-i 151  4  38. 

1895-1899 345  23  15. 

1900-1904 349  9  39. 

1905-1909 8,054  25  322. 

Eecent  outbreaks  bave  occurred  in  Xorway  and  Sweden,  Austria, 
Germany.  Holland.  England,  Spain,  France,  the  United  States,  and 
Cuba.  Of  the  8,054  cases  reported  in  5  years  (1905-09),  the  United 
States  contributed  5,514  cases  or  about  five-sevenths  of  the  total  number. 

Epidemics  of  poliomyelitis  have  prevailed  in  all  quarters  of  the 
world.  The  disease  has  been  most  prevalent  in  the  northern  parts  of 
Europe  and  of  the  United  States.  Epidemics  have  been  more  severe, 
and  the  case  rates  have  been  higher,  in  small  towns  and  rural  dis- 
tricts than  in  the  more  densely  populated  cities.  Even  in  the  cities 
the  disease  does  not  especially  strike  the  crowded  districts.  Cold  coun- 
tries having  marked  seasonal  variations  in  temperature  have  been  most 
affected,  but  the  disease  is  always  most  prevalent  in  the  warm,  dry 
months,  from  May  to  Xovember  in  the  northern  hemisphere  and  Xo- 
vember  to  May  in  the  southern  hemisphere.  Sporadic  cases  may  occur 
at  any  time  throughout  the  year.  The  great  majority  of  cases  occur  in 
children  under  five  years  of  age.  From  the  standpoint  of  prevention  it 
is  important  to  note  that  social  and  hygienic  conditions  apparently  have 
no  influence  whatever  in  determining  the  infection.  All  classes  are 
affected  in  about  equal  proportion. 

The  virus  of  the  disease  is  present  in  greatest  virulence  or  concen- 
tration in  the  spinal  cord  of  infected  persons  and  animals.  One  one- 
hundredth  of  a  cubic  centimeter  of  an  emulsion  of  cord,  or  less,  is  suf- 
ficient to  infect  a  monkey.  The  virus  is  also  quite  constantly  present 
in  the  brain  and  other  organs  and  tissues,  as,  for  instance,  the  mucous 
membrane  of  the  nose  and  pharynx,  the  mesenteric  glands,  the  axillary 
and  inguinal  lymph  nodes,  also  in  the  blood,  and  in  the  cerebrospinal 
fluid.  The  virus  has  been  demonstrated  in  the  feces.  The  suspicion 
that  the  alvine  discharges  may,  therefore,  be  virulent  is  sufficient  indica- 
tion that  they  should  be  disinfected  in  all  cases  until  further  knowledge 
of  the  subject  is  at  hand. 

The  experimental  disease  in  monkeys  may  be  produced  with  cer- 
tainty by  injecting  the  virus  directly  into  the  central  nervous  system, 
preferably  the  brain.  Monkeys  may  also  be  infected  by  introducing 
the  virus  subcutaneously  or  into  the  peritoneal  cavity,  and  even  by  in- 
travenous inoculation.     They  have  been  infected  by  placing  virulent 


INFAXTILE    PARALYSIS  277 

material  upon  the  healthy  mucous  membrane  of  the  nose  and  also  by 
inhalation  of  the  infectious  material  forced  into  the  trachea,  and  finally 
by  introducing  the  virus  into  the  stomach,  along  with  an  opiate,  to  re- 
strain peristalsis.  Leiner  and  Weisner  have  infected  monkeys  through 
the  uninjured  nasal  mucous  membrane.  This,  however,  is  an  uncertain 
method  of  inoculation.  ]\Ionkeys  have  so  far  never  been  known  to  con- 
tract the  disease  spontaneously,  even  though  they  are  kept  in  intimate 
association  with  infected  monkeys.  There  are  many  similar  paralytic 
diseases  of  the  lower  animals,  but.  so  far  as  known,  infantile  paralysis 
as  a  natural  infection  is  peculiar  to  man.  Recently  Eosenau  and  Brues, 
and  also  Anderson  and  Frost,  have  transmitted  the  disease  from  monkey 
to  monkey  through  the  bite  of  the  stable  fly. 

Resistance  of  the  Vims. — The  virus  of  anterior  poliomyelitis  is 
killed  by  a  temperature  of  45°  to  50°  C.  in  half  an  hour;  also  by  com- 
paratively weak  disinfectants,  such  as  a  1-500  solution  of  permanganate 
of  potash,  1  per  cent,  menthol  in  oil,  a  powder  containing  menthol,  0.5 
per  cent.,  salol,  5  per  cent.,  boric  acid,  20  per  cent.  (Landsteiner  and 
Levaditi),  and  a  dilution  of  perhydrol  (Merck)  equivalent  to  1  per 
cent;  of  peroxid  of  hydrogen.  The  virus  is  not  destroyed  by  very  low 
temperatures  nor  by  drying  over  caustic  potash,  or  in  vacuo  for  a  con- 
siderable period.  A  virulent  cord  has  been  kept  for  almost  5  months  in 
pure  glycerin  without  losing  its  virulence,  resembling  in  this  respect 
rabies,  vaccine,  and  other  filterable  viruses,  and  differing  for  the  most 
part  from  non-spore-bearing  pathogenic  bacteria  which  are  usually 
killed  by  pure  glycerin  in  a  short  while. 

Immunity. — One  attack  of  infantile  paralysis  apparently  confers  a 
high  degree  of  immunity.  Recurrent  cases  and  second  attacks  have 
been  reported.  Monkeys  which  have  recovered  from  the  infection  show 
a  high  degree  of  resistance,  in  that  they  are  not  susceptible  to  infec- 
tion by  again  inoculating  them,  and  their  blood  serum  contains  anti- 
bodies capable  of  rendering  the  virus  harmless.  That  is,  if  the  blood 
serum  of  an  immune  monkey  is  mixed  with  an  emulsion  of  virulent 
spinal  cord  and  the  mixture  allowed  to  stand  for  several  hours,  the 
virus  is  no  longer  capable  of  producing  the  infection  in  susceptible 
animals.  This  property  has  been  used  by  Anderson  and  Frost  to  cor- 
roborate the  clinical  diagnosis  in  abortive  cases.  The  blood  of  a  per- 
son who  has  not  had  the  disease  does  not  neutralize  the  virus;  there- 
fore, if  the  injection  of  the  virus  previously  treated  with  human  serum 
fails  to  produce  the  infection  in  susceptible  monkeys,  it  may  be  taken 
as  evidence  that  the  serum  contained  specific  antibodies  and  came  from 
an  individual  who  has  had  the  disease. 

Modes  of  Transmission. — Coxtact  theory   (based  upox  the  as- 

SUMPTIOX  THAT  THE  VIRrS  IS  DISCHARGED  FROM  THE   :M0UTH  AXD  XOSE 

AND  ENTERS  THROUGH  THE  SAME  chaxnel). — There  is  evidence  to  sup- 
20 


278  MISCELLANEOUS    DISEASES 

port  the  theory  that  the  disease  is  directly  transmissible  from  person  to 
person  and  there  is  a  suspicion  that  healthy  carriers  play  an  important 
role  in  spreading  the  infection.  This  view  was  enunciated  by  Wickman 
and  received  support  through  the  experiments  of  Kling,  Pettersson  and 
Wernstedt,  and  also  Flexner.  It  is  known  that  the  mucous  membrane 
of  the  nose  and  throat  contains  the  virus,  and  in  one  case  the  salivary 
glands  were  shown  to  be  infective.  Osgood  and  Lucas  demonstrated 
that  the  nasal  mucous  membrane  of  two  monkeys  experimentally  inocu- 
lated with  poliomyelitis  remained  infective  for  6  weeks  in  one  case  and 
51/2  months  in  another.  This  very  important  observation  strengthens 
the  suspicion  of  the  existence  of  chronic  human  carriers.  If  healthy 
carriers  continue  to  spread  the  infection  months  after  the  attack,  it  in- 
creases the  difficulty  of  suppressing  the  disease,  and  further  renders 
doubtful  the  efficiency  of  strict  isolation  and  prophylactic  measures  di- 
rected only  to  persons  in  the  acute  stage  of  the  disease.  The  fact  that 
the  mucous  membrane  contains  the  virus  is  not,  however,  sufficient  proof 
that  the  virus  is  liberated  and  discharged  in  sufficient  amount  in  the 
secretions  from  the  mouth  and  nose  to  be  a  menace.  In  a  series  of  18 
cases  Eosenau,  Sheppard  and  Amoss  ^  were  unable  to  demonstrate  the 
virus  in  the  nasal  and  buccal  secretions  obtained  from  persons  in  various 
stages  of  convalescence.  Strauss  ^  had  similar  negative  results  in  a  series 
of  10  cases.  On  the  other  hand,  Kling,  Pettersson  and  Wernstedt  ^  re- 
port successful  results ;  by  experiments  upon  monkeys  they  demonstrated 
the  infectiousness  of  buccal  and  intestinal  secretions  of  living  subjects. 
Flexner  has  recently  also  reported  one  successful  attempt  in  demonstrat- 
ing the  virus  in  the  buccal  secretions. 

The  Insect-borne  Theory. — Infantile  paralysis  shows  no  tendency 
to  prevail  in  congested  centers  or  to  spread  in  hospitals,  schools,  institu- 
tions, and  other  crowded  places;  its  seasonal  prevalence  corresponds  to 
the  seasonal  prevalence  of  most  insects,  and  does  not  correspond  to  the 
seasonal  prevalence  of  diseases  spread  through  secretions  of  the  mouth 
and  nose,  such  as  diphtheria,  scarlet  fever,  smallpox,  etc.  ]\Iany  other 
factors,  brought  to  light  by  the  studies  of  the  State  Board  of  Health  of 
Massachusetts  upon  the  epidemiology  of  the  disease,  under  the  able 
direction  of  Dr.  Mark  Eichardson,  indicate  that  the  disease  is  not  a 
contagious  one.     These  studies  *  gradually  focused  attention  upon  some 

'  Eosenau,  M.  J.,  Sheppard,  P.  A.  E..  Amoss,  H.  L.,  Boston  Med.  and  Surg. 
Jour.,  May  25,  1911,  CLXIV,  21,  pp.  743-748. 

^Strauss,  I.,  J.  A.  M.  A.,  April  22,  1911,  LVI,  16,  1192. 

*  Kling,  C.,  Pettersson,  A.,  and  Wernstedt,  W.,  Eeport  from  the  State  Medical 
Institute  of  Sweden  to  the  XV  Internationa]  Congress  on  Hygiene  and  Demog- 
raphy, Washington,  D.  C,  1912.  Also,  Zeitschr.  f.  Immunitdtsforch.  u.  exper. 
Therapie,  Bd.   XII,  Jena,   1912. 

*  Richardson,  M.  W.,  Monthly  Bull,  State  Board  of  Health  of  Mass.,  Sept., 
1912,   7,  9,   pp.   308-315. 

Lovett,  R.  W.,  Report  to  the  Mass.  State  Board  of  Health,  1907. 
Report  to  the  Mass.  State  Board  of  Health,  1908,   1909,   1910,  1911. 


INFANTILE    PAEALYSIS  379 

insect,  the  stable  fly  (Stomoxys  calcitrans)  in  particular.  Eosenau  and 
Brues  ^  demonstrated  that  the  virus  may  be  transmitted  from  monkey 
to  monkey  through  the  bite  of  the  stable  fly.  These  results  were  soon 
confirmed  by  Anderson  and  Frost.-  The  insect-borne  theory  seems  to 
fit  the  case  as  the  disease  is  known  in  Massachusetts.  It  will,  however, 
require  much  additional  study  to  determine  what  role  Stomoxys  cal- 
citrans plays  in  spreading  the  infection  in  nature. 

Other  Theoeies. — It  has  been  suggested  that  the  virus  may  be 
air-borne  in  the  sense  that  it  is  carried  in  the  dust.  Neustaedter  and 
Thro  ^  have  infected  monkeys  from  dust  collected  from  sick  rooms.  In- 
fected food,  or  transmission  through  wounds  and  other  means,  have  not 
been  ruled  out  of  consideration. 

Prevention. — No  definite  or  effective  system  of  prevention  can  be 
formulated  until  we  are  sure  of  the  mode  of  transmission.  Meanwhile 
health  authorities  are  entirely  justified  in  requiring  cases  to  be  reported, 
isolated,  and  all  known  lines  of  preventive  measures  applied,  such  as 
disinfection,  screening,  and  guarding  against  insects,  allaying  unneces- 
sary dust,  etc.  A  fly  campaign  directed  with  especial  reference  to  the 
stable  fly  is  plainly  indicated,  and  the  infection  must  also  be  fought  as 
one  conveyed  from  man  to  man  directly.  Until  the  modes  of  transmis- 
sion of  the  disease  are  established,  however,  we  can  have  no  confidence 
in  our  prophylactic  measures,  which  most  resemble  the  old  "shotgun" 
prescription. 

The  following  measures  are  recommended:  The  patient  should  be 
isolated  as  completely  as  possible  in  a  clean,  bare  room,  well  screened 
to  keep  out  insects.  This  is  a  good  practice  despite  the  fact  that  the 
disease  shows  no  tendency  to  spread  in  children's  asylums,  hospitals, 
and  other  institutions,  or  even  in  the  home.  The  same  statement, 
however,  was  made  of  typhoid  fever  not  many  years  ago.  Visiting 
should  be  interdicted  and  only  the  necessary  attendant  should  be  al- 
lowed to  come  in  contact  with  the  patient.  All  discharges,  including 
sputum,  nasal  secretions,  urine,  and  feces,  should  be  thoroughly  disin- 
fected, and  special  care  should  be  taken  that  cups,  spoons,  remnants  of 
food,  etc.,  which  may  have  become  contaminated  by  the  patient  are 
burned,  scalded,  or  otherwise  purified. 

Towels,  bed  linen,  and  other  fabrics  should  be  boiled  or  dipped 
into  a  germicidal  solution  strong  enough  to  destroy  the  typhoid  bacil- 
lus.    The  nurse  and  physician  should  observe  the  same  precautions  re- 


^  Eosenau,  M.  J.,  and  Brues,  C.  T.,  Monthly  Bull,  State  Board  of  Health  of 
Mass.,  Sept.,  1912,  7,  9,  pp.  314-318.  Also  Brues  and  Sheppard,  Jour,  of  Econom. 
Entomology,  Aug.,   1912,^  V,  4,  305. 

-Anderson,  J.  F.,  and  Frost,  W.  H.,  Puh.  Health  Reports,  Oct.  25,  1912, 
XXVII,  43,  pp.  1733-1736. 

^Neustaedter,  M.,  and  Thro,  W.  C,  N.  Y.  Med.  Jour.,  Sept.  23,  1911, 
XCIV,  13. 


280  MISCELLANEOUS    DISEASES 

garding  their  hands  and  clothing  as  are  recommended  in  attending  a 
case  of  scarlet  fever. 

The  period  during  which  tlie  isolation  should  l)e  maintained  can- 
not even  be  guessed  at.  Children  are  usually  not  permitted  to  return 
to  school  for  at  least  three  weeks,  but,  if  chronic  carriers  play  the  im- 
portant role  now  suspected,  this  time  would  be  far  too  short  in  many 
instances. 

Since  the  virus  can  be  killed  experimentally  by  a  1  per  cent,  solu- 
tion of  jicroxid  of  hydrogen,  antiseptic  gargles,  sprays,  and  nose  washes 
of  this  solution  are  recommended  to  be  used  by  the  patient,  the  nurse, 
and  physician,  and  other  members  of  the  family.  In  the  presence  of 
an  epidemic,  street  and  house  dust  should  be  kept  down  by  sprinkling, 
oiling,  and  the  other  means  employed  for  this  purpose.  Dust  should 
be  allayed  whether  there  is  an  epidemic  of  infantile  paralysis  or  not. 
During  epidemics  children  should  be  kept  away  from  public  gather- 
ings, prohibited  from  using  public  drinking  cups,  and  special  attention 
given  to  the  diet  to  prevent  gastrointestinal  disorders,  for  many  a  case 
of  infantile  paralysis  starts  with  a  digestive  upset. 

CHICKENPOX 

Chickenpox  is  one  of  the  minor  communicable  diseases,  in  that  the 
mortality  is  practically  nil  and  that  complications  and  sequela}  are  rare. 
Chickenpox  is  very  readily  communicable  and  spreads  through  families 
or  institutions,  but  does  not  occur  in  widespread  epidemics.  The  cause 
of  the  disease  and  its  modes  of  transmission  are  not  known.  The  virus 
is  not  contained  in  the  content  of  the  vesicle.  Tyzzer  and  others  made 
numerous  inoculations  with  both  clear  and  clouded  vesicle  contents 
without  results.  The  disease  is  probably  peculiar  to  man;  animal 
inoculations  have  so  far  proven  negative.  The  period  of  incubation  is 
probably  from  fourteen  to  sixteen  days,  and  one  attack  p^'oduces  a  defi- 
nite immunity.     No  age  is  exempt. 

The  differential  diagnosis  between  chickenpox  and  smallpox  is  often 
an  important  and  difficult  public  health  matter.  The  distinction  may 
be  made  by  introducing  some  of  the  contents  of  the  vesicle  into  the  skin 
of  a  well-vaccinated  person.  If  chickenpox,  an  immediate  reaction 
results;  if  smallpox,  no  reaction  results.  Monkeys  are  not  susceptil)le 
to  chickenpox  but  may  be  given  smallpox.  The  differential  diagnosis 
may  also  be  made  from  the  presence  of  vaccine  bodies  in  smallpox  and 
their  absence  in  chickenpox.  These  bodies  are  best  demonstrated  by 
introducing  some  of  the  virus  upon  the  cornea  of  a  rabbit,  and  examining 
the  vesicles  which  form. 

Health  officers  should  require  cases  of  chickenpox  to  be  reported, 
if  for  no  other  reason  than  that  it  is  often  mistaken  for  smallpox.     The 


GLANDEES  281 

differential  diagnosis  may  be  made  in  doubtful  cases  by  a  histological 
examination  of  the  pock,  or  by  inoculating  the  contents  of  the  vesicle 
upon  the  cornea  of  rabbits.  In  sections  of  the  skin  lesion  the  vaccine 
bodies  are  found  in  smallpox,  not  in  chickenpox;  the  vesicle  of  the 
former  is  multilocular,  the  latter  unilocular.  The  vesicle  upon  the 
cornea  of  rabbits  produced  by  smallpox  is  distinct  and  contains  the 
vaccine  bodies;  the  lesion  resulting  from  chickenpox  is  trifling  and 
does  not  contain  the  vaccine  bodies. 

The  prevention  of  chickenpox  depends  upon  isolation  and  disinfec- 
tion at  the  bedside.  Children  with  chickenpox  should  not  be  permitted 
to  go  to  school. 

GLANDERS 

Glanders  or  farcy  is  a  widespread  communicable  disease  of  horses, 
mules,  asses,  and  other  animals,  and  is  readily  communicated  to  man. 
In  both  man  and  horses  it  is  remarkable  for  its  fatality.  The  disease 
is  characterized  by  the  formation  of  inflammatory  nodules  either  in 
the  mucous  membrane  of  the  nose    (glanders)   or  in  the  skin   (farcy). 

Glanders  is  caused  by  the  Bacillus  mallei,  which  corresponds  to 
the  spore-free  bacteria  so  far  as  its  resistance  is  concerned.  In  gen- 
eral the  bacillus  of  glanders  is  killed  by  the  same  agents  used  against 
the  tubercle  bacillus,  which  it  resembles  in  some  particulars. 

The  infection  may  be  introduced  into  the  system  either  through  the 
skin  or  mucous  membrane,  and  is  usually  communicated  directly  from 
the  horse  to  man  by  contact  with  the  infected  discharges.  The  disease 
is  sometimes  communicated  from  man  to  man.  Washerwomen  have 
become  infected  from  the  clothes  of  a  patient. 

The  bacillus  of  glanders  does  not  have  a  spore.  It  is  comparatively 
frail  and  readily  destroyed  by  the  usual  physical  and  chemical  germi- 
cidal agencies  used  against  spore-free  bacteria.  The  bacillus,  however, 
is  frequently  protected  by  albuminous  matter  or  buried  in  the  dirt  of 
stables,  water  troughs,  harnesses,  and  other  objects.  While  the  naked 
germs  of  glanders  are  readily  destroyed,  they  are  frequently  hard  to 
get  at;  cleanliness  is,  therefore,  imperative. 

The  prevention  of  glanders  in  man  depends  primarily  upon  the 
suppression  of  the  disease  in  horses.  The  only  difficulty  in  controlling 
the  disease  in  horses  lies  in  the  early  diagnosis  and  recognition  of 
mild  or  missed  cases,  which  are  very  common.  Horses  affected  with 
occult  or  latent  glanders  are  important  factors  in  the  propagation  of 
the  infection.  The  clinical  diagnosis  in  the  frank  cases  is  made  with- 
out difficulty  from  the  characteristic  symptoms  and  the  lesions,  but 
laboratory  aid  is  necessary  to  discover  the  mild  cases. 

Diagnosis. — The  diagnosis  of  glanders  may  be  made  by:  (1)  the 
mallein  test;    (2)    the   agglutination  test;    (3)    the   Strauss   reaction; 


282  MISCELLANEOUS    DISEASES 

(4)  isolation  of  B.  mallei  in  pure  culture;  and  (5)  complement  fixa- 
tion. All  these  tests  serve  a  definite  purpose.  However,  the  mallein 
test,  the  agglutination  test,  and  the  Strauss  reaction  are  not  sufficiently 
reliable  to  be  entirely  satisfactory.  The  isolation  of  the  glanders  bacil- 
lus in  pure  culture  is  definite  and  final,  but  time-consuming.  The 
diagnosis  of  glanders  by  complement  fixation  is  at  present  our  most 
reliable,  most  satisfactory,  and  quickest  method  of  recognizing  the 
disease. 

The  Mallein  Test. — ^lallein  is  a  product  of  the  glanders  bacillus 
corresponding  to  tuberculin.  The  injection  of  mallein  into  normal  ani- 
mals produces  no  reaction,  whereas  the  injection  into  glanderous  ani- 
mals causes  a  rise  in  temperature  and  a  local  reaction  about  the  le- 
sions. With  the  mallein  test  a  large  proportion  of  latent  and  occult 
cases  of  glanders  can  be  diagnosed,  but  the  test  must  be  made  and  in- 
terpreted by  an  experienced  veterinarian,  else  the  results  may  be  un- 
reliable. The  mallein  test  fails  to  give  a  typical  reaction  in  a  consid- 
erable number  of  glanderous  animals;  on  the  other  hand,  a  reaction 
may  follow  the  injection  of  mallein  in  the  absence  of  glanders.  Thus 
mallein  is  not  an  entirely  reliable  diagnostic  agent  and  has  never  been 
considered  as  specific  in  the  detection  of  this  disease  as  tuberculin 
for  the  diagnosis  of  tuberculosis. 

The  Agglutination  Test. — The  agglutination  test  is  of  value  in 
all  cases  of  recent  infection,  the  blood  serum  possessing  a  very  high 
agglutinating  power — 1-1,000  and  higher.  In  chronic  glanders  the 
agglutinating  power  of  the  blood  may  be  very  low — 1-400  or  less;  in 
some  cases  even  lower  than  that  of  normal  blood  serum — which  may  be 
1-800  and  even  higher.  It  is,  therefore,  plain  that  agglutination  tests 
alone  do  not  constitute  an  entirely  satisfactory  diagnostic  method  for 
glanders.     It  may  be  used  as  an  adjunct  to  other  tests. 

The  Strauss  Reaction. — The  Strauss  ^  reaction  for  the  diagnosis 
of  glanders  consists  in  inoculating  male  guinea  pigs  into  the  peritoneal 
cavity  with  material  containing  virulent  B.  mallei,  which  causes  an 
enlargement  of  the  testicles.  A  positive  reaction  associated  with  organ- 
isms resembling  those  of  glanders,  and  typical  cultures  obtained  from 
the  lesions,  are  unfailing  evidence  of  the  presence  of  the  specific  virus. 
Failure  to  obtain  the  reaction  is  not  proof  that  a  suspected  specimen 
may  not  have  come  from  a  horse  or  animal  with  glanders.  Arms  ^ 
recommends  that  it  is  better  to  use  more  than  one  guinea  pig  in  test- 
ing suspected  material,  and  that,  before  inoculating,  it  is  well  to 
make  a  microscopic  examination  as  a  guide  to  the  dosage.  A  cul- 
ture made  from  the  swab  often  aids  in  the  early  diagnosis.  Gui- 
nea pigs   should   be    kept   under   observation   for    a   month,    and   if   a 

'  Compt.  Bend.  Acad.  d.  Sc,  1889,  CVIII,  p.  530. 
V.  A.  M.  A.,  LV,  7,  Aug.   13,  1910,  p.  591. 


GLANDEES  283 

lesion  of  any  kind  is  present  an  autopsy  should  be  made  and  cultures 
taken. 

The  Isolation  of  B.  Mallei  in  Pure  Culture. — The  bacillus 
of  glanders  may  be  isolated  by  introducing  some  of  the  suspected  ma- 
terial subcutaneously  and  also  intraperitoneally  into  male  guinea  pigs. 
In  this  way  pure  cultures  may  be  obtained  from  the  pus  or  necrotic 
foci  in  the  spleen,  which  follow  subcutaneous  inoculation;  or  from  the 
characteristic  enlargement  of  the  testicle  which  is  observed  in  animals 
inoculated  intraperitoneally.  The  organism  isolated  must  be  studied 
for  cultural,  morphological,  and  biological  characters.  The  isolation  of 
the  bacillus  in  pure  culture  gives  positive  information  of  unquestioned 
character  in  any  critical  case.  The  method  is  not  generally  applicable 
to  the  diagnosis  of  glanders  because  it  requires  too  much  time  and 
may  occasionally  fail  to  discover  the  bacillus. 

Complement  Fixation. — In  1909  Schiitz  and  Schubert  ^  published 
the  results  of  their  important  work  on  the  application  of  the  method 
of  complement  fixation  for  the  diagnosis  of  glanders.  The  splendid 
results  obtained  constitute,  without  doubt,  the  most  reliable  method 
for  the  diagnosis  of  glanders  which  we  have  at  our  command  at  the 
present  time.  The  complement  fixation  test  is,  in  fact,  one  of  the  most 
specific  of  the  biological  tests  in  immunity.  It  is  readily  applicable  to 
the  case  of  glanders.  The  essential  elements  used  in  the  test  are  as 
follows : 

The  hemolytic  system  consists  of  the  washed  red  blood  corpuscles 
of  a  sheep  and  the  blood  serum  of  a  rabbit  which  has  been  injected 
with  the  washed  red  blood  corpuscles  of  a  sheep.  Strong,  vigorous 
rabbits  are  selected  and  three  injections  of  the  sheep's  corpuscles  are 
made  at  intervals  of  7  days,  using  7  c.  c,  10  c.  c,  and  12  c.  c.  of  the 
red  corpuscles  of  the  sheep  suspended  in  like  amounts  of  isotonic  salt 
solution.  The  blood  serum  of  a  rabbit  so  treated  contains  the  hemolytic 
amboceptors.  The  rabbit's  blood  serum  is  heated  to  56°  C.  for  half 
an  hour  in  order  to  destroy  the  complement.  The  titer,  or  amount  of 
amboceptor  contained  in  the  rabbit  serum,  must  be  determined.  The 
hemolytic  system,  then,  consists  of  rabbit  serum  containing  ambocep- 
tor, plus  washed  red  blood  corpuscles  of  the  sheep. 

Complement. — The  complement  is  contained  in  the  fresh  blood 
serum  of  a  healthy  guinea  pig.  The  blood  serum  of  the  guinea  pig 
should  be  titrated  in  order  to  determine  the  amount  of  complement 
present.  It  is  always  necessary  to  determine  the  smallest  quantity  of 
complement  to  be  used  for  the  final  test. 

Antigen. — The  antigen  consists  in  an  extract  obtained  by  shaking 

^  Schiitz  and  Schubert :  ' '  Die  Ermittelung  der  Eotzkrankheit  mit  Hilf  e  der 
Komplementablenkungsmethode. ' '  Archiv  fur  wissenschaftliche  und  praktische 
Tierheilkunde.     Bd.  35,  Heft  1  and  2,  pp.  44-83,  1909. 


284  MISCELLANEOUS    DISEASES 

glanders  bacilli  in  salt  solution.  The  bacillus  is  grown  in  pure  cul- 
ture on  2  per  cent,  acid  glycerin  agar.  A  luxuriant  growth  upon  the 
surface  of  the  medium  is  usually  obtained  in  48  hours.  This  is  sus- 
pended in  salt  solution,  heated  to  60°  C.  for  four  hours  in  order  to 
kill  the  bacilli.  After  heating  the  dead  bacilli  are  shaken  in  the  salt 
solution  in  a  special  apparatus  for  four  days.  The  bacilli  are  separated 
in  the  centrifuge  and  the  clear  supernatant  liquid  is  drawn  off  and  pre- 
served with  carbolic  acid.  The  strength  of  this  extract  must  be  deter- 
mined by  suitable  methods  of  titration. 

Technique. — The  test  is  carried  out  by  adding  together,  in  proper 
proportions,  the  following:  (1)  The  blood  serum  of  the  horse  to  be 
tested;  (2)  the  antigen  (extract  of  glanders  bacilli);  (3)  complement 
(fresh  guinea  pig  serum) ;  and  (4)  the  hemolytic  system.  If  the  blood 
serum  of  the  horse  to  be  tested  contains  the  specific  amboceptors  these 
will  unite  with  the  bacteria,  fix  the  complement,  and  thus  prevent 
hemolysis.  If  the  blood  serum  of  the  horse  to  be  tested  does  not  con- 
tain these  specific  amboceptors,  this  fixation  of  the  complement  cannot 
take  place  and  hemolysis  results.  Therefore,  the  absence  of  hemolysis 
means  the  presence  of  glanders,  and  vice  versa.  The  tests  must  always 
be  carried  out  with  controls  and  carefully  conducted  as  to  the  amount 
of  each  substance  used,  the  temperature  and  time.^ 

Prevention. — T\Tien  glanders  is  discovered  or  suspected  among  horses 
in  a  stable,  the  blood  of  all  the  horses  in  the  infected  stable  should  be 
drawn  and  tested  in  the  manner  above  described.  All  animals  whose 
serum  shows  complement  fixation  should  be  destroyed  without  further 
consideration.  After  the  animals  have  been  killed  and  properly  dis- 
posed of,  the  stable  should  be  thoroughly  cleansed  and  disinfected.  All 
other  horses  which  have  in  any  way  been  associated  with  the  infected 
animals  should  be  carefully  watched  and  tested  again  after  three  weeks, 
and,  should  there  be  no  indication  of  the  disease  in  the  second  test, 
the  stable  may  be  considered  free  from  the  infection;  otherwise  the 
infected  animals  should  be  destroyed  and  the  tests  repeated  every  three 
weeks  until  the  disease  has  been  eliminated. 

The  eradication  of  glanders  from  a  stable  often  means  considerable 
loss  and  sometimes  a  sacrifice  of  valuable  animals,  but  it  is  only  through 
vigorous  measures  that  the  disease  may  be  controlled.  In  the  disin- 
fection and  cleansing  special  attention  should  be  paid  to  the  stalls, 
harnesses,  water  troughs,  bits,  food  containers,  curry  combs,  sponges, 
and  other  objects  exposed  to  the  infection,  which  is  eliminated  mostly 
in  the  secretions  from  the  mouth  and  nose.  The  common  drinking  trough 
for  horses  spreads  the  infection. 

'  A  complete  description  of  the  diagnosis  of  glanders  by  complement  fixation, 
giving  in  full  all  the  details,  will  be  found  in  Bull.  136,  Bureau  of  Animal 
Industry,  Apr.  7,  1911,  by  Mohler  and  Eichhorn. 


ANTHRAX  285 

The  personal  prophylaxis  of  glanders  in  man  depends  upon  the 
education  and  care  of  those  who  have  to  handle  horses.  In  working 
with  horses  known  to  be  infected  rubber  gloves,  disinfection,  and  other 
methods  of  protection  should  be  employed.  Special  care  should  be 
taken  to  prevent  the  spread  of  the  infection  through  the  discharges  or 
by  infected  fomites  from  human  cases.  Fatal  accidents  have  occurred 
in  laboratories  in  research  workers  handling  pure  cultures  of  B.  mallei. 

ANTHRAX 

Anthrax  belongs  to  that  group  of  diseases  which  occurs  primarily 
in  the  lower  animals  and  secondarily  in  man.  The  infection  is  found 
in  horses,  cattle,  sheep,  and  other  cloven-hoofed  animals,  and  may  be 
transmitted  experimentally  to  mice,  guinea  pigs,  rats,  and  rabbits. 
Cold-blooded  animals  and  birds,  as  well  as  dogs  and  swine,  are  re- 
fractory. 

In  man  the  infection  may  enter  the  skin  (malignant  pustule)  or 
may  enter  the  lungs  (wool  sorters'  disease),  or  may  enter  the  diges- 
tive tract  and  produce  intestinal  lesions.  In  anthrax  of  the  skin  the 
infection  usually  enters  through  slight  abrasions,  scratches,  or  small 
wounds,  especially  on  the  forearm,  hand,  or  face.  Most  of  the  cases 
occur  in  butchers  or  persons  who  have  to  handle  infected  carcasses. 
The  spores  have  been  carried  to  the  skin  by  flies  and  may  be  inoculated 
by  the  bite  of  the  stable  fly. 

Wool  sorters'  disease,  or  anthrax  of  the  lungs,  appears  to  be  due 
to  the  inhalation  of  anthrax  spores.  It  is  observed  only  among  per- 
sons who  handle  skins  or  who  work  with  horse  hair  or  other  raw  materials 
from  animals  afflicted  with  anthrax. 

The  mode  of  transmission  in  intestinal  anthrax  is  through  meat 
from  an  anthrax  cadaver  which  is  partaken  of  without  proper  cooking. 

Schuberg  and  Kuhn  ^  have  shown  that  anthrax  may  be  transferred 
from  animal  to  animal  through  the  bite  of  the  stable  fly  (Stomoxys 
calcitrans). 

Resistance. — The  anthrax  spore  is  exceedingly  resistant  to  heat  and 
external  influences,  such  as  dryness  and  sunlight,  and  also  to  germi- 
cidal agents.  Its  resistance  may  be  compared  to  the  tetanus  spore 
page  70. 

Immunity. — A  number  of  species  of  animals  have  a  natural  immu- 
nity to  anthrax,  and  an  artificially  acquired  immunity  may  be  induced 
in  cattle  or  sheep  through  the  injection  of  attenuated  cultures,  in  ac- 
cordance with  the  classical  method  of  Pasteur.  These  procedures  are 
not  applicable  to  man.  The  prevention  of  the  disease  in  man  must 
first  be  directed  to  a  suppression  of  the  disease  in  animals.     The  sick 

'Arbeiten  a.  d.  kajserl.  Ges.-Amt.,  Bd.  XL,  Heft  2,   1912. 


286  MISCELLANEOUS    DISEASES 

animals  should  be  isolated,  or,  better,  killed,  and  the  carcasses  burned 
or  buried  at  least  three  feet  deep.  The  carcasses  may  be  ""tanked," 
that  is,  subjected  to  a  prolonged  exposure  to  steam  under  pressure. 
Tanks  for  tliis  purpose  are  found  in  all  the  larger  slaughter  houses. 
It  is  important  in  handling  the  body  of  an  animal  dead  of  anthrax 
not  to  open  it  or  shed  blood,  for  the  bacillus  does  not  produce  its  spore 
except  in  the  presence  of  oxygen,  that  is,  the  bacilli  are  mainly  in  the 
blood  and  internal  organs  and  will  not  sporulate  as  long  as  access  to  the 
air  is  prevented. 

Prevention. — The  chief  preventive  measure  so  far  as  man  is  con- 
cerned is  the  disinfection  of  all  raw  material  in  those  trades  in  wliich 
horse  hair,  hides,  and  other  substances  liable  to  harbor  the  anthrax  spore 
are  handled.  Veterinary  surgeons  who  conduct  autopsies  upon  anthrax 
animals  should  exercise  unusual  precautions,  and,  if  practicable,  wear 
rubber  gloves. 

Ponder  ^  recommends  the  following  process  to  destroy  anthrax  in- 
fection in  hides:  The  dry  hides  are  placed  for  24  hours  in  a  "soak" 
which  is  made  to  contain  1  to  2  per  cent,  of  formic  acid  and  0.02  per 
cent,  of  bichlorid  of  mercury,  and  then  salting  them  with  sodium 
chlorid.  The  action  of  the  "soak"  is  to  swell  up  the  fibers  of  the  hide 
by  causing  them  to  absorb  water,  the  result  being  that  the  hide  returns 
to  a  condition  closely  resembling  that  in  which  it  was  taken  from 
the  animal's  carcass.  This  permits  the  bichlorid  of  mercury  to  per- 
meate and  exert  its  germicidal  action. 

FOOT-AND-MOUTH  DISEASE 

Foot-and-mouth  disease  is  also  known  as  aphthous  fever,  epizootic 
catarrh,  and  eczema  contagiosa.  It  is  an  acute  and  highly  commu- 
nicable disease,  generally  confined  to  cloven-footed  animals,  and  char- 
acterized by  an  eruption  of  vesicles  on  the  mucous  membrane  of  the 
mouth  and  on  the  skin  between  the  toes  and  above  the  hoofs.  The 
vesicles  rupture,  forming  erosions  and  ulcers.  There  are  also  saliva- 
tion, tenderness  of  the  affected  parts,  loss  of  appetite,  lameness,  emacia- 
tion, and  diminution  in  the  quantity  of  milk  secreted. 

Foot-and-mouth  disease  is  primarily  a  disease  of  cattle  and  sec- 
ondarily of  man.  Hogs,  sheep,  goats,  buffalo,  American  bison,  camel, 
chamois,  llama,  giraffe,  antelope,  and  even  horses,  dogs,  and  cats  may 
occasionally  become  infected. 

The  disease  prevails  in  European  countries  and  occasions  great 
economic  loss.  The  mortality  is  low ;  the  serious  losses  depend  chiefly 
upon  the  diminution  of  the  milk  secretion  and  the  loss  of  flesh  in  the 
affected  animals. 

^Lancet,  London,  Nov.  4,  CLXXXI,  No.  4601,  pp.  1247-1314. 


FOOT-AND-MOUTH    DISEASE  287 

Foot-and-mouth  disease  has  appeared  in  the  United  States  only  on 
five  different  occasions— in  1870,  1880,  1884,  1902-3,  and  1908.  Every 
outbreak  on  American  soil  has  thus  far  been  foUovred  by  its  complete 
suppression  through  the  application  of  well-known  preventive  meas- 
ures, such  as  isolation,  destruction  and  burial,  of  the  affected  herds, 
disinfection,  and  a  systematic  inspection  of  all  farms  in  the  infected 
area  to  detect  cases  of  the  disease. 

Loffler  and  Froesch  in  1898  showed  that  the  virus  will  pass  the 
finest  porcelain  filters.  This  was  the  first  ultramicroscopic  virus  dis- 
covered. The  specific  principle  is  contained  in  the  serum  of  the  ves- 
icles; in  the  saliva,  milk,  and  various  other  secretions  and  excretions; 
also  in  the  blood  during  the  rise  of  temperature. 

No  definite  immunity  is  rendered  by  an  attack.  The  period  of  in- 
cubation is  variable,  usually  from  two  to  six  days  or  longer,  excep- 
tional instances  being  prolonged  to  fifteen  or  even  eighteen  days. 

The  disease  in  man  is  a  direct  counterpart  of  that  in  cattle.  The 
infection  is  transmitted  to  man  through  the  ingestion  of  raw  milk, 
buttermilk,  butter,  cheese,  and  whey  from  animals  suffering  with  foot- 
and-mouth  disease.  It  may  also,  though  more  rarely,  be  transmitted 
directly  from  the  salivary  secretions  or  other  infected  material  which 
gains  entrance  through  the  mucous  membrane  of  the  mouth.  It  is 
doubtful  whether  the  disease  can  be  transmitted  to  man  by  cutaneous 
or  subcutaneous  inoculation,  though  it  is  probable  that  the  infection 
may  be  communicated  if  the  virus  enters  the  blood  directly  through 
wounds  of  any  kind.  Children  are  most  frequently  infected  by  drink- 
ing unboiled  milk  during  the  time  in  which  the  disease  is  prevalent 
in  the  neighborhood,  while  persons  in  charge  of  diseased  animals  may 
become  infected  through  contact  with  the  affected  parts  or  by  milking, 
slaughtering,  or  caring  for  the  animals.  The  disease  is  usually  very 
mild  in  man;  death  practically  never  results,  except  in  weakened  chil- 
dren, and  then  from  secondary  complications. 

The  original  experiments  of  Loffler  and  Froesch,  as  well  as  recent 
experiments  which  have  been  made  in  Denmark  and  Germany,  indicate 
that  the  infection  is  destroyed  comparatively  readily  by  heat  or  the 
usual  antiseptics.  Milk  pasteurized  at  a  temperature  of  60°  C.  for 
20  minutes  is  safe,  so  far  as  infection  from  foot-and-mouth  disease  is 
concerned. 

Foot-and-mouth  disease  has  a  special  interest  on  account  of  the 
fact  that  it  may  be  associated  with  vaccinia.  The  symbiosis  between 
the  infections  of  vaccinia  and  foot-and-mouth  disease  is  remarkable. 
Animals  vaccinated  with  the  mixed  virus,  as  a  rule,  show  the  lesions 
of  only  one  of  these  diseases,  namely,  vaccinia.  Nevertheless,  the  in- 
fectious principle  of  the  other,  foot-and-mouth  disease,  remains  in  the 
vaccinal  eruption.     Vaccine  virus  has  been  known  to  contain  the  in- 


288  MISCELLANEOUS    DISEASES 

fectjon  of  foot-and-mouth  disease.^  Glycerin  acts  as  a  preservative 
for  the  virus  of  foot-and-mouth  disease,  so  that  it  may  remain  viable 
in  fflycerinated  vaccine  virus  a  very  long  time.  No  instance  of  the 
transmission  of  foot-and-mouth  disease  to  man  through  vaccine  virus 
has  been  recorded,  and  it  is  doubtful,  in  view  of  the  known  facts, 
whether  it  is  possible  to  reproduce  the  disease  in  man  by  the  cutaneous 
inoculation  commonly  used  in  the  process  of  vaccination.  The  pre- 
vention of  foot-and-mouth  infection  in  vaccine  virus  is  assured  through 
federal  inspection  and  through  special  tests  (see  vaccine  virus,  page 
20. 

The  prevention  of  foot-and-mouth  disease  consists  (1)  in  a  cattle 
quarantine,  to  keep  it  out  of  countries  where  it  does  not  exist;  (2)  in 
the  elimination  of  the  disease  in  cattle  through  isolation  of  infected 
herds,  destruction  and  burial  of  tlie  sick  animals,  and  disinfection; 
(3)  the  disease  in  man  may  be  avoided  by  care  in  the  selection  of  the 
animals  from  which  milk  is  taken  or  by  pasteurization  of  the  milk 
when  foot-and-mouth  disease  is  prevalent. 

MALTA   FEVER 

Malta  fever  is  a  general  infection  not  unlike  other  specific  bacteri- 
emia,  such  as  typhoid  fever.  It  is  caused  by  the  Micrococcus  meliten- 
sis,  discovered  by  Bruce  in  1887  during  the  earlier  days  of  bacteriology. 
Clinically  the  disease  is  characterized  by  profuse  perspiration,  constipa- 
tion, frequent  relapses  often  accompanied  by  pains  of  a  rheumatic  or 
neuralgic  character,  and  sometimes  swelling  of  the  joints  or  orchitis. 
Malta  fever  is  further  characterized  by  its  low  mortality  and  long- 
drawn-out  and  indefinite  duration.  It  prevails  especially  about  the 
Mediterranean  basin. 

Gentry  and  Ferenbaugh  have  recently  found  a  nest  of  malta  fever 
throughout  the  older  goat-raising  sections  of  Texas.  This  endemic  cen- 
ter embraces  an  area  approximately  300  miles  along  the  Rio  Grande 
extending  90  miles  to  the  north.  All  the  cases  of  malta  fever  found 
have  occurred  in  territory  devoted  to  goat  raising,  and  all  the  patients 
there  gave  a  history  of  drinking  unboiled  goats'  milk  or  were  associated 
with  the  goat-raising  industry.  The  Micrococcus  melitensis  was  isolated 
from  several  of  the  cases. ^ 

Modes  of  Transmission. — From  experimental  evidence  it  would  ap- 
pear that  the  infection  of  malta  fever  may  be  taken  in  through  wounds, 
the  mucous  membranes,  or  by  food  and  drink.  The  usual  mode  of 
infection  is  by  drinking  raw  goats'  milk.     The  Micrococcus  melitensis 

'"The  Origin  of  the  Eecent  Outbreak  of  Foot-and-Mouth  Disease  in  the 
United  States,"  bv  Mohler  and  Eosenau,  Cir.  147,  Bureau  of  Animal  Industry, 
Dept.   of  Agriculture,   1909. 

V.  A.  M.  A.,  Aug.  26,  Sept.  9,  Sept.  23,  Sept.  30,  1911. 


MALTA    FEVEE  289 

leaves  the  body  in  various  secretions  and  excretions.  Great  numbers 
of  the  cocci  in  pure  cultures  may  appear  in  the  urine.  The  milk  of 
goats  also  contains  the  virus.  All  the  secretions  from  the  body  musJD 
be  regarded  as  infectious  until  further  knowledge  on  the  subject  is  at 
hand.  In  man  the  coccus  may  be  isolated  from  the  spleen,  lymph 
glands,  bone  marrow,  and  mammary  glands.  In  goats  it  first  disap- 
pears from  the  blood,  then  the  spleen,  and,  last  of  all,  from  the  mam- 
mary glands. 

Goats  are  susceptible  to  malta  fever  and  continue  to  discharge  the 
infection  in  the  milk  for  a  long  time.  The  disease  is  usually  contracted 
by  drinking  such  infected  milk.  While  this  is  the  common  mode  of 
infection,  occasional  cases  doubtless  arise  through  other  sources;  thus 
one  case  which  arose  in  England  is  supposed  to  have  been  conveyed 
from  son  to  father  by  using  a  clinical  thermometer  in  the  mouth  im- 
mediately after  its  use  by  the  patient.  Monkeys  may  readily  be  in- 
fected either  by  the  inoculation  of  pure  cultures  or  by  feeding  them. 
At  least  five  accidental  infections  have  occurred  in  bacteriological 
laboratories,  one  in  Washington.  MacFayden  lost  his  life  from  a 
laboratory  infection  with  the  Micrococcus  melitensis.  This  microorgan- 
ism has,  therefore,  more  than  complied  with  all  the  requirements  of 
Koch's  laws. 

There  has  long  been  a  suspicion  that  malta  fever  may  be  conveyed 
through  the  bite  of  an  ectoparasite.  In  fact.  Captain  Kennedy  was 
able  experimentally  to  infect  a  monkey  as  a  result  of  bites  of  mos- 
quitoes (Culex  pipiens)  which  had  fed  on  patients  suffering  with  malta 
fever.  This  probably  was  an  instance  of  mechanical  transference  of 
the  infection,  corresponding  in  all  respects  to  a  laboratory  inoculation 
with  fresh  virulent  material  from  a  hypodermic  syringe.  This  cannot 
be  a  frequent  way  by  which  the  infection  is  transmitted  in  nature,  for 
the  specific  organisms  are  found  in  small  numbers  in  the  peripheral 
blood  of  malta  fever  patients.  The  British  Commission  found  the 
Micrococcus  melitensis  only  four  times  from  a  total  of  896  mosquitoes 
dissected. 

From  the  fact  that  the  micrococcus  may  be  successfully  introduced 
either  by  ingestion,  or  by  inoculation,  or  through  the  mucous  mem- 
branes, it  is  evident  that  occasionally  cases  may  receive  their  infection 
through  a  great  variety  of  means,  such  as  insect  bites  and  other  wounds, 
infected  food,  and  the  various  modes  of  contact  infection.  Contact 
infection,  however,  probably  plays  .a  minor  role,  for  there  is  evidence 
that  the  disease  is  not,  as  a  rule,  directly  transmitted  from  the  sick  to 
the  well.  There  is  little  doubt  but  that  the  infection  can  be  acquired 
from  the  urine  secreted  by  cases  of  malta  fever,  and  this  is  probably 
one  way  in  which  the  workers  in  hospitals  become  infected. 

There  is  also  experimental  evidence  to  show  that  monkeys  can  be 


290  MISCELLANEOUS    DISEASES 

infected  by  dry  dust  artificially  contaminated  with  cultures  of  the 
Micrococcus  melitensis.  The  path  of  entrance  may  be  through  the 
nares,  throat,  respiratory  passages,  or  alimentary  canal.  Dry  dust  con- 
taminated with  the  urine  of  cases  of  malta  fever  has  given  rise  to  in- 
fection in  goats  but  not  in  monkeys.  The  experience  gained  during 
the  work  performed  in  Malta  during  1904  and  1905  has  convinced 
Horrocks  that  men  are  more  susceptible  than  monkeys  and  goats. 
Shaw's  work  on  ambulatory  cases  of  malta  fever  among  Maltese  has 
also  shown  that  opportunities  for  the  creation  of  infected  dust  are 
plentiful  in  Malta.  Infected  dry  dust  as  a  mode  of  transmission  can- 
not, therefore,  be  discarded,  but,  as  a  matter  of  fact,  it  probably  seldom 
occurs. 

Goats'  Milk  and  Malta  Fever. — "We  are  indebted  to  the  six  reports 
of  the  British  Commission  for  the  investigation  of  Mediterranean  fever 
(1905-1907)  for  the  fact  that  malta  fever  is  chiefly  spread  through 
goats'  milk.  Before  the  researches  of  this  commission  the  common 
mode  of  infection  was  not  definitely  known. 

The  usual  source  of  milk  in  Malta  is  the  goat.  The  udders,  which 
are  abnormally  long,  often  touch  the  ground  and  are  very  liable  to  be 
soiled.  It  was  first  shown  by  Zammit  in  the  report  of  1905  that  goats 
could  be  infected  by  feeding  them  with  the  Micrococcus  melitensis. 
In  the  same  year  Major  Horrocks  discovered  the  Micrococcus  meliten- 
sis in  the  milk  of  an  apparently  healthy  goat.  Further  studies  showed 
that  one  or  more  healthy  goats  in  every  herd  were  excreting  the  Micro- 
coccus melitensis  in  their  milk  and  urine,  and  that  about  50  per  cent, 
of  the  goats  reacted  positively  when  examined  by  serum  agglutination 
tests.  All  the  available  evidence  points  to  their  food  as  the  main 
vehicle  of  infection  in  goats.  The  young  goats,  of  course,  are  infected 
through  their  mothers  milk.  Horrocks  and  Kennedy  consider  that 
10  per  cent,  of  the  goats  supplying  milk  to  various  parts  of  Malta 
excrete  the  Micrococcus  melitensis  in  their  milk.  The  excretion  of 
the  specific  microorganism  may  continue  steadily  for  three  months 
without  any  change  occurring  in  the  physical  character  or  chemical 
composition  of  the  milk  and  without  the  animal  exhibiting  any  signs 
of  ill  health.  On  the  other  hand,  the  excretion  of  the  Micrococcus 
melitensis  in  the  milk  may  be  intermittent,  appearing  for  a  few  days 
and  then  disappearing  for  a  week  or  more. 

Major  Horrocks  in  Report  No.  5  of  the  British  Commission  shows 
a  direct  relation  between  the  number  of  goats  in  Gibraltar  to  the  num- 
ber of  cases  of  malta  fever.  With  the  reduction  in  the  number  of  goats 
in  Gibraltar  there  was  also  a  decrease  in  the  number  of  cases,  so  that 
finally,  when  the  number  of  goats  had  decreased  to  about  200  in  1905, 
malta  fever  had  practically  disappeared. 

The  story  of  the  steamship  Joshua  Nicholson  is  instructive  in  show- 


MALTA    FEVER  291 

ing  the  relation  between  goats'  milk  and  malta  fever  in  man.  Sixty- 
one  milch  goats,  all  healthy  in  appearance  and  good  milkers  (many 
being  prize  animals),  and  four  billygoats  were  shipped  on  board  the 
cargo  steamer  Joshua  jS'icJiolson  August  19,  1905,  at  Malta  for  pas- 
sage to  the  United  States  via  Antwerp.  Many  of  the  ship's  company 
partook  freely  of  the  milk.  The  officers  drank  "mixed"  milk  collected 
in  a  large  vessel;  the  members  of  the  crew  each  obtaining  the  "whole" 
milk  from  one  goat  in  his  own  separate  panikin.  Subsequent  bacterio- 
logical examination  resulted  in  the  recovery  of  the  Micrococcus  meliten- 
sis  from  the  milk  of  several  of  the  goats.  Of  23  men  on  board  the 
steamer  who  drank  the  goats'  milk  on  one  or  more  occasions,  no  evi- 
dence whatever  is  available  as  to  13,  while  of  the  remaining  10,  9  suf- 
fered from  febrile  attacks,  5  of  them  yielding  conclusive  e^adence  of 
infection  with  the  Micrococcus  melitensis. 

Resistance. — The  Micrococcus  melitensis  is  readily  destroyed  by  heat. 
I  have  shown  that  60°  C.  for  20  minutes  is  sufficient  to  destroy  this 
organism  in  milk  and  provides  at  the  same  time  a  liberal  margin  of 
safety.  It  is  not  destroyed  at  55°  for  a  short  time,  but  succumbs  in  one 
hour;  the  majority  die  at  58° ;  at  60°  all  are  killed.  Phenol,  1  per  cent., 
destroys  the  coccus  in  15  minutes.  While  this  micrococcus  shows  a  com- 
paratively feeble  resistance  against  heat  and  the  ordinar}^  germicides,  it 
shows  a  remarkable  resistance  to  dr3'ness,  for  it  may  remain  alive  in 
this  state  for  months. 

The  micrococcus  grows  well,  but  slowly,  upon  artificial  culture 
media.  Visible  colonies  do  not  appear  until  about  the  fifth  day.  It 
may  be  kept  alive  indefinitely  by  transplanting  to  subcultures  at  fre- 
quent intervals.  Exceedingly  high  agglutinating  power  develops  in 
persons  suffering  with  malta  fever — sometimes  as  high  as  1-100,000. 
In  such  cases  the  proagglutinoid  zone  may  appear,  that  is,  the  serum 
may  refuse  to  agglutinate  in  low  dilutions,  such  as  1-100,  but  aggluti- 
nate actively  in  higher  dilutions,  such  as  1-1,000. 

Prevention. — Our  knowledge  of  the  cause  and  modes  of  transmis- 
sion of  malta  fever  makes  the  prevention  of  this  disease  a  compara- 
tively simple  problem.  The  infection  must  first  .be  eliminated  in  the 
goats.  Until  this  is  done  goats'  milk  should  be  pasteurized.  Patients 
having  the  disease  should  be  treated  upon  the  same  principles  laid  down 
for  typhoid  fever,  in  order  to  prevent  the  spread  of  the  infection 
through  food  fomites  and  indirect  contact.  Convalescents  should  not 
be  released  until  the  micrococcus  has  disappeared  from  the  urine.  Gen- 
eral sanitary  measures,  such  as  the  suppression  of  flies  and  mosquitoes, 
allaying  dust,  and  the  promotion  of  general  cleanliness,  should  not  be 
neglected. 


292  MiSCELLANEOrS    DISEASES 


LEPROSY 


Leprosy  is  a  contagious  disease  in  the  sense  that  it  is  probably 
always  communicated  directly  from  the  sick  to  the  well,  but  j)rolonged 
and  intimate  association  with  a  leper  ordinarily  seems  necessary  to  con- 
tract the  infection.  The  degree  of  tlie  contagiousness  varies  very  much, 
depending  upon  conditions  not  well  understood,  but  it  is  plain  that 
leprosy  shows  little  tendency  to  spread  in  any  of  the  more  highly  civ- 
ilized nations  practicing  personal  cleanliness  and  enjoying  the  benefits 
of  modern  sanitation.  Leprosy  prevailed  in  epidemic  form  in  Europe  in 
the  middle  ages,  but  the  disease  has  disappeared  from  central  Europe, 
remaining  only  upon  the  fringe  of  the  continent,  in  iSTorway,  Sweden, 
Spain,  Italy,  Greece,  Turkey,  Russia,  and  Finland.  It  is  estimated 
that  there  are  from  5,000  to  G,000  lepers  in  the  Philippine  Islands,  and 
there  are  many  cases  in  China,  Japan,  and  India.  The  greatest  inci- 
dence is  found  among  the  natives  of  the  Hawaiian  Islands,  where  one 
in  every  30  or  40  have  the  disease.  Leprosy  was  introduced  into  the 
Hawaiian  Islands  about  1859,  and  there  found  conditions  particularly 
favorable  for  spread.  A  Government  Commission  in  1902  ^  took  a  census 
of  the  lepers  in  the  United  States  and  found  278.  Of  these  145  were 
born  in  the  United  States  and  186  probably  contracted  the  disease  in 
the  United  States.  Of  the  entire  number  72  of  the  cases  were  isolated 
and  205  were  at  large.  Brinckerhofl  again  studied  the  prevalence  of 
leprosy  in  the  United  States  in  1909  and  found  139  cases.  The  official 
figures  for  1912  are  146.  Although  these  numbers  represent  only  the 
cases  officially  known,  it  is  evident  that  the  disease  is  not  on  tlie  increase 
in  our  country  and  that,  while  it  may  be  contracted  here,  it  is  "con- 
tagious'-' with  great  difficulty.  There  are  three  foci  of  leprosy  in  the 
United  States :  one  among  the  Scandinavians  in  the  region  of  the  Great 
Lakes,  another  among  the  Orientals  on  the  Pacific  Coast,  and  the  third 
on  the  Gulf  Coast,  particularly  in  Louisiana  and  Florida.  According 
to  the  official  health  reports  from  our  Territories  and  Dependencies,  there 
were  in  1912  in  HaWaii  696  lepers,  in  Porto  Rico  28,  in  tlie  Philippine 
Islands  2,754,  in  the  Canal  Zone  7.  The  number  in  Guam  and  Alaska 
have  not  been  enumerated.  It  is  known,  however,  that  many  cases 
escape  tabulation  in  the  official  returns. 

The  cause  of  leprosy  is  the  Bacillus  leprce  discovered  by  Armauer- 
Hansen  in  1874.  The  bacillus  of  leprosy  resembles  the  bacillus  of  tu- 
berculosis in  many  respects.  It  stains  more  readily  and  decolorizes 
somewhat  more  readily  than  the  tubercle  bacillus.  It  differs  from  the 
tubercle  bacillus  in  that  it  grows  with  difficulty  on  artificial   culture 

^  White,  Vaughan,  and  Kosenau,  Document  No.  269,  57th  Congress,  Ist  Ses- 
sion, 1902. 


LEPEOSY  293 

media  and  is  much  less,  if  at  all,  pathogenic  for  the  lower  animals. 
Further,  lepra  bacilli  are  usually  found  in  dense  clusters  and  in  much 
greater  numbers  within  the  cells  than  is  the  case  with  the  tubercle 
bacillus. 

The  bacillus  of  leprosy  grows  with  difhcult}-  upon  artificial  culture 
media.  For  years  it  has  evaded  all  attempts  until  Clegg  ^  in  1909  suc- 
ceeded in  cultivating  it  in  symbiosis  with  amebse  and  S.  cJiohrcB  upon 
plain  agar  and  weakly  nutrient  agar.  Clegg  based  his  work  upon  the 
belief  that  the  leprosy  bacillus  derives  its  nutrition  from  the  products 
of  the  tissue  cells  in  which  it  is  mainly  to  be  seen  in  leprosy  lesions. 
These  results  have  been  confirmed  by  Currie,  Brinckerhoff,  and  Holman 
in  Hawaii  and  by  Duval  in  New  Orleans. 

Immunity. — There  is  no  racial  immunity  to  leprosy.  The  white 
races  suffered  severely  during  the  middle  ages.  Malays  and  Mongols 
now  appear  most  liable  to  the  infection,  perhaps  on  account  of  their 
mode  of  life.  The  disease  is  remarkable  for  its  prolonged  period  of 
incubation  and  its  chronic  course.  These  facts  indicate  that  the  body 
must  possess  a  high  degree  of  resistance  to  this  infection.  So  far  as 
known,  man  is  the  only  animal  subject  to  leprosy  under  natural  condi- 
tions. Inoculation  experiments  into  lower  animals  have  recently  proved 
successful  in  the  guinea  pig  (Clegg);  the  Japanese  dancing  mouse 
(Sugai) ;  and  the  monkey  (Duval). 

Rat  Leprosy. — There  is  a  disease  among  rats  which  is  a  close  coun- 
terpart of  leprosy  in  man.  It  occurs  naturally  in  the  Mus  norvegicus 
and  may  be  transferred  by  inoculation  to  the  more  tractable  laboratory 
white  rat.  The  disease  was  first  observed  by  Stenfansky  in  1903  in 
Odessa.  In  the  same  year  Eabinowitsch  found  the  disease  among  the 
rats  of  Berlin,  and  Dean  in  1903  discovered  the  disease  independently 
in  London,  and  in  a  later  publication  (1905)  reported  success  in  trans- 
ferring the  infection  by  artificial  inoculation.  Since  then  rat  leprosy 
has  been  found  by  Tidswell  in  the  rats  of  Sydney,  Australia,  and  the 
England  Plague  Commission  observed  the  disease  among  the  rats  in 
India.  Wherry  and  McCoy  found  a  number  of  cases  among  the  rats 
caught  in  San  Francisco,  California. 

The  proportion  of  rats  infected  with  leprosy  in  different  localities 
varies  greatly.  Thus  in  Odessa  from  4  to  5  per  cent.,  in  San  Francisco 
0.2  per  cent.,  and  in  Sydney  only  0.001  per  cent.  Currie  failed  to 
find  leprosy  among  the  rats  of  Honolulu.  The  fact  that  the  infection 
is  absent  among  the  rats  of  Honolulu  and  present  among  the  rats  in 
Berlin  is  evidence  that  it  plays  no  part  in  the  epidemiology  of  the 
human  disease. 

Leprous  rats  in  a  late  stage  of  the  disease  are  usually  recognized 

^  The  Philippine  Jour,  of  Science,  Vol.  IV,  No.  77,  Apr.,  1909.    FubUc  Health 
Bull.  No.  47,  Sept.,  1911. 
21 


294  MISCELLANEOUS    DISEASES 

by  the  presence  of  patchy  alopecia  associated  with  cutaneous  and  sub- 
cutaneous nodules  which  may  or  may  not  be  the  site  of  open  ulcers. 
The  diagnosis  is  readily  confirmed  by  microscopic  examination  of  a 
smear  from  an  ulcer  or  a  nodule,  which  will  show  the  specific  bacillus 
of  the  disease  in  enormous  numbers. 

Currie  ^  has  recently  shown  that  rats  may  infect  each  other  by 
contact,  also  that  bacilli  of  rat  leprosy  may  often  be  demonstrated  in 
the  heart's  blood  of  infected  rats.  Currie  had  no  difficulty  in  demon- 
strating the  presence  of  acid-fast  bacilli  in  mites  contained  on  the 
bodies  of  rats  when  the  latter's  heart's  blood  contained  the  microorgan- 
isms. The  fact  that  those  mites  so  frequently  contain  the  bacilli  natu- 
rally leads  to  the  suspicion  that  they  may  be  one  of  the  means  of 
transmitting  the  disease  from  rat  to  rat.  but  up  to  the  present  time  no 
positive  evidence  has  been  adduced  that  such  is  the  case. 

In  this  leprosy-like  disease  of  rats  we  have  an  infection  which 
closely  resembles  leprosy  in  man.  The  fact  that  the  infection  may 
readily  be  propagated  in  a  laboratory  animal  permits  of  its  investiga- 
tion, and  it  is  assumed  that  the  further  studies  now  being  made  upon 
rat  leprosy  will  throw  much  light  upon  the  modes  of  transmission 
and  control  of  the  human  disease. 

Modes  of  Transmission. — The  leprosy  bacillus  is  found  in  all  the 
lesions  of  tlie  disease — the  nodules  on  the  skin  and  mucous  membranes, 
in  the  spleen,  liver,  and  testicles — in  fact,  in  all  the  internal  organs. 
In  the  anesthetic  type  the  bacilli  are  found  in  the  cells  of  the  spinal 
cord  and  brain  and  also  in  the  peripheral  nerves.  LeprOv«y  bacilli  may 
also  be  found  in  the  circulating  l)lood  during  the  acute  eruptive  stage. 
Frequently  they  are  in  the  endothelial  or  in  the  white  blood  cells. 
The  leprosy  bacillus  leaves  the  body  from  any  of  the  lesions  that  are 
broken  down.  From  the  degenerated  nodules  of  the  skin  or  mucous 
membranes  they  are  discharged  in  enormous  numbers.  If  we  may  de- 
pend upon  microchemical  evidence,  it  appears  that  most  of  these  bacilli 
are  probably  dead.  Leprosy  bacilli  also  occasionally  appear  in  the 
feces  and  urine.    They  do  not  occur  in  the  expectoration  from  the  lungs. 

There  is  some  doubt  as  to  just  how  the  leprosy  bacillus  enters 
the  body,  whether  through  wounds  of  the  skin  or  through  the  mucous 
membrane  of  the  nose  and  throat  or  through  the  digestive  tract,  or 
possibly  during  coitus. 

It  may  be  definitely  stated  that  leprosy  is  not  due  to  the  eating  of 
any  particular  food,  such  as  fish.  This  theory  has  been  stoutly  main- 
tained by  Jonathan  Hutchinson.  There  is  no  satisfactory  evidence 
in  support  of  the  fish  theory  and  many  facts  against  it.  One  thing 
is  plain,  and  that  is,  leprosy  is  not  contracted  from  any  of  the  lower 

'  U.  S.  Pub.  Health  and  Mar.  Hosp.  Ser.,  Pub.  HeaUh  Bull.  No.  50.  Oct., 
1911. 


LEPEOSY  295 

animals,  but  is  an  infection  which  in  all  cases  passes  rather  directly 
from  man  to  man. 

The  suspicion  that  parasitic  insects  ma}'  play  some  role  in  the 
transmission  of  leprosy  has  existed  for  some  time.  The  evidence  is 
reviewed  by  IS'uttal/  who  says:  '"'It  appears  that  Linnaeus  and  Eolan- 
der  considered  that  Chlorops  {miisca)  lepra  was  able  to  cause  leprosy 
by  its  bite."  Blanchard  and  Corrodor  tell  of  flies  in  connection  with 
leprosy.  Flies  frequently  gather  in  great  numbers  on  the  leprous 
ulcers  and  then  visit  and  bite  other  persons.  An  observation  by  Boeck 
of  the  presence  of  Sarcoptes  scabei  in  a  case  of  cutaneous  leprosy  led 
Joly  to  conclude  that  these  parasites  might  at  times  serve  as  carriers 
of  the  infection.  Pediculi  are  usually  present  among  the  poor  classes 
in  Algeria,  which  furnish  the  greater  number  of  lepers.  Sommer  of 
Buenos  Aires  expresses  the  belief  that  mosquitoes  act  as  active  agents 
in  the  spread  of  leprosy  in  warm  countries.  Carrasquillo  of  Bogota 
found  the  bacillus  of  Hansen  in  the  intestinal  contents  of  flies.  W.  C. 
Goodhue  and  his  assistant,  Father  Joseph,  working  at  the  leper  settle- 
ment at  Moloki,  found  lepra  bacilli  in  the  intestinal  contents  of  a 
female  Culex  pungens.  Later  they  found  similar  organisms  in  the 
common  bedbug.  The  British  Leprosy  Commission  investigated  the 
possible  role  played  by  insects  with  entirely  negative  results.  Wherry 
studied  the  occurrence  of  lepra-like  bacilli  in  certain  flies  and  their 
larva.  He  found  that  the  fly  Chlorops  vomitoria  took  up  enormous 
numbers  of  lepra  bacilli  from  the  carcass  of  a  leper  rat  and  deposited 
them  with  their  feces,  but  the  bacilli  apparently  do  not  multiply  in  the 
flies,  as  the  latter  are  clear  of  bacilli  in  less  than  48  hours.  Larvae 
of  Chlorops  vomitoria  hatched  out" in  the  carcass  of  a  leper  rat  become 
heavily  infested  with  lepra  bacilli.  If  such  larvae  are  removed  and  fed 
on  uninfected  meat  the}'  soon  rid  themselves  of  most  of  the  lepra 
bacilli.  A  fly,  Miisca  domestica,  caught  on  the  face  of  a  human  leper 
was  found  to  be  infested  with  lepra-like  bacilli.  Most  of  the  evidence 
bearing  on  the  possible  role  of  insects  in  the  transmission  of  leprosy 
may  be  classified  as  purely  presumptive  evidence  based  upon  analogy, 
or  as  evidence  based  simply  upon  the  finding  of  acid-fast  bacilli  in 
certain  insects.  It  must  be  plain  that  the  simple  taking  up  of  para- 
sites by  an  insect  does  not  necessarily  imply  that  the  insect  plays  a 
role  in  its  transmission  from  one  host  to  another.  Further,  all  acid- 
fast  bacilli  are  not  leprosy  bacilli.  It  cannot  be  denied  that  leprosy 
may  be  one  of  the  insect-borne  diseases;  the  final  verdict  will  depend 
upon  further  studies. 

A  great  majority  of  lepers  at  some  time  in  the  disease  have  lepra 
bacilli  in  their  nasal  secretions.  The  importance  of  the  nose  in  leprosy 
was  brought  into  prominence  at  the  First  International  Leper  Confer- 

^  Johns  Hop'kins  Hospital  Eeports,  1900,  VIII.  p.  1. 


296  MISCELLANEOUS   DISEASES 

ence  in  1897  by  the  work  of  Sticker,  who  made  sweeping  statements 
concerning  the  nose  as  tlie  site  of  the  primary  lesion  and  the  danger 
of  nasal  secretions  in  transmitting  the  disease.  Jeanselme  and  Lau- 
rans  (1895),  Gerber  (1901),  Werner  (1902),  Sheroux  (1903),  and 
others  have  shown  the  frequency  with  which  the  bacilli  of  leprosy  ap- 
pear in  the  nasal  secretions  and  the  importance  of  the  nose  as  a  site 
of  leprous  lesions.  Sticker  cites  a  five-year-old  child  of  leprous  parents 
seen  by  him  in  India  with  an  ulcer  on  the  right  side  of  the  nasal  sep- 
tum which  contained  lepra  bacilli  and  was  the  only  lesion  of  the  dis- 
ease present  in  the  case.  Plumert  (1903)  mentions  the  finding  of 
lepra  bacilli  in  the  nasal  secretions  of  persons  in  intimate  family  con- 
tact with  advanced  cases  of  leprosy.  The  individuals  in  question  showed 
no  other  evidence  of  the  disease.  Falkao  observed  epistaxis  associated 
with  small  ulcers  on  the  nasal  septum  of  descendants  of  lepers,  and 
lepra  bacilli  were  found  in  the  crusts  from  these  ulcers.  The  results 
of  Sticker,  Plumert,  and  Falkao  would  indicate  that  in  the  early  stages 
of  the  disease  the  nose  is  frequently  the  site  of  a  lesion  discharging 
lepra  bacilli.  Brinckerhoff  and  Moore,  however,  who  made  a  careful 
study  of  this  question  in  Honolulu,  point  out  that  most  of  the  studies 
upon  the  importance  of  the  nose  in  leprosy  have  been  made  upon  rela- 
tively advanced  cases  of  the  disease.  They  found  the  nose  frequently 
the  seat  of  infection  when  the  disease  is  well  developed,  but  practically 
never  as  a  primary  or  incipient  lesion.  If  the  nose  were  the  usual  seat 
of  the  primary  lesion  in  leprosy,  it  would  indicate  that  the  infection 
is  carried  there  upon  the  finger. 

Hollmann  studied  500  persons  in  the  Hawaiian  Islands  suffering 
with  a  recognizable  form  of  leprosy  for  periods  varying  from  three 
months  to  twenty- five  years,  and  found  410  with  lesions  of  the  nasal 
mucous  membrane  and  only  90  in  which  such  lesions  were  absent. 

It  is  sufficient  for  practical  prevention  to  know  that  leprosy  is 
spread  mainly  by  direct  contact  and  perhaps  occasionally  by  indirect 
contact  with  persons  suffering  with  the  disease.  Leprosy  is  most  preva- 
lent under  conditions  of  personal  and  domestic  uncleanliness  and  over- 
crowding, especially  where  there  is  close  and  protracted  association  be- 
tween the  leprous  and  the  non-leprous.  There  is  no  evidence  that 
leprosy  is  hereditary.  The  occurrence  of  several  cases  in  a  single  fam- 
ily is  doubtless  due  to  "contact."'  The  danger  of  infection  from  leprous 
persons  is,  of  course,  greater  when  there  is  a  discharge  from  the  le- 
sions of  the  skin  and  mucous  membranes. 

Prevention. — The  prevention  of  leprosy  depends  almost  entirely 
upon  isolation,  care  of  the  infected  discharges,  personal  cleanliness, 
and  sanitary  surroundings.  That  the  disease  is  transmitted  with  dif- 
ficulty is  shown  by  the  fact  that  doctors,  nurses,  sisters  of  charity, 
ward  tenders,  and  others  directly  exposed  in  leprosaria  seldom  become 


LEPEOSY  297 

infected.  Xotable  exceptions  have  been  Father  Damien  in  Honolulu 
and  Father  Bogliolo  in  Xew  Orleans.  Evidently  close,  prolonged  and 
intimate  contact  is  ordinarily  necessary  to  contract  the  infection.  For 
many  years  a  case  of  leprosy  was  cared  for  as  a  patient  in  a  hospital 
with  which  I  was  associated.  He  had  his  own  dishes,  towel,  soap,  etc., 
otherwise  he  mingled  freely  with  the  patients  and  others,  without 
spreading  the  disease. 

For  the  control  of  leprosy  the  most  important  administrative  meas- 
ure is  to  segregate  the  lepers  in  settlements  or  asylums.  Compulsory 
notification  of  every  case  of  leprosy  should  be  enforced,  if  for  no  other 
reason  than  to  keep  track  of  the  disease  and  to  know  whether  it  is  on 
the  increase.  Segregation  of  lepers  is  the  most  important  single  pre- 
ventive measure.  The  leprosaria  should  be  inviting  and  should  con- 
tain all  modern  improvements  for  the  care  and  treatment  of  the 
disease.  Leprosy  is  by  no  means  invariably  fatal.  In  the  United 
States,  where  there  are  only  a  few  hundred  lepers,  the  Government 
should  establish  a  national  leprosarium  conducted  upon  the  principles 
of  a  modern  sanitarium  for  tuberculosis.  To  require  each  state  to 
provide  suitable  accommodations  to  segregate  its  few  lepers  is  econom- 
ically wasteful.  It  is  claimed  that  the  decrease  in  leprosy  in  Europe 
since  the  middle  ages  has  been  due  in  large  part  to  the  segregation 
of  the  lepers  in  leprosaria,  which  at  one  time  numbered  20,000.  On 
the  other  hand,  the  value  of  segregation  in  countries  where  leprosy  is 
very  prevalent  is  disputed.  As  a  rule,  only  the  advanced  cases  are 
detected  and  isolated.  Segregation  in  the  Hawaiian  Islands  has  so  far 
had  no  effect  upon  the  prevalence  of  the  disease.  There  are  factors  in 
the  control  of  leprosy  not  yet  understood. 

There  can  be  little  objection  in  a  country  such  as  ours,  where  leprosy 
shows  slight  tendency  to  spread,  to  give  a  clean  leper  his  freedom. 
There  is  no  more  danger  from  a  leprosy  patient  of  clean  personal 
habits,  who  exercises  care  concerning  the  discharges  from  the  lesions, 
than  there  is  from  a  discharging  case  of  tuberculosis  of  the  glands  of 
the  neck. 

The  national  quarantine  regulations  forbid  the  landing  of  an  alien 
leper.  The  law  requires  that  such  person  be  deported  on  the  same  ves- 
sel that  brought  him.  A  citizen  of  the  United  States  having  leprosy 
cannot  be  debarred.  Such  individuals  are  admitted  and  then  come  un- 
der the  health  laws  of  the  state  or  port  of  entry. 

Specific  Prevention. — There  is  no  specific  prevention  or  cure  for 
leprosy.  Xastin  is  a  substance  proposed  by  Deycke  and  consists  of  a 
neutral  fat  obtained  from  a  streptothrix.  The  reports  from  its  use 
are  not  particularly  encouraging.  Eost,  of  Bangoon,  Burmah.  uses 
a  substance  which  he  calls  "leprolin,"  a  precipitate  from  leprous  tu- 
bercles.    Tuberculin  in  somewhat  large  doses  injected  subcutaneously 


298  MISCELLANEOUS    DISEASES 

into  leprous  patients  produces  both  a  general  and  local  reaction,  but 
the  repeated  injections  do  not  materially  influence  the  disease,  although 
such  treatment  seems  to  cause  a  local  improvement  or  softening  of  the 
leprous  tubercles.  Heiser  in  Manila  reports  favorable  results  from  the 
aj)plication  of  X-rays.  Dyer  in  Louisiana  has  obtained  good  results 
from  good  food,  fresli  aii\  (leanliness,  and  the  general  principles  applic- 
able to  the  modern  treatment  and  prevention  of  tuberculosis. 

MENTAL  DISEASES 

THE  PREVENTION  OF  MENTAL  DISEASES 
By  Thomas  W.  Salmon,  M.D. 

Passed  Assistant  Surgeon,  U.  8.  Public  Health  Service;  Director  of  Spe- 
cial Studies,  National  Committee  for  Mental  Hygiene;  Formcrli/ 
Chairman  of  the  New  York  State  Board  of  Alienists. 

Although,  in  the  prevention  of  insanity,  we  have  to  deal  with  prob- 
lems more  complex  than  those  which  have  been  considered  in  the 
prevention  of  the  infectious  diseases,  some  mental  diseases  are  known 
to  depend  upon  causes  as  definite  as  the  infection  of  the  body  with 
pathogenic  bacteria.  We  know,  for  instance,  that  if  a  patient  with 
one  of  the  alcoholic  psychoses  had  not  been  addicted  to  the  use  of  al- 
cohol he  would  not  have  acquired  this  mental  disease,  whatever  other 
bodily  or  mental  infirmity  he  might  become  afflicted  with,  for  recent 
methods  of  studying  mental  diseases  have  made  it  possible  to  recog- 
nize certain  groups  of  symptoms  which  can  be  produced  by  alcohol 
and  by  that  cause  alone.  There  are  clinical  symptoms  and  laboratory 
findings  which  enable  us  to  learn,  with  small  chance  of  error,  that  a 
patient  is  suffering  from  general  paresis.  We  know  that  such  a  pa- 
tient owes  his  mental  disease  to  syphilis,  and  that  for  him  the  preven- 
tion of  insanity  would  have  consisted  in  the  prevention  of  syphilis. 

Not  all  types  of  mental  diseases,  however,  have  causes  so  well  un- 
derstood as  these.  There  are  many  in  which  the  pathology  is  unknown 
and  in  which  the  symptoms  are  so  variable  that  at  present  we  are 
obliged  to  place  them  in  provisional  groups  from  which  we  may  be 
able  to  rescue  them  later,  perhaps,  when  present  diagnostic  difficulties 
have  been  overcome  or  when  new  light  has  been  thrown  upon  their 
nature.  It  seems  desirable,  in  discussing  the  preventable  causes  of 
insanity,  to  consider  first  some  of  the  factors  which  -we  know  are  ca- 
pable of  producing  mental  disease,  either  directly  or  indirectly,  at  the 
same  time  referring  to  possible  means  for  their  control,  and  then  to 
consider  some  other  causes  which  we  have  excellent  reasons  for  believ- 


MENTAL    DISEASES  299 

ing  influence  the  prevalence  of  insanity,  but  which  operate  in  a  man- 
ner which  cannot  be  shown  so  conclusively. 

It  is  essential  to  state  at  the  outset  that  a  number  of  different 
diseases  are  included  in  what  we  term  "insanity."  It  would  be  quite 
permissible  to  speak  of  the  various  mental  diseases  as  "insanities,"  so 
greatly  do  they  vary  in  their  symptoms,  course,  and  etiology.  Just 
as  the  popular  term  ^^leart  disease"  properly  includes  congenital  malfor- 
mations, changes  associated  with  acute  infectious  diseases,  reactions  to 
toxic  substances,  disturbances  of  the  nervous  mechanism,  and  the  ef- 
fects of  disease  of  remote  organs,  so  "insanity'"  includes  diseases  de- 
pendent upon  congenital  mental  deficiency  or  developmental  defects, 
.the  exhaustion  accompanying  acute  or  chronic  disease,  the  introduction 
of  toxic  substances  into  the  body  or  their  elaboration  within  it,  organic 
changes  in  the  brain,  and  abnormal  psychic  reactions. 

INFECTIOUS    DISEASES    WHICH    CAUSE    INSANITY 

It  seerns  desirable  to  consider  infectious  diseases  as  a  cause  of 
mental  disease  first,  not  because  they  are  responsible  for  a  larger  pro- 
portion of  cases  than  other  preventable  causes,  but  on  account  of  their 
closer  relation  to  that  with  which  we  are  familiar  in  the  realm  of  pre- 
ventive medicine. 

Typhoid  fever  may  give  rise  to  permanent  or  transitory  mental 
impairment.  The  prevention  of  insanity  in  this  instance  consists,  of 
course,  in  the  prevention  of  typhoid  fever.  When  the  evils  resulting 
from  the  needless  prevalence  of  that  disease  are  counted  up,  the  cases 
of  mental  disease  caused  by  it  must  be  included. 

Other  infectious  diseases,  notably  influenza,  scarlet  fever,  malarial 
fever,  erysipelas,  and  septicemia  (particularly  from  uterine  infection), 
furnish  a  considerable  number  of  cases  of  mental  disease,  chiefly  in 
the  infective-exhaustive  group,  in  which  exhaustion,  elevated  tempera- 
ture, and  poisoning  of  the  nervous  centers  by  bacterial  toxins  are  the 
immediate  causes  of  mental  changes.  About  three  per  cent,  of  all 
first  admissions  to  hospitals  for  the  insane  ^  belong  in  this  group.  It 
is  impossible  to  estimate  the  proportion  of  cases  in  which  infectious 
disease  is  the  only  cause  in  other  types  of  mental  disease,  for  an  acute 
infection  may  "^^iberate"  an  attack  in  a  patient  subject  to  a  psychosis 
in  which  recurrences  are  common,  and  this  cause  may  combine  with 
others,  alcohol,  for  instance,  in  the  production  of  a  psychosis  in  which 
the  infectious  disease  plays  a  secondary  part. 

^  This  percentage  and  others  following  are  based  upon  recent  statistical 
studies  of  admissions  to  the  state  hospitals  of  New  York  and  Massachusetts. 
About  one-fourth  of  all  the  insane  under  treatment  in  the  United  States  are 
patients  in  the  public  institutions  of  these  two  states,  and  statements  based  upon 
the  statistical  studies  in  question  are  fairly  applicable  to  the  United  States  as  a 
whole. 


300  MISCELLANEOUS    DISEASES 

Preventive  measures  in  such  types  of  insanity  must  consist  chiefly 
in  the  general  work  of  limiting  the  prevalence  of  the  infectious  dis- 
eases, but  much  can  be  done  by  improved  methods  of  treating  febrile 
conditions.  The  full  significance  of  delirium  and  its  pathology  must 
be  appreciated  and  hydrotherapy  employed  more  generally  and  more 
carefully  if  we  are  to  lessen  the  number  of  patients  with  infective- 
exhaustive  psychoses.  The  indiscriminate  use  of  sedatives  or  hypnotic 
drugs  in  deliria  sometimes  results  in  an  aftermath  of  mental  disease. 

Syphilis  deserves  separate  consideration  as  a  preventable  cause  of 
mental  disease,  for  it  is  the  essential  cause  of  general  paresis,  a  disease 
responsible  for  about  13  per  cent,  of  all  first  admissions  to  hospitals 
for  the  insane  in  this  country,  and  for  nearly  one-fifth  of  all  male 
admissions.  In  admissions  from  American  cities  more  than  22  per 
cent,  of  male  patients  are  suffering  from  general  paresis.  More  deaths 
resulted  in  New  York  State  from  general  paresis  in  1911  than  from 
smallpox  in  the  whole  registration  area  of  the  United  States  since  1908. 
Half  as  many  deaths  are  known  to  occur  every  year  from  general  pare- 
sis as  from  typhoid  fever.  It  is  believed  that  a  considerable  number 
of  deaths  from  general  paresis,  when  occurring  outside  of  institutions, 
are  reported  as  "softening  of  the  brain"  or  by  some  other  indefinite 
term,  and  the  prevalence  of  general  paresis  is,  therefore,  far  greater 
than  mortality  statistics  would  indicate. 

This  disease  runs  a  uniformly  fatal  course,  the  average  duration 
of  which  is  from  two  to  five  years.  It  attacks  people  who  have,  to  all 
appearances,  recovered  from  syphilis,  and  most  frequently  in  the  fourth 
decade  of  life,  when  their  usefulness  to  the  community  and  to  their 
families  is  greatest.  It  is  the  grimmest  specter  which  follows  youth- 
ful indiscretions  and  "sowing  wild  oats."  Of  course,  the  prevention 
of  general  paresis  depends  wholly  upon  the  prevention  of  syphilis,  a 
well-defined  field  of  effort  in  preventive  medicine,  but  it  seems  that 
impetus  would  be  lent  the  movement  for  venereal  prophylaxis  if  the 
appalling  prevalence  of  this  result  of  syphilis  were  more  widely  known. 
It  is  a  rather  surprising  fact  that  many  of  those  actively  engaged  in 
the  campaign  against  venereal  disease  are  quite  unaware  of  the  preva- 
lence of  general  paresis  or  that  it  depends  upon  previous  infection  with 
syphilis.  It  is  a  fact  that  general  paresis  is  a  much  more  frequent 
manifestation  of  syphilis  than  locomotor  ataxia.^ 

'  It  is  very  desirable  to  know  what  proportion  of  eases  of  syphilis  result  in 
general  paresis,  but,  until  recently,  no  satisfactory  studies  had  been  undertaken 
to  determine  this,  and,  on  account  of  the  long  interval  between  infection  with 
syphilis  and  the  development  of  symptoms  of  general  paresis,  it  seemed  impossi- 
ble to  find  a  group  of  population  in  which  such  studies  could  be  made.  A  short 
time  ago,  however,  Mattauschek  and  Pilcz  made  public  (Berliner  I'linische  Woch- 
enschrift,  Feb.  19,  1912)  the  results  of  a  careful  examination  of  the  histories 
of  4,134  officers  of  the  Austrian  Army  who  had  contracted  syphilis  during  the 
period  1880-1890.  They  ascertained  that  4.67  per  cent,  of  these  ofiicers  developed 
general   paresis. 


MENTAL    DISEASES  301 

A  small  number  of  cases  of  other  types  of  mental  disease  are  also 
directly  the  outcome  of  syphilis.  Mental  deterioration  is  associated 
with  gunimata  of  the  brain  and  mental  changes  accompany  local  menin- 
gitis due  to  syj^hilis.  Syphilis  is  also  responsible  for  a  certain  propor- 
tion of  cases  of  congenital  mental  defect  upon  which  insanity  may 
become  engrafted  later,  and  it  is  often  syphilis  which  first  attacks  the 
integrity  of  the  arterial  wall,  thus  laying  the  train  destined 
to  result,  years  later,  in  arteriosclerosis  and  mental  disease  dependent 
upon  it. 

Tuberculosis  is  a  cause  of  mental  disease  much  less  frequently  than 
has  been  supposed.  It  is  exceedingly  doubtful  if,  as  has  been  asserted, 
tuberculosis  ever  results  in  a  special  clinical  form  of  mental  disease, 
but  the  exhaustion  of  a  chronic,  wasting  illness  and  the  action  of  the 
tubercular  toxin  upon  the  nervous  centers  are  probably  immediate 
causes  of  mental  changes.  Although  there  are  no  especial  measures 
of  prevention  of  mental  disease  dependent  upon  tuberculosis,  the  fact 
that  this  is  one  of  its  possible  effects  might  well  be  added  to  the  in- 
formation disseminated  regarding  tuberculosis,  for  not  the  least  of  the 
benefits  from  curing  incipient  cases  or  preventing  the  spread  of  tuber- 
culosis is  that  the  prevalence  of  insanity  is  thereby  even  slightly  les- 
sened. 

Pellagra. — It  is  hardly  justifiable,  perhaps,  to  speak  of  pellagra  as 
a  preventable  disease  when  the  ground  is  just  being  cleared  for  a  satis- 
factory search  for  its  cause,  which  at  present  is  assumed  to  be  spoiled 
corn  (see  page  577).  With  the  practical  application  of  means  for  the 
control  of  this  disease,  a  certain  number  of  cases  of  insanity  will  be 
prevented  in  the  localities  where  pellagra  prevails. 

ACUTE   AND   CHRONIC   POISONINGS   WHICH   CAUSE    INSANITY 

Alcohol. — It  is  a  strange  commentary  upon  human  frailty  that  all 
the  poisons  which  assail  man  through  accident  and  the  dangerous 
trades  in  which  he  must  engage,  and  all  the  poisons  which  are  elabo- 
rated within  his  system,  as  in  nephritis,  diabetes,  thyroidism,  and  ac- 
romegaly, are  together  responsible  for  but  a  small  fraction  of  the  num- 
ber of  cases  of  mental  disease  due  to  his  deliberate  ingestion  of  one 
poisonous  substance — alcohol. 

It  is  likely  that  alcohol,  as  a  predisposing  or  as  an  immediate 
cause,  is  responsible  for  more  than  a  third  of  all  admissions  to  our 
hospitals  for  the  insane.  When,  however,  we  consider  alcohol  as  a 
cause  in  diseases  in  which  other  etiological  factors  enter,  we  are  upon 
ground  where  statements  must  be  made  with  caution  and  with  many 
qualifications.  Thus  a  man  with  a  considerable  degree  of  congenital 
mental   defect  is   induced  by   some  companions   to   take   a  few   drinks 


302  MISCELLAXEOrS    DISEASES 

of  wliiskey,  and  he  thereupon  develops  an  episode  of  excitement  which 
lasts  several  months.  Alcohol  is  not  the  most  prominent  feature  in 
such  cases,  perhaps,  and  yet  if  it  is  withheld  such  persons  might  never 
develop  acute  mental  symptoms.  In  considering  alcohol  as  a  cause 
of  mental  disease  it  seems  best  to  confine  ourselves  at  first  to  those 
diseases  which,  from  their  symptom-complexes,  we  have  come  to  rec- 
ognize as  the  alcoholic  psyclioses.  In  these  disorders,  acute  alcoholic 
hallucinosis,  chronic  alcoholic  insanity,  and  Korsakow's  disease,  to 
diagnose  the  disease  is  to  know  the  cause,  About  12  per  cent,  of  all 
first  admissions  are  for  these  psychoses. 

They  are  met  in  men  about  three  times  as  frequently  as  in  women, 
and,  as  in  the  case  of  general  paresis,  more  frequently  in  admissions 
from  cities  than  from  the  country,  although  there  is  by  no  means  as 
much  disparity.  These  alcoholic  psychoses  are  the  direct,  unmistak- 
able results  of  intemperance,  acting  in  many  cases  upon  psychopathic 
individuals,  but  it  is  believed  that  in  less  direct  ways  alcohol  is  re- 
sponsible for  nearly  as  large  a  share  of  admissions  to  hospitals  for 
the  insane.  In  the  year  ending  September  30,  1909,  alcohol  was  as- 
signed as  an  etiological  factor  in  31.4  per  cent,  of  the  men  admitted 
to  the  New  York  State  hospitals,  and  in  9.6  per  cent,  of  the  women. 
As  a  habit  disorder,  but  not  a  definite  etiological  factor,  intemper- 
ance was  reported  in  14.3  per  cent,  of  cases  among  male  admissions 
and  6.1  per  cent,  among  female  admissions.  So  45.7  per  cent,  of  all 
the  men  admitted  and  15.7  per  cent,  of  all  the  women  admitted  were 
addicted  to  the  excessive  use  of  alcohol.  This  is  a  prevalence  of  intem- 
perance enormously  greater  than  in  the  general  population,  but  it 
must  be  remembered  that  not  a  few  patients  admitted  to  institutions 
for  the  insane  had  become  intemperate  as  a  result  of  mental  disease,  and 
a  great  number,  including  those  with  alcoholic  psychoses,  as  a  result  of 
constitutional  mental  inferiority.  The  idea  is  spreading  among  psychi- 
atrists that,  iti  a  world  of  drinkers,  the  alcoholic  is  an  abnormal  type. 
This  fact  does  not  in  any  way  lessen  the  importance  of  alcohol  as  a 
cause  of  mental  disease,  but  it  shows  the  great  necessity  of  throwing 
especial  safeguards  about  unstable  persons  in  whom  intemperance  may 
lead  to  such  disastrous  results. 

There  is  hardly  a  mental  disease  which  is  not  influenced  unfavor- 
ably by  alcoholic  habits.  They  lend  a  tremendous  impetus  to  the  retro- 
gressive changes  in  senility,  and,  as  has  been  said,  the  acquisition  of 
alcoholism  by  defectives  often  results  in  acute  mental  symptoms  when 
none  need  have  occurred.  Statistics  collected  independently  by  several 
investigators  show  that  the  parents  of  nearly  50  per  cent,  of  defective 
children  were  alcoholics.  It  is  held  by  many  psychiatrists  that  no  other 
single  cause  of  imbecility  and  idiocy  except  mental  defectiveness  in  the 
parent  can  compare  with  alcoholism  in  the  parents,  intemperance  of 


MENTAL    DISEASES  303 

mothers  during  pregnancy  being  thought  to  be  particularly  likely  to 
result  in  mental  defect  in  the  offspring.^ 

The  prevention  of  mental  diseases  due  to  alcohol,  like  the  preven- 
tion of  those  due  to '  syphilis,  is  only  part  of  the  general  movement 
against  these  enemies  of  the  race.  Excluding  poverty  and  crime,  there 
is  probably  no  more  disastrous  result  of  alcoholism  than  the  continual 
procession  of  unfortunates  who  are  entering  hospitals  for  the  insane 
because  of  intemperance,  and  it  is  certain  that  no  other  fatal  termina- 
tion of  syphilis  is  so  frequent  as  general  paresis. 

Other  Exogenous  Poisons. — Morphinism  and  other  drug  addictions 
are  responsible  for  less  than  one  per  cent,  of  first  admissions  to  hos- 
pitals for  the  insane  in  this  country.  Fewer  such  patients  are  ad- 
mitted in  ISTew  York  and  Massachusetts  now  than  were  a  few  years 
ago.  This  gratifying  fact  is  due,  in  part  at  least,  to  stricter  enforce- 
ment of  the  laws  regulating  the  sale  of  narcotics  and  particularly  to 
the  pure  food  laws  which  have  rendered  it  a  little  more  difficult  to 
dispense  habit-forming  drugs  in  patent  medicines.  It  is  well  within 
our  power  to  eliminate  this  cause  of  mental  disease  by  wise  legislation 
and  its  rigid  enforcement. 

A  very  small  proportion  of'  admissions  is  caused  by  occupational 
poisonings,  such  as  lead  and  carbon  monoxid.  This  small  proportion  can 
be  still  further  reduced  by  increasing  attention  to  measures  safeguard- 
ing workmen  in  dangerous  trades. 

Endogenous  Poisons. — Those  poisons  originating  within  the  system 
which  produce  mental  disease  are  for  the  most  part  the  result  of  other 
diseases,  and  these  diseases — nephritis,  heart  diseases,  and  diabetes — 
are,  unfortunately,  beyond  the  reach  of  preventive  medicine.  When 
the  infectious  diseases  have  come  under  our  control,  and  when  means 
have  been  devised  to  reduce  accidents  to  a  minimum,  the  preeminence 
of  these  diseases  as  causes  of  death  will  only  be  accentuated. 

In  the  case  of  psychoses  dependent  upon  diseases  of  the  thyroid 
gland,  early  treatment  of  the  primary  disease  is  a  hopeful  means  of 
prevention.  It  is  curious  that  vaccines  and  sera  should  be  furnished 
free  by  the  state  while  any  person  can  remain  mentally  defective  from 
cretinism,  because  prolonged  treatment  is  too  expensive.  The  state 
has  such  an   enormous  number  of  the  insane   and  mentally  defective 

^  It  should  be  said  that  recent  studies  by  the  Francis  Galton  Laboratory 
of  Eugenics,  London,  point  to  directly  opposite  conclusions.  The  weight  of 
evidence,  however,  is  in  favor  of  the  relation  between  alcoholism  and  mental 
defect  indicated  above.  Bezzola  and  Hartmann  state  that  examinations  of  the 
birth-dates  of  idiots  and  imbeciles  in  Switzerland  show  that  conception  recurred 
in  a  large  proportion  of  cases  at  seasons  of  the  year  when  the  celebration  of 
certain  festivals  were  accompanied  by  much  intoxication.  It  is  said  that  this  is 
popularly  recognized  and  that  such  children  are  known  in  certain  districts  as 
rauscJcinder  ("jag-children")-  On  the  other  hand,  the  birth-dates  of  defective 
children  in  certain  fishing  villages  in  Northern  Europe  where  there  is  much  peri- 
odic  intoxication  have   been   carefully   studied    a,nd   no    such   relation    discovered. 


304  MISCELLANEOUS    DISEASES 

for  whom  permanent  care  must  be  provided  that  it  would  be  a  matter 
of  sound  policy  to  seek  out  such  cases  and  then  provide  the  best  care 
and  treatment  absolutely  without  cost. 

HEAD    INJUEIES    AND    INSANITY 

A  considerable  number  of  the  cases  admitted  to  every  large  public 
institution  present  a  history  of  head  injuries,  usually  with  fractures  of 
the  skull.  There  are  certain  syinptom-coniplexes  especially  frequent  in 
such  cases,  and  so  it  can  be  said  that  injury  of  the  brain  is  a  specific  cause 
of  mental  disease.  Street  accidents,  railroad  accidents,  and  unprotected 
machinery  are  by  far  the  most  frequent  causes  of  head  injuries  in  civil 
life.  It  is  quite  justifiable  to  consider  this  cause  of  insanity  as  pre- 
ventable, for  one  has  only  to  read  the  recent  literature  on  safeguarding 
workmen  in  factories  and  protecting  railway  employees  to  see  that  this 
is  a  field  in  which  much  may  be  done.  Street  accidents  have  been 
practically  eliminated  in  some  cities  by  efficient  police  regulation  of 
traffic.  In  a  consideration  of  the  prevention  of  insanity  this  phase  is 
not  sufficiently  important  to  receive  much  space,  and  yet  it  seems  de- 
sirable to  mention  it. 

HEREDITY    AND    INSANITY 

It  is  probably  safe  to  say  that  none  of  the  causes  of  insanity  which 
have  been  considered,  unless  it  be  alcohol,  is  as  important  a  factor  as 
heredity,  and  heredity  enters  largely  into  the  production  of  alcoholism, 
or,  at  least,  into  the  production  of  the  mental  type  wliich  succumbs  to 
alcohol.  Opinion  as  to  the  influence  of  heredity  upon  the  development 
of  mental  disease  has  undergone  much  change  in  recent  years,  as  it  has  in 
reference  to  other  diseases,  but  it  can  be  said  that  studies  which  have 
led  to  heredity  being  considered  of  secondary  importance  in  some  con- 
ditions in  which  it  was  thought  to  be  paramount  have  been  offset  by 
studies  in  other  directions  which  have  disclosed  heredity  as  a  factor  of 
the  greatest  importance.  Studies  are  actively  under  way  to  determine 
the  relation  of  Mendel's  laws  to  heredity  in  insanity.  In  large  series 
of  admissions  for  all  forms  of  mental  disease  in  this  country  and  in 
Europe  it  has  been  found  that,  in  the  cases  in  which  a  satisfactory 
history  was  obtainable,  about  50  per  cent,  of  the  patients  had  an  insane 
heredity.  There  are  no  statistics  available  in  this  country  to  show  the 
proportion  of  normal  people  with  an  insane  heredity,  but  Kraepelin 
quotes  Jost  as  giving  the  percentage  as  3  and  Nacke  as  giving  it  as  7.5. 
There  are  some  mental  diseases  in  which  the  percentage  of  insane 
heredity  is  only  slightly  more  than  this,  while  in  manic-depressive  insan- 
ity the  percentage  has  been  found  in  a  large  series  of  cases  to  be  as  high 
as  70,  many  of  the  insane  ancestors  having  other  forms  of  mental  disease. 


MENTAL    DISEASES  305 

This  shows  very  interestingly  the  unity  of  some  of  the  factors  which 
underlie  mental  diseases  of  different  types. 

Without  discussing  the  influence  of  heredity  further,  some  possihle 
means  of  prevention  may  be  considered.  This  is  the  domain  of  eugenics. 
The  means  suggested  all  have  for  their  object  either  the  permanent 
sequestration  of  the  insane  and  mentally  defective  or  the  prevention 
of  offspring  by  control  of  marriage  or  by  sterilization.  It  has  been 
proposed  by  some  that  it  should  be  required  by  law  that  no  woman  in 
the  child-bearing  period  who  secures  admission  to  a  hospital  for  the 
insane  for  a  psychosis  in  which  heredity  is  known  to  play  a  prominent 
part  should  be  discharged,  even  if  recovered,  until  the  menopause  has 
been  reached,  and  it  is  asserted  that  the  welfare  of  the  race  justifies 
such  a  procedure.  It  cannot  be  denied  that  such  a  course  might  in  time 
effect  some  reduction  in  the  prevalence  of  mental  diseases.  It  would 
seem  that  society  can  find  justification  for  adopting  some  such  measures 
to  protect  itself  in  those  cases  in  which  every  period  of  parole  or  dis- 
charge from  a  hospital  is  followed  by  a  pregnancy,  but  the  ethical  con- 
siderations involved  are  so  complex  that  it  is  sufficient  here  merely  to 
state  this  proposal.  It  has  been  proposed  to  sterilize  by  vasectomy  or 
other  means  all  patients  when  they  are  about  to  be  discharged  from  a 
hospital  for  the  insane,  if  their  mental  disease  was  of  a  type  in  which 
heredity  is  prominent.  Here  again  there  are  complex  ethical  questions 
to  be  considered,  but,  as  an  alternative,  it  may  be  suggested  that  all 
such  patients  should  at  least  he  offered  the  opportunity  of  providing 
against  such  an  occurrence.  It  is  believed  that,  if  the  matter  were 
tactfully  and  earnestly  presented,  the  freedom  from  danger  pointed 
out,  or  even  a  small  bounty  paid  by  the  state  in  suitable  cases,  there 
would  be  a  considerable  number  of  acceptances. 

Prohibiting  the  marriage  of  those  in  whom  insane  heredity  within 
a  close  degree  of  relationship  exists  would  depend  for  its  effectiveness 
upon  the  provisions  for  obtaining  such  information  and  any  such  meas- 
ure would  be  practically  without  value  unless  it  were  required  in  a 
number  of  states.  Education  as  to  the  dangers  of  heredity  and  appeal 
to  social  conscience,  by  physicians,  teachers,  and  clergymen,  would  un- 
doubtedly deter  a  few  from  marriage,  but  it  is  the  experience  of  physi- 
cians generally  that  such  advice  is  rarely  heeded.  Before  the  matter 
can  be  presented  in  a  "campaign  of  education"  there  is  need  for  far 
better  information  than  we  possess  at  present.  Facts  should  be  most 
carefully  sifted  and  statistical  studies  of  broad  scope  undertaken  under 
the  auspices  of  the  government  or  some  national  society  before  infor- 
mation regarding  heredity  and  insanity  is  prepared  for  wide  dissemina- 
tion. 


306  MISCELLANEOUS    DISEASES 

PSYCHICAL    CAUSES 

During  the  last  few  years  the  psychical  causes  of  insanity  have  been 
recognized  as  of  great  importance,  and  types  of  mental  disease  which 
were  thought  to  be  almost  wholly  dependent  i^pon  the  constitutional 
make-up  of  individuals  have  been  sliown  by  P'reud,  Jung,  Meyer,  Hoch, 
and  others  to  be  dependent  very  largely  upon  errors  of  education,  un- 
suitable environment,  the  acquisition  of  injurious  habits  of  thought, 
and  the  suppression  of  painful  experiences,  usually  in  the  sexual  field, 
which  later  in  life  form  the  basis  for  psychoses.  The  outlook  for  the 
prevention  of  insanity  is  very  hopeful  in  some  of  these  cases  in  the 
individual. 

Emphasis  must  be  placed  upon  the  important  fact  that  the  founda- 
tions of  aberrations  in  wliich  sexual  trends  are  prominent  are  laid  at 
an  extremely  early  age.  It  is  only  very  recently  that  it  has  been  shown 
that  experiences  in  childhood  and  infancy  exercise  a  controlling  influ- 
ence upon  the  sexual  life  of  later  years.  Tlie  practical  application  of 
this  is  not  that  children  are  to  be  brought  up  in  seclusion,  but  that 
there  is  no  higher  duty  of  parents  than  to  establish  such  relations  with 
their  children  that  sex  difficulties  can  be  discussed  and  straightened 
out  before  they  give  rise  to  permanent  moods  or  trends.  Hypocrisy 
and  false  shame  are  not  natural  attributes  of  the  child,  and  when  we 
create  them  we  raise  a  barrier  behind  which  much  damage  may  take 
place  without  our  knowledge.  In  childhood  and  in  adolescence  there 
must  be  established  the  closest  bonds  of  sympathy  and  understanding 
between  parent  and  child.  Wholesome,  frank  communication  and  sen- 
sible consultations  at  that  time  regarding  sex  quandaries  may  save  a 
child  or  young  adult  from  disaster  later  on.  In  the  aberrations  which 
come  with  adolescence  one  can  usually  recognize  the  results  of  early 
mismanagement  in  these  matters,  and  the  urgent  need  for  sound  ad- 
vice and  correct  guidance  needs  no  elaboration. 

In  dispensaries  for  "border-line"'  cases  some  hidden  sexual  trends 
or  other  factors  in  psychogenesis  may  be  discovered,  and  preventive 
measures  prove  successful.  Nothing  could  aid  more  in  the  discovery 
of  such  factors  than  general  appreciation  by  physicians  that  they  may 
exist  and  may  result  in  insanity.  If  there  were  such  general  recogni- 
tion of  the  part  such  factors  play  many  persons  not  insane  would  be 
referred  to  the  psychiatrists  and  more  psychiatric  clinics  would  be 
established. 

ECONOMIC    FACTORS 

Unemployment,  overwork,  congestion  of  population,  child  labor, 
and  the  hundred  economic  causes  which  increase  the  stress  of  living 


MENTAL    DISEASES  307 

for  the  poor  are  factors  in  the  production  of  insanity  which  often  seem 
to  outweigh  all  others.  Weaknesses  in  constitutional  make-up — de- 
fects in  the  armor  of  personality — are  disclosed  under  the  stress  of  such 
conditions  which  would  have  remained  undiscovered  under  happier  cir- 
cumstances. All  that  can  be  said  of  the  prevention  of  such  causes  is 
that  everything  which  makes  for  the  betterment  of  those  upon  whom 
the  stress  of  living  falls  heaviest  will  save  many  from  mental  disease. 
For  the  individual  careful  training,  encouragement,  wise  counsel,  and 
a  little  financial  assistance  in  times  of  especial  need  are  helpful  meas- 
ures. If  the  operation  of  these  powerful  causes  cannot  be  prevented, 
those  who  are  most  likely  to  be  harmed  would,  perhaps,  be  shielded  a 
little  if  the  dangers  which  they  face  were  more  generally  known. 

IMMIGRATION 

No  consideration  of  the  preventable  causes  of  insanity  in  this  coun- 
try would  be  complete  without  reference  to  this  important  element  in 
our  national  life.  It  is  a  question  peculiar  to  the  United  States.  Since 
1820  more  than  28,000,000  immigrants  have  come  to  this  country. 
This  vast  migration  has  no  parallel  in  history.  In  some  states  the 
increment  to  the  population  from  immigration  every  year  exceeds  that 
from  births.  Under  such  conditions  movements  such  as  those  directed 
against  alcohol,  heredity,  or  the  economic  causes  of  insanity  are  feeble 
compared  with  a  thorough  sifting  of  applicants  for  admission  while 
they  are  still  at  our  threshold.  We  have  the  absolutely  unquestioned 
right  to  require  any  reasonable  tests  which  can  be  proposed,  and  yet 
the  present  immigration  law  results  in  the  mental  examination  of  only 
one  in  every  thousand  of  the  million  immigrants  who  seek  admission 
each  year.  There  is  no  provision  whatever  requiring  immigrants  to 
present  certificates  from  responsible  authorities  at  home,  testifying  to 
their  freedom  from  mental  disease.  These  crowds  of  immigrants,  30 
per  cent,  of  the  adults  illiterate  and  less  than  20  per  cent,  with  any 
trade,  are,  practically  without  mental  examination  or  selection,  projected 
into  our  most  congested  centers  of  population,  to  bear,  during  their 
first  year  in  America,  as  severe  stress  as  any  group  of  population  can 
be  called  upon  to  endure.  One  result  is  that  they  flood  our  hospitals 
for  the  insane.  Hundreds  have  to  be  returned  during  the  first  year 
for  mental  disease  due  to  causes  which  existed  before  their  arrival.  In 
the  succeeding  years  the  proportion  rises  and  in  the  next  generation 
and  the  one  succeeding  it  we  shall  reap  the  harvest  for  which  our  pres- 
ent policy  is  sowing  the  seed.  It  can  be  earnestly  asserted,  after  long 
study  of  this  question,  that  no  measures  for  the  prevention  of  insanity 
which  have  yet  been  suggested  can  prove  so  efficacious  as  artificial 
selection  of  accretions   to  our  population,  on  the  vast  scale  which  an 


308  MISCELLANEOUS    DISEASES 

adequate  mental  examination  of  immigrants  would  permit.  This  is  a 
measure  of  practical  eugenics  which  can  be  applied  as  successfully  now 
as  in  a  generation.  As  Professor  R.  DeC.  Ward  has  said,  "it  is  merely 
a  question  whether  we  or  foreign  steamship  agents  shall  select  the 
parents  of  future  generations  of  Americans."  The  provisions  of  the 
federal  immigration  law  which  deal  with  the  exclusion  of  insane  immi- 
grants are  in  need  of  thorough  and  immediate  revision,  and  the  enforce- 
ment of  the  law  should  receive  the  attention  which  its  importance 
deserves. 

We  have  been  far  too  careless  of  the  welfare  of  recently  landed 
immigrants.  There  seems  to  be  a  general  impression  that,  however 
unsanitary  their  surroundings  or  however  heavy  may  be  the  burdens 
placed  upon  them,  immigrants  are,  in  some  way,  fitted  for  such  hard- 
ships, either  by  nature  or  through  previous  experiences  in  their  homes. 
Of  course,  this  assumption  is  wholly  without  justification,  and  it  is 
time  that  the  social,  economic,  physical,  and  moral  welfare  of  these 
newcomers  be  given  the  earnest  attention  of  the  federal  and  state  gov- 
ernments and  of  societies  and  individuals.  By  so  doing  something 
may  be  done  to  lessen  the  terrible  prevalence  of  mental  disease  in  this 
large  group  of  our  population. 

THE    AGENCIES    AVAILABLE    FOR    THE    APPLICATION    OF 
PREVENTIVE    MEASURES 

It  is  possible  to  outline  only  very  briefly  the  agencies  which  can 
be  utilized  in  the  application  of  preventive  measures. 

Hospitals  for  the  Insane. — A  very  large  proportion  of  the  insane 
persons  in  any  state  will  be  found  under  treatment  in  public  institu- 
tions. This  is  not  the  case  with  other  diseases,  sufferers  from  which 
are  widely  scattered,  in  their  homes,  at  work,  and  in  hospitals.  This 
fact  makes  the  hospital  for  the  insane  seem  the  logical  place  from 
which  preventive  measures  should  emanate. 

Every  large  hospital  for  the  insane,  unless  entirely  inaccessible, 
should  maintain  a  dispensarv'.  To  that  dispensary,  if  it  is  skillfully 
conducted  with  its  broadest  aims  constantly  in  mind,  will  come  in- 
cipient cases,  "border-land''  cases,  those  who  have  had  previous  attacks 
of  mental  disease,  and  relatives  seeking  advice.  Such  dispensaries — 
and  several  have  already  been  instituted — afford  rich  opportunities  for 
the  practical  application  of  preventive  measures  and  for  the  dissemina- 
tion of  information.  Members  of  the  hospital  staffs  should  also  engage 
in  field  work  in  the  districts  from  which  their  hospital  receives  its  pa- 
tients. Talks  on  the  preventable  causes  of  mental  disease,  the  advan- 
tages of  earlier  treatment,  and  the  necessity  of  considering  insanity  as 
a  disease  and  not  a  crime  can  be  given  by  such  medical  field  workers  in 


MENTAL    DISEASES  309 

schools  and  churches  and  before  clubs  and  societies.  Such  talks  should 
be  supplemented  by  illustrated  descriptions  of  modern  methods  of  caring 
for  the  insane  and  promoting  their  happiness  and  comfort.  It  is 
usual  for  citizens  to  haA'e  a  local  pride  in  their  hospital  as  a  public 
institution,  and  this  will  often  insure  interest.  Every  such  lecturer 
■vrill  be  quite  sure  to  have  the  relatives  or  friends  of  some  of  his  patients 
among  his  hearers.  Such  field  work  by  physicians  should  be  supple- 
mented by  that  of  well-trained  social  service  workers  permanently  at- 
tached to  the  institution. 

The  hospital  should  also  be  the  center  for  instruction  in  clinical 
psychiatry  in  the  community.  The  great  wealth  of  clinical  material 
in  a  large  hospital  for  insane  should  be  utilized  to  the  fullest  extent 
if  a  medical  school  is  near  enough,  but  it  is  believed  that  better  knowl- 
edge of  mental  diseases  in  this  country  will  be  brought  about  much 
more  effectively  by  developing  the  opportunities  of  the  general  practi- 
tioner for  receiving  instruction  than  by  increasing  very  greatly  the 
time  devoted  to  psychiatry  in  medical  schools.  The  medical  student 
is  often  overburdened,  and  he  has  much  difficulty  in  deciding  upon  the 
relative  value  of  the  matters  presented  to  him.  In  competition  with 
other  branches  of  medicine  psychiatry  is  very  apt  to  fare  badly,  for  it 
is  likely  to  be  regarded  as  a  specialty  of  slight  value  or  interest  to  one 
who  is  about  to  engage  in  general  practice.  With  the  practitioner  it 
is  different,  for  he  is  a  dull  man  who  does  not  learn  early  in  his  career 
that  mental  diseases  are  frequently  met  with  and  are  very  important 
in  many  of  their  relations.  It  is  a  fact  that  there  is  no  opportunity 
in  the  United  States  for  a  graduate  in  medicine  to  obtain  post-graduate 
instruction  in  psychiatry  unless  he  is  a  member  of  the  staff  of  an  in- 
stitution for  the  insane  or  a  medical  officer  of  one  of  the  government 
medical  corps. 

The  hospital  for  the  insane  has  many  opportunities  for  instructing 
general  practitioners.  Frequent  medical  meetings  at  the  hospitals,  in 
which  clinical  talks  should  have  chief  place,  correspondence  with  physi- 
cians who  sign  commitment  papers  regarding  interesting  features  or 
the  course  of  their  cases,  invitations  to  necropsies  (which  in  most  small 
communities  will  be  gladly  accepted),  and  consultations  when  patients 
are  about  to  be  discharged,  at  which  suggestions  for  after-care  can  be 
made,  are  all  means  of  interesting  physicians  in  mental  diseases  and 
their  prevention.  All  these  new  tasks,  which  are  certain  to  be  assigned 
to  our  hospitals  for  the  insane  within  a  few  years,  will  necessitate  ad- 
ditional medical  officers,  and  they  make  it  more  necessary  than  ever 
that  clinical  and  laboratory  work  in  these  institutions  should  be  upon 
a  high  plane.  This  means  increased  appropriations,  but  it  is  doubtful 
if  a  state  can  utilize  its  funds  for  a  better  purpose  than  in  fostering 
the  work  of  prevention  in  mental  diseases.  Placed  upon  a  purely  eco- 
22 


SlO  MISCELLANEOUS    DISEASES 

nomic  basis,  such  work  is  immensely  profitable.  It  has  been  estimated 
that  prevention  of  the  admission  of  a  single  patient  each  year  would 
yield  a  return  to  a  state  larger  than  the  pay  and  exj)enses  of  two  social 
service  field-workers  for  a  year. 

The  hospital  has  also  excellent  opportunities  for  disseminating  in- 
formation among  the  laity  regarding  the  cause  and  prevention  of  in- 
sanity. Leaflets,  personal  talks,  and  general  literature  regarding  these 
subjects  will  not  fail  to  interest  those  who  have  come  to  the  hospital 
to  visit  a  near  relative. 

Central  Boards  of  Control. — In  most  states  the  administration  of 
hospitals  for  the  insane  is  in  some  measure  under  the  control  of  a  cen- 
tral board.  Such  bodies  can  do  much  in  the  prevention  of  insanity. 
In  many  states  they  can  require  such  activities  on  the  part  of  the  hos- 
pitals as  have  been  outlined,  and  in  others  they  can  exert  powerful 
moral  influence  in  having  them  undertaken.  They  can  conduct  statis- 
tical studies  as  to  the  preventable  causes  of  insanity,  and  secure  wide 
distribution  of  the  material  collected.  They  can  suggest  and  urge  legis- 
lation for  the  early  treatment  of  the  insane  and  for  the  adoption  of 
specific  preventive  measures.  They  can,  particularly  by  cooperation 
with  similar  authorities  in  other  states,  secure  some  reforms. in  federal 
legislation  regarding  the  exclusion  of  insane  and  mentally  defective 
immigrants,  the  urgent  need  for  which  ha?  been  pointed  out. 

National  and  Local  Societies  for  Mental  Hygiene. — Tliere  is  a  very 
clearly  defined  field  of  effort  for  national  and  local  societies  in  the 
work  of  prevention  of  mental  diseases.  As  has  been  indicated,  the  care 
of  the  insane  is,  far  more  than  that  of  any  other  class  of  the  sick,  in 
official  hands.  There  is  besides  a  great  deal  in  the  methods  of  com- 
mitment and  provisions  for  care,  which  is  regarded  wholly  as  an  offi- 
cial matter.  For  this  reason  there  is  decided  need  of  agencies  which 
can  bridge  the  gap  between  tiie  home  and  usual  environment  of  the 
patient  and  the  public  institution  which  is  charged  witli  his  care.  A 
certain  part  of  the  social  service  work  which  has  so  useful  a  place 
in  the  care  of  the  insane,  particularly  in  the  period  following  discharge 
from  institutions,  should  be  done  by  workers  under  the  direction  of 
institutional  authorities,  but  there  is  also  a  very  great  deal  which  can 
be  done  better  by  societies  cooperating  with  institutional  authorities 
but  not  officially  connected  with  them.  In  New  York  State  the  "Com- 
mittee on  Mental  Hygiene"  of  the  State  Charities'  Aid  Association 
has  a  local  committee  in  each  hospital  district.  Although  after-care 
and  efforts  to  improve  the  kind  of  care  afforded  the  insane  in  that  criti- 
cal period  while  commitment  is  pending  constitute  the  chief  work  of 
such  committees,  there  is  often  opportunity  for  effective  work  in  pre- 
vention. In  Connecticut,  Illinois,  and  Massachusetts  there  are  state 
societies  of  mental  hygiene  doing  most  useful  work. 


MENTAL    DISEASES  311 

There  is  a  National  Committee  for  Mental  Hygiene,  coordinating 
and,  in  a  measure,  directing  these  local  activities.  This  committee  has 
commenced  studies  into  existing  provisions  for  the  care  of  the  insane 
in  all  the  states,  methods  of  commitment  and  care,  the  influence  of 
preventable  causes,  etc.  With  a  carefully  prepared  plan  of  work,  ac- 
curate information  is  to  be  obtained  upon  these  matters,  and,  as  fast  as 
the  facts  in  the  possession  of  the  committee  justify  it,  active  work  is 
to  be  undertaken  for  amelioration  or  prevention.  It  is  believed  that 
a  great  deal  can  be  done,  especially  in  the  direction  of  standardizing 
work  for  the  care  of  the  insane  and  the  prevention  of  insanity,  and  in  co- 
ordinating the  efforts  of  the  hospitals,  state  boards  of  control,  and  some 
of  those  organizations  which  sometimes,  perhaps  unawares,  are  attack- 
ing preventable  causes  of  insanity  from  different  angles.  Such  an 
organization  as  the  National  Committee  for  Mental  Hygiene  can  stimu- 
late interest  on  the  part  of  the  state  and  local  authorities  charged  with 
the  care  of  the  insane,  and  it  can  sustain  interest  when  it  might  other- 
wise flag.  Standards  established  in  a  state  where  advanced  ideas  prevail 
can  be  made  known  in  states  where  there  is  indifference  or  lack  of  prog- 
ress. A  central  "clearing  house"  for  the  collection  and  distribution  of 
accurate  information  regarding  the  care  of  the  insane  and  the  preven- 
tion of  insanity  can  be  provided.  Earlier  treatment  and  the  transfer  of 
care  pending  commitment  from  the  policeman  to  the  doctor — the  most 
urgent  needs  of  the  insane — can  be  secured  by  this  organization,  and 
the  lamentable  failure  to  provide  instruction  in  mental  diseases  in  the 
medical  schools  can  be  shown,  and  the  means  suggested  for  remedying 
the  defect.  It  is  a  fact  that  the  number  of  beds  in  the  institutions  for 
the  insane  in  this  country  is  greater  than  the  number  of  beds  in  all  the 
general  hospitals  of  the  United  States.  The  insane  are,  therefore,  the 
most  numerous  class  of  the  sick  receiving  public  care.  As  such,  they 
demand  a  large  share  of  the  interest  of  every  practitioner.  Progress  in 
every  branch  of  preventive  medicine  depends  most  upon  the  efforts  of 
physicians,  and  in  this  particular  field  there  is  need  of  much  wider  in- 
terest on  the  part  of  the  medical  profession  than  exists  to-day. 

Education. — Under  the  direction  of  state  boards  of  control  and  en- 
couraged by  national  and  state  societies  for  mental  hygiene,  much  can 
be  done  toward  placing  the  education  of  defective  children  upon  a  bet- 
ter basis.  These  children  are  now  chiefly  interesting  to  school  authori- 
ties, for  they  constitute  a  special  class  and  should  receive  separate  in- 
struction, both  for  their  own  good  and  the  good  of  normal  children, 
whose  progress  is  retarded  on  account  of  the  excessive  amount  of  time 
teachers  must  give  defective  children.  They  should  have  a  far  greater 
interest  for  the  state  than  this,  for  eveiy  such  child  is  a  possible  patient 
in  a  hospital  for  the  insane  or  in  a  colony  for  the  mentally  defective. 
Every  effort  to  prevent  this  outcome  is  justified,   and  it  would  seem 


312  MISCELLANEOUS    DISEASES 

desirable  for  the  state  to  provide  very  liberally  for  the  study  of  these 
children  and  for  their  education.  Of  even  more  importance,  perhaps,  is 
the  permanent  segregation  of  most  of  them. 

It  has  been  estimated  that  in  a  state  which  adopts  a  high  standard 
of  caring  for  the  insane  about  one-fifth  of  the  annual  income  of  the 
state  will  be  required.  Whether  insanity  is  increasing  or  not,  the  num- 
ber of  the  insane  under  treatment  has,  up  to  this  time,  increased  much 
more  rapidly  than  the  general  population.  New  demands  for  charitable 
and  social  purposes  are  constantly  being  made  upon  state  funds,  but 
it  would  seem  that  any  measures  for  the  prevention  of  insanity  which 
offer  hopes  of  success  should  receive  the  substantial  financial  support 
of  the  state. 

The  attempt  has  been  made  to  outline  some  of  the  preventable 
causes  of  mental  disease  and  to  indicate,  very  broadly,  possible  pre- 
ventive measures.  It  seems  essential  that,  notwithstanding  the  com- 
plexity of  some  of  the  questions  involved,  the  prevention  of  mental 
diseases  should  be  considered  in  the  general  advance  which  is  being 
made  against  microbic  diseases,  for  it  is  very  closely  related  to  all  the 
other  fields  of  preventive  medicine.  Recent  advances  in  the  field  of 
psychiatry  have,  upon  the  whole,  given  grounds  for  encouragement,  for 
if  the  outlook  in  some  directions  is  not  bright  the  accuracy  with  which 
the  part  played  by  certain  causes  has  been  defined  promises  much.  The 
fact  that  it  has  been  definitely  determined  that  there  are  certain  essen- 
tial causes  of  mental  disease,  and  that  some  of  these  essential  causes 
are  entirely  controllable,  makes  it  imperative  that  preventive  measures 
be  undertaken. 


CHAPTEE   VI 
SOME  GENERAL  CONSIDERATIONS 

Sources  of  Infection. — There  are  two  great  sources  of  the  commu- 
nicable diseases  of  man,  viz.:  (1)  man  himself,  and  (2)  the  lower 
animals.  Most  of  the  communicable  diseases  of  man,  especially  those 
which  occur  in  epidemic  form,  are  peculiar  to  man.  This  is  the  case 
with  typhoid  fever,  cholera,  leprosy,  malaria,  yellow  fever,  syphilis, 
mumps,  measles,  scarlet  fever,  typhus  fever,  infantile  paralysis,  small- 
pox, chickenpox,  relapsing  fever,  dengue,  and  even  tuberculosis  in  large 
part.  It  is  quite  true  that  some  of  these  infections  may  be  communi- 
cated to  the  lower  animals  under  experimental  conditions,  but  they  do 
not,  as  a  rule,  occur  in  them  under  natural  conditions.  In  other  words, 
most  of  the  communicable  diseases  from  which  man  suffers  are  specific ; 
the  degree  of  specificity  varying  slightly  with  the  different  infections. 

It  is,  therefore,  plain  that  man  is  the  great  source  and  reservoir  of 
human  infections.  Man  is  man's  greatest  foe  in  this  regard.  The  fact 
that  most  of  the  communicable  diseases  must  be  fought  in  the  light 
of  an  infection  spread  from  man  to  man  is  one  of  the  most  important 
advances  in  preventive  medicine.  This  new  thought  has  crystallized 
out  of  a  mass  of  work  in  the  sanitary  sciences  during  the  past  decade, 
especially  from  researches  upon  tuberculosis,  typhoid  fever,  cerebro- 
spinal meningitis,  and  other  communicable  diseases.  Formerly  sani- 
tarians regarded  the  environment  as  the  main  source  of  infection.  We 
now  know  that  water,  soil,  air,  and  food  may  be  the  vehicles  by  which 
the  viruses  of  the  communicable  diseases  are  sometimes  transferred — 
that  is,  they  are  media  of  conveyance  rather  than  sources  of  infection. 
Most  of  the  microorganisms  causing  the  communicable  diseases  of  man 
are  frail  and  soon  die  in  our  environment,  as  in  the  air,  soil,  or  water. 
Most  of  them  are  obligate  pathogens  and  cannot  or  do  not  grow  or 
multiply  in  our  environment. 

From  the  lower  animals,  particularly  the  domesticated  animals,  man 
contracts  a  number  of  infections.  Thus  we  contract  rabies  from  the 
dog;  plague  from  the  rat;  glanders  from  the  horse;  trichinosis  from 
hogs ;  anthrax  from  cattle ;  malta  fever  from  goats ;  foot-and-mouth  dis- 
ease from  cattle;  tuberculosis,  in  part,  from  cattle;  tapeworms  and 
other  animal  parasites  from  the  meat  of  fish,  fowl,  and  mammals.  Vari- 
ous skin  parasites  are  also  contracted  from  the  lower  animals,  as  ring- 

313 


314  SOME    GENERAL    COXSIDEKATIOXS 

worm  from  cats,  fleas  from  dogs,  etc.  The  number  of  these  diseases 
and  the  extent  of  their  ravages  are  notably  less  than  those  contracted 
from  man  himself. 

The  knowledge  that  most  infections  are  spread  rather  directly  from 
man  to  man  brings  in  all  the  forces  of  sociology  to  that  of  preventive 
medicine.  The  task  of  preventive  medicine  is  thereby  rendered  much 
more  difficult  from  the  fact  that  most  infections  depend  upon  the  con- 
trol of  man  himself.  We  ruthlessly  wage  war  against  insects  or  against 
infected  food  or  water.  In  other  words,  we  can  arbitrarily  control  our 
environment  to  a  very  great  extent,  but  the  control  of  man  himself 
requires  the  consent  of  the  governed.  Thus  it  is  easier  to  stamp  out 
yellow  fever  than  to  control  typhoid  fever.  Tt  is  easier  to  suppress 
malaria  than  tuberculosis,  rabies  than  influenza,  trichinosis  than  measles. 
Cattle  appear  to  be  mutely  thankful  when  protected  by  inoculation 
against  blackleg  or  anthrax,  but  man  rebels  against  one  of  the  best 
of  all  specifics — vaccination  against  smallpox.  The  fact  that  man  is 
the  chief  source  and  reservoir  of  most  of  his  own  infections  adds  greatly 
to  the  scope  and  difficulties  of  public  health  work  and  often  makes  the 
prevention  of  disease  depend  upon  social  changes.  In  this  sense  pre- 
ventive medicine  is  the  true  sociology. 

Modes  of  Transference. — The  viruses  of  the  communicable  diseases 
may  take  various  routes  of  transference  from  man  to  man  or  from 
animal  to  man.  These  routes  are  spoken  of  as  the  modes  of  infection, 
the  modes  of  transference,  or  sometimes  as  the  vehicles  of  infection. 
Formerly  they  were  spoken  of  as  the  "channels  of  infection,"  but  now 
we  restrict  that  term  to  the  special  channels  by  which  the  infection 
enters  the  body.  Thus  the  channel  of  infection  in  tuberculosis  may  be 
the  respiratory  tract,  the  digestive  system,  or  the  skin;  whereas  the 
mode  of  infection  is  from  tuberculous  sputum,  either  by  direct  contact 
or  through  the  air.  as  in  droplet  infection,  or  through  milk  or  some 
other  vehicle. 

The  modes  of  transference  may  be  grouped,  for  convenience,  under 
three  general  heads:  (1)  direct,  (2)  indirect,  and  (3)  through  an  in- 
terrnediate  host.  In  the  great  majority  of  cases  the  virus  is  transferred 
more  or  less  directly  by  what  is  now  known  as  contact  infection.  In 
many  instances  the  virus  is  transferred  indirectly  through  water,  food, 
soil,  air,  etc.  In  a  large  group  of  diseases  the  transfer  is  through  an 
intermediate  host  which  furnishes  the  growing  list  of  insect-borne  dis- 
eases. 

CoxTACT  Infection. — "Contact  infection"  is  a  convenient  term  in- 
tended to  include  a  group  of  circumstances  in  which  infection  is  spread 
more  or  less  directly  or  indirectly  from  person  to  person.  Contact  in- 
fection assumes  a  transfer  of  quite  fresh  infective  material.  Actual 
contact  between  the  two  individuals  is  not  necessary,  but  the  convey- 


CAEEIEES  315 

ance  is,  nevertheless,  pretty  close  in  time  and  space.  Contact  infection 
alone  may  be  responsible  for  epidemic  outbreaks,  even  in  the  case  of 
typhoid  fever. 

The  diseases  in  which  contact  infection  plays  a  dominant  role  are 
those  in  which  the  virus  leaves  the  body  in  the  discharges  from  the 
mouth  and  nose,  as  tuberculosis,  diphtheria,  scarlet  fever,  measles,  in- 
fluenza, common  colds,  cerebrospinal  meningitis,  whooping-cough, 
mumps,  etc.  Contact  infection  also  pays  a  large  role  in  diseases  in  which 
the  virus  leaves  the  body  in  the  fecal  and  urinary  discharges,  as  in 
typhoid,  cholera,  dysenter}^,  and  other  intestinal  infections. 

In  contact  infection  the  virus  may  be  transferred  from  man  to  man 
directly  by  actual  contact,  as  in  kissing,  or  more  indirectly  upon  soiled 
hands,  contaminated  towels,  or  infected  cups,  spoons,  toys,  remnants 
of  food,  and  other  objects  which  have  recently  been  mouthed  or  handled 
by  the  infected  person.  As  a  matter  of  fact,  the  ways  by  which  the 
infection  may  be  transferred,  and  still  be  considered  contact  infection, 
are  numerous  and  varied.  In  every  instance,  however,  the  transfer  is 
brought  about  in  pretty  close  association  with  the  infected  person. 

IxDiEECT  IxFECTiox. — A  large  group  of  diseases  are  conve^-ed  in- 
directly from  persoq  to  person  through  the  water,  food,  soil,  and  occa- 
sionally through  the  air.  Diseases  may  be  conveyed  great  distances 
by  means  of  food  or  water;  they  are  never  conveyed  long  distances 
through  the  air.  In  the  large  majority  of  the  diseases  contracted  by 
indirect  infection  the  virus  is  taken  into  the  system  through  the  mouth 
and  discharged  from  the  body  in  the  feces.  The  best  examples  of 
this  class  are  typhoid  fever,  cholera,  and  dysentery.  The  relation  of 
soil,  food,  water,  air,  and  our  environment  is  discussed  separately. 

The  insect-borne  diseases  form  a  large  and  important  group,  which 
are  fully  discussed  on  pages  181  to  271. 

Carriers. — By  the  term  "carrier"  we  understand  a  person  who  is 
harboring  a  pathogenic  microorganism,  but  who,  nevertheless,  shows  no 
signs  or  symptoms  of  the  disease.  Thus  a  person  may  have  diphtheria 
bacilli  in  the  nose  and  throat,  but,  nevertheless,  be  in  good  health. 
The  same  is  true  with  the  pneumococcus,  the  meningococcus,  strepto- 
coccus, and  many  other  microorganisms.  Persons  may  have  typhoid 
bacilli,  cholera  vibrio,  or  hookworm  in  their  intestinal  tract  without 
showing  manifestations  of  these  parasites.  Furthermore,  persons  may 
have  Plasmodia  in  their  blood  or  spleen  without  having  clinical  malaria, 
and  so  on  through  a  long  list  of  infections. 

Persons  who  harbor  pathogenic  bacteria  without  showing  symptoms 
are  known  as  "'bacillus  carriers,"  those  who  harbor  protozoa  are  known 
as  "protozoon  carriers,"'  etc.  Carriers  may  be  acute,  chronic,  or  "tem- 
porary"— that  is,  a  person  who  discharges  pathogenic  microorganisms 
a  few  weeks  after  convalescence  is  known  as  an  "acute  carrier,"  one  who 


31fi  SOME    GENERAL   CONSIDERATIOXS 

continues  to  harbor  the  microorganism  for  months  and  years  is  known 
as  a  "chronic  carrier."  A  "temporary  carrier"  is  a  person  in  good 
liealth  who  has  never  had  (lie  infection,  l)ut  who  harbors  and  discharges 
a  patliogenic  microorganism  for  a  brief  sjjace  of  time. 

The  demonstration  that  many  persons  are  carriers  of  infection  lias 
thrown  a  new  light  upon  the  control  of  the  communicable  diseases. 
With  the  new  facts  has  come  a  realization  of  added  difficulties.  Carriers 
can  only  be  detected  by  painstaking  laboratory  examinations.  When 
discovered  their  control  is  as  difficult  as  it  is  important.  We  cannot 
lightly  imprison  persons  in  good  health,  even  though  they  are  a  menace 
to  others,  especially  in  the  case  of  bread  winners.  In  some  infections 
there  are  so  many  carriers  that  it  would  require  military  rule  to  carry 
out  such  a  plan.  Fortunately  in  most  cases  absolute  quarantine  is  not 
necessary.  Sanitary  isolation  is  sufficient.  Thus  the  danger  from  a 
typhoid  carrier  may  be  neutralized  if  the  person  exercises  scrupulous 
and  intelligent  cleanliness,  and  is  not  allowed  to  handle  food  intended 
for  others.  Such  a  person  might  well  be  engaged  as  carpenter,  seam- 
stress, or  other  occupation  without  endangering  his  fellowmen. 

The  fact  that  carriers  exist  in  a  large  number  of  diseases  makes 
their  suppression  one  of  great  practical  difficulty.  The  cure  of  carriers 
is  one  of  the  pressing  problems  in  preventive  medicine.  One  hopeful 
feature  of  the  carrier  situation  is  that  their  number  may  be  diminished 
by  isolating  and  diminishing  the  cases  of  the  corresponding  disease. 
Thus,  the  number  of  typhoid  carriers  falls  off  sharply  as  a  result  of  any 
successful  measure  directed  only  against  the  clinical  case.  The  facts  con- 
cerning carriers  have  been  discussed  separately  under  each  disease  in 
which  they  occur. 

Missed  Cases. — By  missed  cases  we  understand  mild  and  atypical 
instances  of  disease  which  are  not  recognized  clinically.  Almost  all 
diseases  vary  greatly  in  severity.  Thus  we  have  walking  typhoid  and 
ambulant  plague.  Measles,  scarlet  fever,  yellow  fever,  influenza,  and 
most  other  infections  may  be  so  mild  that  they  escape  notice.  Even  the 
patient  himself  may  not  know  he  is  sick.  These  mild  cases  go  to  school, 
ride  in  street  cars,  attend  theaters,  continue  at  their  usual  work  in 
crowded  factories  and  other  places,  handle  our  food,  and  thus  spread 
infection.  It  is  now  well  known  that  missed  cases  are  a  prolific  source 
of  spreading  the  infection  of  many  of  the  communicable  diseases;  they 
form  an  important  factor  in  preventive  medicine. 

Channels  of  Infection. — There  are  numerous  channels  by  which  in- 
fection may  enter  the  body.  These  are  usually  grouped  under  three 
headings:  (1)  the  respiratory  tract,  (2)  the  digestive  tract,  and  (3) 
through  the  skin.  Perhaps  90  per  cent,  of  all  infections  are  taken  into 
the  body  through  the  mouth.  They  reach  the  mouth  in  water,  food, 
fingers,  dust,   and  upon   the   innumerable   objects   that    are   sometimes 


"CONTAGIOUS"    AND    "INFECTIOUS"  317 

placed  in  the  mouth.  The  fact  that  the  great  majority  of  infections 
are  taken  by  way  of  the  mouth  gives  scientific  direction  to  personal 
hygiene.  Sanitary  habits  demand  that  the  hands  should  be  washed 
before  eating,  and  fingers  should  be  kept  away  from  the  mouth  and 
nose,  and  that  no  unnecessary  objects  should  be  mouthed.  All  food 
and  drink  should  be  clean  or  thoroughly  cooked.  These  simple  pre- 
cautions alone  would  prevent  many  a  case  of  infection. 

"Contagious"  and  "Infectious." — These  are  popular  terms  which 
lack  scientific  precision.  The  words  have  been  used  in  very  diverse 
senses.  A  contagions  disease  is  one  that  is  readily  communicable — - 
in  common  parlance,  "catching."  Formerly  a  contagious  disease  was 
considered  as  one  which  is  caught  from  another  by  contact,  by  the 
breath,  or  by  effluvia.  If  contagious  diseases  are  limited  to  those  con- 
tracted by  direct  contact  or  touch,  as  the  etymology  of  the  word  signifies, 
only  syphilis  and  diseases  similarly  contracted  would  be  contagious. 
As  a  matter  of  fact,  smallpox  and  measles  are  types  of  contagious 
diseases,  as  the  term  is  now  usually  understood. 

An  infectious  disease  is  usually  considered  as  one  not  conveyed 
directly  and  obviously,  as  in  the  case  of  contagion,  but  indirectly  through 
some  hidden  influence  or  medium.  In  the  days  when  specific  febrile 
diseases  Avere  regarded  as  caused  by  miasmata  and  noxious  effluvia,  the 
terms  "infectious"  and  "miasmatic"  diseases  were  more  or  less  synony- 
mous. Typhoid  fever  was  often  taken  as  a  type  of  an  infectious  disease. 
Malaria  was  the  type  of  a  miasmatic  disease. 

These  distinctions  are  entirely  artificial,  and  serve  no  useful  pur- 
pose. Most  of  the  communicable  diseases  may  be  transmitted  from  the 
sick  to  the  sound  in  several  ways.  Dividing  diseases  into  those  which 
are  contagious  and  those  which  are  infectious  entirely  leaves  out  of 
consideration  the  important  class  of  insect-borne  diseases.  The  terms 
contagious  and  infectious  have  always  lacked  scientific  precision  and 
have  been  the  source  of  some  confusion.  The  word  "communicable" 
is  a  much  better  term  and  should  be  given  preference. 

A  communicable  disease  is  one  caused  by  a  specific  virus  transferred 
from  person  to  person,  or  from  animal  to  animal,  in  a  great  variety  of 
ways.  The  term  "communicable"  ignores  the  mode  of  transference. 
There  is  a  great  difference  in  the  degree  of  communicability ;  some 
diseases  are  readily  communicable,  others  transmitted  with  difficulty. 
The  evidences  of  communicability  are  not  so  obvious  in  chronic  infec- 
tions, such  as  tuberculosis,  or  in  diseases  with  a  long  period  of  incuba- 
tion, such  as  typhoid  fever.  The  relationship  between  one  case  and  the 
next  is  often  far  removed  in  time  and  space.  If  tuberculosis  were  an 
acute  infection  like  diphtheria  it  would  be  regarded  popularly  as  being 
just  as  contagious  as  that  disease. 

Epidemic,  Endemic,  Pandemic,  and  Prosodemic. — A  disease   is  said 


318  SOME    GEXEIUL    COXSIDERATIOXS 

to  be  epidemic  (epi=in,  and  demos:=people)  when  it  is  common  to 
or  affecting  at  the  same  time  a  large  number  of  persons  in  a  commu- 
nity. A  disease  which  spreads  rapidly  and  attacks  many  people  at  the 
same  time  is  usually  said  to  be  epidemic. 

A  disease  is  said  to  be  endemic  (em^iii.  demos=people)  when  it 
is  peculiar  to  a  district  or  particular  locality,  or  limited  to  a  class  of 
persons.  An  endemic  disease  is  one  which  is  constantly  present  to  a 
greater  or  less  degree  in  any  place,  as  distinguished  from  an  epidemic 
disease,  which  prevails  widely  at  some  one  time  or  periodically.  A 
sporadic  (occurring  singly)  disease  is  one  in  which  a  lew  scattering 
cases  occur  now  and  then. 

Endemic  diseases  are  apt  to  flare  up  and  become  epidemic.  In- 
sect-borne diseases  are  the  best  examples  of  endemicity,  as  their  preva- 
lence is  strictly  limited  by  the  geographic  distribution  of  the  intennedi- 
ate  host.  Yellow  fever  has  long  been  endemic  in  Havana,  cholera  in 
India,  typhoid  fever  in  Washington,  and  plague  in  Tibet. 

These  terms  not  only  lack  precision,  but  are  variously  conceived 
and  differently  defined.  Thus  typhoid  fever  is  said  to  prevail  in  Bos- 
ton, but  a  similar  number  of  cases  in  Germany  would  be  regarded  as 
an  epidemic.  For  the  purposes  of  maritime  quarantine  a  disease  is 
considered  epidemic  if  there  is  more  than  one  focus  of  infection ;  that  is, 
if  several  cases  occur  which  have  no  apparent  connection  with  each 
other.  Strictly,  therefore,  according  to  this  definition,  two  cases  may 
constitute  an  official  epidemic  and  the  port  would,  therefore,  be  regarded 
as  infected. 

It  is  not  feasible  to  state  just  how  many  cases  of  a  disease  constitute 
an  epidemic.  Ordinarily  a  few  cases  of  a  communicable  disease  in  a 
village  or  small  town  is  not  regarded  as  an  epidemic;  however,  five 
cases  of  typhoid  fever  in  Podunk  (population  1,000)  is  the  equivalent 
of  5,000  cases  in  a  city  of  1,000,000.  By  the  same  token,  one  or  two 
cases  in  a  small  village  would  proportionately  constitute  an  epidemic 
of  unknown  magnitude  in  a  metropolis. 

"Pandemic"  (pan=rall,  demos:=people)  is  a  term  used  to  describe 
a  disease  which  is  more  or  less  epidemic  everywhere.  Pandemics  affect 
a  large  number  of  people  in  a  large  number  of  countries  at  the  same  time. 
Thus  there  have  been  four  great  pandemics  of  plague,  when  it  spread 
to  the  four  quarters  of  the  globe.  In  1889-90  influenza  was  pandemic. 
It  is  not  usual,  although  quite  proper,  to  regard  tuberculosis  and  typhoid 
fever  as  pandemic. 

Sedgwick  proposes  the  term  " prosodemic"  (proso=through,  demos=: 
people)  to  take  the  place  of  the  unsatisfactory  word  "endemic."'  Proso- 
demic suggests  the  prevalence  of  a  disease  which  is  being  communicated 
from  person  to  person  through  the  community  by  various  means,  but 
especially  by  contact. 


EPIDEMIC    CAMPAIGN  319 

The  Management  of  an  Epidemic  Campaign. — The  first  essential 
for  success  in  the  suppression  of  an  epidemic  is  a  knowledge  of  the 
epidemiolog}^  of  the  disease.  The  most  important  single  information 
from  a  practical  standpoint  is  a  knowledge  of  the  mode  of  transference 
of  the  infection.  We  do  not  know  the  cause  of  yellow  fever;  however, 
}-ellow  fever  campaigns  have  been  crowned  with  success  because  we 
know  it  is  transmitted  through  the  bite  of  a  mosquito.  We  know 
the  cause  of  cerebrospinal  meningitis,  but  there  is  still  uncertainty 
concerning  its  usual  mode  of  transmission,  and,  therefore,  our  efforts 
against  this  disease  have  been  unavailing.  The  fact  that  we  know  that 
hookworm  disease  is  transmitted  by  the  larvge  through  the  skin  is  of 
vital  importance  for  the  control  of  this  disease.  Without  this  knowl- 
edge at  least  90  per  cent,  of  our  efforts  to  repress  hookworm  disease 
would  be  wasted.  Wlien  typhoid  fever  was  regarded  as  chiefly  a  water- 
borne  infection  only  partial  success  was  achieved,  because  contacts, 
milk,  flies,  and  other  modes  of  transference  of  the  typhoid  bacillus 
were  disregarded. 

In  case  the  disease  has  an  intermediate  host  or  the  virus  is  trans- 
ferred by  an  insect  or  other  animal,  a  knowledge  of  the  biology  of  the 
animal  in  question  is  of  prime  importance.  For  example,  the  habits 
and  habitat  of  the  yellow  fever  mosquito  are  quite  different  from  that 
of  the  malarial  mosquito.  A  campaign  against  the  rat  and  flea  without 
an  acquaintance  with  their  breeding  and  feeding  places  and  the  best 
means  available  to  repress  or  suppress  such  vermin  would  be  unsuc- 
cessful. The  same  is  true  in  our  campaign  against  tuberculosis  with 
reference  to  cattle  and  man;  in  rabies  with  reference  to  dogs  and  other 
mammals;  in  sleeping  sickness  with  reference  to  the  tsetse  fly;  in 
Texas  fever  with  reference  to  the  tick;  malta  fever  with  reference  to 
the  goat;  relapsing  fever  to  the  bedbug,  and  typhus  fever  with  refer- 
ence to  the  louse. 

Authority. — Proper  authority  is  necessary  in  order  to  enforce  the 
necessary  measures.  This  authority  may  come  from  the  municipality, 
the  state,  or  the  federal  government.  In  localized  outbreaks,  municipal 
authority  is  sometimes  sufficient.  More  frequently  the  wider  authority 
of  the  state  is  desirable.  In  our  country  it  is  a  recognized  principle  in 
law  that  health  laws  and  regulations  belong  to  the  police  powers  of  the 
individual  states.  In  most  instances  the  general  authority  of  the  gov- 
ernment must  be  had,  especially  as  interstate  problems  are  almost  al- 
ways involved  in  all  epidemic  outbreaks.  The  federal  authority  is  lim- 
ited in  health  matters  by  the  constitution.  It  therefore  cannot  act 
within  a  state  unless  invited  to  do  so  by  the  duW  constituted  authori- 
ties of  the  state.  To  send  government  health  officers  into  a  state  against 
the  will  of  the  state  corresponds  to  th.e  sending  of  the  regular  army 
into  a  state  to  enforce  measures  against  the  will  of  the  governor  of 


320  SOME    GENERAL    CONSIDERATIONS 

that  state.  Such  extreme  measures  are,  tlierefore,  only  taken  in  times 
of  emergency.  Occasionally  a  state,  refusing  to  take  necessary  action 
and  protect  the  other  states,  is  (|iiarantined.  Thus,  when  California 
refused  to  officially  recognize  the  existence  of  plague  in  1899,  the 
government  quarantined  the  entire  state.  On  account  of  our 
dual  form  of  government  it  is  important  that  the  federal  govern- 
ment, the  state,  and  the  local  authorities  cooperate  in  a  friendly 
spirit.  Epidemic  diseases  recognize  no  geographical  houndary,  and 
energetic  and  cooperative  action  is  usually  called  for  to  suppress  an 
outbreak. 

It  is  the  common  experience  of  tiiose  wlio  have  to  deal  with  epi- 
demics that  there  is  usually  insufficient  authority  in  law  to  provide  for 
an  emergency.  It  is,  therefore,  often  necessary  to  take  tlie  bit  in  the 
teeth  and  adopt  arbitrary  measures  which  usually  have  the  support  of 
the  better  element  in  the  community.  Advantage  may  be  taken  of  an 
epidemic  to  obtain  laws  to  improve  the  health  organization  or  the  powers 
of  the  health  officer.  In  this  way  an  epidemic  serves  a  useful  purpose 
in  arousing  action. 

In  the  conduct  of  an  epidemic  it  is  very  important  that  all  the 
authority  should  center  in  one  person.  To  conduct  an  epidemic  with  a 
board  of  health  or  a  health  committee  or  a  commission  of  any  kind  in- 
vites failure.  It  would  be  just  as  foolish  to  have  a  board  of  generals  to  . 
fight  a  battle.  Those  who  have  been  through  many  epidemics  realize 
that  it  is  no  figure  of  speech  to  compare  an  epidemic  campaign  to  a 
battle.  It  is  a  fight  carried  on  at  high  tension,  and,  although  the  foe 
is  invisible,  it  is  a  battle  in  every  sense  of  the  word. 

Ways  and  Means. — It  is  impossible  to  carry  on  a  successful  cam- 
paign against  an  epidemic  without  material  resources.  An  epidemic 
campaign  is  expensive  and  success  depends  upon  generous  support.  In 
most  of  the  campaigns  against  yellow  fever,  plague,  and  cholera  that 
have  been  waged  in  this  country  the  expense  has  been  borne  in  part 
by  the  government,  in  part  by  the  municipality  or  state,  and  in  part 
by  subscriptions  from  citizens.  The  government  has  an  epidemic  fund 
appropriated  by  Congress  and  which  is  usually  kept  at  about  a  million 
dollars.  This  fund  is  available  only  for  plague,  yellow  fever,  and 
cholera. 

Organization. — Headquarters  should  be  organized  at  a  convenient 
part  of  the  city  or  the  infected  area,  and  headquarters  should  have  all 
the  modern  office  equipment  and  transportation  facilities  necessary  for 
the  quick  dispatch  of  business.  The  city  is  then  divided  into  sanitary 
districts.  These  may  correspond  to  the  political  wards  or  the  police 
districts  and  a  subordinate  is  placed  in  charge  of  the  work  in  each 
district.  These  districts  are  known  as  divisions,  and  the  officer  in  charge 
of  each  division  must  establish  headquarters  for  the  work  of  that  divi- 


QUARANTINE  3gl 

sion.     The  actual  work  is  done  from  division  headquarters,  under  the 
direction  of  the  chief  in  charge  of  the  epidemic. 

It  is  also  necessary  to  establish  a  laboratory  in  case  laboratory  diag- 
nosis is  necessary  for  the  recognition  of  cases  or  carriers,  and  emergency 
hospitals  and  detention  barracks  must  be  provided.  Few  cities  have  suf- 
ficient hospital  facilities  to  meet  a  sudden  emergency.  Temporary  ar- 
rangements must  therefore  be  made.  A  modern  school  building  makes 
a  very  good  hospital  and  may  be  equipped  for  the  reception  of  patients 
at  short  notice.  Various  squads  must  now  be  organized  to  carry  on 
the  particular  work  at  hand.  In  the  case  of  yellow  fever  these  will 
be  mosquito  brigades;  in  the  case  of  plague,  rat  brigades  and  disin- 
fectors,  and  in  the  case  of  smallpox,  vaccinators,  etc. 

It  is  frequently  desirable,  in  fact  often  necessary,  to  make  a  house 
to  house  inspection  throughout  the  infected  district  in  order  to  collect 
certain  data,  to  determine  whether  cases  are  being  reported  or  hidden, 
and  to  carry  out  special  measures.  These  house  to  house  canvasses  are 
under  the  immediate  direction  of  the  oificer  in  charge  of  the  sanitary 
district  and  should  be  repeated  as  often  as  the  occasion  may  demand. 

■  It  is  essential  that  all  cases  or  suspected  cases  of  the  disease  be 
promptly  reported,  for  a  case  of  communicable  disease  known  is  a  case 
neutralized.  It  is  the  missed  cases  and  the  hidden  cases  that  are  par- 
ticularly dangerous. 

Education. — A  campaign  of  education  should  be  carried  on  at  the 
same  time  that  the  disease  is  being  attacked.  The  people  are  keenly 
alive  and  hungry  for  information.  Well-worded  articles  in  the  news- 
papers, circulars,  pamphlets,  lectures,  demonstrations,  and  the  other 
usual  methods  are  available.  The  education  of  the  community  is  im- 
portant in  order  to  obtain  cooperation,  for  it  is  a  handicap  to  fight 
an  epidemic  without  the  active  support  of  the  people.  While  the 
first  duty  of  the  officer  in  charge  is  to  allay  panic  and  calm  the  uuT'ca- 
sonable  fears  of  the  stricken  community,  the  opposite  extreme  must  be 
avoided.  A  healthy  fear  of  the  disease  is  one  of  the  best  instruments 
in  the  armamentarium  of  the  sanitarian.  It  is  almost  hopeless  to  make 
progress  against  disease  where  the  peojole  supinely  accept  the  conditions. 
Thus,  if  the  people  of  the  United  States  feared  typhoid  fever  as  they 
do  yellow  fever,  it  would  soon  diminish  to  the  vanishing  point. 

QUARANTINE 

The  word  "quarantine"  is  derived  from  the  Italian  word  "quarante," 
meaning  forty.  Its  present-day  meaning  dates  from  the  middle  ages 
when  Venice  and  other  Hanseatic  cities  detained  arriving  ships  with 
cases  of  pestilence  aboard  for  a  period  of  forty  days.  This  was  the  first 
systematic  application  of  maritime  quarantine,  although  from  the 
earliest  times  lepers  were  segregated  or  quarantined.     To-day  we  have 


322  SOME    GENERAL    CONSIDERATIONS 

many  kinds  of  quarantine :  maritime  quarantine,  interstate  quarantine, 
house  quarantine,  cattle  quarantine,  yellow  fever  quarantine,  shotgun 
quarantine,  etc. 

The  dominating  principle  in  modern  quarantine  is  that  it  must  be 
a  sieve  or  filter  and  not  a  dam.  All  quarantines  based  upon  the  prin- 
ciple of  the  Chinese  wall  are  doomed  to  fail.  The  object  of  quaran- 
tine is,  then,  to  destroy,  detain,  or  isolate  infection  with  the  least  pos- 
sible hindrance  to  trade  and  travel.  The  art  consists  in  regulating  the 
openings  in  the  quarantine  sieve  so  as  to  hold  back  certain  infections, 
but  permit  all  else  to  pass.  Maritime  quarantine  may  be  regarded  as 
a  coast  defense  against  exotic  pestilence,  a  defense  which  guards  against 
an  invisible  foe  ofttimes  more  damaging  than  hostile  armies  and  navies. 
The  cure  for  quarantine  is  sanitation. 

If  all  communities,  especially  seaports,  were  to  place  their  cities  in 
the  best  sanitary  condition  in  accordance  with  the  teachings  of  modern 
science,  there  would  be  little  danger  of  disease  spreading  to  epidemic 
proportions  and  very  little  need  of  maritime  quarantine.  If  the  ports 
in  our  southern  littoral  would  fi'ee  themselves  of  the  Stegomyia  mosquito 
they  could  laugh  at  yellow  fever.  A  city  containing  few  rats  could  not 
have  an  epidemic  of  plague.  A  port  supplied. with  a  pure,  well-pro- 
tected water  supply  need  not  fear  a  water-borne  epidemic  of  cliolera. 
A  thoroughly  vaccinated  community  runs  no  hazard  from  snuillpox. 
Typhus  fever  could  not  spread  in  a  community  with  cleanly  personal 
habits,  that  is,  one  free  from  lice  and  other  vermin. 

Maritime  Quarantine. — Maritime  quarantine  in  this  country  is  en- 
forced only  against  six  diseases,  viz.,  cholera,  yellow  fever,  plague, 
typhus  fever,  smallpox,  and  leprosy.  We  do  not  quarantine  against 
typhoid  fever,  tuberculosis,  measles,  and  other  infections  which  are  not 
greatly  feared  and  which  are  constantly  with  us.  Infections  of  a  non- 
quarantinable  nature,  such  as  scarlet  fever,  measles,  etc.,  arriving  at  a 
port  are  permitted  to  enter,  but  must  then  comply  with  the  local  laws 
and  regulations. 

The  period  of  detention  is  based  upon  the  usual  period  of  incubation 
for  each  disease  and  is  as  follows: 

Cholera 5  days. 

Yellow  fever 5,  sometimes  6  days. 

Plague    7  days. 

Typhus  fever 12  days. 

Smallpox  14  days. 

Leprosy   not  admitted. 

The  time  of  detention  is  usually  counted  from  the  completion  of 
disinfection  or  at  least  from  the  last  possible  exposure  to  the  infection. 
This  is  usually  not  a  very  difficult  matter  for  the  quarantine  officer  to 
decide,  but  in  case  of  doubt  the  public  is  given  the  benefit. 


QUAEANTINE  323 

Ko  communication  is  permitted  with  a  vessel  in  quarantine  except- 
ing under  supervision  of  the  quarantine  officer;  that  is,  no  one  is  al- 
lowed to  board  the  vessel  or  leave  it,  and  nothing  is  allowed  to  be  thrown 
overboard,  taken  ashore,  or  brought  on  board  without  the  express  per- 
mission of  the  quarantine  officer.  These  restrictions  apply  alike  to 
foods  and  to  merchandise  of  all  kinds. 

The  vessel  itself  may  be  disinfected  and  furnished  with  a  fresh 
crew  and  released  from  quarantine  while  the  passengers  and  crew  are 
detained  in  suitable  barracks.  Vessels  trading  with  infected  ports 
should  carry  immune  crews;  that  is,  persons  who  have  either  had  the 
disease  or  have  been  rendered  actively  immune  through  one  of  the  vac- 
cines or  viruses. 

When  a  quarantinable  disease  breaks  out  on  board  a  vessel  it  is  of 
practical  importance  for  the  quarantine  officer  to  determine  whether 
the  infection  was  contracted  on  board  the  vessel  or  on  land.  In  the 
first  case  the  vessel  must  be  regarded  as  infected  and  the  measures  used 
for  its  purification  are  much  more  exacting  than  in  the  second  case. 
Thus,  if  plague  breaks  out  within  five  days  from  the  time  a  vessel  leaves 
an  infected  port,  and  no  other  case  occurs,  it  is  exceedingly  probable 
that  the  patient  contracted  his  disease  ashore  and  was  in  the  period  of 
incubation  when  he  came  on  board.  If,  however,  |)lague  breaks  out  after 
five  days,  and  especially  if  secondary  cases  occur,  it  is  evident  that  the 
ship  itself  is  infected.  The  same  reasoning  applies  to  3^ellow  fever  and 
the  other  communicable  diseases. 

The  measures  taken  at  quarantine  to  keep  out  these  diseases  depend 
upon  an  accurate  knowledge  of  their  cause  and  mode  of  transmission. 
Briefly  summarized,  the  measures  applicable  in  each  case  are  as  follows: 

CJiolera. — Cases  are  removed  from  the  vessel  and  isolated  and  that 
part  of  the  vessel  and  the  objects  exposed  are  disinfected — formalde- 
hyde for  cabins,  sulphur  dioxid  for  the  hold,  bichlorid  solution  for  sur- 
faces, steam  for  fabrics  and  clothing.  A  search  is  made  for  bacillus 
carriers  and  a  bacteriological  examination  is  made  of  all  cases  of  diar- 
rhea. Special  attention  is  given  to  the  water  supply,  food,  and  flies. 
After  the  sick  are  isolated  the  remainder  are  segregated  in  small  groups. 
Those  especially  exposed  are  first  bathed  and  their  body  clothing  disin- 
fected before  they  are  sent  to  the  detention  barracks.  In  case  of  cholera 
arrangements  should  be  perfected  for  the  disinfection  of  the  dejecta. 
Baggage  which  has  been  exposed  is  disinfected  by  an  approjoriate 
method,  but  as  there  is  little  danger  in  the  cargo,  especially  if  it  con- 
sist of  new  manufactured  merchandise,  this  may  be  passed  without  spe- 
cial treatment. 

If  a  vessel  has  taken  water  ballast  at  an  infected  port  it  is  required 
to  empty  the  same  at  sea  and  replace  the  presumably  infected  water 
with  sea  water.     If  this  has  been  neglected  the  vessel  must  return  to 


31M  SOME    GENERAL    CONSIDERATIONS 

sea  past  the  three-mile  limit  for  this  purpose.  The  water  and  the  water 
tanks  may  be  rendered  safe  by  the  use  of  chlorinated  lime. 

The  period  of  detention  in  the  case  of  cholera  is  five  days. 

Smallpox. — Ordinarily  those  who  have  had  smallpox  or  who  have 
had  a  recent  successful  vaccination  are  not  detained.  All  others  must 
submit  to  vaccination.  Persons  declining  vaccination  are  detained  for 
the  full  jjcriod  of  14  days  before  they  are  released.  As  a  rule,  it  is  not 
necessary  to  detain  cabin  passengers  because  there  is  smallpox  in  the 
steerage,  or  to  detain  the  firemen  because  there  is  smallpox  among  the 
stewards.  Vessels  arriving  with  smallpox  on  board  on  which  the  cases 
have  been  properly,  isolated,  personnel  vaccinated,  and  other  sufficient 
precautions  taken  to  prevent  the  spread  of  the  disease,  need  not  be  quar- 
antined further  than  the  removal  of  the  sick,  the  disinfection  of  com- 
partments, baggage,  and  objects  that  have  been  exposed  to  the  liability 
of  infection. 

Plague. — Passengers  and  crew  from  plague-infected  ports  are  care- 
fully inspected  at  quarantine.  The  temperature  of  each  person  should 
be  taken  and  it  is  desirable  to  make  special  examinations  for  bubos. 
A  careful  search  is  made  for  cases  of  Pestis  minor,  and  the  pneumonic 
form  of  the  disease  must  also  be  kept  in  mind.  The  period  of  detention 
in  the  case  of  plague  is  7  days.  The  sick  are  isolated  in  the  hospital 
and  the  remainder  segregated  in  small  groups.  All  persons  exposed 
to  the  infection  are  bathed  and  their  body  clothing  disinfected. 

Rats  and  fleas  on  the  vessel  must  be  killed  and  burned.  Usually 
sulphur  dioxid  is  used ;  sometimes  hydrocyanic  acid  gas  or  carbon 
monoxid. 

Special  precautions  must  be  taken  to  prevent  the  escape  of  rats. 
Vessels  quarantined  on  account  of  plague  should  be  anchored  at  suffi- 
cient distances  from  shore  to  discourage  rats  swimming  to  the  land. 
If  the  vessel  ties  up  to  the  dock,  the  hawsers  must  be  guarded  with 
inverted  cones  or  balls  of  tar  in  order  to  stop  rats  reaching  the  ghore 
along  these  lines.  Gangplanks  must  be  taken  in  before  dark,  and,  as 
rats  are  nocturnal  in  their  habits,  a  searchlight  will  help  to  deter  them 
from  leaving  the  sliip.  Nothing  should  be  thrown  overboard,  not  even 
deck  sweepings;  these  should  be  burned,  but  not  in  the  galley. 

A  plague-infected  ship  is  given  a  simultaneous  disinfection  with 
sulphur  and  the  cargo  is  removed  by  a  special  procedure.  After  sul- 
phuring, the  cargo  is  removed  piece  by  piece  to  lighters,  each  article 
being  examined  as  it  swings  overboard  for  rat  nests.  This  work  goes 
on  during  the  day,  while  the  empty  cargo  spaces  are  fumigated  with 
sulphur  during  the  night  in  preparation  for  the  next  day's  unloading. 

Special  precautions  must  also  be  taken  at  foreign  plague  ports  to 
prevent  the  ingress  of  rats  and  also  to  prevent  unnecessary  human  com- 
munication  with   infected   areas.      All  vessels   trading  regularly  with 


QTJAEAKTmE 


325 


plague  ports  should  carry  an  approved  type  of  sulphur  furnace^  such 
as  the  Clayton  apparatus,  to  use  during  the  voyage,  in  order  to  kill 
rats  that  may  be  on  board.  Such  vessels  should  have  an  immune  crew; 
that  is,  persons  who  have  either  had  the  disease  or  have  been  protected 
with  Haffkine's  prophylactic. 


CLOSED 


DP  EN 


Fig.  47. — A  Device  for  Preventing  Rats  Traveling  along  Hawsers. 


Yellow  Fever. — Vessels  arriving  at  an  infectible  port  from  an  in- 
fected port  are  fumigated  and  detained  five  da3's  as  a  precautionary 
measure  during  the  yellow  fever  season,  even  though  there  is  no  evi- 
dence of  sickness  on  board.  The  yellow  fever  season  usually  extends 
from  May  1  until  October  1.  The  infectible  ports  are  those  situated 
upon  the  Atlantic  seacoast  south  of  the  Chesapeake  and  those  on  the 
Gulf  of  Mexico. 

Five  days  covers  the  period  of  incubation  of  most  cases  of  yellow 
23 


326  SOME    GENERAL    CONSIDERATIONS 

fever  and  is  sufficient  as  a  precautionary  measure,  but  in  special  in- 
stances, as,  for  example,  if  a  case  of  yellow  fever  has  occurred  on  board 
the  vessel,  then  the  detention  is  six  days  following  fumigation.  The 
sick  are  isolated  by  the  use  of  mosquito  screens.  Patients  with  yellow 
fever  should  not  be  moved  if  this  involves  exertion  or  excitement,  which 
may  aggravate  the  disease. 

The  vessel  is  fumigated  with  an  insecticidal  substance,  preferably 
SOo,  in  order  to  kill  the  Stegomyia  calopus.  A  search  is  made  for 
breeding  places,  such  as  water  casks,  fire  buckets,  and  other  collections 
of  fresh  water  where  the  Stegomyia  larvae  and  pupae  may  develop.  The 
disinfection  of  baggage  and  fomites  is  no  longer  practiced  in  the  case 
of  yellow  fever.  Experience  has  shown  that  wooden  vessels  are  more 
apt  to  convey  yellow  fever  than  iron  vessels.  This  is  because  wooden 
vessels  carry  water  casks,  which  are  the  favorite  breeding  places  for 
the  mosquito,  while  iron  vessels  store  their  drinking  water  in  tight 
compartments  deep  in  the  hold,  inaccessible  to  mosquitoes.  Vessels 
plying  between  infected  and  infectible  ports  should  carry  immune  crews. 

Typhus  Fever. — The  period  of  detention  for  typhus  fever  is  12  days. 
If  a  case  of  typhus  fever  occurs  upon  a  vessel  and  has  been  properly 
isolated,  and  the  vessel  is  in  good  sanitary  condition,  there  is  practi- 
cally no  danger  of  its  spread,  the  case  may  be  removed,  disinfection 
practiced  (insecticides),  and  the  vessel,  passengers,  and  crew  permitted 
to  proceed.  But,  if  the  case  has  not  been  isolated,  or  if  the  disease  has 
spread  from  one  person  to  another  upon  the  vessel,  or  if  the  ship  is  in- 
fested with  vermin  and  is  otherwise  in  an  unsanitary  condition,  those 
exposed  are  detained  in  quarantine  until  the  period  of  incubation  has 
elapsed.  Quarantine  procedures  in  the  case  of  typhus  fever  are  now 
focused  entirely  upon  the  louse,  which  is  the  carrier  of  the  infection. 

Leprosy. — An  alien  leper  is  not  allowed  to  land.  The  law  requires 
the  vessel  on  which  he  arrives  to  take  him  back  again.  It  is  unconstitu- 
tional to  forbid  the  landing  of  an  American  leper,  but  as  soon  as  he 
lands  he  comes  under  the  laws  of  the  city  or  state  in  which  he  finds 
himself.  x4.1ien  lepers  are  detained  at  the  quarantine  station  and  placed 
aboard  again  wlien  the  vessel  is  outward  bound. 

Quarantine  Procedures. — All  vessels  arriving  at  any  port  in  the 
United  States  from  a  foreign  port  are  considered  to  be  in  quarantine 
until  they  are  given  free  practique.  The  practique  is  a  certificate 
signed  by  the  quarantine  officer  to  the  effect  that  the  vessel  and  all  on 
board  are  free  from  quarantinable  disease,  or  the  danger  of  conveying 
the  same.  In  other  words,  free  practique  is  a  permit  issued  by  the 
quarantine  officer  which  the  master  of  the  vessel  must  present  to  the 
collector  of  the  port  in  order  that  his  vessel  may  be  admitted  to  entry. 

Vessels  in  quarantine  are  required  to  fly  a  yellow  flag  (letter  "Q" 
of  the  International  Code)  from  the  foremast.     The  quarantine  officer 


QUAEANTINE  327 

boards  the  vessel  usually  upon  the  starboard  side  and  examines  the 
bill  of  health,  the  ship  itself,  the  passengers,  the  crew,  as  well  as  the 
manifests  of  cargo,  and  sometimes  the  food  and  water  supplies,  etc. 
Vessels  arriving  after  sundown  must  wait  until  sunrise  for  this  inspec- 
tion; the  time  and  details,  however,  vary  greatly  and  depend  upon  cir- 
cumstances. Thus,  at  the  port  of  Boston,  there  is  no  more  need  to  ex- 
amine vessels  bringing  residents  of  London  or  Paris  than  there  would 
be  to  examine  a  trainload  of  passengers  from  New  York. 

The  detection  of  infection  on  board  a  vessel  requires  knowledge, 
tact,  and  sometimes  a  detective  instinct  on  the  part  of  the  quarantine 
officer.  Where  one  of  the  communicable  diseases  is  suspected  the  tem- 
perature of  every  person  on  board  should  be  taken.  Sometimes  special 
examinations,  as  for  bubos  in  the  case  of  plague,  are  necessary.  As  a 
rule,  all  hands  are  mustered  at  a  designated  place  on  board  the  ship 
and  then  passed  in  review,  one  by  one,  before  the  examining  physician; 
the  number  of  persons  are  counted  and  compared  with  the  ship's  papers ; 
each  person  is  critically  scrutinized  for  evidence  of  disease,  and  suspects 
are  placed  aside  for  more  careful  examination  later.  The  clinical 
records  of  the  ship's  surgeon  are  inspected  with  special  reference  to  the 
diagnosis  of  those  who  have  received  medical  care  during  the  voyage. 
The  manifest  of  cargo  is  examined  for  second-hand  goods,  upholstered 
furniture,  bedding,  hides,  hair,  or  other  objects  that  may  require  disin- 
fection. Finally,  the  ship  itself  is  inspected,  attention  being  given 
especially  to  the  forecastle,  steerage  quarters,  the  galley,  etc. 

The  Bill  of  Health.— The  United  States  Bill  of  Health  is  a  docu- 
ment issued  by  our  consul  at  the  port  of  departure  to  the  master  of 
the  vessel.  The  Bill  of  Health  contains  a  complete  description  of  the 
vessel,  the  number  of  officers,  crew,  and  passengers  (cabin  and  steer- 
age), its  sanitary  history,  and  the  sources  and  wholesomeness  of  water, 
food  supply,  etc.  Finally,  it  contains  a  statement  giving  the  number 
of  cases  and  deaths  from  yellow  fever,  cholera,  smallpox,  typhus  fever, 
plague,  and  leprosy  at  the  port  of  departure  during  the  two  weeks  pre- 
ceding the  departure  of  the  vessel.  The  American  Bill  of  Health,  which 
is  a  formidable  document,  must  be  obtained  by  the  master  of  the  ves- 
sel in  duplicate;  one  copy  is  destined  for  the  collector  of  customs  at 
the  point  of  entry  and  the  other  for  the  quarantine  officer. 

The  Bill  of  Health  is  a  consular  document  (State  Department)  at 
the  port  of  departure,  but  becomes  a  customs  paper  (Treasury  Depart- 
ment) at  the  port  of  entry.  Vessels  arriving  at  any  port  in  the  United 
States  or  its  dependencies  from  a  foreign  port  without  this  official  Bill 
of  Health  in  duplicate  are  subject  to  a  fine  of  $5,000.  Before  the  days 
of  telegraphy  the  Bill  of  Health  was  an  important  document  and  often 
gave  the  quarantine  officer  the  first  information  of  pestilential  disease 
abroad.     The  quarantine  officer  must  now  keep  himself  informed  not 


328  SOME    GENERAL   COXSIDERATIONS 

only  of  tlie  health  conditions  of  the  port  of  departure,  but  of  the  places 
from  which  the  passengers  and  crew  are  recruited. 

There  are  many  kinds  of  bills  of  health;  each  country  has  a  form 
of  its  own.  Formerly  a  bill  of  health  was  simply  a  statement  that  the 
port  of  departure  was  or  was  not  free  of  pestilential  disease;  that  is, 
the  bill  of  health  was  either  "'clean"  or  "foul."'  The  American  Bill  of 
Health  gives  much  more  valuable  information  in  detail.  The  only  bill 
of  health  that  is  of  service  to  the  vessel  upon  arrival  is  the  American 
Bill  of  Health,  although  several  bills  of  health  may  be  issued  to  the 
vessel  at  the  port  of  departure.  Thus,  a  British  vessel  leaving  the  port 
of  Rio  de  Janeiro  takes  three  bills  of  health,  one  from  the  British  con- 
sul, required  by  the  British  admiralty  laws,  another  from  the  Brazilian 
authorities,  which  is  a  clearance  paper,  and  the  third  from  the  Amer- 
ican consul,  which  is  the  only  one  of  service  upon  reaching  a  port  in 
the  T'nitod  States. 

The  Equipment  of  a  Quarantine  Station. — The  equipment  of 
a  quarantine  station  consists  of  boarding  vessels,  such  as  tugs,  launches, 
and  rowboats;  of  an  inspection  place  where  passengers,  crew,  and  sus- 
pects may  be  examined  (the  facilities  on  board  the  ship  are  usually 
inadequate  for  this  purpose)  ;  of  disinfecting  apparatus  for  the  use  of 
steam,  sulphur  dioxid,  formaldehyde,  and  insecticides;  shower  baths; 
detention  barracks  for  steerage,  intermediate,  and  cabin  passengers,  as 
well  as  the  crew  of  the  vessel;  isolation  wards  in  which  cases  of  the 
quarantinable  diseases  may  be  cared  for,  and  special  wards  where  sus- 
pects or  non-contagious  cases  may  receive  treatment.  A  well-equipped 
quarantine  station  further  needs  dining-rooms  and  kitchens  for  the 
various  groups  detained;  quarters  for  the  cjuarantine  officers  and  help; 
a  wharf  and  boat  house,  and  some  provisions  for  recreation  of  those 
in  quarantine  to  dispel  the  ennui  of  the  isolation.  Finally,  a  crema- 
tor}', a  steam  laundry,  and  special  arrangements  for  the  disposal  of 
sewage  and  garbage  are  essential. 

A  laboratory  is  an  essential  feature  of  a  modern  quarantine  station. 
It  is  necessary  in  order  to  make  diagnoses  and  to  recognize  bacillus 
carriers,  etc.  In  other  words,  a  quarantine  station,  on  account  of  its 
importance  and  isolation,  must  be  a  well-equipped  and  self-supporting 
community. 

Qualifications  of  the  Quarantine  Officer. — The  quarantine  officer 
must  be  a  good  diagnostician.  He  should  have  a  special  acquaint- 
ance with  the  diseases  against  which  he  stands  monitor.  Further,  he 
must  be  familiar  with  the  modes  of  spread  of  the  quarantinable  dis- 
eases and  must  know  the  value  and  limitations  of  the  germicidal  agents 
and  insecticides  he  uses.  Finally,  he  must  be  familiar  with  matters 
nautical,  and  have  an  extensive  knowledge  of  geography.  It  is  the  duty 
of  the  quarantine  officer  to  keep  posted  as  to  the  sanitary  conditions 


QUARANTINE  329 

of  all  countries,  especially  the  towns  and  places  having  commerce  with 
his  port. 

Disinfection  of  Ships. — The  disinfection  of  a  vessel  does  not  dif- 
fer materially  from  the  disinfection  of  houses  and  rooms.  It  should 
not,  however,  be  attempted  by  one  not  familiar  with  the  intricacies 
of  marine  architecture  and  matters  nautical,  for  many  special  condi- 
tions are  met  with  on  board  ship  that  are  very  different  from  those 
found  on  shore.  While  the  principles  of  disinfecting  as  applied  to  a 
vessel  present  nothing  unusual,  the  application  of  these  principles  calls 
for  much  ingenuity  and  the  keenest  vigilance  on  the  part  of  the  dis- 
infector. 

It  is  important  to  enlist  the  sympathies  of  those  on  board  with  the 
necessity  of  disinfection,  for  the  successful  accomplishment  of  the 
purification  of  the  vessel  may  be  materially  helped  by  the  cheerful 
cooperation  of  the  passengers  and  crew;  otherwise  the  difficulties  of  the 
problem  are  greatly  magnified. 

Formerly  a  distinction  was  made  between  the  methods  of  disinfect- 
ing a  wooden  and  an  iron  vessel.  This  arose  from  the  fact  that  almost 
all  wooden  vessels  have  some  rotten  and  spongy  wood,  especially  about 
the  forefoot  and  bilge.  There  are  also  many  more  cracks  and  open 
joints  about  a  wooden  ship  than  a  metal  one  which  afford  lodgment 
for  organic  matter.  In  addition  to  this,  a  wooden  hull  is  always  dam- 
per than  an  iron  hull,  for  almost  all  wooden  vessels  leak  more  or  less. 
It  was  formerly  believed  that  the  microorganisms  of  disease  were  apt 
to  become  deeply  lodged  in  the  moist  dirt  and  organic  matter  of  the 
many  crevices,  but  we  now  know  that  this  is  largely  theoretical. 

A  vessel  is  rarely  so  badly  infected  that  it  needs  a  disinfection 
throughout.  Just  what  portion  of  the  vessel  and  its  contents  requires 
treatment  is  often  a  very  difficult  problem  to  solve.  There  is  no  more 
reason  to  fumigate  the  hold  of  a  vessel  because  smallpox  appeared  in 
the  cabin  or  steerage  than  there  would  be  to  disinfect  the  basement  and 
subbasement  of  a  tenement  house  because  a  case  appeared  in  one  of 
the  upper  stories  of  the  building.  When  a  communicable  disease  oc- 
curs on  board  a  vessel  the  infection  may  be  confined  to  one  or  two 
compartments  or  to  a  limited  area  quite  as  successfully  as  this  may 
be  done  in  buildings  on  shore.  "In  case  of  doubt,  disinfect,"  is  not 
a  bad  rule  for  the  quarantine  officer  to  follow  in  his  practical  deal- 
ings with  ships.  For,  after  all,  the  measures  which  must  be  taken  are 
greatly  in  excess  of  the  absolute  requirements. 

Much  may  be  learned  by  a  thorough  inspection  of  the  vessel.  To  be 
sure,  we  cannot  see  the  germs  with  our  unaided  vision,  but  we  can  see 
the  dirt  and  moisture  and  other  conditions  which  favor  their  life  and 
virulence  and  can  discover  the  feeding  and  breeding  places  for  vermin. 

It  is,  therefore,  the  duty  of  the  quarantine  officer  to  require  a  very 


330  SOME    GENERAL    COXSIDEEATIOXS 

thorough  mechanical  cleansing  of  all  parts  of  the  ship  which,  in  his 
judgment,  require  it.  This  matter  is  dwelt  upon  because  filth  and  ver- 
min are  conditions  too  frequently  met  with  on  tlie  sea  and  one  of  great 
importance  to  communities  and  nations. 

Wliile  the  general  methods  of  treating  vessels  are  the  same  for  most 
of  the  bacterial  infections,  special  methods  are  called  for  with  each  dis- 
ease. For  example,  in  cholera  particular  attention  must  be  paid  to  the 
water  and  food  supply;  for  plague  the  destruction  of  rats  and  fleas 
is  of  prime  importance;  for  yellow  fever  attention  must  ])e  directed 
against  the  mosquito;  for  smallpox  vaccination  and  the  usual  disinfec- 
tion of  the  living  apartments,  clothing,  bedding,  and  the  like  are  re- 
quired, while  for  typhus  fever  the  warfare  must  be  waged  against  lice. 

The  disinfection  of  a  large  vessel  cannot  effectively  be  done  with- 
out all  the  modern  contrivances  of  a  well-equipped  quarantine  station. 
A  rowboat  and  launch  or  a  small  sailing  craft  may  be  disinfected  with 
a  tub  of  bichlorid  solution,  but  good  work  cannot  be  accomplished  on 
a  large  vessel  by  the  use  of  makeshifts. 

Before  the  disinfection  of  a  vessel  is  commenced  it  should  be  brought 
alongside  the  pier  or  barge  containing  the  necessary  apparatus.  All 
the  passengers  are  then  to  be  taken  off  and  all  the  crew,  only  excepting 
the  few  who  are  necessary  for  the  safety  of  the  vessel  and  those  who 
are  to  help  in  the  disinfection.  The  quartermaster,  the  boatswain,  and 
the  carpenter  are  very  useful  hands  to  aid  in  the  process  on  account  of 
their  practical  knowledge  of  the  individual  peculiarities  of  the  construc- 
tion of  the  vessel  and  their  intelligence  in  carrying  out  directions  with 
faithfulness. 

When  the  personnel  have  left  the  vessel  all  their  effects  are  removed 
and  disinfected,  if  necessary,  in  accordance  with  the  methods  outlined 
for  objects  of  that  class.  Baggage,  bedding,  and  other  objects,  no  mat- 
ter what  their  character,  after  disinfection  should  not  be  returned  on 
board  until  the  treatment  of  the  vessel  itself  is  finished.  This  injunc- 
tion applies,  of  course,  equally  well  to  persons.  In  fact,  no  one  should 
be  allowed  on  the  vessel  except  those  actually  engaged  in  the  work, 
who,  as  far  as  practicable,  should  be  immune  and  should  wear  suitable 
garments.  All  the  bedding,  bed  clothing,  hangings,  floor  runners,  and 
other  fabrics  that  have  been  exposed  to  infection  must  now  be  re- 
moved to  the  steam  chamber.  Especial  care  must  be  taken  to  obtain 
all  the  used  and.  soiled  linen,  which  is  usually  kept  in  special  compart- 
ments called  the  "dirty  linen  lockers,"  which  are  usually  under  the  care 
of  one  of  the  stewards.  For  some  reason  there  is  a  dislike  to  disclose 
the  presence  of  this  soiled  wash  to  the  quarantine  officer. 

After  all  the  objects  needing  disinfection  by  special  process  have 
been  removed,  attention  is  then  directed  to  the  vessel  itself.  The  vari- 
ous compartments  of  the  vessel  may  be  disinfected  by  any  one  of  the 


QUAEANTINE  331 

methods  described  under  Eoom  Disinfection,  formaldehyde  being  the 
choice  of  the  gases  and  bichlorid  of  mercury  (1-1,000)  being  the  most 
suitable  solution  for  the  treatment  of  walls,  floors,  etc. 

The  bichlorid  solution,  which  is  sometimes  used  for  flushing  the 
forecastle,  the  steerage  compartments,  and  quarters  for  petty  officers, 
etc.,  may  be  applied  with  a  force-pump  or  by  means  of  mops  and  buck- 
ets. In  applying  the  disinfection  solution  with  a  hose  begin  at  one  end 
of  the  deck  ceiling  and  systematically  flood  every  inch  of  surface,  com- 
ing down  the  walls,  and  finally  the  floor. 

In  disinfecting  large  vessels  it  is  well  to  start  forward  with  the 
forecastle  and  work  aft  systematically,  first  on  the  starboard,  then  on 
the  port  side,  taking  care  to  require  every  door  to  be  unlocked  and 
trusting  only  to  a  personal  inspection  concerning  its  contents  and  uses. 
There  are  certain  places,  such  as  the  lamp-room,  the  paint  locker,  the 
sail  locker,  the  chain  locker,  the  carpenter  shop,  and  chart  room,  the 
pilot  house,  the  engine  and  boiler  rooms,  and  the  machinery,  that  are 
rarely  infected,  and,  as  a  rule,  need  no  treatment.  Special  care,  how- 
ever, must  be  given  to  the  sick  bay  and  any  apartment  in  which  a  pa- 
tient was  cared  for,  and  all  living  apartments,  including  the  steerage. 

The  water  closets  on  board  ship  should  be  thoroughly  cleansed  and 
flushed  with  water  and  may  be  disinfected  with  chlorinated  lime  or 
carbolic  acid.  They  may  also  be  hosed  with  the  bichlorid  solution 
while  that  is  being  applied.  In  sailing  vessels  of  the  older  type  the 
forepeak  needs  similar  treatment. 

The  hold  rarely  needs  treatment  on  account  of  bacterial  infection. 
About  the  best  way  to  disinfect  the  holds  of  vessels  is  by  sulphur  fumi- 
gation or  by  a  solution  of  corrosive  sublimate  applied  with  a  hose. 
The  bilge  may  be  flushed  with  carbolic  solution  or  chlorinated  lime  and 
then  pumped  out.  WTien  the  hold  is  fumigated  with  sulphur,  this  may 
be  burned  in  iron  pots  set  in  pans  of  water.  The  pot  should  be  placed 
in  an  elevated  position  either  on  piles  of  ballast  or  on  the  'tween  decks. 
In  leading  sulphur  fumes  into  the  holds  from  a  sulphur  furnace  it  is 
considered  best  to  lead  the  pipes  down  the  hatch-well  toward  the  bottom 
of  the  hold,  so  that  the  apartment  may  fill  up  with  the  fumes  from  the 
bottom,  displacing  the  air  above.  For  this  reason  openings  above  for 
the  escape  of  the  air  must  be  provided.  This  is  best  managed  by  leav- 
ing one  or  two  of  the  ventilators  open,  or  part  of  the  hatch,  and  after 
the  gas  has  begun  to  escape  in  some  quantity  to  close  up  tight. 

The  amount  of  sulphur  to  be  burned  may  readily  be  computed  from 
the  tonnage  of  the  vessel.  A  registered  ton  is  100  cubic  feet.  Count 
half  a  pound  for  each  ton,  which  will  make  the  necessary  five  pounds 
per  1,000  cubic  feet.  The  gross  tonnage  of  a  vessel  indicates  her  ac- 
tual cubic  capacity.  The  net  tonnage  gives  the  capacity  of  her  cargo- 
carrying  space.     The  difference  between  the  two  will  give  the  capacity 


332  SOME    GENEKAL    C0X8IDERATI0XS 

of  the  spaces  devoted  to  the  engines,  machinery,  living  apartments, 
storerooms,  etc.  In  sailing  vessels  and  in  freighters  the  net  tonnage 
may  be  taken  as  the  cubic  capacity  of  the  hold.  In  estimating  freight 
40  cubic  feet  of  merchandise  is  considered  a  ton,  provided  the  bulk 
does  not  weigh  more  than  2,000  pounds.  This  ton,  used  as  a  commer- 
cial unit  for  freight  charges,  must  not  be  confused  with  the  registered 
tonnage  based  upon  the  measurement  of  the  vessel. 

In  fumigating  vessels  for  yellow  fever,  plague,  and  other  insect-  or 
animal-borne  diseases,  the  fumigation  should  be  simultaneous  in  all 
parts  of  the  vessel.  Following  tliis,  special  rooms  and  apartments  may 
be  given  individual  treatment,  depending  upon  circumstances. 

The  empty  compartments  of  an  iron  steamer  may  be  disinfected  by 
steam,  provided  it  is  above  the  water  line.  The  compartments  of  such 
vessels  usually  have  steam  pipes  for  use  in  case  of  fire.  Clothing  and 
other  fabrics  may  also  be  disinfected  by  steam,  by  exposing  them  in  the 
compartment. 

The  water  tanks  and  casks  of  vessels  sometimes  need  special  treat- 
ment. The  water  may  be  infected  with  cholera,  typhoid,  dysentery, 
or  other  water-borne  infection.  The  water  may  be  disinfected  in  situ 
by  the  addition  of  chlorinated  lime,  using  an  amount  sufficient  to  make 
a  one  per  cent,  solution.  This  should  stand  at  least  24  hours  before 
it  is  pumped  out. 

Water  casks  onr  sailing  vessels  are  very  apt  to  be  breeding  places  for 
mosquitoes.  These  should  be  emptied  and  cleansed.  The  water  con- 
taining the  larvae  may  be  spilled  overboard,  as  neither  the  anopheles 
nor  the  stegomyia  may  develop  in  salt  water,  otherwise  the  larvae  should 
first  be  destroyed. 

For  the  destruction  and  treatment  of  rats,  etc.,  on  vessels  see  pages 
245  and  252. 

Cargo. — As  a  rule,  the  cargo  of  a  vessel  infected  with  pestilential 
disease  needs  no  disinfection.  Individual  articles  of  the  cargo,  such  as 
rags,  household  goods,  second-hand  articles,  or  food  products,  from  in- 
fected localities  may  need  treatment.  New  articles  of  merchandise  or 
new  manufactured  goods  seldom  carry  infection. 

In  the  case  of  plague  the  cargo  may  need  special  treatment  on  ac- 
count of  rats  (see  page  324). 

Ballast. — A'essels  bring  two  kinds  of  ballast:  (1)  water,  (2)  solid. 
Solid  ballast  consists  of  the  greatest  variety  of  substances.  The  kind 
which  is  most  objectionable  from  the  standpoint  of  the  health  officer  is 
called  "sand"  by  the  captain,  but  an  inspection  of  this  sand  will  dis- 
cover the  fact  that  it  often  consists  largely  of  street  sweepings  and  rub- 
bish from  the  port  from  which  the  vessel  hails.  Such  ballast  should  not 
be  unloaded  on  the  city  front,  especially  if  it  comes  from  an  infected 
district.    Ballast  consisting  of  clean,  hard  rock  or  sand  from  the  beach 


QUAKANTINE  333 

is  not  apt  to  carry  infection  of  any  kind,  and  usually  needs  no  attention 
from  the  quarantine  officer. 

Modern  vessels  all  use  water  ballast.  The  tanks  may  be  filled  from 
a  river,  fresh  water  lake,  or  other  body  where  cholera,  typhoid,  or  dysen- 
tery prevails.  It  is  a  rule  in  quarantine  practice  to  require  vessels  in 
fresh  water  ballast  from  cholera-infected  districts  to  return  to  the  open 
sea,  where  the  ballast  tanks  are  pumped  out  and  refilled  with  salt  water, 
provided  this  has  not  been  done  on  the  high  seas.  Before  the  water  is 
pumped  out  it  should  be  treated  with  chlorinated  lime. 

Foreign  Inspection  Service. — To  aid  the  quarantine  officer  every 
American  consul  is  required  to  report  regularly  certain  facts  concern- 
ing the  presence  and  progress  of  epidemic  diseases.  Medical  officers  of 
the  government  are  also  stationed  at  various  countries  in  order  to  su- 
pervise the  sanitary  condition  of  vessels,  their  cargo,  and  passengers 
leaving  for  the  United  States.  This  may  be  called  preventive  quaran- 
tine, for  it  is  a  distinct  help  in  keeping  out  infection  and  facilitates 
trade  and  travel.  Thus,  in  Italy,  during  the  cholera  times,  an  officer  of 
the  Public  Health  and  Marine  Hospital  Service  stationed  at  Naples  suc- 
cessfully kept  that  disease  off  vessels  sailing  from  Naples  to  the  United 
States,  whereas  vessels  sailing  from  Naples  to  other  ports  and  without 
sanitary  supervision  carried  cholera  in  several  instances. 

National  versus  State  ftnarantine.— All  the  maritime  quarantines  in 
this  country  are  now  controlled  by  the  national  government,  except- 
ing the  ports  of  Boston  and  New  York.  At  Boston  the  maritime 
quarantine  is  in  charge  of  the  city  health  authorities,  and  at  New  York 
it  is  a  state  institution.  At  a  few  other  ports  a  local  quarantine  is 
maintained  in  addition  to  the  national  service.  The  federal  quarantine 
service  is  administered  by  the  Public  Health  Service,  a  bureau  in  the 
Treasury  Department. 

It  is  evident  that  maritime  quarantine  should  be  administered  uni- 
formly so  as  not  to  prejudice  or  favor  the  commerce  of  a  port.  Not 
only  is  uniformity  insured  by  a  central  service,  but  there  is  a  decided 
gain  in  efficiency  for  obvious  reasons.  Maritime  quarantine  deals  mainly 
with  foreign  shipping.  The  Constitution  reserves  for  the  federal  gov- 
ernment the  right  of  treating  with  foreign  powers;  from  this  point, 
therefore,  maritime  quarantine  is  mainly  a  function  of  the  federal  gov- 
ernment. 

Interstate  Quarantine. — In  accordance  with  our  Constitution  the 
federal  government  has  limited  power  within  the  state,  but  has  practi- 
cally unlimited  authority  to  prevent  the  spread  of  infection  from  one 
state  or  territory,  or  the  District  of  Columbia,  to  another  state  or  terri- 
tory, or  the  District  of  Columbia.  Interstate  quarantine  involves  in- 
terstate travel  and  commerce;  the  pollution  of  streams  flowing  through 
more  than  one  state;  railroad  and  steamboat  sanitation,  and  all  sinailar 


334  SOME    GENERAL    CONSIDEKATIOXS 

questions.  Congress  has  passed  a  comprehensive  act.  Section  III  of  the 
Act  of  February  15,  1893,  authorizing  the  Public  Health  and  Marine 
Hospital  Service  to  enforce  interstate  quarantines  in  the  case  of  con- 
tagious and  infectious  diseases.  The  regulations,  however,  prepared 
under  this  act  comprehend  only  the  six  quarantinable  diseases,  and  have 
only  occasionally  been  enforced  in  the  case  of  yellow  fever,  cholera,  or 
plague.  There  are  no  interstate  regulations  concerning  typhoid  fever, 
tuberculosis,  measles,  and  other  non-quarantinable  diseases.  It  is  evi- 
dent that  this  is  one  of  the  important  phases  in  which  government 
activity  can  accomplish  especial  good;  for,  while  the  government  has 
limited  power  within  the  state,  it  has  practically  unlimited  authority 
so  far  as  interstate  relations  are  concerned.  Widespread  diseases  will 
never  be  adequately  controlled  by  the  local  authorities  without  the  co- 
operation of  the  government.  It  is  evident  that,  if  one  state  should  rid 
itself  of  typhoid  fever,  measles,  or  tuberculosis,  it  would  soon  become 
reinfected  from  the  neighboring  states.  Interstate  sanitation  is  one  of 
the  burning  questions  needing  vigorous  action  and  cannot  be  adequately 
enforced  without  extending  the  scope  and  powers  of  the  present  federal 
health  authorities. 

ISOLATION 

In  theory  isolation  is  the  most  perfect  single  method  to  check  the 
spread  of  a  communicable  disease.  The  results  in  practice,  however, 
have  been  somewhat  disappointing  on  account  of  unusual  difficulties. 
The  statement  has  frequently  been  made,  especially  with  reference  to 
typhoid  fever,  that  if  all  the  cases  could  be  isolated  (which  includes 
the  disinfection  of  the  discharges)  we  would  soon  see  an'  end  of  the 
infection.  We  now  know  that  this  statement  is  not  true,  on  account 
of  the  bacillus  carriers  and  the  mild  and  unrecognized  or  "missed" 
cases.  Because  the  isolation  of  the  reported  cases  represents  only  a 
portion  of  all  the  foci  of  infection  and,  therefore,  at  best  could  not  in 
itself  control  an  epidemic  disease,  discredit  has  been  thrown  upon  this 
procedure,  which  is  one  of  the  essential  features  of  all  systems  of  quar- 
antine. As  a  matter  of  fact,  it  has  been  shown  that  in  certain  diseases, 
like  measles,  which  is  communicable  for  three  days  or  more  before  the 
nature  of  the  disease  is  recognized,  isolation  has  practically  no  influ- 
ence in  diminishing  the  prevalence  of  this  widespread  infection.  It  is 
true  ordinarily  that  a  case  of  measles  does  most  harm  before  it  is 
isolated;  nevertheless,  this  is  no  reason  why  it  should  be  permitted  to 
further  endanger  the  community.  The  value  of  isolation  is  also  dimin- 
ished by  the  prevalence  of  carriers.  In  fact,  its  practical  usefulness  in 
a  given  infection  is  inversely  proportional  to  the  number  of  carriers. 

If  each  case  isolated  prevents  on  the  average  only  one  other  fresh 
infection,   there  would  still   be  justification  sufficient  to   continue   th? 


ISOLATION  335 

practice.  As  a  matter  of  fact,  the  practical  value  of  isolation  varies  with 
each  disease,  depending  upon  the  degree  of  its  communicability,  the 
time  when  it  is  communicable,  the  promptness  by  which  it  may  be 
recognized,  the  modes  by  which  it  is  transferred,  the  existence  of  latent 
infections,  missed  cases,  carriers,  and  other  factors  which  influence  the 
spread  of  the  infection. 

The  degree  of  isolation  varies  markedly  with  the  different  infections. 
A  case  of  yellow  fever  may  be  isolated  under  a  mosquito  screen,  and  a 
case  of  diphtheria  or  scarlet  fever  may  be  effectively  isolated  in  a  bed  in  a 
general  ward,  provided  intelligent  and  painstaking  care  is  exercised  to 
destroy  the  infection  as  it  leaves  the  body.  Isolation  of  the  more  read- 
ily communicable  diseases,  as  smallpox  and  measles,  should  be  much 
more  absolute.  Typhoid  bacillus  carriers  need  not  be  imprisoned.  It 
is  sufficient  to  limit  their  activities,  especially  to  prevent  their  occupation 
in  kitchens,  dairies,  or  about  foodstuffs.  There  is  no  good  reason  to 
isolate  a  consumptive  or  leper  without  open  lesions — that  is,  cases  in 
which  the  bacilli  are  imprisoned  in  the  tissues  and  not  discharged  into 
the  environment.  A  careful  consumptive  or  leper  may  be  allowed  a 
wide  latitude.  On  the  other  hand,  isolation  in  chronic  infections,  such 
as  tuberculosis  and  leprosy,  with  open  lesions  is  the  most  helpful  and 
at  the  same  time  the  most  difficult  single  procedure  we  have  to  control 
their  spread.  The  careless,  indigent,  ignorant,  or  helpless  consumptive 
is  a  public  menace  that  needs  energetic  and  sometimes  arbitrary  iso- 
lation. 

Isolation  may  most  readily  and  effectively  be  carried  out  in  hospitals 
or  sanatoria.  Proper  isolation  in  the  home  requires  a  special  room 
or  rooms,  intelligent  nursing,  appliances  for  disinfection,  etc.,  a  com- 
bination often  difficult  to  arrange.  House  quarantine  varies  with  the 
different  diseases.  To  carry  it  out  rigorously  in  all  cases  and  under  all 
conditions  is  folly.  Different  diseases  need  different  procedures.  Some- 
times it  is  sufficient  simply  to  placard  the  house  as  a  warning.  At  other 
times  it  may  be  necessary  to  station  sanitary  guards  about  the  premises 
to  enforce  the  quarantine.  The  imperfections  of  strict  isolation  by  the 
"shutting  in  of  houses"  are  graphically  described  in  Defoe's  "Journal  of 
the  Plague  Year." 

Isolation  camps  or  temporary  barracks  in  times  of  epidemics  are 
effective  measures  in  checking  the  spread  of  some  infections.  This 
method  has  proved  effective  in  actual  practice  in  the  case  of  smallpox, 
yellow  fever,  plague,  cholera,  and  other  diseases. 

It  often  becomes  a  difficult  question  to  determine  whether  the  well 
m^embers  of  a  household  should  also  be  quarantined — especially  whether 
the  well  children  should  be  permitted  to  attend  school.  This  perplex- 
ing question  must  be  decided  for  each  disease  separately,  and  the  deci- 
sion in  each  disease  is  sonietimes  modified  by  attending  factors.    Usually 


336  SOME    GENERAL    CONSIDERATIONS 

the  other  children  in  the  family  in  the  case  of  scarlet  fever  are  excluded 
from  school  for  four  weeks  from  the  beginning  of  the  last  case.  In 
most  cities  the  same  rule  holds  for  diphtheria,  although  here  we  are 
able  to  determine  whether  the  children  are  bacillus  carriers  or  not. 
At  least  two  negative  cultures  from  the  nose  and  throat  should  be  re- 
quired before  such  children  are  allowed  freely  to  mingle  with  other 
children.  The  principal  factors  which  determine  whether  the  well 
children  in  a  family  shall  be  permitted  to  attend  school  or  not  in  any 
particular  infection  rest  upon  our  knowledge  as  to  whether  the  disease 
is  conveyed  by  a  third  person  and  the  frequency  of  bacillus  carrying 
and  missed  cases. 

Isolation  becomes  one  of  our  most  valuable  public  health  measures 
when  communicable  diseases  affect  persons  working  about  milk,  meat, 
and  other  foods  capable  of  conveying  infection. 

One  of  the  practical  objections  to  isolation  and  one  reason  that  it 
meets  with  so  much  opposition  from  the  public  is  that  the  compensa- 
tion of  the  wage  earner  ceases  through  no  fault  of  his  own.  It  is  evi- 
dently unjust  to  practically  imprison  and  thus  seriously  punish  a  mem- 
ber of  the  community,  not  for  his  own  good  but  for  the  good  of  the 
community,  because  he  or  some  member  of  his  family  has  contracted 
an  infection,  perhaps  through  some  fault  of  the  community  itself.  It 
is,  therefore,  reasonable  and  just  that  wage  earners  and  others  should 
be  compensated  and  their  personal  interests  safeguarded  during  enforced 
isolation. 

Isolation  only  reduces  to  a  moderate  degree  the  prevalence  of  dis- 
ease. The  limitations  of  this  valuable  procedure  are  now  well  under- 
stood. With  improved  methods  of  diagnosis  and  increased  knowledge 
of  the  methods  of  spread  of  disease,  isolation  will  be  made  increasingly 
effective.  Every  case  isolated  is  a  focus  of  infection  neutralized.  Al- 
though not. as  satisfactory  in  practice  as  it  is  in  theory,  isolation  will 
ever  remain  one  of  the  chief  administrative  procedures  for  the  control 
of  the  communicable  diseases. 


SECTION  II 
IMMUNITY,    HEREDITY,    AND    EUGENICS 

CHAPTEK    I 
IMMUNITY 

Imnmnity  or  resistance  to  disease  is  the  very  foundation  of  pre- 
ventive medicine.  It  is  the  overshadowing  factor  in  hygiene.  In  this 
sense  we  use  the  term  "hygiene"  to  include  the  care  of  the  person,  in 
contradistinction  to  '■sanitation/'  which  deals  with  the  environment. 
There  is  no  sharp  line  of  demarcation — we  speak  of  hygiene  of  the 
teeth,  of  sleep,  of  bathing,  of  exercise,  or  food  and  drink,  and  of  those 
conditions  which  are  more  or  less  intimately  associated  with  the  body; 
we  speak  of  the  sanitation  of  the  home,  of  schools,  of  cities,  of  farms; 
sanitary  science  considers  the  air,  soil,  climate,  and  our  surroundings 
as  they  affect  health.  Sanitation,  then,  is  largely  impersonal;  hygiene 
is  personal,  and,  as  far  as  the  prevention  of  disease  is  concerned,  one  of 
the  most  important  factors  in  hygiene  is  immunity. 

The  word  "immunity"  is  a  very  old  term — we  still  speak  of  immu- 
nity to  crime,^  but  it  is  only  of  late  years  that  we  are  beginning  to  un- 
derstand the  mechanism  by  which  the  body  protects  itself  against  in- 
fection. The  advances  have  been  so  rapid  that  these  studies  may  now 
be  grouped  into  a  separate  science  known  as  Immunology. 

Immunity  is  a  function  of  all  living  beings  (animals  and  plants), 
and  in  its  widest  form  is  one  of  the  fundamental  properties  of  life. 
Thus,  as  long  as  we  are  alive  the  colon  bacillus  in  our  intestinal  tract 
and  the  spores  of  the  hay  bacillus  on  our  skins  do  us  no  harm,  but  the 
moment  we  die,  and  ofttimes  shortly  before  death,-  these  and  other  bac- 
teria invade  our  tissues  and  disintegrate  them. 

Immunity  may  be  defined  as  the  power  which  certain  living  organ- 
isms possess  of  resisting  infections.  Immunity  is  the  contrary  condi- 
tion to  susceptibility.    Hyper  susceptibility  is  a  special  state  of  an  exag- 

^  We  may  speak  of  immunity  "from"  a  disease,  "to"  a  disease,  and 
"against"  a  disease. 

^  Terminal  infections. 

337 


338  IMMUNITY 

gerated  power  of  reaction  and  will  be  discussed  separately  under  anaphy- 
laxis or  allergie.  The  word  resistance  lias  practically  tlie  same  sig- 
nification as  immunity.  The  term  "tolerance"  is  conimoiily  used  to 
describe  a  limited  form  of  immunity  usually  acquired  by  the  repeated 
use  of  alkaloids,  alcohol,  and  other  poisons  of  comparatively  simple 
chemical  structure.  While  a  high  degree  of  tolerance  may  be  acquired 
to  such  substances,  a  true  immunity  in  the  sense  in  which  the  term  is 
now  used  is  never  produced.  In  the  case  of  tolerance,  antibodies  are 
not  found  in  the  blood.  For  the  most  part  true  immunity  is  produced 
against  colloidal  substances,  while  tolerance  is  largely  limited  to  the 
crystalloids;  this  distinction,  however,  is  not  absolute. 

There  are  all  gradations  and  various  kinds  of  immunity.  It  varies 
in  degree  from  the  weakest  appieciable  amount  to  an  almost  absolute 
protection.  It  also  varies  greatly  in  duration — from  the  briefest  period 
to  a  life  span.  Immunity,  therefore,  is  a  relative  term.  It  may  be 
natural  or  acquired,  active  or  passive,  local  or  general,  pure  or  mixed, 
specific  or  general,  family  or  racial,  brief  or  lasting,  strong  or  weak, 
etc. 

Immunity  is  a  function  which  is  not  limited  to  man  and  other  mem- 
bers of  the  animal  kingdom.  It  is  common  througliout  the  vegetable 
kingdom.  ^Ye  are  indebted  to  Welch  for  the  thought  that  the  bacteria 
themselves  also  have  this  fundamental  property  of  life.  Thus,  man  is 
susceptible  to  the  tubercle  bacillus  because  the  tubercle  bacillus  is  im- 
mune to  man;  on  the  other  hand,  man  is  immune  to  the  hay  bacillus 
because  the  hay  bacillus  is  susceptible  to  man.  In  this  sense  a  micro- 
organism is  called  pathogenic  or  non-pathogenic,  depending  upon 
whether  it  harms  or  is  favored  by  its  host.  This  is  the  relation  be- 
tween seed  and  soil.  A  fertile  soil  is  susceptible;  a  barren  soil  is  im- 
mune. The  seed  in  the  first  instance  may  be  pathogenic ;  in  the  second 
non-pathogenic.  The  host  is  able  to  resist  the  intrusion  and  growth  of 
the  non-pathogenic  microorganisms  and  protect  itself  against  harm 
through  its  mechanism  of  immunity.  If  the  protecting  devices  are  in- 
sufficient to  guard  against  attack,  the  germs  multiply,  produce  poisonous 
substances,  or  harm  the  host  in  other  ways.  The  reason  that  the  same 
microorganism  may  be  pathogenic  for  one  host  and  harndess  for  another 
depends  upon  the  presence  or  lack  of  immunity.  The  virulence  of  a 
microorganism  is  an  expression  of  the  intensity  of  the  relation  between 
the  seed  and  the  soil.  Virulence  may  be  strengthened  or  attenuated 
either  b}^  increasing  or  decreasing  the  resistance  of  the  host  or  by  in- 
creasing or  decreasing  the  resistance  of  tlie  microbe. 

Mechanism  of  Immunity — Theories  of  Immunity. — It  is  now  quite 
evident  that  the  mechanism  of  immunity  varies  in  different .  infections 
and,  to  a  certain  extent,  even  in  the  same  infection  under  different  con- 
ditions.    It  must  further  be  admitted  that  we  are  still  in  ignorance  of 


MECHANISM    AND    THEOEY  339 

the  mechanism  by  which  the  body  protects  itself  against  many  dis- 
eased states. 

Historically  considered,  immunology  as  a  science  dates  back  scarcely 
30  years.  Many  primitive  people  attempted  to  immunize  themselves  in 
a  crude  sort  of  way,  but  with  methods  now  recognized  as  essentially 
sound.  Thus,  South  African  tribes  tried  to  protect  themselves  against 
snake  bites  by  using  a  mixture  of  snake  venom  and  gum;  the  Moors 
immunized  cattle  to  pleural  pneumonia  by  placing  some  of  the  virus 
under  the  skin  of  the  animal.  The  inoculation  against  smallpox  used 
from  time  immemorial,  and  vaccination  with  cowpox  introduced  by 
Jenner  in  1798,  are  examples  of  the  first  practical  use  of  specific  meth- 
ods in  .the  history  of  immunity. 

Pasteur  was  greatly  influenced  by  Jenner's  demonstration  that  a 
mild  form  of  a  disease  protects  against  the  severe  form.  Pasteur  ex- 
panded the  fact  taught  by  Jenner  into  a  general  principle.  Practically 
all  of  Pasteur's  work  in  immunity  that  bore  practical  fruit,  such  as 
vaccinations  against  chicken  cholera,  anthrax,  and  rabies,  is  based  upon 
this  guiding  principle. 

Pasteur  in  1888  expounded  his  "exhaustion"  theory,  which  was  the 
first  attempt  at  a  scientific  explanation  of  immunity.  Pasteur  was  a 
chemist  and  his  theory  was  a  simple  chemical  conception,  largely  based 
upon  his  work  upon  the  fermentation  of  sugar  with  yeasts.  He  re- 
garded the  body  immune  because  its  food  supply  was  used  up  and  the 
microorganisms  could,  therefore,  no  longer  grow — just  as  yeasts  cease 
to  grow  when  the  sugar  is  used  up  in  a  culture  medium.  It  is  now 
easy  to  disprove,  the  exhaustion  theory.  Bacteria  do  not  cease  to  grow 
on  account  of  the  exhaustion  of  the  food  supply,  but  rather  on  account 
of  the  production  of  products  toxic  to  themselves.  Further,  bacteria 
may  grow  well  enough  in  the  dead  tissues  and  fluids  of  immune  animals, 
and,  again,  immunity  may  be  induced  by  the  inoculation  of  dead  bac- 
terial products,  substances  which  can  hardly  use  up  food  material.  Ee- 
cently  Pasteur's  exhaustion  theory  has  been  revived  in  a  modified  form 
by  Ehrlich,  who  considers  that  there  is  sufficient  evidence  for  this  form 
of  immunity  in  certain  cases,  as  in  cancer.  Ehrlich  calls  it  "atreptic" 
immunity. 

Chauveau  proposed  the  "retenlion"  theory,  the  exact  opposite  of  the 
exhaustion  theory.  This  theory  is  also  based  upon  the  analogy  of  the 
behavior  of  bacterial  growth  in  vitro  compared  to  their  growth  within 
the  body.  It  soon  became  evident  that  bacterial  growth  ceases  even 
though  abundant  food  is  present,  and.  that  this  inhibition  is  due  to  the 
retention  of  products  of  metabolism  of  bacterial  activity.  Chauveau 
considers  that  such  substances  are  retained  within  the  body,  which  thus 
protects  it  against  further  growth  and  development  of  the  microorgan- 
isms and  thus  accounts  for  immunity. 


340  IMMUNITY 

The  above  theories  are  generalizations  which  have  now  little  more 
than  historical  interest.  We  now  know  that  no  one  mechanism  of  im- 
munity will  explain  all  cases.  In  some  instances  phagocytosis  plays 
an  important  part;  in  others  antibodies  of  various  sorts;  the  side-chain 
theory  appears  to  account  for  most  of  the  facts  in  antitoxic  immunity. 
In  some  cases  the  immunity  is  due  to  a  negative  property  in  that  there 
is  an  absence  of  specific  affinity  between  the  poison  and  the  cells.  In 
others  it  is  a  positive  factor  and  is  due  to  the  presence  of  substances 
able  to  neutralize  the  toxic  action.  The  mechanism  of  immunity  in 
some  instances  resides  mainly  in  the  blood  and  fluids;  in  other  cases 
it  is  evidently  more  directly  associated  with  cellular  activity.  In  some 
instances  immunity  depends  upon  the  power  of  immediate  reaction  in 
the  sense  of  anaphylaxis.  In  all  cases  the  mechanism  is  probably  com- 
plex and  multiple. 

The  unsatisfactory  state  of  our  knowledge  in  certain  fields  of  im- 
munity is  well  illustrated  in  the  case  of  anthrax.  The  mechanism  of 
protection  is  not  at  all  understood  in  this  infection,  which  was  the  first 
and  classic  illustration  of  a  germ  disease.  The  mechanism  of  immu- 
nity in  common  colds  is  also  complex  and  obscure. 

Our  resistance  to  disease  is  in  many  cases  due  to  a  simple  mechani- 
cal or  chemical  protection  against  the  invasion  of  the  pathogenic  micro- 
organisms; that  is,  the  tissues  are  susceptible  enough,  but  are  guarded 
against  the  invasion  of  the  germs  of  disease.  Many  examples  may  be 
cited  in  this  category.  Thus,  one  of  the  important  functions  of  the 
skin  consists  in  this  mechanical  protection  of  the  tissues  underneath. 
The  smooth  conjunctiva  is  protected  by  the  constant  washing  of  the 
tears  and  the  motion  of  the  eyelids.  The  lungs  are  safeguarded  by  the 
shape  of  the  upper  respiratory  passages  and  the  moisture  of  the  mucous 
membranes,  which  act  as  a  mechanical  trap  for  many  bacteria.  Some 
of  those  that  pass  deeper  are  carried  back  by  the  mechanical  action  of 
the  cilia.  The  sensitive  and  susceptible  mucous  membrane  of  the  in- 
testines is  partly  protected  through  the  acidity  of  the  gastric  juice, 
which  is  sufficient  to  destroy  cholera  vibrios  and  other  microorganisms 
susceptible  to  acid. 

Within  the  body  the  mechanism  of  immunity  is  an  adaptation  of 
cell  nutrition.  The  mechanism  varies  with  different  infections  and  in 
different  stages  of  the  same  infection.  In  certain  diseases  the  immu- 
nity seems  to  reside  mainly  in  th^  activity  of  the  cells.  In  other  dis- 
eases the  immunity  is  due  chiefly  to  substances  floating  in  the  blood. 
The  first  is  the  cellular  and  the  second  the  humoral  theory.  As  we  shall 
have  occasion  to  see,  the  immune  bodies  in  the  blood  are  probably  in 
all  cases  derived  from  the  cells,  so  that  the  cells  play  the  fundamental 
part  in  most  cases  of  immunity.  However,  the  great  majority  of  the 
studies  in  immunology  have  been  focused  upon  the  changes  in  the  blood. 


^"ATUKAL    IMMUNITY  341 

This  is  not  due  to  the  fact  that  the  blood  alone  represents  these  changes, 
but  that  it  best  represents  them,  and  thus  affords  the  readiest  method 
of  attacking  the  problem.  The  blood  is  the  most  fluid  and  most  cos- 
mopolitan of  all  the  tissues  of  the  body,  visiting  every  part,  bearing  to 
each  part  certain  substances,  and  removing  from  each  part  certain  other 
substances.  It  is  evident  that  it  is  easy  to  study  the  blood  and  its 
changes,  as  some  of  it  may  readily  and  repeatedly  be  withdrawn  during 
life  in  order  to  observe  its  changes  without  in  any  wa}"  harming  the 
animal.  The  fundamental  processes  of  immunity  within  the  body  must 
all  depend  upon  some  chemical  change,  but  we  know  very  little  con- 
cerning the  chemical  composition  of  the  substances  that  play  the  chief 
role  or  the  chemical  nature  of  the  changes.  Great  advances  have  been 
made  in  immunology  despite  this  lack  of  chemical  knowledge;  for  these 
advances  we  are  indebted  to  experimental  biolog}^,  through  which  we 
have  learned  the  results  of  many  effects  without  a  knowledge  of  their 
nature  or  the  intimate  processes  concerned. 

Natural  Immunity. — Xatural  immunity  is  an  inherited  character 
possessed  in  common  by  all  individuals  of  a  given  species.  It  is  in- 
herent to  a  greater  or  less  extent  in  all  members  of  that  species.  It 
may  be  present  at  birth  or  develop  in  later  years.  There  are  very  many 
examples  of  natural  immunity.  Thus,  most  of  the  communicable  in- 
fections of  man  are  peculiar  to  man;  that  is,  the  lower  animals  have  a 
natural  immunity  to  such  diseases  as  measles,  mumps,  scarlet  fever, 
typhoid  fever,  cholera,  gonorrhea,  syphilis,  yellow  fever,  malaria, 
leprosy,  and  so  on  through  a  long  repertoire.^  Even  tuberculosis,  which 
is  the  most  common  and  widespread  of  infections,  has  its  own  particu- 
lar bacillus  to  which  man  is  especially  susceptible  and  to  whicli  the 
lower  animals  show  a  marked  degree  of  natural  immunity.  On  the 
other  hand,  man  shows  a  high  grade  of  natural  immunity  to  a  large 
number  of  infections  to  which  the  lower  animals  are  subject,  as  rinder- 
pest, black  leg  (symptomatic  anthrax),  Texas  fever,  etc. 

The  monopoly  which  man  possesses  of  being  susceptible  to  infec- 
tions which  the  lower  animals  successfully  resist  is  not  confined  to  the 
bacteria  alone,  but  includes  many  protozoa  and  higher  animal  parasites. 
Thus,  the  hookworm  of  man  is  different  from  the  hookworm  of  the 
horse,  the  dog,  the  seal.  Each  host  has  its  own  species  of  hookworm 
which,  though  closely  allied,  are  not  interchangeable.  That  is,  the 
horse  has  a  natural  immunity  to  the  hookworm  that  is  parasitic  for 
man,  and  vice  versa. 

There  is  a  group  of  infections,  including  the  pyogenic  cocci,  an- 
thrax, tetanus,  malignant  edema,  glanders,  actinomycosis,  rabies,  plague, 

^  It  is  true  that   some   of  these  infections   may  be  conveyed  to  monkeys   or 
other  animals  by   artificially  introducing  large   amounts   of  the   virus,   but  these 
animals  do  not  contract  these  diseases  naturally  and  therefore  show  a  high  degree 
of  natural  immunity. 
24 


342  IMMUNITY 

foot-and-mouth  disease,  malta  fever,  tuberculosis,  milk  sickness,  infec- 
tions with  the  paratyphoid  bacillus,  ringworm,  and  many  higher  forms 
of  animal  parasites,  which  are  common  to  many  species  in  widely  dif- 
ferent genera. 

There  are  certain  remarkable  facts  connected  with  natural  immu- 
nity. For  example,  white  mice  are  susceptible  to  infections  with  the 
jmeumococcus,  whereas  the  field  mouse  poss^esses  a  high  degree  of  natu- 
ral resistance.  When  we  consider  how  slight  must  be  the  differences 
in  tlie  structure,  the  function,  the  chemistry,  and  tlie  metabolism  in 
the  white  mouse  when  compared  with  its  gray  cousin,  we  begin  to  ap- 
preciate the  subtle  differences  and  perhaps  complex  factors  upon  which 
immunity  depends.  If  we  could  find  out,  for  example,  why  the  goat  is 
resistant  to  tuberculosis  while  domestic  cattle  are  particularly  suscep- 
tible, we  would  have  the  foundation  for  a  specific  preventive  and  cure 
for  that  disease. 

Practically  all  the  individuals  of  a  certain  species  have  about  an 
equal  susceptibility  or  an  equal  immunity  to  a  given  infection.  These 
factors  are  more  constant  than  commonly  supposed.  Laboratory  ani- 
mals react  with  certainty  and  with  striking  uniformity  to  an  infection 
of  known  virulence,  provided  the  virus  is  brought  into  association  with 
certain  tissues.  Thus,  strikingly  uniform  results  are  obtained  from  a 
given  culture  of  plague  introduced  subcutaneously  into  the  guinea  pig, 
or  of  tuberculosis  into  the  peritoneal  cavity  of  the  monkey,  or  of  strep- 
tococci into  the  circulation  of  the  rabbit,  or  of  rabies  under  the  dura 
of  the  dog,  or  of  anthrax  into  the  mouse.  ]\Ian  is  no  exception 
to  this  general  statement,  as  far  as  may  be  judged  from  the  data 
at  hand.  Practically  all  persons  are  alike  susce])tible  to  smallpox, 
yellow  fever,  tetanus,  and  many  other  infections.  In  epidemics  some 
individuals  escape.  In  other  epidemics  the  disease  varies  greatly 
in  severity.  These  apparent  exceptions  may  not  be  due  so  much  to 
varying  degrees  of  immunity,  but  rather  to  variations  in  the  dose  and 
virulence  of  the  virus,  the  channel  of  infection,  symbiosis,  and  other 
factors. 

In  some  cases  the  immunity  is  so  weak  that  the  balance  between 
health  and  disease  is  quite  unstable.  This  appears  to  be  tlie  case  with 
tuberculosis  in  man.  We  possess  sufficient  natural  immunity  to  tuber- 
culosis successfully  to  resist  small  amounts  of  infection,  but  this  re- 
sistance may  readily  be  broken  down  by  any  influences  which  undermine 
our  general  vitality. 

Natural  immunity  may  be  broken  down  by  various  means  that 
weaken  the  animal,  such  as  fasting,  the  production  of  an  experimental 
diabetes  with  phloridzin,  fatigue,  excessive  cooling  of  the  body,  as  the 
clipping  of  the  hair  of  thick-furred  animals,  etc.  Thus,  chickens  are 
ordinarily  naturally  immune  to  anthrax,  but  may  be  infected  if  their 


ACQUIRED    IMMUNITY  343 

feet  are  kept  in  cold  water.  White  rats  are  resistant  to  anthrax,  but 
become  susceptible  if  the  hair  is  clipped. 

Acquired  Immunity. — B}-  acquired  immunity  is  meant  a  specific  re- 
sistance to  an  infection  that  is  not  naturally  inherent  in  all  the  in- 
dividuals of  a  species,  but,  as  the  term  indicates,  the  immunity  is  ac- 
quired during  the  lifetime  of  the  individual.  Immunity  may  be  ac- 
quired either  through  some  "natural"  event,  such  as  an  attack  of  a  dis- 
ease, or  may  be  "artificially"  induced  by  the  introduction  of  some 
substance,  such  as  a  serum,  toxine,  vaccine,  or  a  virus. 

Acquired  immunity  may  be  either  active  or  passive.  Active  immu- 
nity is  induced  by  an  attack  of  a  disease  or  by  the  introduction  of  a 
virus  or  suitable  toxin  into  the  system.  Immunity  thus  acquired  is 
active  in  the  sense  that  it  depends  upon  an  aggressive  stimulation  of 
the  protecting  mechanism  as  a  result  of  a  series  of  reactions  within  the 
body.  Passive  immunitv,  or  transferred  immunity,  is  an  antitoxic  im- 
munity. It  is  passive  for  the  reason  that  the  antibodies  (antitoxin) 
are  introduced  into'  the  body,  which,  therefore,  takes  no  part  in  their 
formation.  The  injection  of  diphtheria  toxine  into  the  horse  causes  an 
active  immunity  in  that  animal;  the  injection  of  some  of  the  antitoxin 
contained  in  the  horse's  serum  into  a  child  causes  a  passive  immunity  in 
the  child.  Both  are  acquired  because  horse  and  man  have  no  inherent 
or  natural  immunity  to  diphtheria.  The  protection  against  smallpox 
produced  by  vaccination  is  an  example  of  active  immunity;  so  also  is 
the  immunity  produced  by  bacterial  vaccines. 

Mixed  Immunity. — Mixed  immunity  is  a  combination  of  the  active 
and  passive.  This  is  used  practically  in  plague  prophylaxis  and  has 
been  proposed  for  other  infections.  It  consists  in  injecting  a  mixture 
of  antitoxin  serum  and  the  appropriate  bacterial  virus.  The  advantage 
of  this  procedure  consists  in  the  fact  that  the  active  or  antitoxin  im- 
munity diminishes  the  severe  reactions  which  sometimes  follow  the  in- 
troduction of  a  bacterial  virus.  It  also  affords  an  immediate  protection 
and  thereby  neutralizes  the  negative  phase  which  is  supposed  to  follow 
an  active  immunization. 

How  Immunity  May  be  Acquired.— Immunity  may  be  acquired  by: 

(a)  An  attack  of  a  disease. 

(b)  By  the  introduction  of  a  virus. 

(c)  By  the  introduction  of  a  vaccine. 

(d)  By  the  introduction  of  a  chemical  product   (toxine). 

(a)  An  Attack  of  the  Disease. — Certain  diseases,  whether  acquired 
naturally  or  induced  artificially,  leave  an  immunity  which  varies  greatly 
in  degree  and  duration.  The  following  diseases  leave  a  definite  immu- 
nity of  high,  though  variable,  grade:  smallpox,  yellow  fever,  measles, 
whooping-cough,  scarlet  fever,  cerebrospinal  meningitis,  infantile  paraly- 


344  IMMUNITY 

sis,  typhoid  fever,  typhus  fever,  chickenpox,  mumps.  Second  attacks 
of  smallpox,  measles,  typhoid  fever,  and  other  infections  in  this  list 
are  not  uncommon,  showing  that  the  immunity  is  rarely  if  ever  ab- 
solute. 

Some  diseases,  such  as  pneumonia,  erysipelas,  and  malaria,  seem  to 
predispose  to  subsequent  attacks,  that  is,  diminish  resistance.  Even  in 
this  class  of  infections  there  must  be  a  certain  amoimt  of  immunity, 
however  short,  else  the  patient  would  not  recover. 

The  practice  of  intentionally  inoculating  smallpox  was  the  first  ex- 
ample in  preventive  medicine  in  which  use  was  made  of  the  fact  that 
one  attack  of  a  disease  confers  immunity  to  a  subsequent  attack  of  the 
same  disease.  The  present-day  vaccination  of  cowpox  (a  modified  small- 
pox) may  be  considered  as  belonging  to  this  category.  The  principle 
is  used  to  a  much  greater  extent  in  veterinary  practice  either  by  using 
a  small  amount  of  the  infection  or  by  introducing  it  in  an  unusual 
way  or  by  inoculating  the  animals  at  a  time  when  they  are  found  to  be 
least  susceptible.  In  this  way  a  benign  form  of  the  disease  is  produced 
which  protects  against  the  severe  and  fatal  forms.  These  methods  are 
used  in  Texas  fever,  rinderpest,  pleuropneumonia,  anthrax,  etc. 

(b)  By  the  Introduction  of  a  Virus  Into  the  System. — A  distinc- 
tion is  made  between  a  virus  and  a  vaccine.  If  the  material  used  con- 
tains the  living  active  principle  it  should  be  called  a  virus.  If  the 
virus  is  dead  it  should  be  called  a  vaccine.^ 

The  highest  and  most  lasting  degrees  of  immunity  may  be  produced 
by  the  introduction  of  the  living  active  principle  into  the  system,  thus 
imitating  nature.  The  virus  may  be  diminished  in  virulence  as  in  an- 
thrax, vaccinia,  or  rabies.  A  high  grade  of  immunity  to  plague  and 
cholera  may  be  induced  in  man  by  the  injection  of  living  cultures.  In 
the  case  of  plague  the  cultures  must  be  greatly  diminished  in  virulence. 
In  the  case  of  cholera  virulent  strains  nuiy  be  used,  as  this  disease  is 
neither  a  bacteremia  nor  septicemia,  and  there  is  very  much  less  danger 
in  introducing  the  cholera  vibrios  into  the  subcutaneous  tissue  than 
in  taking  them  by  the  mouth.  This  principle  of  introducing  the  virus 
into  a  resistant  tissue  can  be  taken  advantage  of  in  various  infections, 
provided  the  virulence  of  the  disease  depends  largely  upon  the  channel 
of  infection.  The  virulence  of  the  virus  may  also  be  diminished  by 
certain  definite  processes,  such  as  growing  the  culture  at  an  unusually 
high  temperature,  as  in  the  case  of  anthrax ;  or  by  prolonged  artificial 
cultivation,  as  in  the  classic  instance  of  chicken  cholera ;  or  by  drying, 
as  in  rabies;  or  by  passage  through  animals,  as  in  smallpox  (cowpox)  ; 
or  by  growing  on  unfavorable  media ;  by  the  use  of  very  small  amounts 
of  the  virus,  as  in  tuberculosis  and  many  other  infections;  or  by  the 

^Vaccine  (vacca,  a  cow)  is  not  a  good  term,  but  is  now  too  deeply  rooted  to 
change. 


ACQUIRED    IMMUNITY  345 

use  of  closely  related  strains,  such  as  the  human  tubercle  bacillus  for 
bovine  immunization.  Repeated  injections  of  a  virus  induce  a  very  high 
and  more  lasting  immunity  than  single  inoculations. 

(c)  By  the  Introduction  of  a  Bacterial  Vaccine. — The  immunity 
produced  by  the  introduction  of  a  vaccine  into  the  body  corresponds 
precisely  to  the  immunity  acquired  by  the  introduction  of  a  virus,  the 
only  difference  being  that  the  living  virus  produces  a  more  lasting  and 
higher  degree  of  protection  than  that  produced  by  the  dead  vaccine. 
The  advantages  of  using  a  vaccine  instead  of  a  virus  are  obvious. 

Dead  bacteria,  when  injected  into  the  tissues,  usually  produce  a  local 
reaction  at  the  site  of  inoculation  and  also  a  general  reaction.  The 
local  reaction  consists  of  swelling,  pain,  redness,  and  other  indications 
of  irritation  and  inflammation.  The  general  reaction  consists  of  fever, 
headache,  pains  in  the  muscles,  especially  in  the  back  and  legs,  malaise, 
and  sometimes  nausea.  The  reactions  usually  come  on  within  a  few 
hours  after  the  vaccine  has  been  introduced  and  rarely  last  longer  than 
24  to  48  hours.  It  is  customary  to  give  the  vaccines  in  the  evening,  for 
then  most  of  the  symptoms  have  passed  by  the  next  morning. 

The  vaccine  is  usually  prepared  from  a  fresh  twenty-four-hour  growth 
of  a  pure  culture  of  the  microorganism  upon  the  surface  of  agar.  In 
this  way  secondary  metabolic  products  in  the  medium  are  avoided  by 
simply  removing  the  surface  growth.  When  liquid  cultures  are  used 
the  foreign  substances  contained  in  the  medium  complicate  the  reactions. 
The  cultures  r,re  usually  killed  by  exposure  to  heat  at  from  53°  to  60°  C. 
for  one  hour.  High  heat,  while  certain  to  kill  the  virus,  is  undesirable, 
for  the  reason  that  it  coagulates  the  albuminous  substances  in  the  germ 
cell  and  otherwise  alters  the  chemical  structure  of  the  microorganism. 
The  closer  the  vaccine  approaches  the  virus  the  better  the  results,  so 
far  as  immunity  is  concerned.  Therefore,  many  investigators  prefer  to 
kill  the  poisons  with  carbolic  acid,  chloroform,  or  some  other  suitable 
germicide. 

The  injections  are  always  given  subcutaneously.  Usually  three  or 
four  injections  are  given  at  intervals  of  about  five  to  ten  days.  Several 
injections  produce  an  immunity  of  much  higher  grade  and  longer  dura- 
tion. In  most  instances  the  acquired  immunity  lasts  from  two  to  five 
years,  and  may  be  renewed. 

Preventive  inoculations  with  bacterial  vaccines  are  now  much  prac- 
ticed in  the  case  of  typhoid  fever,  plague,  and  cholera,  and  are  destined 
to  be  extended  to  other  infections.  The  dose  and  details  have  been 
discussed  under  each  disease. 

A  negative  phase  is  said  to  follow  the  introduction  of  a  vaccine  or  a 
virus;  that  is,  a  diminished  resistance  appears  to  be  produced  before  the 
curve  rises.  The  negative  phase  varies  in  degree,  depending  upon  the 
amount  and  virulence  of  the  vaccine  and  the  power  of  the  body  to  react. 


346  IMMUNITY 

It  varies  in  time  from  a  few  hours  to  several  days.  The  negative  phase 
is  an  assumption  based  upon  a  primary  diminution  in  the  amount  of 
specific  opsonins  in  the  blood,  but  it  is  doubtful  whether  the  opsonic 
index  is  a  true  index  of  the  presence  or  absence  of  immunity,  wliich  is 
dependent  upon  other  factors.  From  a  practical  standpoint,  the  negative 
phase  can,  as  a  rule,  be  disregarded ;  that  is,  bacterial  vaccines  are  not 
contraindicated  during  the  period  of  incubation. 

Specificity.' — Most  of  the  reactions  in  immunology  are  specific — 
not  absolutely  so,  but  relatively;  that  is,  antibodies,  such  as  agglutinins, 
lysms,  precipitins,  or  opsonins,  usually  act  upon  the  corresponding  an- 
tigen with  much  greater  vigor  than  upon  any  other.  An  immunity  to 
one  disease,  no  matter  how  produced,  whether  natural  or  acquired,  af- 
fords no  protection  against  other  diseases.  There  is,  however,  no  abso- 
lute specificity,  just  as  there  is  no  absolute  immunity. 

Certain  microorganisms  and  their  toxic  products  show  a  remarkable 
predilection  for  certain  cells  or  tissues.  In  this  sense  a  microparasite 
or  a  toxin  may  be  as  specific  in  its  action  as  a  qualitative  chemical  re- 
action. Thus,  there  is  a  specific  relation  between  tetanus  toxin  and 
nervous  matter,  while  the  poison  has  little  or  no  affinity  for  other  tis- 
sues. The  poison  of  infantile  paralysis  picks  out  certain  cells  in  the 
central  nervous  system  upon  which  it  acts  specifically.  Also  in  rabies 
the  brunt  of  the  lesions  fall  upon  the  cells  of  the  central  nervous  sys- 
tem. The  toxic  products  of  the  BacUJus  hotidismus  is  also  a  specific 
nerve  poison,  and  at  least  one  of  the  poisons  in  diphtheria  toxine  (toxone) 
acts  specifically  upon  the  nerves.  The  toxic  substances  may  also  reacf 
upon  less  important  or  indifferent  tissues,  but  such  action  is  often 
masked.  The  specific  action  of  toxins  explains  in  part  the  local  immu- 
nity enjoyed  by  some  tissues  and  further  explains  why  certain  viruses 
are  comparatively  harmless  when  introduced  into  the  body  through 
unaccustomed  channels.  We  have  already  seen  an  example  of  this  in 
a  case  of  cholera  when  introduced  into  the  subcutaneous  tissue.  In 
this  case  the  subcutaneous  tissue  is  resistant  to  the  invasion  of  the 
cholera  vibrio,  and  these  microorganisms  cannot  find  their  way  to  the 
intestinal  tract.  The  case  of  smallpox  is  instructive,  for  this  is  an  in- 
fection for  which  the  epithelial  structures  have  a  specific  susceptibility. 
It  is  practically  impossible  to  infect  a  susceptible  animal  with  cowpox 
when  the  virus  is  introduced  subcutaneously  or  directly  into  the  cir- 
culation. The  same  is  probably  true  of  smallpox.  When  smallpox 
virus  is  introduced  by  inoculation  upon  the  skin  the  disease  is  much 
milder  than  when  the  virus  is  introduced  by  way  of  the  respiratory 
tract.  Evidently  the  skin  offers  greater  resistance  to  the  smallpox 
virus  than  is  offered  by  the  mucous  membranes.  On  the  other  hand, 
foot-and-mouth  disease  cannot  be  given  to  man  or  the  cow  when  rubbed 
upon  the  skin,  although  these  animals  are  very  susceptible  when  this 


LOCAL    AXD    GEXEEAL    IMMUXITY  347 

virus  is  introduced  into  the  general  circulation  or  rubbed  upon  the  mu- 
cous membrane  of  the  mouth.  Every  worker  in  a  bacteriological  labora- 
tory is  familiar  -with  the  difference  in  susceptibility  of  different  tis- 
sues and  knows  the  imporiance  in  experimental  work  of  bringing  the 
virus  in  association  with  appropriate  structures. 

Certain  microorganisms,  such  as  tuberculosis,  pus  cocci,  the  pneumo- 
coccus,  etc.,  have  the  power  of  affecting  almost  every  tissue  and  organ 
of  the  body.  Xo  part  of  the  body  is  immune  to  the  tubercle  bacillus, 
but  even  in  this  infection  some  tissues  are  more  susceptible  than  others. 
Thus,  tuberculosis  of  the  muscle  is  extremely  rare ;  the  lungs  and  hnnph 
nodes  are  especially  vulnerable. 

The  stomach  is  comparatively  rarely  attacked  by  infective  processes, 
although  constantly  exposed.  The  vaginal  mucous  membrane  in  the 
adult  and  the  bladder  are  resistant  to  gonorrheal  inflammations.  There 
are  many  similar  instances  of  specific  immunity  of  tissues. 

The  specific  action  of  toxins  gives  us  a  ready  reason  why  certain 
species  of  animals  are  immune  to  certain  infections.  In  this  case 
the  immunity  is  not  the  result  of  any  special  or  specific  reaction,  nor 
is  it  the  result  of  any  positive  character  possessed  or  acquired  by  the 
body,  but  is  a  negative  trait  entirely,  due  to  the  absence  of  specific 
chemical  affinity  between  the  cells  and  the  toxin.  The  turtle  is  im- 
mune to  tetanus  because  there  is  no  combining  affinity  between  the  nerve 
cells  of  the  turtle  and  tetanus  toxin.  The  immunity,  therefore,  depends 
upon  the  absence  of  the  appropriate  cell  receptors.  Eats  are  highly 
immune  to  diphtheria  toxin  and  hogs  to  snake  venom.  In  these  cases 
antitoxin  cannot  be  demonstrated  in  the  blood  of  the  rat  or  the  hog, 
and,  so  far  as  can  be  determined,  when  the  toxin  is  injected  into  these 
animals  it  is  not  neutralized  in  the  body.  The  simplest  conception  of 
the  mechanism  of  immunity  in  these  cases  is  to  regard  it  as  depending 
upon  a  negative  factor  resulting  upon  the  absence  of  suitable  receptors 
in  the  sense  of  Ehrlich's  side-chain  theory. 

Local  and  General  Immunity. — Local  and  general  immunity  de- 
pends upon  this  variation  in  susceptibility  of  the  different  tissues  to 
different  infections.  It  is  doubtful  if  there  is  a  true  general  immu- 
nity in  any  case,  for  a  general  immunity  is  in  almost  all  instances 
based  upon  a  local  resistance.  Even  antitoxic  immunity  in  diphtheria, 
due  to  the  antibodies  in  the  general  circulating  blood,  is  the  result 
of  a  localized  neutralization  in  which  many  of  the  organs  and  tis- 
sues of  the  body  take  no  part.  There  are  many  examples  of  local 
immunity.  Trichina  spiralis  affects  especially  the  muscles  and  never 
the  bones.  Diphtheria  seldom  extends  down  the  esophagus.  The  most 
marked  example,  perhaps,  is  the  almost  perfect  local  immunity  of  the 
scalp  to  ringworm  in  adults,  which  contrasts  so  markedly  with  the  ab- 
solute susceptibility  of  children,  whereas  the  susceptibility  of  the  skin 


348  IMMUNITY 

of  the  body  to  the  same  parasite  is,  if  anything,  greater  in  adults  than 
in  children   (Emery). 

Many  remarkable  instances  of  local  immunity  are  shown  by  the  tis- 
sues and  must  be  familiar  to  all.  Thus,  erysipelas  does  not,  as  a  rule, 
extend  into  the  subcutaneous  tissues,  although  the  streptococcus  may  be 
there;  rarely  does  it  extend  back  into  the  area  of  the  skin  recently 
affected. 

The  immunity  of  a  part  is  increased  or  diminished  by  the  presence 
or  absence  of  an  adequate  blood  supply.  As  a  rule,  very  vascular  struc- 
tures enjoy  a  comparative  immunity  to  infections  which  frequently 
attack  other  tissues  relatively  poor  in  blood  supply.  It  may  be  stated 
as  a  general  rule  that  the  more  copious  the  supply  of  healthy  circulat- 
ing blood  the  greater  the  resistance  to  infection,  and  vice  versa.  This 
largely  accounts  for  the  local  immunity  enjoyed  by  the  mucous  mem- 
brane of  the  mouth  and  lips,  which  are  constantly  exposed  to  wound 
infections.  Herein  we  also  have  an  explanation  of  the  utility  of  fo- 
mentations and  other  hot  applications  in  the  initial  stages  of  an  in- 
fective lesion.  The  same  explanation  is  applied  to  Bier's  method  of 
passive  congestion,  in  which  an  excess  of  blood  (though  partly  stag- 
nant) is  made  to  flush  the  tissues.  The  local  immunity  of  the  part 
may  be  diminished  by  a  local  anemia  from  any  cause,  by  the  presence 
of  dead  or  injured  tissue,  by  the  action  of  irritants,  trauma,  etc. 

Metchnikoff  has  pointed  out  tliat  in  many  infections  general  pro- 
tection is  in  inverse  ratio  to  the  local  reaction  at  the  site  of  introduc- 
tion of  the  virus.  A  severe  and  prompt  local  inflammatory  reaction 
indicates  an  active  power  of  protection.  The  increased  volume  of  blood, 
the  cells,  the  fluids  of  the  blood  and  tissues  are  concentrated  about  the 
invading  bacteria  to  wall  them  off  and  destroy  them,  that  is  the  im- 
munity of  the  body  against  a  general  infection  frequently  depends  upon 
the  promptness  and  the  activity  of  the  local  power  of  reaction. 

Some  infections,  notably  streptococci,  plague,  or  organisms  belong- 
ing to  the  hemorrhagic-septicemic  group,  may  invade  the  body  with 
little  or  no  local  inflammatory  reaction;  that  is,  little  or  no  barrier  is 
set  up  against  these  microorganisms,  they  invade  the  blood  and  tissues 
without  resistance  and  thus  cause  fatal  septicemias. 

Bacillus  Carriers  or  Immunitas  Non  Sterilans.— Upon  recovery  from 
an  infective  process  the  body  usually  rids  itself  completely  of 
the  infecting  agent.  In  other  words,  the  immunity  which  follows  an 
attack  of  an  infectious  disease  is  usually  associated  with  a  power  the 
body  has  of  disinfecting  itself.  In  most  cases  the  patient  is  convales- 
cent or  completely  restored  to  health  before  the  cause  of  the  disease 
has  disappeared  from  the  tissues.  This  bespeaks  a  .vigorous  protecting 
mechanism,  but  when  this  resistance  is  lowered  for  any  reason  a  relapse 
may  ensue. 


BACILLUS    CAEEIEES  349 

In  many  instances  recovery  takes  place,  but  tlie  living  virulent 
microorganisms  continue  to  live  in  the  body.  This  constitutes  immu- 
nity without  sterilization,  a  term  introduced  by  Ehrlich,  though  a 
more  precise  expression  would  be  "immunity  without  disinfection." 
Such  persons  are  now  known  as  'Tjacillus  carriers."  The  immunity 
protects  the  carrier  but  endangers  his  fellownien.  Bacillus  carrying 
is  common  in  diphtheria,  typhoid  fever,  cholera,  pneumonia,  epidemic 
cerebrospinal  meningitis,  influenza,  and  many  other  bacterial  infec- 
tions. Protozoon  carriers  are  also  a  common  phenomenon.  The  best 
examples  are  found  in  malaria,  trypanosomiasis,  Texas  fever  in  cattle, 
etc.  Analogous  instances  are  also  found  in  the  higher  parasitic  worms 
in  which  the  individual  who  carries  the  parasite  is  not  affected.  Thus, 
the  negro  and  the  Filipino  show  a  relatively  high  degree  of  immunity 
to  the  hookworm  and  thus  endanger  their  more  susceptible  white  com- 
panion. 

An  acute  bacillus  carrier  is  one  who  sheds  the  specific  agent  of  the 
disease  for  a  few  weeks — four  to  six  following  convalescence.  A  chronic 
bacillus  carrier  is  one  who  harbors  and  discharges  the  specific  agent  a 
longer  period  than  six  weeks.  A  temporarij  carrier  is  one  who  harbors 
the  specific  infective  agent,  although  he  himself  has  never  had  symp- 
toms of  the  disease.  Temporary  carriers  may  be  acute  or  chronic,  de- 
pending upon  the  length  of  time  they  harbor  the  particular  parasite. 

Bacillus  carriers  play  an  important  role  in  spreading  infections. 
They  explain  many  mysterious  facts  in  the  epidemiology  of  diphtheria, 
typhoid  fever,  cholera,  cerebrospinal  meningitis,  malaria,  etc.  The 
bacillus  carrier  is  sometimes  a  danger  to  himself.  This  is  seen  in  diph- 
theria, pneumonia,  influenza,  and  sometimes  in  typhoid  and  cholera. 
Thus,  a  person  may  carry  the  pneumococcus  in  his  throat  for  years 
awaiting  certain  favorable  conditions  for  infection  before  he  contracts 
the  disease.     The  same  is  more  or  less  true  of  other  carriers. 

While  it  is  undoubtedly  true  that  bacillus  carriers  play  a  very  im- 
portant role  in  spreading  infection  from  man  to  man,  the  relative  im- 
portance compared  with,  other  modes  of  transmission  cannot  be  stated 
in  percentage.  The  subject  is  still  too  young  for  definite  quantitative 
figures.  There  is  no  doubt  that  bacillus  carriers  are  more  important 
in  some  diseases  than  others  and  play  a  variable  role  under  different 
circumstances  in  the  same  disease.  In  our  studies  of  typhoid  fever 
in  Washington  one  carrier  was  discovered  in  the  examination  of  986 
healthy  individuals.  This  would  mean  approximately  300  typhoid 
bacillus  carriers  in  the  District  of  Columbia.  If  this  proportion  is  cor- 
rect, it  would  account  for  the  endemicity  of  typhoid  fever  in  Washing- 
ton. Perhaps  the  residual  typhoid  fever  in  many  places  is  largely  kept 
alive  through  bacillus  carrying,  and  there  is  little  doubt  that  the  grad- 
ual decline  of  typhoid  fever  after  great  sanitary  reforms,  such  as  the 


350  IMMUNITY 

change  from  polluted  to  pure  water,  is  due  to  the  decrease  in  the  number 
of  carriers.  It  now  seems  evident  that  polluted  water  and  infected  milk 
will  not  always  cause  the  disease  directly  in  the  persons  drinking  these 
fluids,  but  may  produce  numerous  carriers  who  either  contract  the  disease 
themselves  subsequently  or  give  it  to  others  by  passing  the  virus  on  in  a 
more  concentrated  and  virulent  form,  or  to  more  susceptible  individuals. 

It  is  evident  from  the  nature  of  the  case  that  the  cure  and  control 
of  bacillus  carriers  is  one  of  the  vital  problems  in  preventive  medicine. 
It  is  not  only  largely  through  them  that  infection  is  spread,  but  the 
infections  themselves  are  kept  alive  in  these  carriers,  who  bridge  over 
the  interval  between  outbreaks.  It  is  quite  conceivable  that  with  our 
modern  methods  of  isolation  and  disinfection  certain  diseases  would 
soon  cease  to  exist  were  it  not  for  immunitas  non  stenlans. 

Immunity  is,  therefore,  a  double-edged  sword,  in  that  it  protects  the 
carrier  but  endangers  his  neighbor.  The  control  of  bacillus  carriers  is 
a  difficult  problem.  Such  unfortunate  persons  cannot  always  be  im- 
prisoned, nor  is  strict  isolation  always  necessary.  It  is  sufficient  in  the 
case  of  t}'phoid  fever  to  restrict  the  activity  of  the  carrier.  Thus,  a 
typhoid  carrier  should  not  cook,  prepare,  or  handle  food,  or  have  any- 
thing to  do  with  the  production  or  distribution  of  milk.  We  have  no 
satisfactory  cure  for  carriers;  this  is  a  problem  for  the  future;  but 
their  number  may  be  lessened — this  is  a  problem  for  the  present. 

It  should  always  be  remembered  that  the  number  of  carriers  will 
diminish  proportionately  with  the  number  of  cases  of  any  infection, 
and  that  every  improvement  in  the  water  supply,  the  milk  supply,  the 
food  supply,  and  our  sanitary  conditions  generally  will  have  a  tendency 
to  sharply  diminish  the  number  of  carriers  in  any  given  infection. 
Therefore,  while  isolation,  disinfection,  and  other  methods  used  to 
control  the  spread  of  infection  will  never  be  completely  successful  as 
long  as  the  carrier  is  omitted,  nevertheless,  these  methods  are  entirely 
justified  even  though  only  partially  useful.  It  is  the  duty  of  public 
health  officers  to  check  the  spread  of  infection  wherever  it  may  be 
found.  In  time  ready  methods  of  recognizing  bacillus  carriers  and 
means  of  neutralizing  their  potential  danger  will  be  more  effective 
than  is  now  possible. 

Latency  is  closely  allied  to  bacillus  carrying.  The  malarial  para- 
site may  remain  latent  in  the  spleen  and  other  internal  organs  for 
years,  during  which  time  the  person  remains  in  good  health.  But 
when  the  resistance  is  reduced  by  exposure,  fatigue,  starvation,  or  other 
depressing  influences  the  disease  again  breaks  out.  The  gonococcus 
may  also  remain  latent  for  years.  I  am  familiar  with  one  instance  in 
which  the  tubercle  bacillus  remained  latent  in  the  axillary  glands  for 
10  years  and  then  became  active  owing  to  a  condition  of  depressed 
vitality.     Typhoid  ostitis  may  develop  years  after  an  attack  of  typhoid 


LOWEEED    RESISTANCE  351 

fever,  and  we  can  only  assume  that  the  bacilli  have  remained  latent 
in  the  tissues  all  that  time.  The  phenomenon  of  latency  also  occurs 
in  rabies,  tetanus,  and  other  infections. 

Lowered  Resistance. — The  factors  which  lower  our  general  resist- 
ance to  disease  are  many  and  varied.  The  condition  known  as  depressed 
vitality,  lowered  tone,  general  debility,  weakened  constitution,  and 
terms  of  similar  import  imply  a  condition  in  which  immunity  is  low- 
ered in  a  general  and  not  in  a  specific  sense.  The  principal  causes 
which  diminish  resistance  to  infection  are:  wet  and  cold,  fatigue,  in- 
sufficient or  unsuitable  food,  vitiated  atmosphere,  insufficient  sleep  and 
rest,  worry,  and  excesses  of  all  kinds.  The  mechanism  by  which  these 
varying  conditions  lower  our  immunity  must  receive  our  attention,  for 
they  are  of  the  greatest  importance  in  preventive  medicine.  It  is  a 
matter  of  common  observation  that  exposure  to  wet  and  cold  or  sudden 
changes  of  temperature,  overwork,  worry,  stale  air,  poor  food,  etc.,  make 
us  more  liable  to  contract  certain  diseases.  The  tuberculosis  propa- 
ganda that  has  been  spread  broadcast  with  such  energy  and  good  effect 
has  taught  the  value  of  fresh  air  and  sunshine,  good  food,  and  rest  in 
increasing  our  resistance  to  this  infection. 

There  is,  however,  a  wrong  impression  abroad  that,  because  a  low- 
ering of  the  general  vitality  favors  certain  diseases,  such  as  tuber- 
culosis, common  colds,  pneumonia,  septic  and  other  infections,  it 
plays  a  similar  role  in  all  the  communicable  diseases.  Many  infections, 
such  as  smallpox,  measles,  yellow  fever,  tetanus,  whooping-cough,  ty- 
phoid fever,  cholera,  plague,  scarlet  fever,  and  other  diseases,  have  no 
particular  relation  whatever  to  bodily  vigor.  These  diseases  often  strike 
down  the  young  and  vigorous  in  the  prime  of  life.  The  most  robust 
will  succumb  quickly  to  tuberculosis  if  he  receives  a  sufficient  dose  of 
the  virulent  microorganisms.  A  good  physical  condition  does  not  al- 
ways temper  the  virulence  of  the  disease;  on  the  contrary,  many  in- 
fections run  a  particularly  severe  course  in  strong  and  healthy  subjects, 
and,  contrariwise,  may  be  mild  and  benign  in  the  feeble.  Physical 
weakness,  therefore,  is  not  necessarily  synonymous  with  increased  sus- 
ceptibility to  all  infections,  although  true  for  some  of  them.  In  other 
words,  "general  debility"  lowers  resistance  in  a  specific,  rather  than  in 
a  general,  sense. 

The  mechanism  by  which  the  various  causes  that  lower  vitality  and 
increase  susceptibility  act  is  in  most  cases  quite  obscure.  Here  is  a  field 
for  laboratory  research  in  immunology  that  offers  rich  reward  of  im- 
measurable practical  good.  Some  of  the  factors  concerned  will  be 
briefly  discussed. 

Exposure  to  wet  and  cold,  especially  in  combination,  is  a  frequent 
source  of  lowered  resistance.  The  exact  way  in  which  such  exposure 
acts  is  not  definitely  known^  but  laboratory  researches  offer  material 


352  IMMUNITY 

for  a  number  of  suggestions.  Emery  ^  sums  up  our  knowledge  upon 
this  subject  as  follows: 

"Immunity  is  to  a  very  large  extent  a  function  of  the  leukocytes, 
which  are  specialized  cells  to  which  the  defense  of  the  body  is  entrusted. 
Now,  the  functions  (movement  and  phagocytosis)  which  can  be  easily 
investigated  are  found  to  be  do])endent  in  a  very  high  degree  on  tem- 
perature, acting  best  at  the  temperature  of  the  body,  or  sliglitly  above; 
and  it  is  highly  probable  that  the  more  subtle  functions  of  the  leuko- 
cytes may  be  similarly  depressed  by  a  low  temperature.  The  exposure 
of  the  skin  to  cold,  especially  if  the  animal  heat  be  abstracted  more 
quickly  by  evaporation  of  moisture  on  the  surface,  will  lead  to  a  cool- 
ing of  the  blood  which  circulates  through  it,  and  hence  to  a  slight, 
though  appreciable,  cooling  of  the  whole  blood.  This,  it  is  true,  is 
soon  compensated  for,  and  no  great  amount  of  cooling  of  the  whole  body 
occurs;  Ijut,  even  so,  it  is  quite  possible  that  the  periodical  chilling  of 
the  leukocytes  during  their  repeated  passages  through  the  cold  skin 
may  be  sufficient  to  diminish  greatly  their  functional  activity,  and  to 
lower  the  resistance  to  a  point  at  which  infection  may  occur,  and  when 
once  pathogenic  bacteria  have  gained  a  foothold  the  resistance  will  for 
a  time  tend  to  decrease.  There  is  also  some  evidence  going  to  show 
that  exposure  to  cold  may  lessen  the  production  of  the  defensive  sub- 
stances which  occur  in  the  blood  (alexin,  antibodies,  etc.),  though  this 
is  not  fully  proved.  It  is  worthy  of  note  that  the  loss  of  immunity  due 
to  the  action  of  cold  and  wet  on  one  part  of  the  body  (such  as  the 
feet)  is  a  general  one,  and  may  result  in  a  nasal  catarrh,  an  attack  of 
pneumonia,  acute  rheumatism,  etc.,  according  to  the  nature  of  the  in- 
fection at  hand.  It  is  not  necessarily  a  local  infection  of  the  chilled 
region.  This  is  very  well  shown  experimentally.  Fowls  are  immune 
to  anthrax,  but  are  rendered  susceptible  if  they  are  kept  for  some  time 
standing  in  cold  water;  and  this  acquired  susceptibility  is  then  a  gen- 
eral one,  and  not  merely  of  thp  feet. 

"Cold  and  wet,  as  is  well  known,  have  less  action  when  accompanied 
by  energetic  muscular  exercise,  so  long  as  this  does  not  reach  the  ex- 
tent of  undue  fatigue.  This  is  not  because  less  heat  is  lost  during 
exercise.  The  reverse  is  the  case.  The  suggested  explanation  is  that 
the  muscular  metabolism  leads  to  an  increased  production  of  heat,  and 
at  the  same  time  the  cutaneous  capillaries  are  dilated  and  the  heart 
accelerated,  or  that  the  circulation  of  blood  through  the  skin  occurs 
quickly;  further,  the  internal  temperature  of  the  body  may  actually  be 
raised  several  degrees.  The  result  is  tliat  the  temperature  of  any  given 
leukocyte  never  falls  much  below  normal,  if  at  all,  since  it  comes  from 
the  internal  regions  where  the  temperature  is  raised,  passes  rapidly 
through  the  skin,  and  returns  again  to  the  interior  of  the  body, 

^"Immunity  and  Specific  Therapy,"  1909,  p.  9. 


LOWEEED  RESISTANCE  553 

"The  effect  of  fatigue,  either  alone  or  in  conjunction  with  cold  and 
wet,  is  also  well  known,  and  is  one  reason  for  the  excessive  mortality 
from  disease  of  armies  in  the  field.  It  is  less  explicable,  but  may  prob- 
ably be  connected  in  some  way  with  the  presence  in  the  blood  of  kata- 
bolic  products  of  muscular  activity,  which  have  an  injurious  action  on 
the  cells  of  the  tissues  in  general  and  on  the  leukocytes  in  particular. 
Further,  the  metabolic  products  formed  during  the  action  of  the  muscles 
are  acid  in  reaction,  and  it  is  found  that  some  at  least  of  the  protective 
substances  which  occur  in  the  blood  (alexins  and  opsonins)  act  best 
in  alkaline  medium.  This  diminution  of  immunity  after  muscular 
fatigue  is  manifested  in  animals  as  well  as  in  man.  White  rats  which 
have  been  made  to  work  in  a  revolving  cage  are  more  susceptible  to 
anthrax  than  normal  white  rats,  the  preexisting  immunit}^  being  broken 
down." 

De  Sandro  ^  "injected  dogs,  rabbits,  guinea  pigs  with  typhoid  toxins 
after  severe  muscular  strain.  Under  the  influence  of  the  chemical 
changes  induced  by  the  physical  strain,  the  nervous  exhaustion,  fatigue 
of  the  heart,  and  disturbances  in  the  blood  production,  the  defensive 
powers  were  evidently  much  weakened;  phagocytosis  was  reduced  and 
also  the  chemotactic  power  of  the  cells,  the  bacteriolysins,  antitoxins, 
agglutinins,  and  opsonins  showed  a  marked  falling  off." 

Insufficient  and  unsuitable  food  is  a  prime  factor  in  undermining 
vitality  and  lowering  resistance.  Tlie  influence  upon  health  of  food 
poor  in  quality  or  lacking  in  quantity  is  a  matter  of  common  experi- 
ence, but  the  scientific  explanation  of  the  way  in  which  this  result  is 
brought  about  is  not  at  all  clear.  First  of  all,  it  must  be  remembered 
that  starvation  or  improper  food  does  not'  depress  immunity  to  all 
infections,  but  lowers  resistance  only  to  certain  infections.  It  was  for- 
merly supposed  that  famine  was  the  direct  cause  of  pestilence.  In 
fact,  in  India  it  has  commonly  been  stated  that  "plague  follows  famine 
with  some  regularity,"  but  we  know  now  that  plague  in  man  is  second- 
ary to  the  disease  in  rats  and  is  transmitted  through  the  flea.  Ee- 
lapsing  fever  was  formerly  called  famine  fever,  and  outbreaks  of  ty- 
phus fever  were  frequently  connected  with  famine,  but  we  know  now 
that  the  former  is  transmitted  by  the  tick  and  the  latter  by  the  louse. 
It  is  evident  that  famine  may  be  indirectly  a  cause  of  epidemic  out- 
bursts without  necessarily  depressing  immunity.  Famine  is  usually 
accompanied  by  misery  and  squalor  and  an  increase  of  vermin  and  other 
factors  that  favor  the  transmission  of  disease. 

Tuberculosis,  of  all  diseases,  is  favored  by  insufficient  and  unsuit- 
able food.  This  is  an  infection  in  which  poor  nourishment  lowers, 
and  good  nourishment  raises,  our  immunity.  Poor  and  insufficient  food, 
however,   is  usually  associated  with  poverty,  insufficient  clothing,   un- 

"■Eiforma  Medica,  Naples,  Aug.  1  &  8,  Nos.  31  &  32. 


354  IMMUNITY 

cleanly  habits,  vitiated  atmosj)here.  overwork,  insufficient  rest,  and 
other  depressing  influences,  so  that  it  is  difficult  to  assign  relative  im- 
portance to  any  one  of  these  factors.  For  this  reason  we  may  perhaps 
be  led  to  exaggerate  its  importance;  and,  wliile  it  is,  of  course,  true 
that  semistarvation,  in  common  with  other  weakening  influences,  does 
pave  the  way  for  infective  processes,  we  do  not  find  that  a  supply  of 
food  restricted  enough  to  cause  a  marked  reduction  of  the  bodily  strength 
and  some  degree  of  anemia  is  necessarily  associated  with  any  infective 
disease,  though  the  patient  may  live  under  conditions  in  which  infec- 
tive material  is  present  in  abundance.  This  is  well  seen  in  fasting 
men,  in  hysterical  anorexia,  and  in  patients  with  impermeable  esopha- 
geal strictures.  The  blood,  it  may  be  pointed  out,  is  not  one  of  the 
tissues  that  suffers  first  in  starvation,  and  its  importance  to  the  body 
in  many  ways  is  so  great  that  it  is  kept  in  good  functional  activity 
while  other  tissues  waste  quickly. 

There  is  a  general  belief  that  exposure  to  infection  is  less  dangerous 
after  a  meal  than  upon  an  empty  stomach.  There  is  little  ground  for 
this  belief,  unless  we  take  into  consideration  the  notable  increase  in  the 
number  of  leukocytes  in  the  peripheral  blood  during  active  digestion. 
It  was  recognized  long  ago  that  wounds  inflicted  during  autopsies  are 
much  more  dangerous  when  received  while  fasting  than  during  the 
process  of  digestion,  and  it  is  possible  that  this  may  be  due  to  some 
extent  to  the  increased  number  of  leukocytes  which  occur  in  the  blood 
during  the  process.  Further,  infection  reaching  an  empty  stonuich  has 
greater  chances  of  passing  into  the  small  intestines  than  if  it  reaches  the 
stomach  after  a  full  meal  when  acidity,  time,  and  the  digestive  enzymes 
have  a  chance  to  destroy  the  microorganisms.  This  may  be  of  impor- 
tance in  cholera,  typhoid,  dysentery,  and  other  intestinal  infections. 

Exposure  to  a  vitiated  atmosphere,  if  of  long  duration,  is  one  of 
the  potent  causes  of  breaking  down  resistance.  Here  again,  however, 
immunity  is  lowered  in  a  specific  and  not  in  a  general  sense.  Thus, 
vitiated  air  renders  the  individual  more  susceptible  to  tuberculosis, 
pneumonia,  common  colds,  and  other  acute  respiratory  affections.  On 
the  other  hand,  it  can  have  little  influence  in  determining  the  infec- 
tion of  most  of  the  communicable  diseases,  although  the  lowered  tone 
of  the  body  caused  by  vitiated  air  may  influence  the  severity  of  the 
attack.  The  mechanism  by  which  vitiated  air  increases  susceptibility 
is  not  understood  at  all.  The  subject  is  discussed  in  the  chapter  upon 
air. 

Excesses  of  all  kinds,  symbolized  by  Bacchus,  Venus,*  and  Vulcan, 
are  mighty  factors  in  lowering  vitality  and  in  increasing  susceptibility 
to  certain  diseases.  In  this  category  are  also  found  worry,  overwork, 
loss  of  sleep,  and  fatigue. 

Certain  drugs,  of  which  the  most  important  is  alcohol,  have  an  im- 


SIDE-CHAIK    THEOEY  355 

portant  action  in  lowering  resistance.  Emery  states  that:  "The  liabil- 
ity of  alcoholic  subjects  to  pneumonia  and  some  other  infective  dis- 
eases is  well  known,  and  in  them  the  prognosis  is  more  than  usually 
unfavorable.  We  have  but  little  knowledge  of  the  action  of  alcohol  in 
this  respect.  It  may  be  that  it  acts  as  a  direct  inhibitant  of  the  ac- 
tivity of  the  leukocytes,  and  it  is  known  to  destroy  certain  delicate  de- 
fensive substances  (alexins  and  opsonins)  which  play  some  part  in  the 
defense  of  the  body  against  microbic  invasion,  but  it  is  not  known 
-whether  these  effects  are  actually  manifested  in  the  circulating  blood. 
It  is  also  possible  that  alcohol  tends  to  inhibit  the  formation  of  these 
defensive  substances. 

"Alcohol  tends  to  lower  the  temperature  of  the  body  by  increasing 
the  amount  of  heat  lost.  It  dilates  the  superficial  vessels  and  accelerates 
the  heart  action  in  a  way  somewhat  similar  to  muscular  exercise,  but 
does  not,  like  it,  raise  the  temperature  of  the  interior  of  the  body. 
Hence  the  effect  of  alcohol  in  conjunction  with  cold  and  wet  is  to  in- 
crease their  ill  effects.  More  blood  is  forced  through  the  chilled  skin 
and  more  heat  is  lost.  The  injurious  effect  of  alcohol  during  exposure 
to  cold  is  well  known.  The  results,  however,  are  different  when  al- 
cohol is  taken  after  exposure,  and  when  the  sufferer  has  reached  warmth 
and  shelter.  There  the  increased  flow  in  the  cutaneous  capillaries  leads 
to  a  warming  of  the  skin  and  consequent  cessation  of  the  chilling  of 
the  blood,  although  the  loss  of  heat  may  go  on.^^ 

Ehrlich's  Side-chain  Theory  of  Immunity. — Ehrlich's  ^  side-chain 
theory  is  a  brilliant  chemical  conception,  giving  the  only  satisfactory 
explanation  we  have  of  some  of  the  phenomena  concerned  in  immu- 
nity. In  one  sense  it  has  been  likened  to  Weigert's  teachings  of  in- 
flammation and  the  process  of  repair  in  so  far  that  cognizance  is  taken 
of  nature's  prodigality.  For  instance,  a  much  larger  amount  of  ma- 
terial is  thrown  out  than  necessary  to  repair  a  wound.  So,  too,  in  an- 
titoxic immunity  a  much  larger  amount  of  antitoxin  is  produced  than 
necessary  to  neutralize  the  toxin. 

In  Ehrlich's  conception  the  fundamental  processes  of  immunity  re- 
side in  the  cells  of  the  body.  These  cells  are  attacked  by  the  poison, 
and  if  not  destroyed  are  stimulated  to  an  overproduction  of  "anti- 
bodies" capable  of  combining  with  and  neutralizing  the  poison. 

Just  what  cells  of  the  body  play  the  most  important  role  in  the 
production  of  this  form  of  immunity  is  not  exactly  clear.  It  may  be, 
as  Ehrlich  supposes,  that  this  power  resides  in  any  organ  or  tissue. 

According  to  Ehrlich,  the  hungry  protoplasm  of  any  cell,  with  its 

^  Ehrlich  •  ' '  Die  Wertbemessung  des  Diphtherieheilserums  unci  deren  theo- 
retische  Grundlagen. "  Klin.  Jahrb.,  Jena,  VI     (2),  1897,  pp.  299-326. 

"Ueber  die  Constitution  des  Diphtheriegif tes. "  Deut.  med.  Woch.,  Leip- 
zig, XXIV   (38),  1898,  pp.  597-600. 

- — ■ — Croonian  lecture.  ' '  On  immunity  with  special  reference  to  cell  life. ' ' 
Froc.  Boy.  Soc,  London,  LXVI,  pp.  424-448,  pis.  6-7. 


35G  IMMUNITY 

complicated  molecule,  having  side  chains  of  various  combining  affini- 
ties ready  to  unite  witli  suitable  food  molecules  brought  to  it  by  the 
blood  and  body  juices,  lies  at  the  foundation  of  his  explanation  of  the 
chemical  production  of  the  antitoxin.  It  is  strange  that  the  same  com- 
bining affinity  should  exist  between  the  protoplasm  of  the  cell  and  the 
proteid  molecules  that  furnish  it  food,  as  between  tlie  cell  protoplasm 
and  the  toxins  of  the  bacterial  poisons. 

In  considering  Ehrlich's  ^  side-chain  theory  it  is  necessary  to  dis- 
regard the  microscopic  structure  of  the  cell  and  to  lliink  of  the  proto- 
plasm as  consisting  of  living  molecules  of  extraordinary  chemical  com- 
plexity. The  molecule  of  protoplasm  has  a  central  "nucleus"  with 
"side  chains,"  "lateral  chains,"  or  "bonds"  of  varying  combining  ca- 
pacities. These  "side  chains"  serve  to  bind  the  molecule  to  other  mole- 
cules having  proper  combining  affinities. 

This  arrangement  of  molecules  with  side  chains  is  a  well-known 
occurrence  in  organic  compounds.  The  bezol  ring  forms  one  of  the 
best  and  simplest  examples. 

H  (OH)  (OH) 

C  C  C 

/\  /\  /\ 

HC       CH  HC      CH  HC       C  (OH) 

I       "  i       "  i       " 

HC       CH  HC       C  (CH3)  HC       C  (OH) 

\/  \/  \/ 

c       •  c  c 

H  H  H 

Benzol  CeHe  Metacresol  C6H4(CH3)  (OH)      Pyrogallic  acid  C6H3(OH)3 

By  replacing  one  of  the  H  atoms  in  the  bezol  ring  wdth  the  methyl 
radical  (CH3)  we  have  toluol;  by  replacing  one  of  the  H  atoms  with 
the  hydroxyl  group  (OH)  we  have  phenol;  by  substituting  two  hydroxyl 
groups  w^e  have  resorcin;  three,  pyrogallic  acid,  etc.;  by  substituting 
one  hydrogen  atom  of  the  ring  with  the  hydroxyl  radical  and  another 
one  with  the  methyl  radical  we  have  the  cresols. 

These  simple  illustrations  from  well-known  organic  compounds  il- 
lustrate the  central  molecular  mass  with  its  side  chains  and  combining 
affinities,  to  which  the  molecule  of  protoplasm  is  likened. 

In  applying  this  analogy  to  the  molecule  of  protoplasm  the  name 
"receptor"  is  given  these  side  chains,  or  secondary  atomic  complexes  of 
the  molecular  group.  Contrary  to  the  simple  analogies  above  given, 
each  molecule  of  protoplasm  has  many  different  kinds  of  receptors,  as 
shown  by  the  schematic  diagram  in  Fig.  44.  These  receptors  have 
a  specific  affinity  for  the  molecules  of  food,  and  also  combine  with  the 
toxic  molecules. 

The  toxin  molecule,  according  to  Ehrlich,  consists  of  two  important 

^Ehrlich:  "Die  Wertbemessung  des  Diphtherieheilserums  und  deren  theo- 
retische  rundlagen,"  Klin.  Jahrb.,  Jena,  VI   (2),  1897,  pp.  299-326. 


SIDE-CHAI]ST    THEORY 


357 


Fig.  48.— The  Cell 
■WITH  Its  Various 
Combining  Groups 
OR  Side  Chains, 
Knovtn  as  Recep- 
TORS.  Various 
toxins  are  shown 
having  specific  af- 
finity for  the  proper 
shaped  receptors. 


Ho.p-loplior'C 
Qfoup 


Toitophore 


parts.     One  is  known  as  the  toxopltore  group,  the   other  as  the  hapto- 
phore  group. 

The  toxopJiore  group  of  the  toxin  is  that  portion  of  the  molecule 
which  exerts  a  poisonous  effect  upon  the  protoplasm 
of  the  cell.    This  group  is  less  stable  than  the  liapto- 
phore  group. 

The  haptopliore  group  is  the  seizing  or  combining 
portion  of  the  toxin  molecule  (aTtyo)^  to  seize  or 
attack).  The  haptophore  group  of  the  toxins  have 
specific  combining  affinities  for  the  receptors  of  cer- 
tain cells,  which  in  part  explains  the  selective  action 
of  these  poisons. 

Toxines  such  as  diphtheria  toxine  gradually  dim- 
inish in  toxicity,  but  retain  the  same  power  of  chemi- 
cal combination  with  the  antitoxin.  This  phenom- 
enon explains  the  formation  of  toxoids. 

Ehrlich  inferred  the  presence  of  the  toxoid  from 
the  following  simple  experiment:  He  had  a  toxine 
which  required  0.003  c.  c.  to  kill  a  guinea  pig.     After  nine  months  this 

poison  weakened,  so  that  it  required  three 
times  as  much,  that  is.  0.009  c.  c,  to  kill 
a  guinea  pig.  Xevertheless,  the  combin- 
ing power  of  the  toxine  for  antitoxin  re- 
mained the  same. 

Toxoids  are  altered  toxins.  They  con- 
sist of  the  toxic  molecule  in  which  the 
toxophore  group  has  been  destroyed,  leav- 
ing only  the  haptophore  or  combining 
group,  which,  while  able  to  satisfy  the 
combining  affinities  of  the  antitoxin,  is  no 
longer  able  to  poison  the  protoplasm  of  the  cell. 

The  diphtheria  bacillus,  during  the  process  of  its 
growth  and  multiplication  in  the  body  or  in  an  arti- 
ficial culture  medium,  produces  several  poisons,  one 
of  which  is  known  as  diphtheria  toxin.  As  above 
stated,  the  diphtheria  toxin  consists  of  a  toxophore 
and  haptophore  group.  In  the  body  the  latter  unites 
chemically  with  the  receptors  of  the  cells.  When  this  Fig-  50.— The 
takes  place  one  of  two  consec{uences  may  result :  either 

(1)  the  cell  is  so  severely  poisoned  that  it  dies,  or 

(2)  the  living  molecule  of  protoplasm  is  stimulated 
so  as  to  excite  a  defensive  action  by  the  reproduction 

of  the  receptors.     Continued  stimulation  produced  by  the  periodical  in- 
jection of  toxine  results  in  an  overproduction  of  receptors,  which  finally 
25 


Fig 


49. — The  Toxin  Molecule; 
Showing  the  Haptophore 
(Combining)  Group,  and  the 
Toxophore  (Poison)  Group. 


First 
Awii- . 
TOXIN  Formation: 
a  Toxin  Mole- 
cule Anchored  to 
a     Receptor. 


358 


IMMUNITY 


loosen  and  float  free  in  tlie  blood  serum  and  body  juices.  Eeceptovs 
fixed  upon  the  cells  are  called  sessile,  and  those 
that  leave  the  cell  are  spoken  of  as  free  receptors. 
Antitoxin  consists  of  these  free  receptors  float- 
ing in  the  blood  serum.  If  we  now  introduce  toxin 
into  the  blood,  it  is  immediately  neutralized  by 
combining  witli  the  free  receptors  through  its  hap- 
tophore  group.  All  the  combining  allinities  of  the 
toxin  are  thus  satisfied  or  saturated,  so  tluit  the 
toxin  is  no  longer  able  to  unite  with  the  receptors 

Fig.    51. — The    Second   still  attached  to  the  cell,  and  the  poison  is  thus 

Stage:     Continued    jendered  harmless. 

Stimulation  Causes 

A  Reproduction  of         It  is  by  no  means  a  necessary  corollary  of  the 

Receptors.  side-chain  theory,  as  is  often  supposed,  that  tlie 

receptors   are  found   only   in   those    organs  upon   which   the   poisonous 

effects  of  a  toxin  are  particularly  manifested.     On 

the   contrary,    Ehrlich   and   Morgenroth  ^    believe 

that  receptors  capable  of  combining  with  the  toxin 

are  produced  in  many  different  parts  of  the  body, 

especially  in  tissues  and  organs  having  the  power 

of   anchoring  the   toxin   without   causing   serious 

poisonous  effects. 


The  connective  tissue  is  believed  to  be  specially 


Fig.  52.— Third     Stage: 


rich  in  receptors,  evidenced  by  the  local  reaction        ^^^    Receptors   Be- 

caused  by  the  subcutaneous  inoculation  of  diph-        ginning  to  LeaVe  the 

theria  toxine,  ricin,  abrin,  and  similar  poisons.    In 

fact,  one  would  not  be  far  wrong  in  assigning  a  particular  significance, 
in  the  production  of  receptors,  to  just  those  organs 
which  show  unimportant  vital  response,  because  in 
such  tissues  the  inj.urious  effects  of  the  toxophore 
group  are  absent  or  of  such  diminished  importance 
\  ft  fli(?J?o  n/9  ^^^^^  ^^^®  regenerative  powers  of  such  tissues  are  not 

retarded. 

The  presence  or  absence  of  receptors  capable  of 
binding  the  toxine,  as  well  as  their  number  and 
distribution,  are  factors  which  determine  the  sus- 
ceptibility of  different  species  of  animals  against 
the  various  toxines.  These  factors  also  determine 
the  individual  variations  in  the  susceptibility  to 

poisons    and    further   explain    some    instances  of  natural  immunity  to 

toxines. 


Fig.  53. — Fourth  Stage: 
the  Receptors  H.we 
Left  the  Cell  and 
Float  Free  in  the 
Blood — Antitoxin. 


'  Ehrlich,  P.,  &  Morgenroth,  J. :  Wirkung  und  Entstehung  der  aktiven 
Stoffe  im  Serum  nach  der  Seitenkettentheorie.  Handbuch  der  pathogen  Mikro- 
organismen,  W.  Kolle,  and  A.  Wassermann,  Jena,  1904. 


glDE-CHAIN   THEORY 


359 


Fig.  54. — The  Neutral- 
ization OF  A  Toxin 
BY  Antitoxin  ;  the 
Free  Receptors 
IN  the  Blood 
Have  United  with 
the  Toxin  =  Anti- 
toxic Immunity. 


An  example  is  given  by  Sachs/  who  studied  the 

reaction  of  guinea-pig  blood  against  arachnolysin, 

a  toxine  found  in  spiders.     In  this  case  the  com- 
plete immunity  of  the  red  blood  cells  of  the  guinea 

pig  against  arachnolysin  is  accounted  for  by  the 

entire  absence  of  the  proper  receptors,  while  the 

susceptibility  of  the  red  blood  cells  of  the  rabbit 

to  very  small  quantities  of  this  poison  is  accounted 

for  by  the  strong  combining  affinity  which  exists 

between  these  cells  of  the  rabbit  and  the  arach- 
nolysin. 

In  some  cases  the  production  of  receptors  may 

apparently  be  traced  in  the  development  of  cer- 
tain species.    Cannus  and  Gley  ^  have  followed  the 

development  (  ?)  of  the  receptors  in  the  red  blood 

cell  of  the  rabbit  toward  the  hemolysin  found  in  eel  serum. 
Young  rabbits  are  much  less  susceptible  to  this  poison  than 
adult  rabbits,  which  is  accounted  for  by  Ehrlich  as  being 
due  to  a  gradual  development  of  the  receptors  having 
proper  combining  affinities  for  the  hemolysin  found  in  the 
eel  serum. 

The  union  between  the  receptor  of  the  cell  and  its 
poison  is  not  always  a  direct  one,  as  described  above^  but 
sometimes  takes  place  through  the  intervention  of  a  sec- 
ond body,  known  variously  as  the  amboceptor,  zwischen- 
korper,  immune  body,  sensitizer,  fixative,  preparative,  des- 
mon,  etc. 

This  second  order  of  immunity  is  particularly  evident 
in  the  poisons  that  have  a  lytic  or  dissolving  action  upon 
bacteria  or  the  cells  of  the  body,  such  as  the  bacteriolysins, 

hemolysins,    and    other    cytolysins.      The    poisonous 

bodies  in  this  order  of  immunity  are  usually  spoken 

of  as  "complement,"  but  also  as  the  "alexin"  (Buch- 

ner)  or  "cytase"  (Metchnikoff). 

One  of  the  remarkable  facts  connected  with  the 

phenomena  of  the  lytic   poisons  is  that  the  poison 

itself   (the  complement)   is  normally  present  in  the 

blood.     Complement  is  thermolabile,  that  is,  it  has 

less  resistance  to  heat  than  the  intermediary  body, 

which    is    thermostabile.      According    to    Ehrlich's 

theory,  immunity  can  only  be  obtained  against  the  ^^°'  ^6.— The    Third 

munity,  Showing 
an  Immune  Body 
Having  Two  Af- 
finities. 


^fefct-AfsSEj*. 


Fig.  55.— The 
Second  Or- 
der of  Im- 
munity, 
Showing 
C  o  mple- 
ment  and 
Immune 
Body. 


intermediary  body,  which  is  believed  to  be  specific. 


^  Sachs,   Hans :     ' '  Hof meisters  Beitr., ' '  Bd.  2,  h. 
^  Quoted  by  Ehrlich,  loc.  cit. 


1-3. 


360  IMMUNITY 

Ehrlich  compares  the  intermediary  body  with  diazobenzaldehyde, 
which  by  means  of  its  diazo  group  is  capable  of  combining  with  a 
series  of  bodies,  such  as  aromatic  amins,  phenols,  ketomethyl  bodies, 
etc.,  while  by  means  of  its  aldehyde  group  it  may  combine  with  a  dif- 
ferent series,  such  as  the  hydrazins,  ammonia  radicals,  and  hydrocyanic 
acid.  Phenol  and  hydroc3'anic  acid  will  not  directly  combine,  but,  with 
diazobenzaldehyde  acting  as  an  intermediary  body,  these  two  substances 
can  be  brought  into  combination.  Pushing  this  comparison  further, 
we  may  say  that  the  aromatic  body,  or  the  phenol,  represents  a  constitu- 
ent of  the  blood  corpuscle.  The  diazobenzaldehyde  is  the  intermediary 
body,  while  the  poisonous  hydrocyanic  acid  constitutes  the  comple- 
ment.^ 

Welch  ^  very  ingeniously  extended  Ehrlich's  conception  of  immunity 
to  the  bacterial  cell.  According  to  Welch's  views,  the  bacterial  cell 
has  the  same  power  of  defensive  action  against  the  poisons  produced 
by  the  cells  of  higher  animals  that  they  have  against  the  toxic  products 
of  the  bacteria. 

In  other  words,  there  is  a  chemical  battle.  Both  the  bacterial  cell 
and  the  body  cell  excrete  poisonous  substances  against  each  other,  and 
both  in  turn  are  building  up  a  chemical  defense  against  the  action  of 
these  respective  poisons. 

Antitoxic  Immunity. — In  order  to  understand  antitoxic  immunity 
it  is  necessary  to  consider  the  nature  and  action  of  toxins,  the  forma- 
tion and  production  of  antitoxins,  and  the  reaction  between  toxins  and 
antitoxins  and  related  subjects. 

TOXINES 

Bacteria  produce  many  different  kinds  of  poisonous  substances,  but 
not  all  of  these  are  toxines  in  the  specific  sense  in  which  that  term  is 
now  used.  A  toxine  may  be  defined  as  a  specific  poison  elaborated  by 
bacterial  metabolism ;  it  is  soluble  in  water ;  poisonous  in  minute 
amounts;  reproduces  the  essential  symptoms  and  lesions  of  the  dis- 
ease ;  acts  only  after  a  period  of  incubation ;  and  produces  antibodies, 
especially  antitoxin.  The  toxines  are  thermolabile,  unstable,  and  have  a 
complex  chemical  structure. 

Toxines  are  known  only  by  their  effects  upon  animals :  they  cannot 
be  recognized  in  any  other  way.  Presumably  they  belong  to  the  higher 
proteins,  but  nothing  definite  can  be  stated  concerning  their  chemical 
structure.  They  have  never  been  isolated  in  pure  form;  they  are  not 
toxalbumins,  as  was  once  believed,  and  they  only  have  a  remote  analogy 

»Vaughan  and  Novy:     "Cellular  Toxins,"  1902.  p.   131. 

'  Welch,  William  H. :  "  Huxley  lecture  on  recent  studies  of  immunity  with 
special  reference  for  their  bearing  on  pathology. ' '  Bull.  Johns  Hopkins  Hosp., 
Balto.,  XIII   (141)    De».,   1902,  pp.  285-299. 


TOXINES  361 

to  the  enzymes.  Toxines  may  be  globulins,  at  least  they  come  down 
in  the  globulin  fraction.  They  may  readily  be  precipitated  with  am- 
monium sulphate,  for  example,  but  whether  they  are  mechanically  car- 
ried down  in  the  precipitate  is  not  known.  The  toxine  molecule  is  at 
least  small  enough  to  readily  pass  through  the  pores  of  the  finest  porce- 
lain filter,  and  large  enough  not  to  dialyze  through  a  membrane. 

There  are  three  well-known  toxines :  diphtheria,  tetanus,  and  botu- 
lismus.  A  number  of  bacteria,  such  as  cholera,  dysentery,  pyocyaneus, 
and  others,  produce  a  certain  amount  of  toxic  substances  soluble  in 
water,  but  it  is  very  doubtful  whether  they  are  true  toxines  in  accord- 
ance with  the  above  definition.  Bacteria  produce  many  poisonous  sub- 
stances other  than  the  true  toxins,  such  as  acids,  alkalies,  nitrites, 
ptomains,  alcohol,  hydrogen  sulphid,  etc.  Some  of  these  substances 
may  play  a  part  in  the  pathogenesis  of  disease,  but  while  they  are 
poisonous  they  are  not  true  toxines. 

Toxines  are  sometimes  divided  into  exotoxins  and  endotoxins.  The 
former  are  the  true  or  soluble  toxines;  the  latter  are  insoluble  under 
ordinary  circumstances,  and  differ  markedly  from  the  true  exotoxins. 
The  endotoxins  will  be  considered  separately. 

The  tubercle  bacillus,  the  bacillus  of  glanders,  and  other  micro- 
organisms jiroduce  soluble  toxic  substances  specific  in  nature  but  quite 
different  from  the  true  toxines,  in  that  they  are  harmless  to  a  normal 
animal,  but  poisonous  to  one  suffering  with  the  specific  disease.  Tuber- 
culin, mallein,  and  similar  "toxins"  are  very  stable,  resist  heat  and 
other  influences,  do  not  produce  the  specific  lesions  and  symptoms  of 
the  disease,  do  not  stimulate  antitoxin  formation,  and  in  other  ways 
differ  from  the  genuine  toxines. 

A  toxine  is  produced  as  a  result  of  bacterial  metabolism  within  the 
body,  but  whether  it  is  a  secretion,  an  excretion,  or  a  product  of  the 
action  of  the  bacteria  upon  the  medium  (as  alcohol  and  carbon  dioxid 
are  produced  by  yeasts)  is  not  known.  It  is  known,  however,  that 
toxines  do  not  result  simply  from  the  breaking  down  of  the  dead  bac- 
terial cells,  as  was   once  stated. 

It  is  now  evident  that  different  groups  of  bacteria  produce  poisons 
that  differ  essentially  in  chemical  structure  as  well  as  in  physiological 
action,  just  as  different  species  of  higher  plants  produce  various  poisons 
that  differ  markedly  in  composition  and  physiologic  action. 

Very  few  of  the  bacterial  poisons  are  injurious  when  taken  by  the 
mouth.  Diphtheria  and  tetanus  toxines  are  practically  inert,  being  de- 
stroyed largely  by  the  digestive  juices  and  not  being  absorbed  in  any 
harmful  amount.  Enormous  doses  of  these  toxins  may  be  adminis- 
tered by  the  mouth  to  susceptible  animals  without  appreciable  harm. 
The  antibodies  and  the  consequent  slight  immunity  probably  produced 
by  the  absorption  of  dead  bacterial  cells  and  their  toxic  products  (such  as 


362  IMMUNITY 

typhoid  and  tubercle)  from  the  digestive  tube  is  an  entirely  different 
phenomenon  and  does  not  apply  so  far  as  the  true  toxins  are  concerned. 
There  is  one  notable  exception  in  the  case  of  the  toxine  of  the  Bacillus 
botuUsmus,  for  this  poison  is  absorbed  by  the  intestinal  mucosa,  and 
it  is  in  this  way  that  it   produces  its   harmful  effects   in  man. 

There  are  several  poisons  produced  by  higher  plants  that  resemble 
the  true  bacterial  toxines  in  all  important  respects.  Among  them 
are:  ricin  from  the  castor  bean,  and  abrin  from  the  jequirity  bean. 
These  toxines  of  vegetable  origin  are  known  as  phytotoxins.  They  are 
soluble,  act  only  after  a  period  of  incubation,  are  exceedingly  poison- 
ous in  small  amounts,  are  destroyed  by  heating,  and  produce  specific 
antibodies.  They  are  probably  of  protein  nature,  according  to  Osborne, 
Mendel,  and  Harris,  who  obtained  ricin  in  very  pure  form.  These 
poisonous  substances  of  vegetable  origin  have  more  than  theoretical  in- 
terest, for  it  was  through  a  study  of  their  action  that  Ehrlich  first 
obtained  a  deeper  insight  into  the  nature  of  toxines  and  antitoxic  im- 
munity. 

There  are  poisons  in  the  animal  kingdom  which  closely  resemble 
the  toxines,  such  as  the  venom  of  snakes,  scorpions,  spiders,  wasps,  etc. 

True  toxines  are  unstable  and  are  readily  affected  by  heat,  sunlight, 
acids,  and  various  chemicals.  They  are  much  more  unstable  in  solu- 
tion than  in  dry  powdered  form.  Tetanus  toxine  is  more  labile  than 
diphtheria  toxin,  but  when  precipitated  with  ammonium  sulphate  and 
preserved  as  a  dry  powder  in  a  vacuum  tube,  and  in  a  cool,  dark  place 
it  may  be  kept  without  deterioration  for  several  years.  Diphtheria 
toxine,  in  solution,  weakens  rapidly  at  first,  and  then  comes  to  a  stage 
of  equilibrium  which  it  maintains  indefinitely  if  preserved  in  a  cold, 
dark  place  and  protected  from  the  oxygen  of  the   air. 

The  poisonous  properties  of  toxines  of  diphtheria,  tetanus,  and  botu- 
lismus  are  destroyed  at  once  by  boiling,  and  at  65°  C.  in  a  short  time. 
At  60°  C.  for  one  hour  they  lose  most  or  all  toxic  power. 

It  has  been  stated  that  one  of  the  characteristics  of  the  toxines  is 
that  they  are  poisonous  in  exceedingly  small  amounts.  Thus,  .000,000,05 
of  a  gram  of  a  partially  purified  tetanus  toxine  will  kill  a  mouse.  Diph- 
theria toxines  have  been  obtained  so  that  .0008  c.  c.  of  the  unconcen- 
trated  fluid   (crude  filtrate)  will  kill  a  guinea  pig. 

A  true  toxine  reproduces  the  essential  symptoms  and  essential  le- 
sions of  the  disease.  In  this  sense  they  have  a  specific  action.  The 
symptoms  produced  in  a  susceptible  animal  by  the  inoculation  of  tet- 
anus toxine  cannot  be  distinguished  from  the  disease  naturally  con- 
tracted. The  symptoms  produced  by  the  injection  of  diphtheria  toxine 
closely  resemble  diphtheria,  including  coagulation  necrosis  at  the  site 
of  the  injection,  fever,  depression,  post-diphtheritic  paralysis,  etc.  The 
symptoms  following  the  ingestion  of  the  toxine  of  the  Bacillus  hotulis- 


TOXINES  363 

mus  are  an  exact  counterpart  of  the  disease  produced  by  eating  food 
containing  the  poison  of  this  microorganism.  This  specific  action  is 
very  important,  and,  if  it  were  more  generally  known,  would  save  many 
mistakes  in  experimental  biology  and  its  application  to  serum  therapy, 
it  is  comparatively  easy  to  obtain  useful  antitoxins  from  true  toxines. 
On  the  other  hand,  it  seems  to  be  impossible  to  obtain  antitoxines  of 
any  therapeutic  potency  from  other  bacterial  poisons.  Thus,  tuberculin 
and  mallein  and  other  "toxins"  do  not  stimulate  antitoxic  production 
and  the  so-called  antitoxic  sera  thus  produced  have  no  protective  or 
curative  value.  It  must  not  be  forgotten  that  only  a  comparatively 
few  infections  depend  upon  toxines  and  may  be  prevented  or  cured  by 
corresponding  antitoxins. 

One  of  the  characteristics  of  the  true  toxins  is  that  they  act  only 
after  a  period  of  incubation.  In  this  respect  they  resemble  the  natural 
disease.  Simple  chemical  poisons  may  act  at  once,  but  the  toxines 
produce  no  apparent  effect  until  a  definite  time  elapses  after  they  have 
been  introduced  into  the  system — even  when  overpowering  doses  are 
administered.  Thus,  the  ordinary  period  of  incubation  when  tetanus 
or  diphtheria  toxine  is  injected  into  a  susceptible  animal  is  several  days. 
When  enormous  amounts  are  injected  this  may  be  reduced  to  about 
8  or  12  hours,  but  never  less.  The  period  of  incubation  is  inversely 
proportional  to  the  amount  of  poison  injected.  The  longer  the  period 
of  incubation  the  milder  the  symptoms;  when  the  period  of  incubation 
is  short  the  result  is  almost  invariably  fatal.  The  cause  of  the  period 
of  incubation  is  not  well  understood.  A  certain  length  of  time  is  re- 
quired for  the  toxine  to  reach  the  susceptible  cells.  This  varies  espe- 
cially in  the  case  of  tetanus,  which  travels  up  the  nerves.  After  the 
poison  reaches  the  cells  further  time  is  required  to  combine  chemically, 
and  then  more  time  to  produce  the  injury.  On  account  of  the  period 
of  incubation  large  amounts  of  toxine  may  be  present  in  the  circulat- 
ing blood  before  the  appearance  of  symptoms.  Thus,  in  horses  enough 
tetanus  toxin  has  been  found  in  the  blood  two  days  before  the  onset  of 
symptoms  to  kill  a  guinea  pig,  when  only  0.1  c.  c.  of  the  blood  serum 
was  injected. 

The  distribution  of  the  toxines  in"  the  body  is  unequal.  Most  of  the 
poison  unites  with  the  cells;  some  is  destroyed  and  some  neutralized 
if  antitoxin  is  present.  Most  of  it  probably  unites  with  the  cells,  as 
it  soon  disappears  from  the  blood.  Tetanus  toxine  may  remain  a  long 
time  in  the  blood  of  an  insusceptible  animal.  Thus,  ]\Ietchnikoff  could 
demonstrate  the  presence  of  tetanus  toxine  in  the  tortoise  four  months 
after  the  injection.  After  tetanus  toxine  is  injected  it  soon  disappears 
from  the  blood,  but  if  the  tissues  are  injected  into  a  susceptible  ani- 
mal tetanus  is  produced,  for  it  is  now  known  that  this  poison  has  a 
specific  affinity  for  the  motor  nerve  endings.     In  the  case  of  fowls  it 


364  IMMUNITY 

seems  that  this  power  of  combining  with  the  tetanus  toxine  is  most 
marked  in  the  leukocytes.  Toxines  will  not  combine  with  all  cells  in- 
differently. They  have  a  specific  combining  affinity  for  certain  cells. 
Tetanus  toxine  lias  a  special  affinity  for  the  cells  of  tlic  central  nervous 
system.  Diphtheria  toxone  also  acts  specifically  upon  nervous  struc- 
tures. Diphtheria  toxin,  on  the  other  hand,  is  a  general  protoplasmic 
poison.  These  facts  are  of  immense  importance  in  the  prevention  and 
cure  of  certain  infections,  for  a  correct  understanding  of  the  chemical 
relation  between  the  poison  and  the  particular  cell  is  of  the  greatest 
fundamental  and  practical  value.  A  realization  of  this  fact  has  stim- 
ulated studies  which  are  now  in  progress  upon  the  relation  between 
the  chemical  constitution  and  the  physiological  action  of  various  sub- 
stances— studies  which  have  already  borne  fruitful  and  useful  results. 

Tetanus  toxine  may  combine  with  certain  cells  without  apparently 
injuring  them.  Diphtheria  toxine  also  combines  with  inditferent  struc- 
tures, such  as  the  connective  tissue.  There  is  evidently  a  wide  dif- 
ference between  the  power  to  combine  and  the  power  to  injure.  The 
power  to  injure,  however,  is  not  always  evident,  as  it  depends  upon  the 
importance  and  extent  of  the  cells  affected.  Thus,  tetanus  toxine  may 
combine  with  the  leukocytes  in  such  a  way  as  to  prevent  phagocytosis. 
This  may  be  demonstrated  by  injecting  tetanus  spores  washed  free  of 
toxine,  in  which  case  the  spores  are  taken  up  by  the  leukocytes  and  their 
development  is  prevented.  If,  however,  a  slight  amount  of  toxine  is 
injected  with  the  spores,  the  poison  inhibits  phagocytosis  and  permits 
the  growth  and  multiplication  of  the  tetanus  microorganisms  and  the 
further  production  of  toxin. 

From  our  standpoint  the  most  important  property  of  a  true  toxine 
is  its  power  to  produce  specific  antitoxins.  This  will  be  given  separate 
consideration. 

Ehrlich  conceives  the  toxin  to  be  a  complex  molecule  containing 
both  a  haptophore  and  a  toxophore  group.  The  haptophore  or  seizing 
group  is  that  part  of  the  molecular  structure  which  combines  in  a 
chemical  sense  with  the  antitoxin  or  with  the  receptors  of  the  cell. 
The  toxophore  group  is  the  poisonous  part  of  the  toxin  molecule.  This 
is  usually  represented  diagrammatically  (see  Fig.  49,  p.  357). 

It  may  readily  be  demonstrated  by  simple  experiments  that  the 
toxophore  group  is  much  more  unstable  than  the  haptophore  group. 
The  toxin  may  degenerate  so  that  it  has  little  or  no  poisonous  prop- 
erties left;  however,  its  combining  properties  remain  unaltered.  Such 
a  degenerated  toxin  is  known  as  a  toxoid.  A  toxoid,  then,  is  an  altered 
toxin  which  possesses  the  combining  property  of  the  original  toxin,  but 
has  lost  its  poisonous  power.  Some  years  ago  I  proposed  to  draw  a 
distinction  between  the  terms  "toxine"  and  "toxin."  The  toxine  is  the 
crude  filtered  culture  and  contains  several  poisonous  substances  as  well 


ANTITOXINS  365 

as  other  bodies.  The  toxin  is  the  specific  poison  in  the  toxine.  Thus, 
a  filtered  broth  culture  of  diphtheria  is  known  as  diphtheria  toxine. 
This  filtrate  contains  at  least  two  primary  metabolic  poisons :  toxin  and 
toxone.  The  toxin  produces  the  acute  symptoms  and  death;  the  toxone 
produces  the  late  paralysis.  A  filtered  broth  culture  of  tetanus  is 
called  the  tetanus  toxine.  The  filtrate  contains  at  least  two  primary 
metabolic  poisons:  tetanoplasmin  and  tetanolysin.  For  a  further  dis- 
cussion of  the  diphtheria  and  tetanus  poisons  see  page  373. 


ANTITOXINS 

An  antitoxin  is  an  antibody  formed  in  an  animal  through  the  stimu- 
lation of  a  specific  toxin.  The  usual  method  of  producing  an  anti- 
toxin is  by  the  repeated  injections  of  increasing  amounts  of  toxine 
into  a  susceptible  animal.  The  strongest  antitoxins  are  obtained  from 
animals  that  'are  very  susceptible  to  the  toxine,  but  all  susceptible  ani- 
mals by  no  means  produce  antitoxins,  although  repeatedly  injected  with 
the  appropriate  poison.  Thus,  a  guinea  pig  which  is  very  susceptible 
to  diphtheria  will  not  form  diphtheria  antitoxin,  even  after  the  repeated 
administration  of  diphtheria  toxine.  Guinea  pigs  are  also  exceedingly 
susceptible  to  tetanus  and  react  characteristically  and  violently  to  te- 
tanus toxine,  but  the  repeated  injections  of  subminimal  lethal  doses  of 
tetanus  toxine  into  a  guinea  pig  do  not  immunize  that  animal,  nor 
do  they  induce  the  formation  of  antitoxin.  In  fact,  ,Knorr  and  also 
Behring  and  Kitashima  have  shown  that  guinea  pigs  develop  an  in- 
creasing sensitiveness  to  repeated  injections  of  tetanus  toxine  instead 
of  an  increasing  resistance.  In  other  words,  the  guinea  pig,  a  suscep- 
tible animal,  lacks  the  mechanism  of  antitoxin  formation  which  is  pos- 
sessed in  such  a  high  degree  by  horses  and  other  animals.  Antitoxin 
produced  by  the  horse  or  other  animal  when  injected  into  the  guinea 
pig  will  .protect  it. 

On  the  other  hand,  insusceptible  animals,  as  a  rule,  do  not  produce 
antitoxin,  but  there  are  notable  exceptions  to  this  rule.  Metchnikoff 
has  shown  that  the  cayman,  an  animal  insusceptible  to  tetanus,  will, 
however,  produce  tetanus  antitoxin  if  the  animal  is  kept  at  an  ele- 
vated temperature  (32°  to  37°  C),  but  not  if  kept  cold  (20°  C).  The 
mechanism  of  antitoxin  formation  is  not  understood,  and  the  only 
way  of  determining  whether  a  certain  species  of  animal  is  suitable  or 
not  is  by  experimental  trial.  There  is  a  very  great  difference  in  the 
ability  to  produce  antitoxin  even  among  different  individuals  of  a  suit- 
able species.  Thus,  some  horses  have  this  power  developed  to  such  an 
exquisite  degree  that  they  produce  a  high  grade  of  antitoxin  for  pro- 
longed periods — years.     Other  horses  cannot  be  stimulated  to  antitoxin 


366  IMMUNITY 

production.  This  difference  among  horses  is  well  known  to  manufac- 
turers, who  have  no  means  of  knowing  beforehand  which  horses  will  be 
profitable.  The  only  practical  method  at  present  known  is  to  discard 
those  animals  which  refuse  to  respond  to  the  stimulation  of  the  toxine 
injections. 

There  are  several  reasons  for  selecting  the  horse  for  the  production 
of  immune  sera  for  human  use.  On  account  of  its  size  it  furnishes 
large  quantities  of  blood;  the  serum  of  the  horse  is  the  blandest  blood 
serum  of  any  known  species;  finally,  the  horse  furnishes  antitoxin  in 
higher  potency  than  any  other  known  animal. 

Just  how  and  by  what  cells  antitoxins  are  formed  in  the  body  is 
not  known.  They  are  not  formed  directly  from  the  toxines.  In  some 
way  the  toxine  excites  the  cell  to  the  formation  of  the  antibody.  The 
antibody  leaves  the  cell  and  becomes  "dissolved"  in  the  blood  and  tis- 
sue juices.  Perhaps  the  white  blood  cells  (Metchnikoff),  perhaps  the 
connective  tissue  cells  (Ehrlich),  are  chiefly  concerned.  \Yithin  the 
body  most  of  the  antitoxin  is  found  in  the  blood,  but  *it  also  exists 
in  greater  or  less  concentration  in  practically  all  the  fluids  of  the  body 
and  may  also  appear  in  the  excretions,  as  the  urine,  saliva,  milk,  and  bile. 

Nothing  definite  can  be  stated  concerning  the  chemical  nature  of 
antitoxins.  Evidence  strongly  points  to  the  fact  that  they  belong  to 
the  higher  proteins.  In  all  probability  antitoxins  are  globulins,  at 
least  they  come  down  with  the  globulins  from  which  they  have  not  been 
separated. 

•  Antitoxins  are  somewhat  more  stable  than  the  toxines;  therefore, 
the  standards  by  which  diphtheria  and  tetanus  antitoxins  are  meas- 
ured consist  of  dried  and  precipitated  antitoxins  (and  not  toxines) 
preserved  under  special  conditions.  Further,  the  toxines  have  a  more 
complex  constitution  than  the  antitoxins.  When  the  toxines  deteriorate 
they  change  qualitatively  as  well  as  quantitatively.  The  antitoxins  have 
a  simpler  constitution  and  deteriorate  simply  by  a  loss  of  power. 

Antitoxins  are  destroyed  by  heat,  acids,  and  many  chemicals.  They 
gradually  deteriorate  spontaneously  when  in  solution.  Thus,  Anderson 
has  found  that  the  average  yearly  loss  of  the  potency  of  diphtheria 
antitoxin  at  room  temperature  is  about  20  per  cent.;  at  15°  C.  it  loses 
about  10  per  cent.;  and  at  5°  C.  about  6  per  cent.  There  is  little  dif- 
ference between  the  keeping  qualities  of  untreated  sera  and  sera  con- 
centrated and  refined  by  the  Gibson  process.  Dried  diphtheria  anti- 
toxin kept  in  the  dark  at  5°  C.  retains  its  potency  practically  unim- 
paired for  at  least  51/2  years.  Antitoxic  sera  should  always  be  kept  in 
a  cool,  dark  place.  While  antitoxin  loses  some  of  its  potency  with  time, 
and  while  recently  tested  sera  of  known  unit  value  are  always  desirable, 
there  is  absolutely  no  reason  why  a  serum,  however  old.  should  not  be 
employed  provided  a  fresh  supply  is  not  at  hand.    It  should  be  remem- 


ANTITOXINS  367 

bered  that  antitoxins  deteriorate  quantitatively  only,  in  other  words,  an 
old  antitoxin  is  quite  as  useful  in  proportion  to  its  unit  strength  as  a 
fresh  serum;  in  fact,  antitoxic  sera  are  frequently  two  years  old  when 
placed  upon  the  market  by  manufacturers,  for  the  reason  that 
it  is  believed  an  old  serum  is  less  apt  to  produce  rashes  (the  serum 
disease). 

Antitoxins  are  strictly  specific;  that  is,  they  neutralize  the  corre- 
sponding toxine  and  have  no  other  apparent  action  within  the  body. 
The  occasional  ill  effects,  such  as  the  serum  sickness,  following  the  injec- 
tion of  antitoxic  sera  are  due  to  other  substances  (the  proteins  in  the 
serum)  and  not  to  the  antitoxins  themselves. 

Antitoxins  may  be  injected  subcutaneously,  intravenously,  into  the 
subarachnoid  space,  into  a  nerve,  into  the  brain  substance,  or  into  any 
of  the  body  cavities.  Antitoxins  are  practically  useless  when  given  by 
the  mouth,  as  very  little  is  absorbed.  Antitoxins  when  injected  into 
an  organism  disappear  rather  quickly.  Some  of  the  antitoxin  is  bound 
to  the  corresponding  toxine,  if  any  is  present,  some  combines  with  the 
cells,  but  the  greater  part  is  eliminated  as  antitoxin  in  the  urine,  bile, 
saliva,  etc.  The  antitoxin  contained  within  the  organism  that  produces 
it  actively,  as  the  result  of  an  attack  of  the  disease  or  as  a  result  of 
the  injection  of  toxin,  disappears  much  more  slowly  from  the  body  than 
when  the  antitoxin  is  injected  into  the  organism,  as  in  passive  immu- 
nity. Passive  or  antitoxic  immunity  is,  therefore,  transient;  it  cannot 
be  depended  upon  for  more  than  ten  days  or  two  weeks. 

When  antitoxic  serum  is  injected  subcutaneously  the  antitoxin  is 
absorbed  slowly.  It  requires  about  48  hours  under  these  circumstances 
for  the  antitoxin  to  appear  in  the  blood  in  maximum  amount.  There- 
fore, when  very  prompt  action  is  desired,  the  antitoxic  serum  may  be 
introduced  directly  into  the  circulation  by  intravenous  injection. 

There  are  a  number  of  antibodies  that  are  either  true  antitoxins 
or  closely  resemble  these  antibodies.  Some  of  these  antibodies  neutralize 
the  true  bacterial  toxines,  others  the  poisons  of  animal  origin,  others 
the  poisons  of  plant  origin,  and  others  neutralize  the  activity  of  fer- 
ments. The  principal  antitoxins,  according  to  this  classification,  are 
brought  together  as  follows : 

(1)  Bacteria  Antitoxins. — The  three  principal  and  most  potent 
bacterial  antitoxins  are  those  of  diphtheria,  tetanus,  and  botulismus. 
The  following  are  also  considered  to  have  antitoxic  properties:  pyo- 
cyaneus,  symptomatic  anthrax,  antileukocidin  and  antilysin  against  bac- 
terial hemolysins. 

(2)  Animal  Antitoxins. — These  antitoxins  are  produced  by  animal 
poisons  belonging  to  the  venoms.  True  antibodies  are  obtained  against 
snake  venom  and  similar  poisons  in  spiders,  eels,  wasps,  scorpions, 
fish,  salamanders,  and  toads. 


368  IMMUNITY 

(3)  Plant  Antitoxins. — These  are  antirisin,  antiabrin,  antirobin, 
anticrotin,  and  pollantin,  the  pollen  antitoxin  against  hay  fever. 

(4)  Ferment  Antitoxins. — Antibodies  may  be  obtained  against  fer- 
ments, such  as  pepsin,  urease,  rosinase,  steapsin,  trypsin,  fibrin  ferment, 
lactase,  cyranase;  and  antibodies  may  also  be  obtained  against  tlie  fer- 
ments found  in  bacterial  cultures. 

There  are  comparatively  few  antitoxic  sera  of  practical  use  in  human 
therapy,  just  as  there  are  relatively  few  true  bacterial  toxines.  The 
best  known  antitoxins  are  those  of  diphtheria,  tetanus,  and  botulismus. 
Numerous  other  antitoxic  sera  are  found  upon  the  market  or  have  been 
described,  but  they  are  of  doubtful  or  no  practical  value;  any  power 
such  so-called  antitoxic  serum  may  have  is  due  to  antibodies  other  than 
antitoxins. 

Antitoxins  are  valuable  both  as  curative  and  immunizing  agents. 
Their  preventive  action  depends  upon  the  fact  that  they  meet  the  tox- 
in, unite  with  and  neutralize  it,  thus  rendering  it  harmless.  As 
already  stated,  the  antitoxins  remain  in  the  body  a  brief  time  and  their 
immunizing  power,  while  of  a  high  grade,  is  transitory.  They  disappear 
in  about  ten  days  or  two  weeks;  the  immunity  must,  therefore,  be 
renewed  in  special  cases  by  repeated  injections  of  the  antitoxin  until 
the  danger  is  passed.  This  phase  of  the  subject  is  considered  in  more 
detail  under  the  prevention  of  diphtheria  and  tetanus.  The  usual  im- 
munizing dose  for  diphtheria  is  1,000  units,  for  tetanus  1,500  units. 

As  a  curative  agent  antitoxin  must  be  administered  early  and  in 
sufficient  amount  to  insure  success.  It  is  most  important  to  give  the 
antitoxin  early — before  the  damage  is  done.  Too  great  emphasis  can- 
not be  laid  upon  this  point.  After  the  toxin  has  united  with  the  cells 
it  cannot  be  dislodged  by  the  antitoxin.  The  importance  of  giving 
antitoxin  early  is  well  illustrated  in  the  case  of  diphtheria.  Wlien 
moderate  amounts  (3,000  to  10,000  units)  are  injected  on  the  first  day 
of  the  disease  the  mortality  is  practically  nil.  The  mortality  increases 
with  each  hour's  delay. 

The  importance  of  giving  this  sovereign  remedy  early  is  also  illus- 
trated in  the  experiments  of  Rosenau  and  Anderson  ^  upon  the  influ- 
ence of  antitoxin  upon  post-diphtheritic  paralysis.  It  was  found  that 
one  unit  of  antitoxin,  given  not  less  than  24  hours  after  a  fatal  dose 
of  diphtheria  toxine  in  a  guinea  pig,  greatly  modified  the  post-diph- 
theritic paralysis  and  saved  the  life  of  the  animal,  whereas  4,000  units 
given  48  hours  after  the  infection  did  not  modify  the  paralysis  or  save 
the  life  of  the  animal.  Four  thousand  units  of  antitoxin  is  an  enor- 
mous amount  for  a  guinea  pig  weighing  about  one-half  a  pound.  Weight 
for  weight,  it  corresponds  to  400,000  units  for  a  50-pound  child.  The 
fact  that  one  unit  of  antitoxin  saves  life  when  administered  timely, 

^Byg.  Lab.  Bull.,  No.  38,  1907. 


Antitoxins  369 

whereas  enormous  doses  fail  totally  when  delayed,  should  be  sufficient 
to  place  physicians  on  their  guard;  increased  dosage  cannot  atone  for 
delay.  When  cases  are  seen  late  in  the  progress  of  the  disease  it  is 
good  practice  to  give  large  doses  of  antitoxin,  for  the  reason  that  the 
poison  is  being  elaborated  continuously  and  some  of  it  is  free  in  the 
circulating  blood.  The  antitoxin  unites  with  and  neutralizes  the 
uncombined  poison  and  thus  protects  the  cells  against  further 
damage.  This  refers  to  tetanus  as  well  as  diphtheria.  Tetanus  anti- 
toxin is  a  very  valuable  immunizing  agent,  but  is  of  less  value 
after  symptoms  have  appeared,  for  then  most  of  the  damage  has 
been  done. 

Preparation  of  Antitoxin. — The  antitoxin  used  in  human  therapy  is 
practically  always  contained  in  the  blood  serum  or  blood  plasma  of 
the  horse.  The  blood  is  drawn  from  the  jugular  vein  into  sterile 
bottles.  The  bleeding  should  never  be  done  until  a  week  or  more  has 
elapsed  since  the  last  injection  of  toxine,  so  as  to  allow  time  for  the 
disappearance  of  the  poison  from  the  circulation.  The  horses  are  given 
no  food  for  about  24  hours  preceding  the  bleeding,  so  that  the  blood 
may  not  contain  the  fresh  products  of  digestion  and  metabolism.  After 
the  blood  is  drawn  it  may  be  allowed  to  clot  spontaneously.  In  the  case 
of  horse  blood  this  takes  place  more  quickly  at  room  temperature  than  in 
the  ice  chest.  The  clot  is  allowed  to  contract  for  a  few  days  and  the 
serum  containing  the  antitoxin  is  then  drawn  off  with  a  pipette  or  simply 
decanted.  In  this  way  a  clear  transparent  serum  is  obtained  which,  if 
protected  against  contamination  by  the  usual  bacteriological  precautions, 
is  sterile  and  may  be  preserved  indefinitely.  It  is  almost  a  universal  prac- 
tice, however,  to  add  a  preservative;  either  chloroform  (0.3  per  cent.), 
phenol  (0.5  per  cent.),  or  tricresol  (0.4  per  cent.).  These  preserva- 
tives in  the  amounts  named  are  harmless  when  injected  and  have  prac- 
tically no  effect  upon  the  antitoxin  itself.  They  gradually  precipitate 
the  albuminous  matter  from  the  serum,  which  settles  as  a  white  amor- 
phous deposit  and  which  may  be  disregarded,  as  it  is  harmless.  Chloro- 
form produces  a  better-looking  serum,  but  the  less  volatile  preservatives 
are  usually  preferred  on  account  of  their  stability  and,  hence,  greater 
reliability. 

By  the  method  of  allowing  the  blood  to  coagulate,  as  above  described, 
only  about  one-third  of  its  volume  is  recovered  as  antitoxic  serum.  A 
much  greater  yield  may  be  obtained  by  citrating  the  blood:  sodium 
citrate  prevents  the  clotting  of  blood.  A  solution  of  this  salt  is  placed 
in  the  bottle  which  is  to  receive  the  blood  directly  from  the  horse,  in 
sufficient  amount  to  be  present  in  1  per  cent,  of  the  whole  blood.  The 
corpuscles  soon  settle  to  the  bottom,  leaving  the  clear  supernatant 
plasma,  which  is  then  decanted  or  drawn  off  with  a  pipette.  In  this 
way  "the  yield  of  antitoxic  fluid  is  about  90  per  cent,  of  the  volume  of 


370  IMMUNITY 

the  blood,  and  is,  therefore,  preferred  to  the  less  economical  method 
of  allowing  the  blood  to  clot. 

The  citrated  plasma  may  further  be  ''purified"  or  concentralcd  by 
various  methods,  that  generally  used  being  a  modification  of  Gibson's  * 
method,  based  upon  the  earlier  experiments  of  Atcbinson. 

Ordinary  antitoxic  serum  contains  scrum  globulins  (antitoxic), 
serum  globulins  (non-antitoxic),  serum  albumins  (non-antitoxic),  serum 
nucleoproteids  (non-antitoxic),  cholesterin,  lecithin,  traces  of  bile  col- 
oring matter,  traces  of  bile  salts  and  acids,  traces  of  inorganic  blood 
salts,  and  other  non-proteid  compounds,  defined  serum  contains  serum 
globulins  (antitoxic),  traces  of  serum  globulins  (non-antitoxic)  dissolved 
in  dilute  saline  solution. 

Gibson's  Method  of  Concentrating  Diphtheria  Antitoxin.  — Gibson  - 
prepared  a  refined  and  concentrated  diphtheria  antitoxin  by  first  pre- 
cipitating the  antitoxic  serum  with  a  half  saturation  of  ammonium  sul- 
phate. This  throws  down  the  globulins.  The  precipitate  is  collected 
and  dissolved  in  a  saturated  solution  of  sodium  chlorid.  Only  a  por- 
tion of  the  globulins,  but  all  of  the  antitoxin,  passes  into  the  solution. 
Through  th.e  precipitation  by  ammonium  sulphate  and  .solution  in  so- 
dium chlorid  the  nucleoproteins  and  the  insoluble  globulins  are  elim- 
inated. The  soluble  globulins  with  the  antitoxin  are  now  precipitated 
by  the  addition  of  acetic  acid.  The  precipitate  is  collected  upon  a  fil- 
ter, partially  dried,  and  finally  placed  in  a  sac  of  parchment  membrane 
and  dialyzed  in  running  water.  The  resulting  fluid  is  tlien  an  anti- 
toxic solution  of  soluble  globulins  which  is  rendered  neutral,  and  suffi- 
cient sodium  chlorid  is  added  to  make  it  isotonic.  In  carrying  out  the 
process  there  is  a  loss  of  about  30  per  cent,  of  antitoxin  units  because 
of  retention  on  filters,  loss  in  dialysis,  etc.,  but  the  resulting  solution 
of  antitoxic  globulins  has  a  greater  concentration  than  the  original 
serum  from  which  it  was  obtained.  Thus,  a  serum  containing  only 
200  units  of  antitoxin  per  c.  c.  may,  after  concentration  with  Gib- 
son's method,  contain  as  much  as  500  units  of  antitoxin  per  c.  c. ;  and 
one  having  an  original  potency  of  300  may  contain  700  units  per  c.  c. 
in  the  final  product. 

The  advantages  of  the  antitoxic  globulins  are  that  a  smaller  bulk  is 
required  to  give  a  corresponding  number  of  units  of  antitoxin.  Less 
foreign  proteins  are  injected,  and  there  is  a  resulting  decrease  in  the 
number  and  severity  of  those  showing  the  serum  sickness.  By  the 
method  of  concentration  and  refining,  antitoxic  sera  too  weak  for  prac- 
tical purposes  are  thus  saved. 

Dried  Antitoxin. — The  antitoxic  serum  or  the  antitoxic  plasma  may 
be  dried  by  any  of  the  methods  in  common  use,  care  being  taken  to 

'  Jour,  of  Biolog.  Chem.,  Vol.  I,   1906. 
*Ibid.,  Vol.  I,  Nos.  2  &  3,  Jan.,  1906,  p.  161. 


ANTITOXIN'S  371 

prevent  bacterial  contamination  and  also  to  prevent  overheating.  The 
antitoxic  fluid  is  usually  dried  in  shallow  layers  on  pans  in  a  vacuum 
apparatus,  to  the  form  of  golden  yellow  amorphous  flakes.  These  are 
ground  to  a  powder.  About  100  c.  c.  of  serum  or  plasma  yields  ap- 
proximately 10  grams  of  dried  residue.  It  is,  therefore,  necessary  to  re- 
dissolve  the  dried  antitoxin  in  at  least  10  parts  of  normal  saline  solu- 
tion. The  advantages  of  antitoxin  in  the  dried  form  are  that  when  pre- 
served in  a  cool,  dark  place  it  retains  its  potency  practically  indefinitely. 
The  only  disadvantage  is  that  it  goes  into  solution  with  some  difficulty, 
and  the  making  of  this  solution  requires  not  only  time,  but  is  rather 
inconvenient. 

Mode  of  Action. — The  mode  of  action  of  antitoxins  is  now  fairly 
well  understood.  One  thing  is  certain,  and  that  is  that  the  antitoxin 
unites  directly  with  the  toxin.  This  may  be  readily  demonstrated  by 
adding  a  little  antitoxin  to  some  toxin  in  a  test  tube  and  then  injecting 
the  mixture  into  a  susceptible  animal;  no  symptoms  result.  Diphtheria 
antitoxin  combines  with  diphtheria  toxin  more  quickly  than  tetanus  an- 
titoxin combines  with  its  poison.  Thus,  in  the  case  of  diphtheria  the 
union  between  the  poison  and  its  antibody  is  complete  in  less  than 
twenty  minutes  at  room  temperature,  while  in  the  case  of  tetanus  it 
requires  one  hour.  These  facts  are  of  practical  importance  in  the  work 
of  standardization,  in  which  case  the  toxines  and  antitoxins  are  mixed 
in  the  test  tube  and  the  combining  action  must  be  complete  before  the 
mixtures  are  injected  into  the  test  animals  in  order  to  insure  accurate 
results. 

Ehrlich  believes  and  strongly  defends  his  assumption  that  an  anti- 
toxin unites  with  a  toxin  just  as  an  acid  unites  with  an  alkali,  that  is, 
the  one  has  a  strong  chemical  affinity  for  the  other,  and  the  union  is 
simple  and  direct.  On  the  other  hand,  Arrhenius  and  Madsen  insist 
that,  instead  of  considering  the  toxine  as  a  complex  mixture  of  various 
substances,  such  as  a  toxin,  toxone,  etc.,  it  would  be  simpler  to  consider 
it  as  a  single  (at  least  homogeneous)  substance  which  has  a  very  weak 
affinity  for  the  antitoxin  and  that  in  mixtures  containing  toxine  and 
antitoxin  there  are  always  both  free  toxin  and  free  antitoxin.  Arrhenius 
draws  his  analogy  from  known  facts  in  physical  chemistry,  particularly 
from  studies  upon  the  relation  between  solutions  of  boracic  acid  and 
ammonia.  These  two  substances  have  a  comparatively  weak  affinity 
for  each  other,  and  in  mixtures  all  the  boracic  acid  does  not  combine 
with  all  the  ammonia,  but  there  are  always  present  both  free  ammonia 
and  free  boracic  acid. 

When  ammonia  and  boracic  acid  are  brought  together  in  watery 
solution  some  of  the  ammonia  at  once  unites  with  some  of  the  boracic 
acid  to  form  ammonium  borate.  This  reaction  starts  with  a  certain 
velocity,  but  as  the  mass  of  ammonium  borate  increases  the  velocity  of 


372  IMMUNITY 

the  reaction  gradually  diminishes.  After  a  time  a  condition  is  reached 
when  the  ammonium  borate  has  a  maximum  value  and  does  not  further 
increase,  no  matter  how  long  the  reaction  is  allowed  to  proceed  under 
the  given  conditions. 

When  this  condition  of  equilibrium  is  reached  the  mass  contains 
a  certain  quantity  of  water,  ammonia,  boracic  acid,  and  ammonium 
borate;  but  these  substances  are  not  at  rest.  The  ammonia  and  boracic 
acid  will  always  react  when  in  the  presence  of  each  other,  whether  or  not 
ammonium  borate  is  present.  But,  as  the  appropriate  amount  of  am- 
monium borate  remains  constant,  it  is  understood  while  this  continuous 
association  between  the  ammonia  and  the  boracic  acid  is  going  on 
there  is  at  some  time  a  reversible  action — that  is,  a  dissociation  of  the 
ammonium  borate  to  reform  ammonia  and  boracic  acid.  These  two 
reactions  take  place  simultaneously. 

Arrhenius  believes  that  the  diphtheria  poison  changes  slowly  ac- 
cording to  the  laws  of  monomolecular  reactions,  that  the  toxin  combines 
feebly  with  the  antitoxin,  the  equilibrium  constant  being  equal  for  both. 
The  claim,  however,  that  the  toxine  is  a  simple  substance  having  a 
weak  affinity  for  the  antitoxin  and  that  the  combination  of  toxin  and 
antitoxin  follows  the  Guldberg-Waage  law,  and  that  the  reaction  is, 
therefore,  reversible,  seems  untenable  in  the  light  of  the  evidence  brought 
forward  by  Ehrlich,  Nernst,  Michaelis,  and  others. 

ENDOTOXINS 

In  contradistinction  to  the  soluble  or  exotoxins,  there  is  a  group  of 
poisons  known  as  endotoxins.  The  existence  of  endotoxins  was  taken 
for  granted  before  they  were  actually  demonstrated.  As  soon  as  it 
was  found  that  only  some  bacteria  produce  soluble  specific  toxines  it 
was  at  once  assumed  that  the  other  bacteria  must  contain  similar  pois- 
ons, but  closely  bound  within  the  cell  and  insoluble  in  ordinary  culture 
fluids.  It  was  further  assumed  that  these  endotoxins  were  in  some  way 
set  loose  in  the  body  and  thereby  produced  the  lesions  and  symptoms  of 
the  disease.  The  endotoxins  are  conceived  to  be  poisons  very  closely 
bound  up  with  the  protein  contents  of  the  bacterial  cell,  and  are  liberated 
in  the  body  when  the  bacterial  cell  dies  and  disintegrates.  However,  it 
by  no  means  follows  that  these  endotoxins  are  poisons  similar  in  action 
and  composition  to  the  soluble  true  toxins;  in  fact,  there  is  evidence  to 
indicate  the  contrary.  It  is  true  that  some  bacteria,  such  as  the  dysen- 
tery bacillus,  cholera  vibrio,  and  a  few  other  microorganisms  that  pro- 
duce little  or  no  soluble  toxine,  may  be  ground  up  so  that  the  bacterial 
cells  are  mechanically  ruptured,  thus  liberating  the  endotoxin.  In 
most  cases  of  so-called  endotoxic  action  the  reaction  of  anaphylaxis  ap- 
pears to  be  the  best  explanation. 


TETAXUS    TOXIXE  373 


TETANUS    TOXINE 

On  account  of  its  virulence,  its  solubility,  and  the  characteristic 
contractions  which  it  induces,  the  poison  of  tetanus  has  been  a  con- 
venient and  favorite  subject  of  investigation.  It  was  the  first  of  the 
bacterial  toxines  to  give  fruitful  results  in  serum  therapy.  The  toxine 
is  readily  soluble  in  the  medium  in  vhich  tetanus  grows,  whether  fluid 
or  solid;  it  diffuses  throughout  gelatin  or  agar.  The  culture  filtered 
free  of  all  bacterial  cells  is  called  the  tetanus  toxine.  This  is  really 
a  complex  substance  containing  various  poisons  and  other  bodies.  Two 
of  these  poisons  in  particular  have  been  studied:  tetanospasmin  and 
tetanolysin.  It  is  the  former  which  produces  the  con^'ulsions  charac- 
teristic of  the  disease  and  concerns  us  especially.  This  poison  is  a 
type  of  a  true  toxine.  It  is  exceedingly  poisonous  in  very  small  quan- 
tities; is  readily  rendered  inert  by  heat  (60°  C.)  ;  contains  both  a  tox- 
ophore  and  haptophore  group ;  produces  antibodies  when  introduced  into 
susceptible  animals,  and  produces  symptoms  only  after  a  definite  period 
of  incubation.  In  all  these  characteristics  tetanus  toxine  resembles 
diphtheria  toxine. 

Tetanus  toxine  is  one  of  the  most  poisonous  substances  known. 
Amounts  as  small  as  .000,006  gram  of  the  standard  precipitated  toxine 
prepared  by  me  in  the  Hygienic  Laboratory  at  ^Yashington  invariably 
kills  a  guinea  pig  weighing  350  grams  in  about  four  days.  As  this  pre- 
cipitate consists  mostly  of  albumxins.  peptone,  amino  acids,  volatile  sub- 
stances, ammonium  sulphate,  and  other  salts,  it  will  be  seen  that  but 
a  small  proportion  of  the  weight  consists  of  pure  poison.  Brieger  and 
Cohn  found  that  their  strongest  tetanus  toxine  killed  mice  weighing 
15  grams  when  given  subcutaneously  in  doses  of  .000,000,05  gram,  and 
they  calculate  that  .000,23  gram  would  be  a  fatal  dose  for  a  man  weigh- 
ing 70  kilograms. 

Tetanus  toxine  is  not  equally  toxic  for  all  species  of  animals;  on 
the  other  hand,  there  is  an  extraordinary  constancy  in  its  toxicity  upon 
individuals  of  the  same  species;  that  is,  the  same  quantity  of  toxine  per 
gram  weight  of  a  particular  animal  always  produces  similar  results. 

Tetanus  toxine  is  harmless  when  given  by  the  mouth.  It  is  not  ab- 
sorbed from  the  intact  intestinal  tract,  but  is  affected  by  the  digestive 
juices.  I  have  fed  guinea  pigs  with  as  much  as  24.000  and  mice  18,000 
times  the  minimal  lethal  dose  of  tetanus  toxine  without  producing  any 
apparent  ill  effects. 

All   attempts  to   isolate  the   specific   toxine   as   a   definite   chemical 

compound   have    proved   unavailing.      "We    are   totally    ignorant   of   its 

chemical   nature.      The   only   way   by  which   it  may   be   recognized   is 

through  its  effects  upon  animals.     By  this  means  we  are  enabled  to  de- 

26 


374  IMMUXITY 

termine  not  only  the  presence  of  the  poison,  but  also  to  estimate  its 
concentration  in  a  solution  and  to  watch  its  deterioration. 

Brieger  in  1886  isolated  from  a  contaminated  growth  a  basic  sub- 
stance or  ptomain  which  he  called  '"tetanin"  (C13H3X2O4).  Shortly 
afterward  he  obtained  another  ptomain  which  he  named  "tetanotoxin" 
(C3H11X).  These  substances  caused  muscular  contractions  when  in- 
jected into  mice,  and  Bricgcr  believed  them  to  be  the  true  poison  of 
tetanus.  They  are  now  only  of  historical  interest,  for  the  studies  of 
Kitasato  and  Weyl  in  1890  with  pure  cultures  of  tetanus  found  that 
Brieger's  purified  extracts  did  not  produce  the  characteristic  symptoms 
of  tetanus  in  experimental  animals. 

Brieger  and  Fraenkel  in  1890  obtained  an  alcoholic  precipitate  from 
filtered  broth  cultures  which  they  termed  '"toxalbumin"  and  which  had 
undoubted  toxic  properties.  Hayahsi  concludes  from  his  work  upon  the 
subject  that  the  toxin  isolated  according  to  the  Brieger-Boers  method, 
as  well  as  by  his  own  modification,  shows  a  definite  albumin  reaction. 
However,  this  does  not  prove  that  the  toxin  itself  is  a  protein. 

The  powerful  action  of  the  tetanus  poison  in  such  minute  amounts, 
its  thermolability,  and  the  period  of  incubation  lend  countenance  to 
the  view  that  the  toxin  may  be  a  ferment.  There  is,  therefore,  nothing 
but  analogy  to  class  tetanus  toxin  with  the  ferments. 

Ehrlich,  in  a  parallel  work  to  his  researches  upon  the  constitution 
of  diphtheria  toxine,  showed  that  tetanus  toxine  contains  both  a  toxo- 
phore  and  a  haptophore  group  and  that  the  antitoxic  immunity  is 
explained  by  the  presence  of  free  receptors  in  the  blood.  The  receptors 
combine  directly  in  a  chemical  sense  with  the  haptophore  group,  thus 
neutralizing  the  poison. 

Elirlich,^  1898,  definitely  proved  that  tetanus  toxin  contains  at  least 
two  poisons:  (1)  tetanolysin,  and  (2)  tetanospasmin.  He  showed  that 
these  two  poisons  do  not  always  appear  in  the  same  relative  propor- 
tion in  different  preparations.  Some  of  the  toxins  that  have  strong 
tetanic  properties  have  weak  hemolytic  action,  and  vice  versa.  The 
hemol3'tic  affinity  of  the  toxin  weakens  much  quicker  than  the  tetano- 
spasmin. This  occurs  spontaneously  as  well  as  when  it  is  heated  to 
50°  C.  for  20  minutes.  The  two  poisons  have  different  combining  af- 
finities. If  tetanus  toxine  is  brought  into  contact  with  red  blood  cor- 
puscles, the  greatest  part  of  the  tetanolysin  is  bound  by  the  red  cor- 
puscles, while  the  tetanospasmin  remains  in  the  solution.  Each  one 
of  these  two  poisons  has  its  own  antitoxin.  If  several  different  tetanus 
sera  are  examined,  it  will  be  found  that  they  have  no  parallel  neutrali- 
zation for  tetanolysin  and  tetanospasmin.  In  one  particular  case  Ehr- 
lich found  a  serum  that  was  strongly  antispastic  and  had  practically 
no  antilytic  power. 

1  Ehrlich,  P.:     Berl  Uin.    Woch.,   1898,  No.   12. 


TETANUS    TOXINE  375 

Bolton  and  Fisch  ^  have  shown  that  the  toxine  makes  its  appearance 
in  the  blood  of  the  horse  several  days  before  any  symptoms  of  tetanus 
are  observed,  and  that  it  gradually  increases  until  about  two  days  be- 
fore symptoms  become  noticeable,  and  then  it  suddenly  diminishes  and 
even  disappears  in  some  cases.  The  amount  of  toxine  varies  consider- 
ably in  different  horses.  In  one  instance  the  serum  of  a  horse,  about 
two  days  before  symptoms  of  tetanus  appeared,  was  sufficient  to  kill  a 
guinea  pig  in  the  dose  of  0.1  c.  c.  The  fact  that  tetanus  toxine  may 
appear  in  such  large  quantities  in  the  blood  without  symptoms  of  tetanus 
is  of  very  great  practical  importance  in  the  production  of  both  diphtheria 
and  tetanus  antitoxins  and  other  therapeutic  sera. 

Tetanus  toxine  is  readily  destroyed  by  heat,  sunlight,  acids,  and 
other  agencies.  Anderson,  in  1907,  found  that  when  tetanus  toxine 
is  exposed  to  5  per  cent,  formalin  for  six  hours  a  guinea  pig  is  able 
to  withstand  100  minimal  lethal  doses  of  this  formalinized  poison.  Three 
per  cent,  formalin  after  twenty-four  hours'  exposure  destroys  the  toxine ; 
it  destroys  a  part  of  the  toxine  in  one  hour,  its  action  increasing  with 
the  length  of  exposure.  This  indicates  that  formalin  should  prove  a 
useful  antiseptic  and  antitoxic  substance  for  local  application  to  wounds. 

Tetanus  toxine  is  prepared  from  bouillon  cultures  grown  anaerobi- 
cally  at  37°  C.  for  6  to  15  days.  The  culture  fluid  is  then  filtered 
through  porcelain  or  diatomaceous  earth;  the  germ-free  filtrate  con- 
tains the  poison.  This  is  used  to  inject  into  horses  for  the  purpose  of 
producing  tetanus  antitoxin.  Tetanus  toxin  in  solution  is  so  unstable 
that  it  cannot  be  depended  upon  for  the  purpose  of  accurate  tests. 
From  a  practical  standpoint  it  is  all-important  to  obtain  a  stable  poison. 
Herein  lies  the  crux  of  the  problem,  so  far  as  the  standardization  of 
tetanus  toxin  is  concerned.  If  soluble  poisons  are  used  to  measure  the 
value  of  antitoxic  serums,  as  is  the  case  with  the  German  method,  it 
is  found  necessary  to  redetermine  through  a  series  of  mice  the  strength 
of  the  toxine  each  time  a  serum  is  tested.  The  fact  that  tetanus  toxine 
does  not  exhibit  the  same  constancy  as  diphtheria  toxine  in  solution 
has  thrown  much  confusion  and  no  little  difficulty  into  the  work  of 
standardizing  its  antitoxin. 

Eosenau  and  Anderson  succeeded  in  obtaining  a  dry  poison  by  pre- 
cipitating it  from  solution  with  ammonium  sulphate.  The  excess  of 
salt  is  removed  in  the  dialyzer.  The  toxine  may  be  further  purified  by 
again  bringing  it  into  solution  and  reprecipitating  it  several  times. 
This,  however,  is  not  necessary  in  ordinary  work.  The  precipitate  is 
collected  and  dried  in  a  vacuum  over  sulphuric  acid  and  preserved  in 
vacuum  tubes,  under  the  influence  of  pentaphosphoric  (PoOg)  acid  in 
a  cool,  dark  place.  Under  these  conditions  the  poison  does  not  dim- 
inish in  toxicity  during  a  period  of  over  two  years.    It  loses  its  toxicity 

"■  Trans.  Assoc,  of  Am.  Phys.,  XVII,  1902,  pp.  462-467. 


376  IMMUNITY 

rather  slowly  when  exposed  to  light,  heat,  and  other  influences.  One 
of  the  sealed  tubes  sent  from  Washington  to  Manila  arrived  there  with- 
out appreciable  loss  of  strength.  It  is  this  dried  poison  which  is  dis- 
tributed to  manufacturers  and  other  laboratories  engaged  in  the  work 
of  standardizing  tetanus  antitoxin. 

Mode  of  Action. — It  has  been  known  for  a  very  long  time  that  te- 
tanus toxin  affects  chiefly  the  central  nervous  system,  but  it  is  only 
comparatively  recently  that  it  has  been  demonstrated  experimentally  in 
what  way  the  poison  reaches  the  nerve  centers.  For  this  information 
we  are  indebted  especially  to  the  work  of  Marie  and  Morax/  1902,  and 
Meyer  and  Ransom,-  1903.  It  is  now  definitely  known  that  the  motor 
nerves  have  a  specific  affinity  for  tetanns  toxin.  When  the  toxin  is 
placed  subcutaneously  the  adjacent  motor  nerve  endings  at  once  begin 
to  take  it  up  and  it  is  then  transported  in  the  axis  cylinder  to  the 
cord.  This  action  may  be  compared  to  the  absorption  of  nourishing 
liquids  by  the  roots  of  a  plant.  The  lymphatics  also  absorb  much  of  the 
toxin  and  in  a  short  while  it  appears  in  the  blood  stream,  which  carries 
it  to  all  parts  of  the  body,  where  again  it  is  absorbed  by  the  motor  nerve 
endings  wliieh  are  bathed  in  the  toxin-laden  fluid.  The  toxin  does  not 
reach  the  nerve  cells  directly  through  the  blood,  for  even  after  introduc- 
ing the  poison  into  the  subarachnoid  space  there  is  a  general  poisoning 
and  not  a  cerebral  tetanus. 

The  injection  of  tetanus  toxin  into  the  posterior  root  of  the  spinal 
nerves  leads  to  a  tetanus  dolorosus  which  is  characterized  by  strictly 
localized  sensitiveness  to  pain.  According  to  Meyer  and  Eansom,  the 
reason  why  the  sensory  nerves  do  not  play  any  role  in  the  conduction 
of  the  poison  lies  in  the  presence  of  the  spinal  ganglion,  which  places 
a  bar  to  the  advance  of  the  poison. 

Milchner  in  1898  showed  that  tetanus  toxin  combines  chemically 
with  the  central  nervous  system.  A  direct  combination  takes  place  when 
tetanus  toxin  and  brain  substance  are  mixed  in  the  test  tube.  This 
action  has  been  studied  by  Metchnikoff,  Wassermann,  and  Takaki, 
Eoux  and  Borrel,  Denys,  and  others.  It  seems  that  the  phenomenon 
of  the  fixation  of  the  tetanus  toxin  by  nervous  tissue,  in  spite  of  some 
analogies,  cannot  be  likened  to  the  action  of  antitoxin  on  toxin.  Tlie 
toxin  at  first  fixed  by  the  nervous  substance  again  becomes  free  in  vitro 
and  in  vivo.  The  union  between  the  tetanus  toxin  and  the  nervous 
tissue  appears  to  be  a  feeble  chemical  absorption  which  may  be  readily 
dissociated  and  which  does  little  harm  to  the  toxin.  On  the  other 
hand,  the  union  between  toxin  and  antitoxin  is  much  more  stable  and 
definite. 

'Marie  and  Morax:    Annales  de  VInstitut  Pasteitr,  XVIII,  1902.  p.  818. 
-Meyer  and  Ransom:    Archives  fiir  experimentelle  PathoJogie  und  Pharma- 
cologie,  Vol.  49,  1903. 


TETANUS    ANTITOXIN  377 


TETANUS   ANTITOXIN 

Tetanus  antitoxin  is  contained  in  the  blood  serum  of  horses  highly 
immunized  by  repeated  injections  of  tetanus  toxine.  It  is  necessary  to 
begin  with  exceedingly  small  doses,  for  the  reason  that  horses  are  very 
susceptible  to  tetanus.  Time  may  be  gained  and  accidents  avoided  by 
guarding  the  first  few  injections  with  tetanus  antitoxin.  The  injections 
are  given  at  intervals  of  about  a  week  and  may  be  rapidly  increased 
so  that  in  a  few  months  a  horse  will  be  able  to  stand  several  hundred 
cubic  centimeters  of  an  exceedingly  strong  poison.  The  horse  should 
never  be  bled  for  the  purpose  of  procuring  the  antitoxic  serum  until  at 
least  two  weeks  have  elapsed  since  the  last  injection  of  the  toxine,  in 
order  to  be  sure  that  all  the  poison  has  disappeared  from  the  circu- 
lating blood. 

Tetanus  antitoxin  is  an  antibody  which  corresponds  in  all  essential 
respects  to  diphtheria  antitoxin.  It  neutralizes  the  poison  probably  by 
direct  chemical  combination  whether  in  the  body  and  in  the  test  tube. 
In  human  therapy  it  is  used  either  by  subcutaneous  or  intravenous  in- 
jection, by  injecting  it  directly  into  the  large  nerve  trunk  leading  from 
the  wound,  by  placing  it  in  the  subarachnoid  space,  or  by  injecting  it 
directly  into  the  brain  substance.  It  is  also  used  in  dried  form  as  a 
dusting  powder  upon  the  wound.  T^Hien  tetanus  antitoxin  is  adminis- 
tered subcutaneously  it  is  absorbed  rather  slowly.  Knorr  found  the 
maximum  quantity  in  the  blood  only  after  24-40  hours,  and  from  this 
time  on  the  amount  steadily  decreases,  so  that  by  the  sixth  day  only 
one-third  of  the  actual  quantity  is  present;  by  the  twelfth  day  only 
one-fiftieth,  and  at  the  end  of  three  weeks  no  antitoxin  whatever  could 
be  demonstrated.  Hence,  it  is  imnortant  to  give  the  first  dose  in  a 
case  of  tetanus  intravenously. 

The  specific  action  of  tetanus  antitoxin  makes  it  a  valuable  prophy- 
lactic; it  has  less  use  as  a  curative  agent,  for  the  reason  that  after 
symptoms  have  appeared  most  of  the  damage  to  the  nerve  cells  has 
been  done.  While  antitoxin  has  a  limited  value  as  a  remedial  meas- 
ure, it  is  by  no  means  to  be  neglected,  for  the  reason  that  it  neutral- 
izes the  free  poison  in  the  circulating  blood  and  elsewhere  in  the  body 
and  thus  prevents  further  damage  of  the  nerve  cells.  In  the  use  of 
tetanus  antitoxin  as  a  preventive  it  should  be  remembered  that  it  is 
quickly  eliminated  from  the  body,  so  that  in  wounds  which  continue 
to  suppurate  with  foul-smelling  pus,  especially  when  the  pus  contains 
end-spore-bearing  rods,  and  in  all  wounds  in  which  there  is  a  suspicion 
of  special  danger  about  1,500  units  of  the  tetanus  antitoxin  should  be 
administered  at  intervals  of  about  ten  days. 


378  IMMUNITY 

STANDARDIZATION    OF    ANTITOXIC    SERA 

The  method  of  measuring  the  strength  of  diphtheria  and  tetanus 
antitoxins  is  exceedingly  accurate  and  satisfactory.  The  tests  are  physi- 
ological, that  is,  depend  upon  animal  experimentation.  Guinea  pigs 
are  used  because  they  are  particularly  susceptible  to  both  tetanus  and 
diphtheria  toxines  and  react  to  these  poisons  so  uniformly  that  they 
serve  the  purpose  of  an  accurate  analytical  balance.  In  order  to  ob- 
tain precise  results  it  is  essential  that  all  the  conditions  of  the  test 
be  uniform.  It  is,  therefore,  advisable  to  follow  the  official  methods, 
which  have  been  prescribed  in  great  detail.  All  antitoxic  sera  upon 
the  American  market  are  standardized  in  accordance  with  the  official 
unit  dispensed  by  the  federal  government.  This  work  is  done  in  the 
H3'gienic  Laboratory  of  the  Public  Healtli  Service. 

The  Standardization  of  Diphtheria  Antitoxin. — The  immunity  unit 
for  measuring  the  strength  of  diphtheria  antitoxin  may  be  defined  as 
the  neutralizing  power  possessed  by  an  arbitrary  quantity  of  diphtheria 
antitoxic  serum  kept  under  special  conditions  to  prevent  deterioration 
in  an  authorized  laboratory. 

From  a  theoretical  viewpoint  the  unit  may  be  defined  as  that  quan- 
tity of  diphtheria  antitoxic  serum  which  will  just  neutralize  200  mini- 
mal lethal  doses  of  a  pure  poison.  By  a  "pure"  poison  is  understood 
one  containing  only  toxin  and  no  toxoid,  toxone,  or  other  substance 
capable  of  uniting  with  the  antibodies. 

The  first  definition  may  be  compared  to  the  platinoiridium  bars 
kept  under  special  conditions  in  Paris  or  Washington  as  the  standard 
yard  or  meter.  If  all  the  meter  bars  or  yardsticks  were  lost  it  would 
be  difficult,  if  not  impossible,  to  reproduce  others  having  the  exact 
lengths  of  the  originals.  These  standard  measures  are,  therefore, 
guarded  against  deterioration  just  as  the  standard  antitoxic  sera  are  pre- 
served under  strict  conditions  of  light,  heat,  moisture,  etc.,  in  the 
Hygienic  Laboratory  of  the  Public  Health  Service  at  Washington.  From 
time  to  time  duplicates  of  this  serum  are  made  to  guard  against  de- 
terioration or  accident  to  the  original. 

The  second  definition  may  be  compared  to  the  original  conception 
of  the  meter,  which  was  intended  to  be  one  ten-millionth  of  the  quad- 
rant of  a  great  circle  of  the  earth.  Theoretically,  therefore,  if  all 
the  meter  bars  were  lost  this  unit  of  measurement  could  be  reproduced 
with  approximate  fidelity.  In  the  same  way  it  is  theoretically  possible 
to  reproduce  the  diphtheria  antitoxic  unit  in  consideration  of  the  fact 
that  it  has  just  200  combining  units. 

The  test  by  which  the  strength  of  antitoxin  is  measured  is  a  physio- 
logical one,  and  depends  upon  the  neutralization  of  the  toxin  by  the 


STAKDAEDIZATION    OF    ANTITOXIC    SEEA  379 

antitoxin.  This  neutralization  can  only  be  determined  by  injecting 
the  toxine-antitoxin  mixtures  into  guinea  pigs  and  noting  the  results. 
The  unit  for  measuring  the  strength  of  diphtheria  antitoxin  is  a  meas- 
ure of  physiologic  strength,  not  of  quantity. 

In  all  the  early  work  on  this  subject  the  toxine  was  used  as  a  basis 
for  measuring  the  strength  of  the  antitoxin,  but  as  the  toxine  is  a  much 
more  complex  substance  than  the  antitoxin,  and  as  it  is  less  stable,  ac- 
curate results  were  not  possible.  Ehrlich  showed  that  the  antitoxin 
under  certain  conditions  was  permanent  both  in  power  of  chemically 
combining  with  and  physiologically  neutralizing  the  toxine.  One  anti- 
toxin, however,  cannot  be  compared  with  another  antitoxin  directly. 
This  can  only  be  done  through  the  toxine. 

From  a  practical  standpoint,  the  following  illustration  of  a  test  will 
give  a  clear  conception  as  to  how  the  unit  of  strength  of  a  serum  is 
determined. 

Example  of  a  Test. — It  is  first  necessary  to  obtain  our  official 
yardstick.  This  may  be  done  by  applying  to  the  Hygienic  Laboratory 
in  Washington,  where  the  standard  serum  is  kept  in  a  dry  powdered 
form  in  vacuum  tubes  under  the  influence  of  pentaphosphoric  acid  in 
a  cold  place  and  carefully  preserved  from  the  light.  This  powder  is 
dissolved,  carefully  tested,  and  sent  to  the  applicant  in  a  glycerinated 
solution.  Each  cubic  centimeter  of  a  certain  dilution  of  this  standard 
serum  contains  just  1  unit.  Before,  however,  we  can  measure  the 
potency  of  an  antitoxic  serum  of  unknown  strength  it  is  first  necessary 
to  standardize  a  toxine.  This  is  done  by  mixing  one  unit  of  the  stand- 
ard antitoxic  serum  with  varying  quantities  of  the  toxine,  as  follows : 

Mixtures    of  Antitoxic    Serum   and 

Toxine  Injected  Subcutaneously  Result, 

into  Guinea  Pigs. 
1  immunity  unit  +  0.14  c.  c.  toxine  ^=  No  reaction. 
"  "      +  0.15     "        "      =  No  reaction. 

"  "      +  0.16     "        "      =  Slight  congestion  at  site  of    injection. 

'        [This  is  the  Lo  dose.] 
"  "      +  0.17     "        "      =^  Apparent  reaction  at  site  of  injection. 

"  "      +  0.18     "        "      ^  Injection   and   edema   at   site. 

"  "      +  0.19     "        "      =  Injection     and     edema     at     site ;     late 

paralysis. 
"  "      +  0.20     "        "      =  Sometimes  death  in  5  or  6  days,  some- 

times .late  paralysis. 
"  "      +0.21     "        "      ^=  Always   causes   acute   death   about   the 

fourth  day.     [This  is  the  L^.  dose.] 
"  "      +  0.22     "        "      =  Acute     death     usually     on     second     or 

third   day. 
"  "      +  0.23     "        "      =  Acute  death  on  second  day. 

From  this  series  we  learn  that  one  unit  contains  just  sufficient  anti- 
toxin to  neutralize  0.16  c.  c.  of  the  toxine.     This  is  known  as  the  L,, 


380  IMMUNITY 

dose.^  By  the  L^  dose,  then,  is  meant  that  quantity  of  poison  which 
just  neutralizes  or  saturates  one  immunity  unit  as  shown  at  tlie  necropsy 
done  48  hours  after  the  subcutaneous  injection  of  the  mixture  into  tlie 
guinea  pig.  The  reaction  at  the  site  of  inoculation  at  this  examination 
must  be  hardly  noticeable. 

In  the  above  illustration  the  L^  dose  of  this  toxine  is  just  0.21  c.  c. 
By  the  L^  dose  is  meant  the  smallest  quantity  of  poison  that  will  neu- 
tralize one  immunity  unit  plus  a  quantity  necessary  to  kill  the  animal 
on  the  fourth  day.  The  L^  dose  is  the  test  dose  which  is  used  to  de- 
termine the  strengtli  of  our  unknown  antitoxic  serum,  as  follows : 

The  L  +  (or  Test  Dose  of  Toxin)  +  Vaiying 

Amounts  of  Antitoxin  Injected  into  Results. 

Guinea  Pigs. 
0.21  c.  c.  toxine  +  1/150  c.  e.   antitoxic   serum  ^  No   effect. 


+  1/175 
+  1/200 
+  1/225 
+  1/250 
+  1/275 
+  1/300 


"  "  =No    effect. 

"  "  ^=-  Late  paralysis. 

"  "  ^=-  Late  paralysis. 

"  "  =Dies  4th   day. 

"  "  =Dies   3d   day. 

"  "  =Dies   2d   day. 

From  this  series  it  is  evident  that  1/250  c.  c.  of  the  serum  contains 
that  amount  of  antitoxin  which  will  neutralize  the  toxine  in  the  test 
dose,  leaving  sufficient  free  poison  to  kill  the  animal  on  the  fourth  day. 
The  serum,  therefore,  contains  one  antitoxic  unit  in  1/250  c.  c.  of  serum. 
One  c.  c.  of  the  serum  would,  therefore,  contain  250  units.^ 

Standardization  of  Tetanus  Antitoxin. — There  are  four  methods  of 
measuring  the  strength  of  tetanus  antitoxin:  (1)  the  German  method 
described  by  Behring;  (2)  the  French  method  described  by  Eoux; 
(3)  the  Italian  method  after  Tizzoni.  and  (4)  the  American  method 
established  by  Eosenau  and  Anderson.  European  standards  are  ad- 
mitted to  be  unsatisfactory  and  for  the  most  part  not  accurate.  Fur- 
ther, they  are  complicated  and  difficult  to  carry  out.  The  American 
method,  which  has  been  made  the  official  government  standard  for  this 
and  other  countries,  commends  itself  for  its  simplicity,  directness,  and 
precision. 

The  tetanus  antitoxic  unit  is  based  upon  the  neutralizing  value 
of  an  arbitrary  quantity  of  antitoxic  serum  preserved  under  special 
conditions  to  prevent  deterioration  in  the  Hygienic  Laboratory  of  the 
Public  Health  Service.  This  arbitrary  cpantity  now  contains  ten  times 
the  amount  of  tetanus  antitoxin  necessary  to  neutralize  somewhat  less 

^L  stands  for  Limit.  L(,  stands  for  the  limit  of  no  reaction,  and  L  +  the  limit 
of   acute   death. 

^  For  the  details  for  carrying  out  these  tests  the  reader  is  referred  to  the 
Hygienic  Laboratory  Bulletin  No.  21  upon  "The  Immunity  Unit  for  Standard- 
izing Diphtheria  Antitoxin, "  by  M.  J.  Rosenau,  which  contains  the  oflBcial 
description  and  details  of  the  process  and  its  theoretical  considerations. 


STAXDAKDIZATIOX    OF    ANTITOXIC    SEEA  381 

than  100  minimal  lethal  doses  of  a  standard  toxine  for  a  350-gram  guinea 
23ig.  That  is,  0.1  of  a  unit  mixed  with  100  minimal  lethal  doses  of  the 
standard  toxine  contains  just  enough  free  poison  in  the  mixture  to  kill 
the  guinea  pig  in  four  days  after  subcutaneous  injection. 

The  official  definition  of  a  tetanus  antitoxic  unit  is  the  following: 
The  immunity  unit  for  measuring  the  strength  of  tetanus  antitoxin 
shall  be  ten  times  the  least  c[uantity  of  antitetanic  serum  necessary  to 
save  the  life  of  a  350-gram  guinea  pig  for  96  hours  against  the  official 
dose  of  a  standard  toxine  furnished  by  the  Hygienic  Laboratory  of  the 
Public  Health  and  Marine  Hospital  Service. 

The  standardization  of  tetanus  antitoxin  does  not  differ  radically 
from  the  standardization  of  diphtheria  antitoxin.  The  toxins  and  an- 
titoxins are  mixed  and  the  mixture  injected  into  guinea  pigs.  "While, 
however,  the  unit  is  based  upon  the  neutralizing  value  of  an  arbitrary 
quantity  of  antitoxic  serum,  the  antitoxin  is  not  issued  for  a  basis  of 
comparison,  as  in  the  case  of  diphtheria.  A  stable  precipitated  toxine, 
the  test  dose  of  which  has  been  carefully  determined,  is  issued  to  other 
laboratories  for  the  purpose  of  testing. 

The  value  of  an  unknown  serum  is  measured  directly  from  this 
standard  precipitated  toxine,  the  L ,  ,  or  test  dose,  of  which  is  stated. 
The  L_|. ,  or  test  dose,  of  the  particular  toxin  now  dispensed  by  the  gov- 
erimient  contains  just  100  minimal  lethal  doses  for  a  350-gram  guinea 
pig.  This  particular  toxine  is  very  stable  and  has  not  changed  ap- 
preciably in  two  years.  As  soon  as  it  alters  or  is  exhausted  the  next 
toxine  that  will  be  issued  may  contain  more  or  less  than  100  minimal 
lethal  doses,  but  the  test  dose  will  contain  precisely  the  same  neutral- 
izing power. 

The  tetanus  antitoxic  unit  may  be  better  understood  from  an  ex- 
ample of  a  test. 

An  Example  of  a  Test. — Carefully  tare  a  weighing  bottle,  then 
add  approximately  20  to  50  nig.  of  the  dried  poison.  Again  carefully 
weigh.  Dissolve  the  toxine  in  the  weighing  bottle  with  salt  solution 
(0.85)  in  the  proportion  of  0.1  gram  of  the  dried  poison  to  166.66  c.  c. 
of  the  salt  solution.  This  proportion  is  used  for  the  reason  that  each 
cubic  centimeter  of  this  solution  will  represent  0.000,6  gm.  of  the  orig- 
inal dried  poison  (=:100  MLD's).  This  proportion  is  taken  because 
it  is  very  convenient  in  measuring  out  the  test  dose,  which  represents 
1  c.  c.   of  the  solution.     Thus : 

44.5692  gm.,  bottle  +  toxine. 
44.5300  gm.,  bottle. 


.0392  gm.,  toxine. 
0.1  gm.    :  166.66  c.  e.    : :  0.0392   :  x. 
X  =  65.33  c.  c. 


382 


IMMUNITY 


In  other  words,  if  the  quantity  of  toxine  placed  in  the  weighing 
bottle  should  weigli,  as  in  this  instance,  just  0.0392  gm.,  carefully 
deliver  from  an  accurately  graduated  burette  just  G5.33  c.  c.  salt  solu- 
tion into  the  weighing  bottle;  and,  as  before  stated,  each  cubic  centi- 
meter of  this  solution  will  be  the  L ,   or  test  dose. 

Now  dissolve  tiie  serum  of  unknown  value  in  accordance  with  the 
table  of  dilutions,  and  mix  ali(]uot  parts  of  the  serum  with  the  test 
dose  of  toxine,  as  follows : 


No.  of 

Weight  of 
guinea  pig 

Subcutaneous  injection  of  a 
mixture  of — 

Time  of  death 

(grams) 

Toxine  (test  dose) 

Antitoxin 

1 

350 
350 
350 
350 
350 

Gram. 

0.0006 
.0006 
.0006 
.0006 
.0006 

c.  c. 
0.001 
.0015 
.002 
.0025 
.003 

2  days,  4  hours. 

2 

4  days,  1  hour. 

3 

Symptoms. 

4 

Slight  symptoms. 

5 

Xo  symptoms. 

According  to  this  series  the  guinea  pig  which  received  the  mixture 
containing  0.0015  c.  c.  of  the  serum  died  in  four  days  and  one  hour. 
Therefore,  0.0015  c.  c.  of  the  serum  contains  one-tenth  of  an  immunity 
unit,  as  the  unit  has  been  defined  as  ten  times  the  least  amount  of  anti- 
tetanic  serum  necessary  to  save  the  life  of  a  350-gram  guinea  pig  96 
hours  against  the  official  test  dose.  This  serum  would,  therefore,  contain 
just  66  units  per  c.  c. 

Methods. — In  order  to  obtain  reliable  and  comparable  results,  it  is 
necessary  to  take  into  account  all  the  factors  concerned — the  composition 
of  the  poisons,  their  concentration,  the  diluting  fluid,  length  of  time 
the  mixtures  are  allowed  to  stand,  the  site  of  inoculation,  etc. 


ESTABLISHMENTS  LICENSED  FOR  THE  PROPAGATION  AND  SALE  OF  VIRUSES, 
SERUMS,   TOXINS,   AND  ANALOGOUS  PRODUCTS. 

The  following  table  contains  a  list  of  the  establishments  holding  on 
July  1,  1911,  licenses  issued  by  the  Treasui-y  Department  in  accordance 
with  the  act  of  Congress  approved  July  1,  1902,  entitled  "An  act  to  regu- 
late the  sale  of  viruses,  serums,  toxins,  and  analogous  products  in  the  Dis- 
trict of  Columbia,  to  regulate  interstate  traffic  in  said  articles,  and  for 
other  purposes." 

The  number  of  the  license  of  each  firm  is  also  given,  together  with 
the  names  of  the  several  products  for  which  licenses  have  been  granted. 


STANDARDIZATION    OF    ANTITOXIC    SEEA 


383 


Establishments 


Parke  Davis  &  Co.,  Detroit, 
Mich. 


H.    K.    Mulford    Co.,    Phila- 
delphia, Pa. 


Dr.  H.  M.  Alexander  &  Co., 
Marietta,  Pa. 

Fluid  Vaccine  Co.,  Milwaukee, 

Wis. 
The       Cutter       Laboratory, 

Berkeley,    Cal. 

Frederick  Stearns  &  Co.,  De- 
troit, Mich. 

Pasteur  Institute  of  Paris, 
Paris,  France. 


Chemische  Fabrik  auf  Actien, 

Berhn,  Germany. 
Health  Department  of  the  City 

of  New  York . 

Dr.  W.  R.  Hubbert  Serum  La- 
boratory, Detroit,  Mich. 

National  Vaccine  and  Anti- 
toxin Institute,  Washington, 
D.  C. 


Lederle     Antitoxin      Labora- 
tories, New  York  City. 


Burroughs,  Wellcome  &  Co. 
London,  England. 


Memorial  Institute  for  Infec- 
tious Diseases,  Chicago,  111. 

Swiss  Serum  and  Vaccine  In- 
stitute, Berne,  Switzerland. 


Institut  Bacteriologique  Lyon, 
Lyons,  France. 

Bacterio-Therapeutic  Labora- 
tory, Asheville,  N.  C. 


Products 


Diphtheria  antitoxin,  antigonococcic 
serum,  antistreptococcic  serum,  antite- 
tanic  serum,  antitubercle  serum,  bac- 
terial vaccines,  erysipelas  and  prodigio- 
sus  toxines  (Coley),  tuberculins,  and 
vaccine  virus. 

Diphtheria  antitoxin,  antidysenteric  serum, 
antigonococcic  serum,  antimeningococcic 
serum,  antipneumonic  serum,  antistrep- 
tococcic serum,  antitetanic  serum,  tuber- 
cuUns,  vaccine  virus,  bacterial  vaccines, 
normal  horse  serum,  and  rabies  virus. 
Diphtheria  antitoxin,  antirabic  virus,  tu- 
bercuUns,  vaccine  virus,  and  normal 
horse  serum. 

Vaccine  virus. 

Diphtheria  antitoxin,  antistreptococcic 
serum,  tuberculins,  bacterial  vaccines, 
and  vaccine  virus. 

Diphtheria  antitoxin,  streptolytic  serum, 
and  pneumolytic  serum. 

Diphtheria  antitoxin,  antidysenteric  serum, 
antimeningococcic  serum,  antiplague 
serum,  antistreptococcic  serum,  serum 
antivenimeux,  antitetanic  serum,  and 
antiplague  vaccine. 

Diphtheria  antitoxin  and  antistreptococcic 
serum. 

Diphtheria  antitoxin,  antitetanic  serum, 
antirabic  virus,  vaccine  virus,  tubercu- 
lin, and  antimeningococcic  serum. 

Diphtheria  antitoxin. 

Diphtheria  antitoxin,  antigonococcic  vac- 
cine, vaccine  virus,  normal  horse  serum, 
antistaphylococcic  vaccine  and  antistrep- 
tococcic vaccine. 

Diphtheria  antitoxin,  antistreptococcic 
serum,  antitetanic  serum,  suspension  of 
lactic  acid  baciUi,  vaccine  virus,  and  anti- 
typhoid vaccine. 

Diphtheria  antitoxin,  antigonococcic  se- 
rum, antidysenteric  serum,  anticolon  ba- 
cillus serum,  antistaphylococcic  serum, 
antistreptococcic  serum,  antityphoid 
serum,  tubercuhns,  and  bacterial  vac- 
cines. 

Diphtheria  antitoxin. 

Diphtheria  antitoxin,  antidysenteric  serum, 
antimeningococcic  serum,  antipneumonic 
serum,  antiplague  serum,  antistrepto- 
coccic serum,  tuberculins,  anticholera 
vaccine,  antiplague  vaccine,  antityphoid 
vaccine,  and  antitetanic  serum. 

Antidiphtheric  serum  and  normal  goat 
serum. 

Tubercuhns. 


384 


IMMUNITY 


No.  of 
license 

Establishments. 

Products 

24 

Farbwerke,    vormals    Meister 

Diphtheria    antitoxin,    antidysenteric    se- 

Lucius   u  n  d    B  r  ii  n  i  n  s , 

rum,  antimeningococcic  serum,  antipneu- 

Hoechst-on-Main,  Germany. 

monic  serum,  antistreptococcic  serum, 
antitctanic  serum,  and  tubercuhns. 

25 

Tuberculin  Society  of  St.  Pe- 
tersburg,    St.     Petersburg, 
Ru.ssia. 

Tuberculinum  purum. 

27 

Institut     Pasteur     de     Lille, 
Lille,  France. 

Serum  antivenimeux. 

28 

Bacteriologisches  Institut 
Lingner,  Dresden,  Germany. 

Pyocyanase. 

29 

The  Belxringwerk,     Marburg, 
Germany. 

Antitetanic  serum  and  tubercuUn. 

30 

Dr.  G.  H.  Sherman,  Detroit, 
Mich. 

Bacterial  vaccines. 

31 

E.    Merck,    Darmstadt,    Ger- 

Antidiphtheric   serum,    antimeningococcic 

many. 

serum,  antipneumonic  serum,  antistrep- 
tococcic serum,  normal  horse  serum 
(dried),  and  normal  horse  serum. 

32 

Kalle    &    Co.,    B  i  e  b  r  i  c  h  , 
Germany. 

Tuberculin  (Rosenbach) . 

33 

American  Biologic  Co.,  Kansas 
City,  Mo. 

Antirabic  virus. 

34 

The     Beraneck     Laboratory, 
Neuchatel,  Switzerland. 

Tuberculin  (Beraneck). 

35 

Dr.     Carl    Spengler,     Davos- 
Platz,  Switzerland. 

I.  K.  immune  blood. 

PHAGOCYTOSIS 


Metchnikoff  gave  us  the  first  physical  explanation  of  immunity 
through  his  brilliant  studies  upon  phagocytosis.  Metchnikoff  is  a  biol- 
ogist, and  as  a  result  of  his  stimulating  observations  upon  the  phago- 
cytes in  all  the  orders  of  the  animal  kingdom  he  has  contributed  much 
to  our  knowledge,  not  alone  of  immunity,  but  to  our  fundamental  knowl- 
edge of  nutrition  and  inflammation.  The  ingenuity  and  fertility  of 
his  views  caused  a  flood  of  work  from  others  upon  these  basic  subjects 
in  medical  biology. 

Phagocytosis  is  a  process  common  to  all  cells  having  amebic  mo- 
tion. A  phagocyte  is  any  cell  capable  of  absorbing  particulate  matter 
into  its  substance.  The  process  is  best  seen  with  an  ameba  under  the 
microscope. 

For  a  clear  understanding  of  phagocytosis  it  is  necessary  to  con- 
sider three  phases  of  the  process:  (1)  the  approach,  (2)  the  engulf- 
ment,  and   (3)   the  digestion. 

The  approach  or  cJtcmotaxis  is  a  phenomenon  wdiich  is  displayed 
by  almost  all  motile  and  unicellular  organisms,  whether  animal  or 
vegetable,  as  well  as  by  the  leukocytes.  It  manifests  itself  by  a  move- 
ment of   the   unicellular   organism  or  the   phagocytic  cell   toward  the 


PHAGOCYTOSIS  385 

particle  and  seems  to  be  a  response  to  a  chemical  stimulus.  Chemo- 
taxis  is  said  to  be  positive  when  the  leukocytes  are  quickly  and  ener- 
getically attracted  to  a  substance,  and  negative  when  this  attraction  is 
lacking.  There  is  considerable  doubt  whether  there  is  true  negative 
chemotaxis  in  the  sense  of  repulsion.  The  degree  of  chemotaxis  pos- 
sessed by  any  substance  may  readily  be  determined  by  placing  it  in  a 
capillary  tube  closed  at  one  end  and  then  inserting  the  open  end  of 
the  tube  into  the  tissue  of  an  animal  or  into  a  fluid  containing  active 
phagocytes.  If  the  substance  has  positive  chemotactic  power  the  phago- 
cytes soon  approach  the  free  end  of  the  capillary  tube,  which  they  en- 
ter; if  the  substance  has  negative  chemotactic  power  the  phagocjdes 
are  not  attracted  and  do  not  enter  the  capillary  tube.  As  Emery  points 
out,  the  leukocytes  are  in  many  cases  attracted  into  an  infected  area 
to  their  own  undoing,  and  it  must  not  be  forgotten  that  "even  in  in- 
flammatory processes  which  are  mild  in  nature  and  favorable  in  result 
the  number  of  leukocytes  which  may  be  killed  in  the  conflict  is  enor- 
mous. The  leukocytes  are  not  independent  protozoa  inhabiting  the 
blood  and  tissues,  but  an  integral  part  of  the  organism.  It  is  to  the 
advantage  of  the  latter  that  the  former  should  be  attracted  at  once 
to  the  seat  of  invasion,  and  hence  the  processes  of  evolution  have  led 
to  the  development  of  this  function  in  the  nomadic  cells  of  the  body. 
These  are  extraordinarily  susceptible  to  chemotactic  influences.  They 
seem  to  be  attracted  by  any  deviation  from  the  normal  situation  of 
the  tissues  and  fluids — a  slight  injury,  a  hemorrhage,  the  presence  of 
a  poison,  or  a  foreign  body  of  any  sort,  or  any  dead  or  useless  tissue 
— and  the  leukocytes  are  immediately  attracted  into  the  area  affected. 
The  more  we  regard  the  process  the  more  we  must  regard  it  as  one 
of  the  most  exquisite  examples  of  means  to  ends  met  with  in  the  ani- 
mal economy." 

The  engulf ment  of  the  bacteria  may  readily  be  studied  in  amebse 
in  their  free  living  stage.  The  protoplasm  of  the  ameba  is  thrown 
out  in  the  form  of  pseudopodia;  these  encircle  the  particle,  which  soon 
appears  within  the  substance  of  the  ameba.  The  engulfment  of  particles 
by  the  leukocytes  and  other  cells  is  precisely  the  same. 

The  digestion  within  the  cell  is  entirely  comparable  to  gastric  di- 
gestion in  higher  animals.  It  is  now  known  that  active  proteolytic 
ferments  dissolve  the  albuminous  particles,  and  that  this  takes  place  in 
an  acid  medium  may  be  demonstrated  by  the  use  of  delicate  indicators, 
such  as  neutral  red. 

The  phagocytes  may  take  up  and  digest  either  live  or  dead  bacteria; 
they  are  not  simply  scavengers.  They  engulf  particles  of  all  kinds, 
both  organic  and  inorganic.  Thus,  in  anthracosis  the  particles  of  coal 
are  mainly  carried  and  contained  in  the  phagoc}i;ic  cells.  The  phago- 
cytes play  a  similar  role  with  the  malarial  pigment,  with  the  granules 


386  IMMUNITY 

of  pigment  left  after  a  hemorrhage,  and  with  other  foreign  particles 
in  the  body.  Phagocytes  are  also  enabled  to  absorb  colloidal  substances 
and  fluids  as  well  as  particulate  matter.  They  are  enabled  to  dispose 
of  comparatively  large  masses  by  removing  it  piecemeal.  Thus,  the 
"core''  of  boils  is  gradually  removed  mainly  by  the  phagocytes.  Cat- 
gut and  silk  ligatures  are  similarly  removed  and  the  absorption  of  the 
tadpole's  tail  is  disposed  of  through  the  same  process. 

Metchnikoff  divides  the  phagocytes  into  free  and  fixed,  macrophages 
and  microphages. 

The  free  phagocytes  are  the  leukocytes,  lymphocytes,  and  other  blood 
cells,  as  the  myelocytes  from  the  bone  marrow.  The  fixed  phagocytes 
are  the  connective  tissue  cells  and  endothelial  cells.  The  free  phago- 
cytes, according  to  Metchnikoff,  play  the  more  important  role. 

The  microphages  or  microcytes  are  the  mononuclear  leukocytes,  the 
polymorphonuclear  leukocytes,  and  the  wandering  connective  tissue  cells. 
The  macrophages  or  macrocytes  are  the  large  lymphocytes,  the  mononu- 
clear pulp  cells  of  the  spleen  and  bone  marrow,  endothelial  cells  of 
the  large  vessels,  and  Kupfer's  stellate  cells  of  the  liver.  The  micro- 
phages play  an  active  part  in  all  acute  infections.  They  are  the  first 
to  come  in  the  field  and  for  the  most  part  are  vegetarians,  that  is,  they 
take  up  bacteria  especially.  The  macrophages,  on  the  other  hand,  are 
carnivorous,  engulfing  other  cells  and  protozoon  parasites,  and  are  es- 
pecially concerned  in  chronic  inflammations,  such  as  tuberculosis  and 
leprosy,  rather  than  in  the  acute  processes.  These  distinctions  between 
the  free  and  fixed  phagocytes,  the  microphages  and  macrophages,  are 
entirely  arbitrary.  All  the  leukocytes  have  the  power  of  phagocytosis, 
though  in  varying  degree.  This  is  readily  seen  in  an  opsonic  prepara- 
tion or  in  an  examination  of  a  smear  of  gonorrheal  pus,  when  some 
of  the  polymorphonuclear  leukocytes  will  be  loaded  with  the  cocci  while 
others  contain  few  or  none.  The  small  phagocytes  (microcytes)  are 
able  to  engulf  protozoa  and  animal  cells  as  well  as  bacteria. 

Metchnikoff  has  insisted  since  the  beginning  of  his  studies  upon 
phagocytosis  that  this  process  plays  an  important,  if  not  the  sole,  role 
in  immunity.  He  conceives  that  a  true  battle  takes  place  between  the 
cells  and  tlie  invading  germs.  When  phagocytosis  is  active  and  suc- 
cessful, immunity  is  the  result.  If  jjliagocytosis  is  absent,  or  tlie  phago- 
cytes are  unsuccessful,  the  result  is  susceptibility  instead  of  immunity. 
Metchnikoff  first  studied  the  protective  power  of  the  phagocytes  in  a 
fresh  water  crustacean,  the  daphnia,  which,  from  its  transparency  and 
small  size,  is  a  very  suita])le  creature  for  observation.  He  found  that 
the  daphnia  is  subject  to  a  disease  due  to  the  invasion  of  its  body 
cavity  by  the  spores  of  a  yeast  (^lonospora),  and  that  if  these  spores 
gain  access  in  large  numhers  they  multiply,  form  into  mature  or- 
ganisms, and  finally  kill  their  host.     ^Vhen,  however,  a  few  spores  gain 


PHAGOCYTOSIS  387 

access  he  found  the  leukocytes  of  the  daphnia  approach  them,  form  a 
wall  around  them,  and  finally  digest  and  destroy  them.  It  is  obvious, 
therefore,  that  the  immunity  of  the  daphnia  to  this  infection  depends 
upon  the  activity  of  its  leukocytes.  Analogous  instances  are  found  in 
many  other  animals,  including  man.  In  the  streptococcus  infections 
particularly  Metchnikoff  believes  their  virulence  depended  upon  the 
absence  of  phagocytic  action. 

It  soon  became  evident  to  Metchnikoff  himself  that  the  mechanism 
of  immunity  was  a  much  more  complicated  process  than  could  be  ac- 
counted for  simply  by  the  number  and  physical  activity  of  the  phago- 
cytes. The  simple  act  of  phagocytosis  alone  could  not  explain  all  the 
phenomena.  It,  therefore,  became  necessary  to  study  the  processes  of 
digestion  and  the  products  of  excretion  of  the  phagocytes.  It  soon  be- 
came evident  that  the  digestive  power  of  the  phagocytes  is  a  very  pow- 
erful one,  and  substances  usually  deemed  entirely  insoluble  may  be 
gradually  removed  by  their  action.  Metchnikoff  considers  two  of  these 
substances  to  be  concerned  in  immunity :  the  microcytase  and  the  macro- 
cytase. 

The  microcytase  is  a  ferment-like  substance  obtained  from  the 
microcytes.  It  is  thermolabile  and  corresponds  in  all  essential  respects 
to  the  alexin  of  Buchner  or  the  complement  of  Ehrlich. 

The  macTOcytase  is  a  thermostable  substance  obtained  from  the 
macrocytes.  It  is  concerned  with  specific  acquired  immunity.  The 
macrocyte  fastens  itself  to  the  bacteria,  hence  was  called  by  Metchni- 
koff the  fixator.  It  is  similar  in  all  essential  respects  to  the  "^sub- 
stance sensibilitrice"  of  Bordet,  or  the  amboceptor  of  Ehrlich. 

Buchner,  as  well  as  most  other  unprejudiced  students  in  immunol- 
ogy, takes  the  middle  ground  between  the  doctrines  of  the  cellular 
theory  represented  by  Metchnikoff  and  his  school  and  the  doctrines 
of  the  humoral  theory  represented  by  Ehrlich.  It  now  seems  quite 
evident  that  both  the  cells  and  the  body  fluids  play  an  important  role 
in  the  mechanism  of  immunity.  It  is  also  equally  evident  that  the 
mechanism  of  immunity  differs  widely  with  different  infections;  in 
some  phagocytosis  plays  a  dominant  part;  in  others  it  seems  that  the 
fluids  of  the  body  are  chiefly  concerned.  It  must  not  be  forgotten  that 
even  where  the  fluids  of  the  body  are  the  chief  actors  the  antibodies 
are  probably  in  all  cases  derived  from  the  cells.  Just  what  cells — 
whether  the  fixed  tissue  cells  or  the  free  phagocytes — are  chiefiy  con- 
cerned in  the  production  of  these  antibodies  is  not  quite  clear. 

All  observers  are  agreed  upon  one  thought,  and  that  is,  fundamen- 
tally immunity  is  closely  allied  to  the  processes  of  cell  nutrition.  The 
receptors  of  Ehrlich  are  the  mouths  of  the  cells  for  food.  The  phago- 
cytosis of  Metchnikoff  is  primarily  a  mechanism  by  which  cells  pos- 
sessing  amebic  motion   obtain   their   food.     Anaphylaxis,  which   offers 


388  IM.MLXITY 

another  explanation  of  immunity  to  certain  infections,  deals  with  the 
fundamental  problems  of  protein  metabolism.  It  is,  therefore,  plain 
that  any  experimental  research  that  gives  a  deeper  insight  into  protein 
metabolism  as  well  as  the  more  direct  researches  in  immunology  has 
a  fundamental  bearing  upon  the  prevention  and  cure  of  disease. 

OPSONINS 

The  name  opsonin  (opsono:  I  cater  for,  I  prepare)  is  given  to  sub- 
stances which  occur  in  the  blood  and  which  have  the  power  of  prepar- 
ing bacteria  and  other  cells  for  ingestion  by  the  leukocytes.  The  op- 
sonins combine  with  the  bacteria  and  in  that  way  prepare  them  for 
being  taken  up  more  easily  by  the  phagocytic  cells.  In  the  absence  of 
opsonins,  phagocytosis  does  not  take  place,  and  their  great  importance 
is,  therefore,  at  once  manifest.  There  is  now  no  doubt  concerning  the 
existence  of  these  substances,  and  the  brilliant  work  of  Wright  has 
stimulated  a  flood  of  researches  which  have  thrown  much  light  upon 
this  chapter  in  immunology. 

The  opsonins  are  normally  present  in  the  blood  or  may  be  increased 
or  diminished  in  amount  by  the  injection  of  bacteria  or  appropriate 
antigen.  The  opsonins  are  specific,  that  is,  the  blood  serum  may 
contain  opsonins  which  prepare  staphylococci  for  the  phagocytes,  but 
may  contain  no  suitable  substance  to  prepare  streptococci,  tubercle 
bacilli,  or  some  other  microorganism.  The  opsonins  are  probably  sim- 
ilar to  the  bacteriotropius;  their  chemical  nature,  however,  in  coiumou 
with  other  antibodies,  is  not  understood. 

The  Opsonic  Index. — Sir  Almroth  Wright  has  modified  Leishmann's 
method  for  measuring  the  opsonic  power  of  the  blood  serum,  but  the 
method  is  somewhat  complicated  and  gives  variable  results  even  in  the 
hands  of  trained  workers.  It  may  be  questioned  whether  any  of  the 
tests  now  in  use  are  a  true  index  of  the  amount  of  opsonins  in  the 
serum,  although  they  may  be  taken  to  indicate  roughly  the  measure  of 
their  activity.  The  opsonic  index  has  been  especially  used  as  a  guide 
to  vaccine  therapy  rather  than  in  preventive  medicine.  If,  however, 
we  had  a  satisfactory  and  ready  method  by  which  the  specific  opsonins 
of  the  blood  could  be  measured  so  that  deficiencies  could  be  readily 
determined  and  strengthened,  we  would  theoretically  at  least  have  a 
valuable  addition  to  prophylaxis. 

LYSINS 

Lysins  are  substances  that  have  the  power  of  disintegrating  or  dis- 
solving cells  or  other  organized  structures.  Those  that  dissolve  bac- 
teria  are   known   as   the   bacteriolysins,   those   that   dissolve   red   blood 


LYSINS  389 

cells  are  called  hemolysins,  those  that  dissolve  epithelial  or  other  body 
cells  are  called  cytolysins  or  cytotoxins.  The  lysins  in  themselves  are 
not  poisonous,  but  through  their  action  they  liberate  or  generate  toxic 
substances  and  thus  play  an  important  role  not  only  in  the  pathogenesis 
of  many  infectious  diseases  and  diseased  states,  but  also  in  their  cure 
and  prevention. 

jSTormally  the  blood  possesses  bactericidal  properties,  and  it  is  be- 
lieved that  this  is  almost  entirely  due  to  its  power  of  dissolving  the 
bacterial  cells.  The  bacteriolytic  property  of  normal  blood  serum  is 
not  specific,  whereas  the  bacteriolysins  induced  through  special  proc- 
esses by  immunization  are  strictly  specific.  The  fact  that  the  blood  has 
the  power  of  resisting  decomposition  longer  than  other  animal  fluids 
was  known  to  Hunter  before  the  era  of  bacteriology.  It  was  also  early 
known  that  this  property  of  the  blood  diminishes  spontaneously  after 
it  was  shed  and  could  be  destroyed  by  heat — about  55°  C.  The  bac- 
teriolytic substances  in  the  blood  were  first  studied  by  Buchner  and 
Nuttall,  who  called  them  alexins.  When  it  was  discovered  that  the 
blood  possesses  marked  powers  of  destroying  bacteria  the  conclusion 
was  naturally  drawn  that  herein  lies  the  explanation  of  immunity.  It 
was  soon  learned,  however,  that,  though  the  blood  of  certain  animals 
may  possess  marked  bactericidal  properties,  nevertheless  they  are  very 
susceptible;  and,  further,  that  the  power  to  kill  bacteria  is  much  more 
marked  in  the  serum  than  in  the  circulating  blood  in  the  animal.  Thus, 
according  to  Lubarsch,  16,000  virulent  bacilli  will  kill  a  rabbit  if  in- 
jected intravenously;  that  is,  the  blood  within  the  body  has  not  the 
power  of  killing  this  number,  yet  1  c.  c.  of  fresh  blood  serum  will  destroy 
this  number  or  more  in  a  test  tube. 

Eabbits  are  very  susceptible  to  anthrax,  although  the  blood  serum 
of  these  animals  possesses  marked  bactericidal  properties  for  the  an- 
thrax bacillus;  on  the  other  hand,  the  dog  is  very  resistant  to  anthrax, 
despite  the  fact  that  its  blood  serum  is  very  slightly  bactericidal. 

The  bacteriolysins  were  discovered  by  Eichard  Pfeiffer  ^  in  his  at- 
tempt to  actively  immunize  animals  against  cholera  by  the  injection 
of  live  cultures.  He  observed  that  the  cholera  organisms  were  disin- 
tegrated anJ  dissolved  in  the  peritoneal  cavity  of  the  immunized  ani- 
mals. This  gave  rise  to  what  is  now  known  as  Pfeiffer's  phenomenon, 
which,  on  account  of  its  importance,  must  be  considered. 

Pfeiffer's  Phenomenon. — Guinea  pigs  are  immunized  by  the  subcu- 
taneous injection  of  increasing  doses  of  a  cholera  culture  about  once  a 
week  until  they  are  able  to  withstand  large  amounts  of  a  fresh  viru- 
lent strain.  This  usually  required  at  least  three  or  four  injections. 
Some  of  the  live  microorganisms  are  now  injected  into  the  peritoneal 
cavity  of  the  immunized  animal,  and  from  time  to  time  minute  drops 

'^Zeit.  f.  Hyg.,  Vol.  XVIII,  and  Deutsche  med.  Wochen.,  1896,  pp.  97,  119. 
27 


3fl0  IMMUNITY 

of  this  injected  iiiiitcrial  with  the  itci'iloncjil  exudate  are  witlidrawn  l)y 
means  of  ea])illan  tiilies  and  exaniiued  tindei-  tlie  iiiier()se()[)e.  It  will 
be  found  that  the  bacteria  previously  actively  motile  soon  lose  their 
power  of  motion  and  die.  They  then  become  somewhat  swollen  and 
agglutinate  into  Iialls  or  clumps,  which  gi'adually  become  jialer  and 
paler.  The  disintegrating  bacterial  cells  become  granular  and  finally 
are  completely  dissolved  in  the  peritoneal  fluid.  This  process  usually 
takes  about  twenty  minutes,  provided  the  animal  has  been  sufficiently 
highly  immunized.  For  a  control  a  like  quantity  of  the  cholera  cul- 
ture is  injected  into  the  peritoneal  cavity  of  a  normal  guinea  pig.  In 
this  case  the  microorganisms  are  not  ininiol)ilized,  agglutinated,  or 
dissolved.  Further,  the  immunized  aninuil  remains  unaffected  while 
the  control  aninuil  dies  as  a  result  of  the  infection.  This  reaction  is 
specific,  that  is,  a  guinea  pig  immunized  against  cholera  will  immolnlize, 
agglutinate,  and  dissolve  only  the  cholera  vibrios;  a  guinea  pig  immu- 
nized with  typhoid  will  act  upon  typhoid  and  not  upon  cholera. 

It  was  soon  discovered  by  Bordet  that  tiiis  reaction  takes  ])lace  not 
only  in  the  peritoneal  cavity  of  the  immunized  animal,  but  will  occur 
in  the  test  tube  when  the  peritoneal  exudate  or  the  blood  serum  of 
the  innnunized  aninuil  is  mixed  with  tlie  cholera  organisms.  It  was 
through  a  study  of  tliis  reaction  that  Pfeiffer  and  Kolle  and  later  Gru- 
ber  and  then  Widal  discovered  and  described  the  ability  of  blood  serum 
to  clump  or  agglutinate  l)acteria.  It  seems  evident  that  tliis  power 
of  the  blood  serum  or  the  peritoneal  exudate  of  the  immunized  guinea 
pig  is  an  important  factor  in  the  mechanism  of  its  immunity. 

Bacteriolysins  are  absolutely  distinct  from  antitoxins  and  agglutinins. 
Even  when  these  three  substances  coexist  they  may  be  distinguished 
one  from  the  other  through  physical,  chemical,  or  biological  tests. 
Nothing  is  known  as  to  their  chemical  composition. 

Any  general  statement  concerning  the  thermal  death  point  or  other 
characters  of  the  lysins  must  be  misleading,  from  the  fact  that  we  now 
know  that  lytic  action  is  always  due  to  a  combination  of  two  substances: 
one  stable,  the  other  unstable;  one  readily  destroyed  by  heat,  the  other 
quite  resistant  to  heat.  This  important  observation  was  made  by  Bor- 
det, who  was  the  first  to  show  that  two  substances  are  necessary  for 
the  phenonu'non  of  bacteriolysis.  He  considered  that  one  of  these  sub- 
stances sensitized  the  bacteria,  and,  therefore,  called  it  the  "substance 
sensibilitrice";  this  substance  is  thermolabile.  The  other  substance, 
which  is  thermostable,  he  continued  to  call  alexin.  Bordet  found  that 
all  the  essential  features  of  bacteriolysis  could  be  reproduced  exactly 
if  red  blood  corpuscles  were  substituted  for  the  bacteria.  It  was  this 
analogy  between  bacteriolysis  and  hemolysis  that  led  Ehrlich  to  an  in- 
vestigation of  the  latter  phenomenon,  and  his   researches  led  to  much 


LYSmS  391 

new  light  upon  the  subject.  Ehrlich  introduced  new  names  for  the 
substances  which  Bordet  has  shown  to  be  necessary  for  the  phenomenon, 
and  applied  his  side-chain  theory  to  explain  the  reaction. 

Many  names  have  been  given  to  the  two  substances  which  take  part 
in  lysis.  The  thermostable  substance  has  been  called  substance  sen- 
sibilitrice,  or  simply  sensibilitrice,  immune  body,  amboceptor,  fixator, 
intermediary  body,  interbody,  philocytase,  immunisin,  desmon,  copula, 
and  preparator;  while  the  thermolabile  substance  has  been  called  the 
alexin,  complement,  addiment,  and  cytase.  We  shall  speak  of  the  first 
as  the  immune  body  and  the  second  as  the  complement. 

One  of  the  remarkable  fa;cts  connected  with  the  phenomenon  of  the 
lytic  poisons  is  that  the  poison  itself  (complement)  is  normally  pres- 
ent in  the  blood.  This  substance  is  a  fragile  body,  readily  destroyed 
at  a  moderate  temperature — 55°  C.  It  disappears  spontaneously  from 
the  serum  when  kept  for  a  few  days;  it  is  destroyed  by  acids  and  al- 
kalies and  is  not  specific  in  its  action.  Complement  appears  to  be 
formed  by  the  breaking  down  of  the  leukocytes,  which  accounts  for  the 
fact  that  blood  serum  after  clotting  is  much  more  potent  than  the  whole 
blood;  further,  complement  is  absent  from  fluids  containing  no  leuko- 
cytes, such  as  the  aqueous  humor. 

According  to  Ehrlich,  the  immune  body  has  two  combining  affini- 
ties, and,  therefore,  he  called  it  the  amboceptor.  It  unites  on  the  one 
hand  with  the  complement  and  on  the  other  with  the  receptor  of  the 
cell.  Bordet,  however,  considers  that  the  cell  unites  directly  but  separ- 
ately with  both  the  complement  and  the  immune  body.  The  immune 
body  is  stable  and  specific ;  it  is  more  stable  than  the  agglutinins  or  even 
the  antitoxins.  It  is  not  injured  by  heating  to  60°  C,  it  is  weakened  at 
70°  C,  and  finally  destroyed  by  prolonged  exposure  at  this  temperature. 
It  is  called  the  immune  body  because,  according  to  Ehrlich's  views,  im- 
munity can  only  be  obtained  through  it  on  account  of  its  specific  re- 
action. 

In  bacteriolytic  immunity  it  is  the  immune  body  rather  than  the 
complement  that  is  increased. 

Just  what  service  the  lysins  are  in  the  mechanism  of  immunity  is 
not  clear.  Eecent  studies  indicate  that  they  may  at  times  be  harm- 
ful as  well  as  useful.  Thus,  by  dissolving  the  bacterial  cell  they  have 
the  power  of  releasing  "endotoxins." 

The  studies  upon  anaphylaxis  have  thrown  much  collateral  light 
upon  the  probable  action  of  the  bacteriolysins  in  the  pathogenesis,  cure, 
and  prevention  of  disease.  When  the  bacteria  are  dissolved  within 
the  body  the  protein  matter  which  they  contain  is  set  free.  This  may 
not  be  poisonous  in  itself,  that  is,  may  not  have  any  of  the  properties 
ordinarily  attributed  to  the  endotoxins.  This  foreign  bacterial  protein, 
however,  may  sensitize  the  organism  so  that  the  second  time  the  pro- 


393  IMMUNITY 

tein  is  liberated  it  may  cause  a  reaction  which  may  account  for  some 
of  the  pathogenic  effects  and  symptoms  of  the  disease.  Buxton  and 
Coleman  explain  the  pathogenesis  of  typhoid  fever  as  largely  due  to 
a  solution  of  the  typhoid  bacilli  within  the  body,  and  it  is  probable 
that  in  pneumonia  and  other  infections  a  like  action  takes  place. 
An  organism  that  has  once  reacted  to  a  particular  bacterium  remains 
immune  so  long  as  it  possesses  an  altered  power  of  reaction,  when 
brought  in  association  with  the  microorganism  in  question.  Immunity 
in  this  sense  is  an  example  of  allergie  and  is  discussed  more  in  detail 
under  anaphylaxis. 

HEMOLYSIS 

The  hemolysins  are  substances  that  lake  the  blood;  that  is,  they 
dissolve  the  hemoglobin  from  the  red  blood  corpuscle  and  set  it  free  in 
solution.  A  certain  part  of  the  stroma  of  the  red  corpuscle  is  also 
destroyed  in  complete  hemolysis.  Some  of  the  hemolysins  are  specific 
and  others  are  not.  Thus,  distilled  water  will  dissolve  the  lieinoglobin 
from  the  red  corpuscles  of  almost  all  animals.  Other  known  non- 
specific hemolytic  substances  are  various  alkalies  and  acids;  plant 
poisons,  such  as  recin  and  abrin;  bacterial  poisons,  such  as  tetanolysin 
and  staph ylolysin ;  and  animal  poisons,  such  as  snake  venom,  scorpion 
venom,  etc.  The  specific  hemolysins  are  obtained  by  treating  (i.  e., 
immunizing)  one  animal  species  with  the  blood  corpuscles  of  another. 
For  example,  the  blood  corpuscles  of  a  guinea  pig  are  injected  into 
a  rabbit.  After  several  such  injections  the  blood  serum  of  the  rabbit 
will  contain  hemolytic  substances  for  the  guinea  pig's  corpuscles.  The 
corpuscles  used  for  immunization  are  obtained  by  drawing  the  blood 
of  the  animal  into  isotonic  salt  solution  (0.85  per  cent.)  containing 
about  1  per  cent,  of  sodium  citrate,  which  prevents  coagulation.  The 
citrated  blood  is  then  centrifugalized,  the  supernatant  fluid  drawn  off 
and  replaced  with  isotonic  salt  solution.  This  process  is  repeated 
three  or  four  times  and  is  known  as  washing  the  corpuscles.  The  ob- 
ject is  to  remove  all  trace  of  serum  containing  complement  and  other 
substances.  If  this  is  not  done  the  results  will  be  unnecessarily  com- 
plicated and  misleading.  The  washed  corpuscles  are  injected  into  the 
peritoneal  cavity  about  once  a  week  or  ten  days  until  the  blood  contains 
the  desired  hemolytic  action.  When  this  point  is  reached  can  only  be 
determined  by  withdrawing  small  quantities  of  the  blood  and  testing  it. 

Hemolytic  tests  are  made  by  adding  together  the  complement  and 
the  immune  bodies.  The  corpuscles  are  obtained  as  above  described, 
washed  three  or  four  times,  and  suspended  in  isotonic  salt  solution,  so 
that  they  are  present  in  the  proportion  of  about  5  to  10  per  cent,  by 
volume  of  the  salt  solution.     One  c.  c.  of  this  suspension  is  placed  in  a 


CYTOTOXINS  393 

small  test  tube.  To  this  is  then  added  the  immune  body  contained  in 
the  serum  of  the  animal  that  had  been  injected  with  the  corpuscles. 
This  immune  serum  is  first  heated  to  55°  or  56°  C.  for  one  hour  in 
order  to  destroy  the  complement.  This  degree  of  heat  does  not  injure 
the  immune  body.  Uniform  amounts  of  the  complement  are  obtained 
by  adding  a  definite  quantity  (0.3  of  a  c.  e.)  of  fresh  serum  to  each 
test  tube.  Each  test  tube  then  contains  a  uniform  quantity  of  the 
corpuscles  to  be  tested,  a  uniform  quantity  of  complement  in  the  fresh 
serum,  and  a  variable  quantity  of  heated  immune  serum  containing 
the  immune  body.  In  most  cases  normal  saline  solution  is  added  to 
bring  the  whole  up  to  a  definite  volume — say  5  c.  c. 

These  mixtures  are  now  incubated  at  37°  C.  for  two  hours,  being 
stirred  or  shaken  once  or  twice  in  the  meantime.  The  test  tubes  are 
now  removed  and  placed  in  a  vertical  position  in  the  ice  chest  from 
12  to  24  hours  and  then  examined.  If  no  hemolysis  has  taken  place 
the  supernatant  fluid  will  be  untinged  and  the  corpuscles  will  have 
settled  in  a  distinct  layer  at  the  bottom.  If  there  is  complete  hemol- 
ysis the  fluid  will  be  deeply  and  uniformly  colored  and  there  will  be 
no  sediment  or  only  a  minute  deposit  of  stromata.  If  the  reaction  is 
partial,  the  fluid  will  be  less  deeply  colored  and  there  will  be  more  or 
less  of  a  deposit  of  undissolved  corpiTScles.  It  must  be  remembered 
that  many  bacteria  produce  hemolysis  and  that,  if  the  mixtures  of  cor- 
puscles and  sera  be  incubated  for  long  periods,  fallacies  may  arise  from 
such  contaminations. 

CYTOTOXINS 

If  instead  of  red  blood  cells  an  animal  is  treated  with  the  body 
cells  or  glandular  cells  of  another  species,  it  develops  the  power  to 
dissolve  the  cells  in  question.  This  power  is  contained  in  the  blood 
serum  and  is  brought  about  by  substances  known  as  cytotoxins,  which 
are  entirely  similar  to  the  bacteriolysins,  the  hemolysins,  and  other 
lytic  substances.  Cytotoxins  have  been  obtained  with  the  spleen  (leu- 
kocidin),  with  the  sperm  (spermotoxin),  liver  cells  (hepatotoxin),  kid- 
ney cells  (nephrotoxin),  gastric  mucosa  (gastrotoxin),  placental  tis- 
sue (syncytiolysin  or  placentolysin),  prostatic  tissue  (prostatolysin), 
brain  (neurotoxin),  and  other  organs  and  tissues.  When  the  cyto- 
toxins were  discovered  they  aroused  great  enthusiasm  in  the  hope  that 
it  would  now  be  possible  to  dissolve  and  destroy  such  foreign  cells  as 
cancer  and  other  tumors,  and  pathological  processes  in  which  it  is  de- 
sirable to  get  rid  of  certain  cellular  elements.  The  practical  results 
have  been  exceedingly  disappointing,  as  further  investigations  have 
shown  that  these  cytotoxins  are  exceedingly  weak  and,  further,  are 
not  very  specific. 


394  IMMUNITY 


THE    BORDET  GENGOU     PHENOMENON— FIXATION    OF 
COMPLEMENT 

Bordct  and  (k'lii^ou  ^  foiiiul  thai  bacteria  and  also  red  blood  cells 
could  be  "sensitized"-  by  placing  them  in  heated  immune  serum.  The 
immune  serum  is  heated  to  55°  or  56°  C.  in  order  to  destroy  the  com- 
plement, leaving  only  the  thermostable  "substance  sensibilitrice"  which 
unites  with  the  bacteria  or  the  red  blood  cells,  and  thus  prepares  or 
sensitizes  them  to  the  action  of  the  complement.  If,  now,  these  sen- 
sitized bacteria  or  red  corpuscles  are  added  to  fresh  serum,  all  the  com- 
plement contained  in  the  fresh  serum  is  removed  or  fixed  so  that  the 
fluid  will  no  longer  dissolve  l)actoria  or  cells.  These  facts  are  of  very 
great  importance,  and  upon  them  are  based  the  Wassermann  reaction  for 
syphilis  and  other  practical  applications  in  immunology. 

The  Wassermann  reaction  for  syphilis  is  a  special  method  of  ap- 
plication of  the  Bordet-Gengou  phenomenon. 

The  antigen  is  a  watery  extract  of  the  syphilitic  liver  of  a  case  of 
hereditary  syphilis  which  contains  the  Treponema  pallidum  in  great 
numbers;  usually  about  0.1  to  0.2  c.  c.  of  the  liver  extract  is  used. 
Lecithin  and  other  fatty-like  bodies  may  also  act  as  antigen. 

The  complement  is  obtained  from  some  fresh  guinea  pig  serum; 
about  0.3  c.  c.  is  used. 

The  antibody  is  usually  the  unknown  quantity,  that  is,  the  blood 
serum  of  the  patient  to  be  tested.  This  serum  is  heated  to  55°  C.  to 
destroy  the  complement  and  then  diluted  in  the  proportion  of  1  to  20 
or  1  to  40  with  normal  saline  solution,  and  1  c.  c.  of  the  dilution  is 
used.  The  amount  must  be  determined  by  preliminary  tests  with  known 
syphilitic  serum. 

The  antigen,  the  unknown  serum,  and  the  complement  are  then 
mixed  in  proper  proportions  in  a  test  tube  and  incubated  at  37°  C.  for 
one  hour,  at  the  end  of  which  time  all  the  complement  will  be  removed 
from  the  fluid  if  syphilitic  antigen  is  present  in  the  unknown  serum 
that  has  been  used. 

The  hemolytic  system  is  tlien  added' to  the  mixture.  The  hemolytic 
system  usually  consists  of  sheep's  corpuscles  sensitized  with  the  heated 
blood  serum  of  a  rabbit  which  has  been  injected  with  sheep's  corpuscles. 
These  corpuscles  then  only  need  the  addition  of  complement  to  pro- 
duce hemolysis.  The  corpuscles  are  washed  and  suspended  in  normal 
salt  solution,  to  which  the  heated  immune  serum  (serum  of  rabbit 
which  has  been  treated  with  sheep's  corpuscles)    is  added. 

^Bordet:  Ann.  de  I'lnst.  Pasteur,  Vol.  XIV,  1900,  p.  257;  Vol.  XV,  1901,  p. 
289. 

Gengou:    Ann.  de  I'Inat.  Pasteur,  Vol.  XVI,  1902,  p.  734. 

Bordet  and  Gengou:    Compte  rendu.  Acad.,  Vol.  CXXXVII,  p.  351. 


DEVIATION    OF    COMPLEMENT  395 

The  whole  mixture  containing  the  antigen,  the  antibody,  the  com- 
plement, and  the  hemolytic  S5^stem  is  incubated  at  37°  C.  for  two  hours, 
occasionally  shaking  and  stirring  the  mixture,  and  is  then  placed  in 
the  ice  chest  and  the  result  read  after  12  to  24  hours.  A  positive 
reaction,  showing  the  presence  of  syphilitic  antibody,  is  determined  by 
the  absence  of  hemolysis.  The  presence  of  hemolysis  indicates  the 
absence  of  the  specific  antibody.  Control  tests  are  always  necessary, 
especially  to  determine  that  the  corpuscles  will  be  completely  dissolved 
by  the  heated  immune  serum  (antibody)  and  the  guinea  pig  serum 
(complement)  if  the  other  two  ingredients  are  not  added,  and  there 
should  be  no  hemolysis  if  all  the  substances  except  the  fresh  guinea  pig 
serum  are  used. 

The  reaction  of  fixation  based  upon  the  work  of  Bordet  and  Gen- 
gou  has  many  useful  practical  applications  in  addition  to  the  Wasser- 
mann  reaction  for  the  diagnosis  of  syphilis.  If  either  the  antigen  or 
the  antibody  are  unknown,  their  presence  may  be  determined  through 
the  reaction  of  fixation,  because  it  is  strictly  specific.  The  problem  is 
something  like  the  theorem  in  geometry  with  the  triangle;  two  sides 
and  an  angle  of  a  triangle  being  known,  the  other  side  and  angles  may 
be  determined. 

The  antigen  is  any  substance  which,  when  injected  into  a  suitable 
animal,  has  the  power  of  generating  as  antibody.  Practically  all  patho- 
genic bacteria  and  pathogenic  protozoa  act  as  antigens ;  many  albuminous 
bodies,  such  as  the  venoms,  the  enzymes,  and  bland  proteins,  may  also 
act  as  antigens.  As  the  reaction  is  specific,  it  is  possible  to  determine 
whether  a  particular  microorganism  is  the  true  cause  of  a  disease  or 
not.  Thus,  Bordet  was  enabled  to  satisfy  himself  that  the  bacillus 
which  he  isolated  during  the  early  stages  of  whooping-cough  was  the 
true  cause  of  that  disease,  as  it  gave  the  reaction  of  fixation  with  a 
specific  antibody.  On  the  other  hand,  if  the  antigen  is  known,  the 
diagnosis  may  be  made  through  the  reaction  of  fixation,  as  in  the  case 
of  syphilis  and  the  Wassermann  reaction. 


THE  NEISSER-WECHSBERG  PHENOMENON  OR  DEVIATION 
OF  THE   COMPLEMENT 

Neisser  and  Wechsberg  in  1901  ^  found  that,  although  the  addition 
of  a  small  amount  of  immune  serum  renders  normal  serum  more  bac- 
tericidal or  increases  its  power  of  protection,  a  greater  addition  robs 
it  of  most,  and  sometimes  of  all.  of  its  bactericidal  power.  In  other 
words,  the  solvent  effect  of  the  immune  body  on  cells  or  bacteria  in 
the  presence   of   complement   diminishes  as  an  excess  of  the   immune 

^  Munch,  med.  Wochensclir.,  1901,  No.  18. 


396  IMMUNTTY 

body  is  added.  This  particular  action  is  explained  by  Neisser  and 
AVechsberg  as  due  to  a  locking  up  (ablenkung)  or  deviation  of  the  com- 
plement which  is  brought  about  by  an  excess  of  the  ininiuno  body. 
The  phenomenon  is  hotter  understood  from  a  study  of  nn  example  given 
by  Neisser: 

(1)  Bacteria-]- 1'^  units  immune  serum  (i.  e.,  heated  immune  scrum 
containing  the  immune  body  but  not  complement )-j-complement  (i.  e., 
fresh  serum)  =:no  destruction  of  the  bacteria. 

(2)  Bacteria-|-5  units  immune  serum-|-coraplement=complete  de- 
struction. 

(3)  Bacteria-|-1  unit  immune  serum-(-complement=no  destruction. 
In    (3)    the   destruction   of   the   bacteria    is   not    complete,   because 

there  is  not  enough  immune  body  to  sensitize  the  bacteria  to  the  action 
of  the  complement,  or,  in  the  terms  of  Ehrlich,  not  enough  ambocep- 
tor to  unite  the  complement  to  the  bacterial  cell. 

In  (2)  the  proper  proportions  of  immune  body  and  complement 
occur  and  the  lytic  action  is  complete. 

In  (3)  there  is  an  excess  of  immune  body  which,  therefore,  com- 
bines with  and  deviates  the  complement  and  thus  renders  it  power- 
less to  unite  with  the  bacterial  cell,  and  thereby  the  l3'tic  action  is 
prevented. 

The  action,  therefore,  while  specific,  is  strictly  quantitative,  depend- 
ing upon  the  amount,  especially  of  immune  serum,  present  in  the  mix- 
ture; that  is,  though  immune  sera  protect  against  specific  infection, 
they  do  so  only  in  certain  doses.  It  is  easy  to  understand  how  too 
small  an  amount  of  immune  serum  will  fail  to  protect,  but  difficult  to 
understand  why  a  large  amount  should  fail;  in  other  words,  why  an 
excessive  amount  of  bacteriolytic  serum  should  cause  the  bacteria  to  be 
protected  rather  than  be  destroyed. 

ISOHEMOLYSINS 

Isohemolysins  have  the  property  of  destroying  the  red  blood  cells 
of  the  same  species.  They  occur  naturally  in  certain  animals,  prin- 
cipally in  the  horse  and  in  man.  They  may  also  be  produced  experi- 
mentally in  certain  animals,  as  in  goats,  by  the  injection  of  the  blood 
of  other  goats.  There  is  further  the  possibility  that  autohemolysins 
may  be  produced  which  destroy  the  blood  cells  of  the  individual  him- 
self. These  have  not  been  produced  artificially,  but  are  said  to  occur 
in  paroxysms  of  hemoglobinuria. 

PRECIPITINS 

Another  class  of  immune  bodies  known  as  the  precipitins  may  read- 
ily be  produced  in  the  blood  serum  of  animals  by  the  injection  of  bac- 


PEECIPITINS  397 

teria  or  albuminous  substances.  The  precipitating  action  of  immune 
sera  was  discovered  by  B.  Kraus  in  1897.  When  the  clear  antiserum 
is  added  to  the  clear  antigen  in  solution^  the  mixture  of  the  two  fluids 
becomes  opalescent,  then  opaque  from  the  formation  of  a  precipitate, 
and  after  a  time  this  settles  to  the  bottom  of  the  test  tube,  leaving 
a  clear  supernatant  fluid.  The  precipitate  consists  of  an  insoluble  com- 
bination of  two  substances,  one  of  which  is  present  in  the  antiserum, 
the  other  in  the  antigen.  This  insoluble  precipitate  is  known  as  the 
precipitum.  The  substance  in  the  antigen  is  known  as  the  precipitable 
substance  or  precipitinogen,  and  the  substance  in  the  antiserum  is  called 
the  precipitin.  Precipitums  are  doubtless  formed  both  within  and  with- 
out the  body  when  proper  conditions  of  antibody  and  antigen  are  pres- 
ent, without,  however,  always  causing  a  visible  precipitum. 

The  precipitins  are  quite  analogous  to  the  agglutinins,  and  from 
the  standpoint  of  physical  chemistry  are  often  classified  with  them.  It 
is  now  known  that  proteids  do  not  form  true  solutions,  but  molecular  or 
colloidal  suspensions.  The  effect  of  the  addition  of  a  precipitin  is  to 
cause  the  agglutination  of  these  molecules  in  a  manner  entirely  analogous 
to  the  agglutination  of  bacilli.  According  to  Emery,  the  laws  which 
govern  the  action  of  the  precipitins  and  agglutinins  are  entirely  similar, 
and  theoretically  it  would  probably  be  more  accurate  to  consider  them 
under  one  head.  The  practical  applications  of  the  two  classes  of  anti- 
bodies are,  however,  very  different,  and  it  is  more  convenient  to  treat 
them  as  separate  substances. 

The  bacterial  precipitins  were  those  first  discovered.  Kraus  added 
some  typhoid  serum  to  a  filtered  culture  of  typhoid  bacilli  and  obtained 
a  precipitate  when  the  two  clear  solutions  were  brought  together.  The 
same  happens  with  cultures  of  cholera,  plague,  and  other  bacteria. 
Certain  bacteria,  however,  do  not  produce  a  precipitable  substance.  This 
is  notably  the  case  with  diphtheria.  Thus,  when  diphtheria  antitoxin 
is  added  to  diphtheria  toxin,  no  visible  reaction  takes  place.  In  this 
case  the  di]3htheria  antitoxin  should  contain  the  antibody  or  precipi- 
tinogen. The  filtered  broth  culture  is  the  antigen  and  should  contain 
the  precipitin;  however,  one  or  both  of  these  substances  must 
be  absent,  as  a  precipitum  is  not  formed  when  they  are  brought  to- 
gether. 

Tsistowiteh  in  1899  found  that  precipitins  may  be  produced  by 
injecting  albuminous  substances  into  suitable  animals.  Thus,  if  rabbits 
are  injected  with  horse  serum  or  with  eel's  blood,  the  blood  serum  of 
the  treated  rabbit  will  precipitate  the  blood  serum  of  the  horse  or  the 
eel's  blood  respectively.  This  reaction  is  used  in  forensic  medicine  for 
the  recognition  of  blood  stains,  which  will  presently  be  discussed. 

The  chemical  nature  of  the  precipitins  is  not  known.  They  come 
down  with  the  globulins.     In  the  terms  of  the  side-chain  theory  they 


398  IMMUNITY 

contain  two  groups,  one  a  thermostable  haptophore  or  combining  group, 
the  other  a  thermolabile  functioning  group.  Precipitins  are  destroyed 
bv  heat,  light,  moisture,  and  other  external  influences  about  as  readily 
as  the  agglutinins.  Precipitating  sera  should,  therefore,  be  kept  in  a 
dry  state,  in  a  cool  place,  and  preserved  from  light.  A  proprecipitoid 
zone  entirely  analogous  to  the  proagglutinoid  zone  is  observed  under 
certain  conditions.  Precipitins  like  agglutinins  act  more  quickly  at 
the  body  temperature  and  reciuire  the  presence  of  certain  salts  for  their 
action.  According  to  Friedemann,  the  amount  of  precipitura  formed 
depends  on  the  quantity  of  the  salts  present. 

The  relation  of  precipitins  to  immunity  is  not  entirely  clear.  There 
is  a  strong  suspicion  tliat,  like  all  antibodies,  they  play  some  part  in 
the  mechanism  of  immunity  in  certain  infections,  but  just  what  part 
is  obscure.  It  is  quite  evident  that  the  presence  of  precipitins  in  the 
blood  must  have  valuable  protective  properties  against  the  poisons  of 
certain  infections.  The  immunity  in  this  case  would  be  due  to  the 
throwing  out  of  solution  of  the  poison,  thus  rendering  it  insoluble  and 
inert. 

Nuttal  in  his  "Blood  Eelationship"  made  a  very  careful  study  of 
the  question  of  specificity  of  the  precipitins. 

He  showed  that  the  reaction  of  the  precipitins,  like  the  reaction  of 
other  similar  antibodies,  is  relatively  specific  or  quantitatively  specific. 
If  the  antiserum  is  powerful  enough  it  will  react  with  all  the  bloods 
of  animals  in  the  same  great  division  of  the  animal  kingdom.  Thus, 
a  strong  antihuman  serum,  that  is,  a  serum  obtained  by  injecting  hu- 
man blood  into  rabbits,  will  give  a  precipitate  when  this  rabbit  serum 
and  human  serum  are  brought  together;  it  will  also  react  with  apes, 
monkeys,  etc.,  but  not  in  such  liigh  dilutions,  and  a  sliglit  trace  of 
precipitum  appears  after  a  long  period  even  when  mixed  with  the 
serum  of  more  remote  mammalia,  but  no  precipitate  occurs  with  the 
blood  of  birds,  fishes,  etc.  A  quite  similar  relationship  holds  with  lac- 
tosera  and  with  the  precipitating  sera  for  muscle  proteids;  the  anti- 
sera  for  egg  proteids  are  apparently  less  specific.  Precipitins,  then,  are 
not  specific  as  regards  the  animal  species  from  which  they  are  derived, 
but  possess  that  partial  specificity  seen  in  the  cytotoxins  and  in  the 
group  reaction  of  the  agglutinins.  According  to  Emery,  they  are  spe- 
cific as  regards  the  antibodies  which  bring  them  into  existence,  irre- 
spective of  the  source  from  which  the  antigen  is  derived.  For  medico- 
legal purposes  the  specificity  of  the  reaction  may  be  considered  satis- 
factory, provided  the  tests  are  made  quantitatively,  in  which  ease  the 
reaction  is  both  specific  and  delicate.  In  fact,  the  delicacy  of  the  re- 
action is  truly  astonishing.  Thus,  Ascoli  obtained  an  antiegg  albumin 
serum  which  gave  a  precipitate  with  1-1,000,000  dilution  of  egg  al- 
bumin; and  Stern  an  antihuman  serum  which  reacted  with  serum  at  a 


PEECIPITmS  399 

dilution  of  1-50^000.  While  these  are  extreme  figures,  it  is  not  unusual 
to  obtain  precipitates  in  dilutions  of  1-5,000. 

Tests  for  Blood. — In  carrying  out  the  precipitin  tests  for  the  recog- 
nition of  blood  stains,  as  suggested  by  Uhlenhuth  and  Wassermann,  it  is 
necessary  first  to  obtain  an  antiserum.  This  is  usually  gained  from  rab- 
bits, which  are  injected  intravenously  or  intraperitoneally  at  intervals  of 
three  or  four  days  with  human  serum.  The  human  serum  may  readily 
be  obtained  by  puncturing  a  vein  at  the  bend  of  the  elbow,  or  from  the 
placenta,  or  from  a  cadaver;  pleuritic  or  ascitic  fluid  may  also  be  used. 
The  amount  injected  rises  from  1  to  3  or  4  c.  c.  in  the  case  of  intravenous 
injections,  or  twice  as  much  or  even  more  into  the  peritoneum.  The 
course  of  treatment  lasts  three  or  four  months.  A  simpler  method  is  to 
give  larger  doses  up  to  10  c.  c.  or  more  intraperitoneally  at  intervals  of  a 
week.  The  intervals  should  not  be  longer  than  this,  for  danger  of 
complicating  anaphylactic  reactions.  The  blood  may  be  drawn  from  a 
vein  or  the  heart  of  the  rabbit  from  time  to  time  as  needed,  or  the  ani- 
mal may  be  chloroformed  and  exsanguinated  through  the  carotid  artery, 
or  as  much  blood  as  possible  may  be  collected  from  the  heart. 

The  blood  to  be  tested  is  usually  in  the  form  of  a  clot  or  stains 
upon  linen,  pistols,  and  other  surfaces.  These  stains  are  macerated 
with  normal  saline  solution  or  with  1  per  cent,  sodium  hydrate.  In 
the  case  of  very  old  stains  Zienka  recommends  the  use  of  a  strong 
solution  of  potassium  cyanid  which  is  subsequently  neutralized  with 
tartaric  acid.  The  fluid  is  then  examined  with  the  microscope  and 
tested  spectroscopically  to  determine  the  presence  of  blood  corpuscles 
and  pigments,  so  as  to  be  sure  we  are  really  dealing  with  blood.  The 
solution  is  then  filtered.  In  order  to  determine  the  approximate  strength 
of  the  solution  it  is  sufficient  to  bubble  air  through  the  fluid.  A  dilu- 
tion of  blood  serum  in  the  proportion  of  1-1,000  will  produce  a  stable 
foam.  If  a  stable  foam  is  not  produced  it  indicates  that  the  protein 
material  has  not  actually  passed  into  solution  or  is  too  dilute  to  be 
of  service  in  the  test.  Three  tests  are  made.  In  the  first  tube  one 
part  of  the  fiuid  under  examination  is  mixed  with  two  parts  of  the 
antiserum,  the  second  contains  the  fiuid  alone,  and  the  third  antiserum 
plus  normal  saline  solution.  Further  controls  in  which  the  antiserum 
is  mixed  with  diluted  serum  from  animals  other  than  man  may  also 
be  made.  The  tubes  are  then  incubated  at  37°  C.  and  examined  from 
time  to  time.  A  positive  result  is  obtained  if  there  is  a  precipitate  in 
the  first  tube  and  not  in  the  others.  In  case  a  precipitate  is  obtained 
further  tests  are  then  made  with  greater  dilutions.  With  a  powerful 
antiserum  a  reaction  may  usually  be  obtained  in  dilutions  so  high  that 
evidence  of  the  presence  of  proteids  is  barely  obtainable  by  ordinary 
chemical  means.  The  weak  point  in  the  method  is  that  it  is  never  possi- 
ble to  say  exactly  how  much  of  the  protein  matter  of  the  clot  has  been 


400  IMMUNITY 

dissolved,  and  thus  it  is  not  possible  to  obtain  precise  quantitative 
results.  With  an  unknown  blood  serum,  unaltered,  and  in  the  fluid 
state  the  test  can  be  carried  out  with  almost  complete  certainty,  but 
this  is  rarely  if  ever  possible  in  medicolegal  cases. 

Another  test  for  blood  has  been  introduced  by  Xeisser  and  Sachs 
and  based  on  tlie  Gengou  reaction  of  fixation  of  the  complement.  The 
test  is  extraordinarily  sensitive.  Xeisser  and  Sachs  found  that  one- 
millionth  part  of  a  cubic  centimeter  of  human  serum  is  readily  demon- 
strable. The  technique  is  complicated,  and,  according  to  Emerv%  it 
appears,  moreover,  that  complement  may  be  extracted  in  an  altogether 
non-specific  manner  by  substances  other  than  the  combination  of  anti- 
gen and  antibody.  'Another  serious  objection  is  that  a  similar  deviation 
of  the  complement  may  be  brought  about  by  means  of  sweat,  so  that 
if  the  reaction  were  obtained  in  a  stain  on  body  linen  it  would  be  of 
little  value. 

The  precipitin  reaction  further  finds  practical  application  in  deter- 
mining the  nature  of  meat,  whether  fresh,  as  in  the  case  of  beef  sus- 
pected to  be  horse  flesh,  or  prepared,  as  in  sausages,  etc.  For  these 
tests  the  antiserum  is  prepared  iby  injecting  rabbits  with  meat  juices 
or  an  unheated  watery  extract  of  the  meat,  and  the  test  is  carried 
out  on  lines  similar  to  those  described  above. 


AGGLUTININS 

Agglutinins  were  definitely  described  in  1896  by  Gruber  and  Dur- 
ham, and  a  few  days  later  by  Pfeiffer  and  Kolle.  Shortly  thereafter 
Widal  announced  the  fact  that  the  blood  serum  of  a  typhoid  patient 
will  agglutinate  the  typhoid  bacillus  in  high  dilutions.  The  phenom- 
enon of  agglutination  with  special  reference  to  typhoid  fever  is,  there- 
fore, often  called  the  Widal  reaction  or  the  Gruber  reaction.^ 

Agglutination  consists  in  a  clumping  or  grouping  of  the  bacteria 
into  clusters,  just  as  though  they  were  iron  filings  drawn  about  a  mag- 
netic point.  Usually  they  are  immobilized  before  they  are  drawn  to- 
gether into  a  clump  or  cluster.  Theobald  Smith  has  shown  that  the 
first  phenomenon,  the  immobilization  of  bacteria,  may  be  due  to  a 
flagellar  agglutinin,  and  that  the  second  phenomenon,  the  clumping, 
may  be  due  to  a  cellular  agglutinin. 

The  agglutination  of  bacteria  apparently  does  little  harm  to  them 
other  than  rendering  them  motionless,  for  they  are  not  altered  in  ap- 

^  The  phenomenon  of  agglutination  had  been  previously  observed  by  Charrin 
and  Eoger  in  1S99  in  the  case  of  the  Bacillus  pyocyaneus.  It  was  also  observed 
by  Metchnikoff  in  the  case  of  the  Vibrio  metchnikovi  in  1891.  Similar  appear- 
ance had  also  been  seen  by  Issaeff  in  1893. 


AGGLUTININS  401 

pearance,  viability,  or  virulence.  Bacteria  that  have  been  agglutinated 
may  again  multiply  and  grow  vigorously.  Agglutination  is  an  im- 
portant source  of  error  in  counting  the  number  of  bacteria  in  any  fluid. 
A  cluster  will  develop  into  one  colony  and  thereby  give  misleading  re- 
sults. The  apparent  diminution  in  the  number  of  bacteria  in  freshly 
drawn  milk,  judged  by  the  number  of  colonies  that  develop  upon  agar 
plates  and  known  as  the  germicidal  property  of  milk,  is  largely  a  phe- 
nomenon of  agglutination. 

Agglutination  may  occur  quickly  or  slowly,  depending  upon  the 
temperature,  the  dilution  of  the  serum  or  fluid  containing  the  agglu- 
tinin, and  upon  other  factors;  hence,  it  is  important  in  reporting  posi- 
tive or  negative  tests  in  the  diagnosis  of  typhoid  fever,  malta  fever, 
and  other  infections  always  to  state  the  dilution,  the  time,  the  tem- 
perature, and  other  conditions  under  which  the  test  was  made.  The 
interpretation  of  the  results  may  depend  upon  these  factors. 

Agglutination  may  readily  be  seen  by  the  naked  eye.  A  uniform 
suspension  of  bacteria  in  a  test  tube  under  the  action  of  an  agglutinin 
first  becomes  granular;  the  granules  increase  in  size  and  flock  into 
masses  with  intervening  clear  spaces.  Then  these  flocculi  settle  to  the 
bottom  as  a  precipitate,  leaving  the  supernatant  fluid  clear.  Under  the 
microscope  the  bacteria  are  first  seen  to  lose  their  motion,  then  to  be 
drawn  together  into  irregular  clumps  or  clusters,  which  increase  in 
size.  The  macroscopic  method  is  much  more  dependable  in  testing  ag- 
glutinins than  the  microscopic  method.  The  latter  is  subject  to 
several  sources  of  error,  and  the  end  point  is  not  as  sharply  defined  as 
in  the  macroscopic  method. 

Agglutination,  like  almost  all  chemical  processes,  takes  place  more 
quickly  when  warm  than  in  the  cold.  The  reaction  is  best  at  37°  C. 
The  clumping  usually  takes  place  more  slowly  with  the  non-motile  bac- 
teria. Certain  strains  of  some  species  of  bacteria  agglutinate  more 
readily  than  others.  Thus,  the  typhoid  bacillus  is  usually  agglutinated 
readily  with  its  specific  serum,  but  some  strains  are  agglutinated  with 
considerable  difficulty;  in  general,  when  first  isolated,  they  resist  ag- 
glutination. This  resistance  or  "immunity"  of  the  microorganism 
usually  wears  off  after  a  number  of  subcultures.  A  very  interesting 
phenomenon  in  agglutination  which  has  considerable  practical  impor- 
tance is  the  so-called  proagglutinoid  zone;  that  is,  bacteria  sometimes 
will  not  agglutinate  in  a  stronger  dilution,  whereas  they  agglutinate 
readily  in  a  weaker.  The  proagglutinoid  zone  is  occasionally  found 
with  the  typhoid  bacillus,  but  especially  with  the  Micrococcus  melit en- 
sis.  Thus,  this  coccus  may  give  no  reaction  in  a  dilution  between 
1-10  and  1-100,  whereas  it  will  clump  strongly  at  1-200. 

Agglutinins  are  not  very  resistant  to  light,  putrefactive  processes, 
and  dryness.     They  are  not  much  harmed  at  a  temperature  of  55°  to 


402  IMMUNITY 

56°  C,  but  are  destroyed  at  65°  to  70°  C.  They  are  very  sensitive  to 
acids;  they  are  partially  held  back  by  a  Pasteur-Chaniberland  filter; 
they  are  not  dialyzable.  They  may  be  preserved  for  a  very  long  time 
in  dried  serum  protected  from  light  and  moisture. 

The  chemical  composition  of  the  agglutinins  is  not  known.  Like 
antitoxin  and  other  anlihodics,  they  come  down  with  the  globulins  when 
precipitated  with  ammonium  sulphate.  They  unite  directly  with  the 
bacteria  or  otlier  cells  and,  according  to  Ehrlich,  contain  botli  a  hap- 
tophore  and  an  "agglutinophore"  group. 

Agglutinins  may  readily  be  ])roduced  by  injecting  either  live  or 
dead  bacterial  cells  into  a  suitable  aninuil.  The  injections  may  be 
given  either  subcutaneously,  intravenously,  intraperitoneally,  or  the 
microorganisms  may  be  rubbed  upon  the  closely  shaven  skin.  Agglu- 
tinins may  even  be  produced  by  giving  the  microorganisms  by  the  mouth. 
Agglutinins  in  highest  concentration  may  be  obtained  by  repeated  in- 
jections, every  10  or  12  days,  continued  over  a  long  period  of  time. 
In  experimental  work  in  the  laboratory  rabbits  are  suitable.  Three 
or  four  injections  into  the  ear  vein  of  the  rabbit,  spaced  at  intervals 
of  8  or  10  days  with  cultures  of  cholera  or  typhoid,  will  develop  ag- 
glutinins in  the  blood  serum  when  diluted  as  high  as  1  to  5,000  or  1  to 
10,000.  Where  large  amounts  are  needed  the  horse  is  the  most  suitable 
animal. 

Agglutinins  also  appear  spontaneously  in  attacks  of  certain  infec- 
tious diseases  and  continue  in  the  blood  for  some  time  after  convales- 
cence. In  typhoid  fever  they  appear  about  the  end  of  the  first  week. 
They  are  usually  weak  at  first,  clumping  the  typhoid  bacilli  in  a  dilu- 
tion of  1-30  in  one  hour  at  the  body  temperature,  arid  increase  with 
the  progress  of  the  disease,  so  that  the  serum  may  agglutinate  in  dilu- 
tions of  1-1,000  or  more.  In  malta  fever  agglutinins  appear  about  the 
fifth  day  of  the  disease  and  may  develop  in  large  amount.  Thus,  the 
blood  serum  from  a  case  of  malta  fever  may  agglutinate  the  Micrococcus 
meliiensis  in  dilutions  as  high  as  1-500,000.  The  reaction  of  agglu- 
tination is  not  only  practical  as  an  aid  to  diagnosis  of  disease,  but  is 
of  considerable  practical  use  as  an  aid  of  recognition  of  the  bacteria 
themselves. 

The  reaction  of  agglutination  is  not  absolutely  specific;  thus,  a  ty- 
phoid agglutinin  will  occasionally  clump  proteus  or  other  not  very 
closely  related  microorganisms.  Thus,  Frost  found  a  Psedomonas  pro- 
tea  in  the  Potomac  River  water  that  showed  quite  constantly  the  char- 
acteristic of  being  agglutinated  by  specific  typhoid  immune  serum. 
However,  when  animals  were  injected  with  the  Ps.  protea  they  developed 
agglutinins  for  this  organism,  but  not  for  the  B.  typhosus.  Further, 
there  is  the  phenomenon  of  group  agglutination  or  group  reaction; 
that  is,  a  typhoid  serum  will  clump  the  colon  bacillus,  the  paratyphoid. 


ANAPHYLAXIS  403 

the  paracolon  bacillus,  and  closely  related  organisms  in  the  colon  ty- 
phoid group.  However,  this  occurs  only  in  weak  dilutions.  The  reac- 
tion is,  therefore,  specific  in  a  quantitative  sense.  Thus,  a  good  cholera 
or  typhoid  serum  will  agglutinate  these  organisms  in  dilutions  of  1- 
1,000  and  over,  whereas  the  group  reactions  occur  in  dilutions  of  about 
1-50  or  less. 

In  addition  to  the  bacteria,  the  red  blood  cells,  or  cells  of  any 
sort,  trypanosomes  and  other  protozoa  may  be  agglutinated. 

We  have  no  satisfactory  explanation  of  agglutination.  Analogous 
phenomena  occur  in  the  study  of  the  physical  chemistry  of  colloidal 
substances.  It  seems  that  in  agglutination  two  separate  phenomena  are 
involved:  the  approach  of  the  particles,  one  to  the  other,  and  their  ad- 
hesion subsequently.  The  phenomenon  may  be  imitated  by  coating 
match  sticks  with  soap,  floating  them  upon  the  surface  of  water  in  a 
basin,  and  then  adding  sulphuric  acid.  The  agglutinins  affect  the  sur- 
face tension  between  the  bacteria  and  the  fluid  in  which  they  are  sus- 
pended in  some  way,  but  just  how  is  not  quite  clear.  The  agglutinins 
are  probably  formed  in  the  lymphoid  organs,  red  marrow,  and  spleen; 
at  least,  Pfeiffer  and  Marx  found  them  early  in  these  organs  after 
injections  of  cholera  vibrios.  Metchnikoff  found  that  the  peritoneal 
exudate  may  be  richer  in  agglutinins  than  the  blood,  and  believes  in 
that  fluid  they  come  from  the  leukocytes  and  endothelial  cells. 

The  part  played  by  the  agglutinins  in  immunity  is  not  clear.  Al- 
though the  bacteria  are  immobilized,  this  does  not  particularly  favor 
phagocytosis.  Large  clusters  of  bacteria  or  agglutinated  clumps  of 
closely  packed  cells  afford  a  mechanical  protection  against  the  dissolv- 
ing action  of  the  lysins. 

ANAPHYLAXIS 

Anaphylaxis  (ana,  against,  and  pliylax,  guard,  or  phylaxis,  protec- 
tion), also  called  hypersusceptibility,  is  a  condition  of  unusual  or  exag- 
gerated susceptibility  of  the  organism  to  foreign  proteins.  In  other 
words,  anaphylaxis  is  an  altered  power  of  reaction  on  the  part  of  the 
body  to  foreign  proteins.  The  word  anaphylaxis  was  introduced  by 
Eichet  to  describe  a  condition  contrary  to  prophylaxis.  As  we  now 
regard  the  phenomenon,  the  word  is  a  misnomer,  for  we  look  upon  the 
condition  of  hypersusceptibility  as  a  distinct  benefit  and  advantage  to 
the  organism;  in  fact,  immunity  against  a  large  class  of  infectious 
diseases  probably  depends  upon  an  altered  power  of  reaction,  that  is, 
upon  hypersusceptibility  or  anaphylaxis. 

The  condition  of  anaphylaxis  may  be  congenital  or  acquired,  local  or 
general,  and  is  specific  in  nature.  It  may  be  brought  about  by  the  intro- 
duction of  any  strange  protein  into  the  body.     Hypersusceptibility  to 


404  nOIUNITY 

proteins  that  are  non-poisonous  in  themselves  may  readily  be  induced 
in  certain  animals.  The  animal  may  be  in  a  condition  of  hypersuscepti- 
bility  and  immunity  at  the  same  time.  The  two  conditions  are  closely 
interwoven.  The  latter  is  often  dependent  upon  the  former.  Von 
Pirquet  suggests  the  term  "allergic"  to  indicate  conditions  of  acquired 
immunity  associated  with  anaphylaxis.  Allergic,  as  the  word  indicates 
{alios,  change,  and  ergon,  action),  is  an  altered  power  of  the  organism 
to  react.  When  this  power  of  reaction  is  increased  we  say  the  body  is 
hypersusccptible,  or  in  a  state  of  anaphylaxis. 

Examples  of  Anaphylaxis. — In  the  case  of  vaccinia,  the  reaction  to  a 
primary  "take"  ajjpears  after  an  incubation  of  four  days.  In  a  secondary 
vaccination  the  period  of  incubation  is  shortened  and  the  clinical  reac- 
tion lessened.  In  other  words,  the  power  of  the  organism  to  react  is 
changed.  This  power  of  accelerated  or  immediate  reaction  protects  the 
individual.  Therefore,  there  is  no  absolute  immunity  in  the  class  of  dis- 
eases represented  by  smallpox ;  the  prophylaxis  depending  upon  the 
anaphylaxis. 

The  tuberculin  and  mallein  reactions  are  well-known  instances  of 
anaphylaxis.  These  substances  are  not  poisonous  when  introduced  into 
a  healthy  individual,  but  the  tuberculous  individual  is  anaphylactic  to 
tuberculin,  and  an  individual  suffering  from  glanders  is  in  a  state  of 
hypersusceptibility  to  mallein. 

A  clinical  instance  of  anaphylaxis  is  the  hypersusceptibility  of  some 
individuals  to  pollen — hay  fever. 

Experimental  anaphylaxis  may  be  brought  about  in  various  ways,  such 
as  the  introduction  of  an  alien  serum  into  the  body — ser^^m  anaphylaxis. 
Experimental  Serum  Anaphylaxis. — The  essential  features  of  experi- 
mental anaphylaxis  are : 

(1)  The  first  injection,  consisting  of  a  bland  alien  protein  non- 
poisonous  in  itself,  which  sensitizes  the  animal; 

(2)  An  interval  of  about  8  to  14  days; 

(3)  The  second  injection  of  the  same  protein  which  produces  a 
reaction  known  as  acute  anaphylactic  shock. 

Horse  serum,  when  injected  into  normal  guinea  pigs,  causes  no 
symptoms.  As  much  as  20  c.  c.  may  be  injected  into  the  peritoneal 
cavity  of  a  guinea  pig  without  causing  any  apparent  inconvenience 
to  the  animal.  Small  amounts  of  horse  serum  may  even  be  injected 
directly  into  the  brain  without  causing  any  untoward  symptoms. 

Very  characteristic  symptoms,  however,  are  produced  by  horse  serum 
when  injected  into  a  susceptible  guinea  pig;  i.  e.,  one  that  has  received 
a  prior  injection  of  horse  serum.  In  five  or  ten  minutes  after  injection 
the  pig  becomes  restless  and  then  manifests  indications  of  respiratory 
embarrassment  by  scratching  at  the  mouth,  coughing,  and  sometimes  by 


AFAPHYLAXIS  405 

spasmodic,  rapid,  or  irregular  breathing;  the  pig  becomes  agitated  and 
there  is  a  discharge  of  urine  and  feces.  This  stage  of  exhilaration  is 
soon  followed  by  one  of  paresis  or  complete  paralysis,  with  arrest  of 
breathing.  The  pig  is  unable  to  stand  or,  if  it  attempts  to  move,  falls 
upon  its  side;  when  taken  up  it  is  limp:  spasmodic,  jerky,  and  con- 
vulsive movements  now  supervene.  This  chain  of  symptoms  is  very 
characteristic,  although  they  do  not  always  follow  in  the  order  given. 
Pigs  in  the  stage  of  complete  paralysis  may  fully  recover,  but  usually 
convulsions  appear,  and  are  almost  invariably  a  forerunner  of  death. 
Symptom-'S  appear  about  ten  minutes  after  the  injection  has  been  given; 
occasionally  in  pigs  not  very  susceptible  they  are  delayed  thirty  to  forty- 
five  minutes.  Pigs  developing  late  symptoms  are  not  very  susceptible 
and  do  not  die.  Death  usually  occurs  within  an  hour  and  frequently  in 
less  than  thirty  minutes.  If  the  second  injection  be  made  directly 
into  the  brain  or  circulation,  the  symptoms  are  manifested  with 
explosive  violence,  the  animal  frequently  dying  within  two  or  three 
minutes. 

A  fall  in  temperature  occurs  which  in  fatal  cases  may  be  as  great 
as  13°  C.  (Pfeiffer).  The  blood  during  anaphylactic  shock  shows  a 
leukopenia  and  a  diminution  in  complement.  When  the  chest  is  opened 
the  lungs  show  a  striking  condition  resemblirg  emphysema.  They  do 
not  collapse  but  remain  fully  distended,  forming  a  cast  of  the  pleural 
cavities.  The  heart  continues  to  beat  long  after  respiration  has  ceased. 
Asphyxia,  due  to  inspiratory  immobilization  of  the  lungs,  is,  therefore, 
probably  the  immediate  cause  of  death. 

Judged  by  the  severity  of  the  symptoms  of  the  acute  anaphylactic 
reaction,  the  guinea  pig  is  apparently  the  most  susceptible  of  animals 
(being  400  times  more  sensitive  than  the  rabbit,  according  to  Doerr), 
but  probably  all  animals  may  be  sensitized  to  a  greater  or  less  degree, 
although  our  methods  of  observation  are  still  too  crude  to  admit  of 
any  accurately  graded  comparison.  White  mice  were  long  thought  to  be 
non-responsive  on  account  of  the  absence  of  anaphylactic  shock  and 
death  from  asphyxia,  so  striking  in  the  guinea  pig;  but  Schultz  and 
Jordan  have  shown  that  white  mice  do  react  toward  horse  serum  with 
restlessness,  marked  irritability  of  the  skin,  passage  of  urine  and  feces, 
and  temperature  and  blood  pressure  changes. 

In  dogs,  according  to  Eichet,  the  principal  symptoms  are  gastro- 
intestinal. There  is  immediate  vomiting,  followed  by  tenesmus  and 
bloody  discharges  from  the  intestines.  Death  is  infrequent,  but  there 
may  develop  a  condition  of  hemorrhagic  inflammation  in  both  the  large 
and  the  small  intestine  which  is  called  by  Eichet  "chronic  anaphylaxis," 
and  by  Schittenhelm  and  Weichardt,  "enteritis  anaphylactica."  Another 
important  sign  is  the  rapid  fall  in  blood  pressure,  sometimes  80-100 
mm. ;  coagulation  of  the  blood  is  delayed.  Dyspnea  is  not  marked,  but, 
28 


406  IMMUNITY 

as  in  other  animals,  there  is  initial  restlessness  and  skin  irritability; 
there  may  be  paralysis  and  death. 

Eabbits  are  apt  to  react  to  a  re-injection,  of  horse  serum  by  edema 
and  even  necrosis  at  the*  site  of  injection — the  "Artlnis  phenomenon,"  a 
local  anaphylaxis.  Arthus  also  described,  in  non-fatal  cases  in  rabbits, 
respiratory  disturbance,  general  prostration,  fall  in  blood-pressure,  and 
increased  peristalsis.  In  cases  of  acute  lethal  anaphylaxis  produced  in 
rabbits  highly  sensitized  by  repeated  minute  injections,  Auer  describes 
the  slow  respiration,  the  sudden  falling  of  the  animal  on  its  side  with  a 
short  clonic  convulsion,  stoppage  of  the  respiration,  weak  heart  beat, 
and  death  within  a  few  minutes. 

The  reaction  to  a  second  injection  of  serum  has  been  observed,  though 
not  studied  so  carefully,  in  numerous  otlier  animals,  e.  g.,  in  cows,  horses, 
goats,  sheep,  and  cats,  in  hens  and  pigeons,  and  in  certain  cold-blooded 
animals,  with  symptoms  varying  according  to  the  species. 

It  is  evident  that  no  one  symptom,  or  group  of  symptoms,  can  be 
taken  as  an  adequate  criterion  of  anaphylaxis  in  all  cases.  Different 
species  give  a  widely  differing  picture  with  the  same  proteid  agent, 
because  the  same  organs  are  not  involved  to  the  same  degree.  An  ex- 
planation of  these  differences  from  the  physiological  point  of  view  has 
been  given  by  Schultz.  He  has  shown  that  serum  anaphylaxis  is  essen- 
tially a  matter  of  hypersensitization  of  smooth  muscle  in  general.  He 
concludes,  as  a  result  of  his  experiments,  that,  during  anaphylactic 
shock,  all  smooth  muscle  contracts.  This  is  fatal  to  the  guinea  pig, 
owing  to  the  peculiar  though  normal  anatomical  condition  of  its  bron- 
chial tree :  the  mucosal  layer  of  the  secondary  bronchi  is  relatively  thick 
in  comparison  witli  the  lumen,  and  the  contraction  of  the  smooth  muscle 
throws  it  into  folds  which  completely  occlude  the  bronchi  (Schultz  and 
Jordan).  The  guinea  pig  dies  of  asphyxia,  the  cause  of  which  is  purely 
local  and  not  in  the  central  nervous  system,  as  the  first  investigators  be- 
lieved. The  bronchi  of  mice,  dogs,  and  rabbits,  however,  are  relatively 
poor  in  mucous  membrane,  which  accounts  for  the  almost  complete  ab- 
sence of  death  from  asphyxia.  In  the  dog  the  contraction  of  smooth 
muscle  sets  up  a  vigorous  intestinal  peristalsis  and  a  forced  emptying 
of  the  urinary  bladder;  the  characteristic  initial  rise  in  blood  pressure 
may  be  due  to  constriction  of  the  pulmonar}',  coronary  and  systemic 
arteries,  and  according  to  Auer.  the  subsequent  marked  fall  to  direct 
action  on  the  heart  muscle  itself,  particularly  of  the  right  side,  causing 
a  venous  accumulation  of  blood,  an  effect  typified  most  strikingly  in 
the  rabbit.  This  provides  also  an  adequate  pharmacological  explanation 
of  the  action  of  atropin  and  the  anesthetics  in  alleviating  the  symptoms 
of  acute  anaphylaxis. 

Specificity. — The  anaphylactic  reaction  is  specific.  Thus,  a  guinea 
pig  sensitized  with  horse  serum  does  not  react  to  a  subsequent  injection 


ANAPHYLAXIS  407 

of  egg-white,  vegetable  proteid,  or  milk.  The  specificity  extends  even 
further  than  this.  In  order  to  give  rise  to  anaphylactic  symptoms,  the 
proteid  material  given  at  the  first  and  second  injections  must  be  from 
the  same  species  or  from  some  closely  related  species.  Thus  a  guinea 
pig  sensitized  with  cow's  milk  will  not  react  to  a  subsequent  injection 
of  woman's  milk.  Guinea  pigs  sensitized  with  the  albumen  of  hen's 
eggs  will  not  react  to  a  subsequent  injection  of  the  albumen  of  the  eggs 
of  pigeons,  but  do  react  mildly  to  duck  egg-white.  This  specificity  ac- 
cording to  species  is,  therefore,  of  the  same  degree  as  that  of  certain 
immune  reactions,  notably  the  precipitins;  that  is,  there  is  a  group 
reaction  in  the  proteids  of  allied  species,  but  no  reaction  between  the 
proteids  of  widely  different  species  or  between  proteids  of  widely  dif- 
ferent origin.  The  maximum  effect  at  second  injection  is  obtained 
by  the  use  of  the  identical  proteid  used  for  sensitization.  Certain 
sera  which  react  interchangeably  to  precipitins,  as,  for  example, 
human  and  ape,  horse  and  ass,  sheep  and  goat,  rat  and  mouse,  remain 
indistinguishable  also  by  the  anaphylactic  reaction.  The  same 
specificity  holds  with  respect  to  bacterial  proteids:  an  animal  sensi- 
tized with  typhoid  bacilli  will  react  strongly  toward  paratyphoid, 
and  somewhat  toward  colon  bacilli,  but  not  at  all  to  unrelated 
species. 

One  of  the  remarkable  facts  in  relation  to  the  specificity  of  anaphy- 
laxis is  that  guinea  pigs  may  be  in  a  condition  of  anaphylaxis  to  three 
proteid  substances  at  the  same  time ;  for  instance,  a  guinea  pig  may  be 
sensitized  with  egg-white,  milk,  and  horse  serum,  and  subsequently  react 
separately  to  a  second  injection  of  each  one  of  these  substances.  The 
guinea  pig  may  be  sensitized  by  giving  these  strange  proteids  either  at 
the  same  time  or  different  times,  in  the  same  place  or  in  different  places, 
or  by  injecting  them  separately  or  mixed.  The  guinea  pig  differentiates 
each  anaphylactogenic  proteid  in  a  perfectly  distinct  and  separate  man- 
ner. The  animal  is  susceptible  to  the  second  injection  of  each  one  of  the 
three  substances  in  the  same  sense  that  it  is  susceptible  to  three  separate 
infectious  diseases. 

That  there  may  be  exceptions  to  the  rule  of  species-specificity  is  shown 
in  the  case  of  the  crystalline  lens.  A  guinea  pig  sensitized  to  the  lens- 
extract  of  one  species  of  animal  will  react  to  the  lens-extract  of  widely 
different  species,  or  even  of  its  own  species,  but  not  to  other  tissues 
(Andrejew).  Here,  too,  there  is  an  exact  parallel  in  the  precipitin 
reaction  which  fails  to  distinguish  the  lens  of  one  species  from  that  of 
another  (Uhlenhuth).  This  is  an  example  of  organ-specificity.  In  the 
vegetable  world  Osborne  has  shown  that,  whereas  preparations  of  globu- 
lins from  hemp,  flax,  and  squash  do  not  react  with  each  other,  gliadin 
from  rye  reacts  strongly  with  gliadin  from  wheat,  a  result  in  accord 
with  the  fact  that  by  chemical  and  physical  means  no  differences  have 


408  IMMUNITY 

been  detected  which  were  sufficient  to  indicate  that  these  gliadins  were 
different  substances. 

It  is  probable  that  only  proteids  which  have  a  complete  or  partial 
chemical  identity  of  structure  will  react  with  each  other.  Differences 
too  small  to  be  detected  by  analytic  means  at  our  disposal  may  yet  pre- 
vent any  tendency  toward  interaction,  and  tlie  anapliylactic  phenomenon 
may  thus  be  used  to  determine  the  finer  relationships  of  proteids.  It  is 
evident  from  these  facts,  as  Osborne  concludes,  that  structural  differences 
exist  between  very  similar  proteids  of  different  origin,  and  that  chemi- 
cally identical  proteids  apparently  do  not  occur  in  animals  and  plants 
of  different  species  unless  they  are  biologically  very  closely  related. 

Sensitization  by  Feeding. — Guinea  pigs  may  be  sensitized  by  feed- 
ing them  meat  or  serum.  The  fact  that  guinea  pigs  may  be  ren- 
dered susceptible  by  the  feeding  of  strange  protein  matter  opens  an 
interesting  question  as  to  whether  sensitive  guinea  pigs  may  also  be 
poisoned  by  feeding  with  the  same  protein  given  after  a  proper  interval 
of  time.  If  man  can  be  sensitized  in  a  similar  way  by  the  eating  of 
certain  protein  substances,  this  may  throw  light  on  those  interesting  and 
obscure  cases  in  which  the  eating  of  fish,  sea  food,  or  other  articles 
of  diet  sometimes  cause  sudden  and  often  serious  symptoms  resembling 
those  of  anaphylaxis  in  all  essential  respects. 

Maternal  Transmission. — It  has  been  found  that  hypersusceptibility 
to  the  toxic  action  of  horse  serum  is  transmitted  from  the  mother 
guinea  pig  to  her  young.  This  function  is  solely  maternal;  the  male 
takes  no  part  whatever  in  the  transmission  of  these  acquired  properties. 
Whether  this  maternal  transmission  is  hereditary  or  congenital  cannot 
be  definitely  stated. 

There  are  certain  analogies  between  the  action  of  tuberculosis  and 
horse  serum.  Both  produce  hypersensitiveness,  and  also  a  certain  de- 
gree of  immunity.  Xow  that  it  has  been  proved  that  hypersensitive- 
ness or  anaphylactic  action  may  be  transmitted  in  guinea  pigs,  may  it 
not  throw  light  upon  the  fact  that  tuberculosis  "runs  in  families"? 
While  there  are  several  recorded  instances  demonstrating  that  immunity 
to  certain  infectious  diseases  may  be  transmitted  from  a  mother  to  her 
young,  this  is,  so  far  as  is  known,  the  only  recorded  instance  in  which 
hypersensitiveness  or  a  tendency  to  a  disease  has  been  experimentally 
shown  to  be  transmitted  from  a  mother  to  her  young. 

Serum  Anaphylaxis  in  Man,  or  Serum  Sickness. — Serum  anaphylaxis 
in  man  is  met  with  most  frequently  following  the  use  of  antitoxic  sera, 
and  has  been  carefully  described  by  v.  Pirquet  and  Schick  (1905).^ 
After  an  injection  of  serum  (usually  in  from  eight  to  twelve  days)  there 
is  apt  to  be  a  febrile  reaction,  now  generally  known  as  "serum-sickness," 
or  serum  disease.     The  common  symptoms  are  local  redness,  itching  and 

'"Serum   Krankheit,"  Wien,   1905. 


AITAPHYLAXIS  409 

pain  at  the  point  of  injection,  swelling  of  the  lymph  nodes,  fever,  and 
a  general  urticaria  lasting  from  two  to  six  days.  In  more  severe  cases 
there  is  malaise,  albuminuria,  pronounced  joint  pains  and  even  effusions, 
swelling  of  the  mucous  membranes,  hoarseness  and  cough,  nausea  and 
vomiting,  vertigo,  and  remarkable  skin  manifestations  varying  from 
hyperemias  and  erythemas  to  efflorescences  resembling  measles  or  scar- 
latina, and  other  vasomotor  disturbances. 

Earely  there  may  be  subnormal  temperature,  a  weak  and  rapid  pulse, 
a  catarrhal  or  hemorrhagic  enteritis  and  extreme  weakness  approaching 
collapse.  These  results  are  independent  of  the  antitoxic  qualities  of 
the  serum,  for  Johannessen  obtained  the  same  symptoms  by  introducing 
normal  horse  serum  into  the  bodies  of  perfectly  healthy  human  beings. 
Indeed,  the  very  earliest  animal  experiments  were  particularly  concerned 
in  determining  whether  the  antitoxin  played  any  part  in  the  phenomenon, 
and  it  was  soon  conclusively  eliminated  as  a  factor. 

Both  the  incidence  and  the  severity  of  serum  sickness  are  propor- 
tional to  the  amount  injected  up  to  a  certain  point,  but  the  acute 
(sometimes  fatal)  reaction  in  man  is  more  dependent  upon  the  hyper- 
susceptibility  of  the  individual  than  upon  the  amount  of  serum  injected. 
If  the  serum  is  "concentrated"  (i.  e.,  serum-globulin),  the  reactions  are 
correspondingly  lessened  because  smaller  quantities  of  the  foreign  pro- 
teid  are  injected,  the  albumens  and  certain  other  proteids  having  been 
eliminated  by  the  partial  purification. 

The  peculiarity  of  serum  sickness  in  man  is  that  it  may  follow 
the  first  injection  of  a  foreign  serum,  though  only  after  a  definite  incu- 
bation period  corresponding  to  the  time  required  to  sensitize  an  experi- 
mental animal.  There  is  no  proof  that  other  animals  do  not  develop 
a  reaction  to  the  first  dose  which  never  rises  to  the  threshold  of  clinical 
observation;  in  fact,  Ehrlich,  Francione,  and  others  have  observed  a 
temporary  diminution  of  complement  in  the  blood  of  guinea  pigs  10-13 
days  after  the  first  injection. 

Besides  the  typical  serum  sickness,  there  has  been  reported  since 
the  introduction  of  serum  therapy  a  certain  small  number  of  unforeseen 
and  fatal  catastrophes  attending  the  injection  of  serum  into  human 
beings.  The  following  case  published  by  H.  F.  Gillette  will  serve  to 
illustrate  them  all: 

"The  patient  was  a  man  of  53,  a  subject  of  asthma.  He  asked 
me  to  administer  diphtheria  antitoxin  to  him,  hoping  it  might  cure 
his  asthma.  I  administered  2,000  units  under  the  left  scapula  with 
the  usual  precautions.  He  had  about  completed  dressing  when  he  said 
he  had  a  pricking  sensation  in  the  neck  and  chest;  soon  he  sat  down 
and  said  he  could  not  breathe,  nor  did  he  breathe  again.  .  .  .  His 
pulse  at  the  wrist  remained  regular  and  full  for  some  time  after  respira- 
tion ceased.     He  had  a  mild  degree  of  cyanosis  and  edema  of  the  face. 


410  IMMUNITY 

He  died  in  tonic  spasms  ten  minutes  after  injection.     Autopsy  revealed 
no  palpable  cause  of  death." 

The  same  author  collected  28  cases  of  collapse  or  dcatli  after  serum 
injection,  of  which  15  died.  There  was  a  common  history  of  previous 
asthmatic  trouble  in  all  but  five  of  the  28,  and  all,  after  injection, 
showed  common  symptoms  of  sudden  intense  dyspnea,  a  sense  of  over- 
whelming anxiety,  edema  and  cyanosis  of  the  face,  a  sudden  massive 
urticaria,  tonic  muscular  spasms  and  continued  beating  of  the  heart 
long  after  the  ceasing  of  respiration.  Rosenau  and  Anderson  collected 
19  cases  and  were  able  to  examine  the  serum  used  in  two  of  them.  It 
was  found  to  be  no  more  toxic  to  sensitized  guinea  pigs  than  normal 
horse  serum.  These  cases  or  severe  systemic  shock  seem  susceptible  of 
no  other  explanation  than  that  the  unfortunate  individuals  had  been 
in  some  manner,  at  a  previous  time,  sensitized  to  horse  proteid.  They 
present  a  picture  which  is  almost  the  counterpart  of  typical  anaphylactic 
shock  in  guinea  pigs,  and  the  most  striking  thing  about  them  is  that 
practically  all  give  a  history  of  respiratory  trouble  in  the  past,  especially 
horse-asthma.  Schultz  and  Jordan  suggest  that  these  occasional  cases 
of  sudden  death  in  man  may  perhaps  be  due  to  an  abnormal  develop- 
ment of  the  mucous  membrane  and  smooth  muscle  of  the  bronchi  (as  in 
asthmatics),  and  that  the  smooth  muscle,  being  hypersusceptible,  pro- 
duces asphyxia  by  sudden  contraction.  Eosenau  and  Amoss  ^  have  re- 
cently indicated  a  possible  explanation  of  the  way  in  which  such  persons 
may  become  sensitized.  They  have  proved  that  a  proteid  material  is 
given  off  in  the  expired  breath  of  human  beings.  There  is  some  reason 
to  suppose  that  the  proteid  given  off  by  one  animal  may  be  absorbed 
by  individuals  of  different  species  by  way  of  the  lungs.  One  thing  is 
clear,  that  these  immediate  and  sometimes  fatal  reactions  are  not  de- 
pendent upon  any  peculiar  property  in  the  serum,  but  to  an  altered 
power  of  reaction  of  the  individual  to  the  foreign  proteid  injected. 
The  anaphylactic  reactions  following  the  injection  of  serum  in  man  may 
be  summed  up  briefly  as  follows: 

Reactions  following  first  injection: 

(a)  "Serum  sickness,'"  incubation  8-12  days   (common). 

(b)  Acute  anaphylactic  shock,  with  collapse  or  death  (rare). 
Beactions  following  second  injection: 

(a)  Interval  between  injections  less  than  8  days,  no  reaction. 

(b)  Interval   12-40   davs,  immediate  reaction. 

(c)  Interval  15  days-6  mos.,  either  immediate  or  accelerated  reaction, 
or  both, 

(d)  Interval  over  6  mos.,  accelerated  reaction. 

•Rosenau,  M.   J.,  &  Amoss,   H.  L. :     Jour,  of  Med.  Bes.,  Sept.,   1911,  XXV, 
1,  pp.  35-84, 


ANAPHYLAXIS  411 

The  above  table  represents  the  usual  course  of  events,  but  exceptions 
may  occur,  and  the  time  intervals  are  onl}^  approximate.  Sometimes  the 
reactions  do  not  appear  until  the  third,  fourth,  or  some  subsequent 
injection. 

Two  precautions  are  suggested  in  serum  therapy: 

(1)  Except  in  urgent  cases,  avoid  injecting  horse  serum  into  indi-* 
viduals  knovsm  to  be  asthmatic,  especially  those  whose  symptoms  are 
brought  on  by  being  around  horses. 

(2)  If  hypersensitiveness  is  suspected,  give  at  first  a  very  small 
portion  of  the  dose,  following  it  in  an  hour  or  so  with  the  rest,  injecting 
it  exceedingly  slowly  and  avoiding  direct  injection  into  the  circulation. 

Hypersusceptibility  and  Immunity  Produced  by  Bacterial  Proteins. 
— The  problem  of  hypersusceptibility  has  an  important  bearing  on  the 
question  of  immunity,  and  hence  the  opinion  has  been  expressed  that 
"resistance  to  disease  ma}^  largely  be  gained  through  a  process  of  hyper- 
susceptibility. Whether  this  increased  susceptibility  is  an  essential  ele- 
ment or  only  one  stage  in  the  process  of  resistance  to  disease  must, 
now  engage  our  attention."  We  cannot  escape  the  conviction  that  this 
phenomenon  of  hypersusceptibility  has  an  important  bearing  on  the 
prevention  and  cure  of  certain  infectious  processes. 

Hypersusceptibility  may  easily  be  induced  in  guinea  pigs  with  pro- 
tein extracts  obtained  from  the  bacterial  cell.  The  first  injection  of 
most  of  the  extract  seems  comparatively  harmless  to  the  animal.  A 
second  injection  of  the  same  extract  shows,  however,  that  profound 
physiologic  changes  have  taken  place.  A  definite  period  must  elapse 
between  the  first  and  the  second  injection.  The  symptoms  presented 
by  the  guinea  pigs  as  a  result  of  the  second  injection  resemble  those 
caused  by  horse  serum.  The  phenomenon  induced  by  a  second  injec- 
tion is  followed  (in  certain  cases)  by  an  immunity  to  the  correspond- 
ing infection. 

These  results  strengthen  the  belief  that  the  phenomenon  of  hyper- 
susceptibility has  a  practical  significance  in  the  prevention  and  cure 
of  certain  infectious  processes.  It  also  gives  a  possible  explanation  of 
the  period  of  incubation  of  some  of  the  communicable  diseases.  Is  it 
a  coincidence  that  the  period  of  incubation  of  a  number  of  infectious 
diseases  is  about  ten  to  fourteen  days,  which  corresponds  significantly 
with  the  time  required  to  sensitize  animals  with  a  strange  protein  ? 

In  certain  infectious  diseases  with  short  periods  of  incubation,  such 
as  pneumonia,  the  crisis  which  commonly  appears  about  the  tenth  day 
may  find  a  somewhat  similar  explanation.  It  is  evident  that  disease 
processes  produced  by  soluble  toxins,  such  as  diphtheria  and  tetanus, 
do  not  belong  to  the  category  now  under  consideration. 

Relation  of  Anaphylaxis  to  Protein  Metabolism. — The  whole  prob- 
lem of  protein  metabolism  seems  to  be  an  adjustment  in  the  sense  of  a 


412  IMMUNITY 

defense.  The  power  to  assimilate  and  use  foreign  proteins  is  not 
achieved  without  a  certain  amount  of  violence  to  the  body.  The  rela- 
tion between  the  fundamental  facts  of  protein  metabolism  and  immunity 
to  certain  diseases  becomes  clearer  in  tlie  light  of  observations  upon 
anaphylaxis.  A  deeper  insight  into  these  problems  will  throw  light  on 
the  fundamental  processes  concerned  in  both  protein  metabolism  axid 
immunity. 

Relation  of  Anaphylaxis  to  Endotoxins, — The  fact  that  the  great 
majority  of  bacteria  do  not  produce  soluble  poisons,  such  as  diphtheria 
and  tetanus,  has  led  to  the  belief  that  in  such  cases  we  are  dealing  with 
an  "endotoxin."  The  endotoxin  has  long  been  regarded  as  a  poisonous 
substance  so  intimately  associated  with  the  cell  that  it  is  not  released 
until  the  microbic  cell  is  broken  up  in  the  body.  The  inability  to  dem- 
onstrate many  of  these  endotoxins  has  cast  a  doubt  on  their  existence  and 
increased  the  mystery  of  their  action.  It  now  seems  probable  that  the 
studies  on  anaphylaxis  may  throw  light  upon  this  question. 

\Mien  bacteria  grow  in  the  body  they  are  dissolved  by  lytic  agencies 
and  the  foreign  protein  in  the  individual  germ  cells  may  sensitize  the 
body  and  afterward  poison  it.  The  bacterial  proteins  may  not  be  pois- 
onous in  themselves  in  the  sense  of  an  "endotoxin."  We  have,  in  fact, 
shown  that  protein  extracts  of  bacterial  cells  at  the  first  injection  may 
produce  characteristic  symptoms,  and  this  reaction  may  be  followed 
by  an  immunity  to  the  corresponding  infection. 

The  Relation  of  Anaphylaxis  to  Tuberculosis. — The  tuberculin  re- 
action is  one  of  the  best  known  instances  of  anaphylaxis.  Following 
a  local  infection  with  the  tubercle  bacillus  the  tissues  generally  become 
hypersusceptible  to  tuberculin.  It  has  been  shown  that  a  local  hyper- 
susceptibility  may  be  produced  by  the  direct  application  of  tuberculin 
to  certain  tissues  (conjunctiva).  The  same  has  been  demonstrated  for 
the  skin,  and  is  probably  true  of  other  tissues.  This  hypersusceptibility 
of  the  tissues  immediately  surrounding  a  tuberculous  focus  helps  to  en- 
capsulate and  limit  the  process.  Should  a  tubercle  bacillus  lodge  in 
or  on  a  tissue  in  a  state  of  tuberculin  anaphylaxis,  the  result  is  that 
all  of  nature's  protecting  agencies  are  quickly  concentrated  on  the 
point  where  most  needed.  We  conceive  that  this  active  power  of  reacting 
quickly  is  not  only  an  important  factor  in  individual  prophylaxis  against 
tuberculosis,  but  is  an  important  agency  by  which  the  spread  of  the 
disease  after  it  has  obtained  a  lodgment  in  the  body  is  prevented. 

The  normal  individual  does  not  react  to  tuberculin.  The  tubercu- 
lous individual  reacts  promptly,  except  in  the  final  stage  of  the  disease. 
The  difference  between  the  normal  individual  and  the  individual  in 
the  final  stage  of  tuberculosis  is  that  the  former  has  not  had  his  ana- 
phylactic powers  developed,  while  the  latter  has  had  them  developed 
and  exhausted.     A  tuberculous  individual  in  whom  the  specific  power 


ANAPHYLAXIS  413 

of  hypersusceptibility  to  the  poisons  of  the  tubercle  bacillus  is  broken 
down  presents  little  or  no  resistance  against  the  advance  of  the  in- 
fection. 

We  may  adduce  a  practical  lesson  from  this.  When  tuberculin  is 
used  in  large  or  too  oft-repeated  doses  there  is  a  tendency  to  break 
down  or  to  exhaust  the  useful  and  beneficial  hypersusceptible  state  of 
the  tissues.  In  accordance  with  this  line  of  reasoning,  therefore,  tuber- 
culin would  be  of  benefit  in  tuberculosis  only  when  used  in  such  a  way 
as  to  develop  and  not  diminish  the  power  of  anaphylaxis  of  the  tissues. 
This  explanation  has  been  borne  out  in  the  use  of  tuberculin. 

Relation  of  Anaphylaxis  to  Vaccination. — When  the  virus  of  cowpox 
is  introduced  into  the  skin  we  implant  a  colony  of  microorganisms.  They 
grow  day  by  day,  and  on  the  eighth  day  there  is  an  enormous  number 
of  them.  The  contents  of  the  vesicle  will  start  new  colonies  on  thou- 
sands of  other  arms,  but  now  the  antibodies  appear  and  the  colony  is 
attacked  and  digested,  and  toxic  bodies  are  formed.  This  is  diffused 
in  the  neighborhood  and  we  get  an  intense  local  inflammation  called  the 
areola.  Some  of  the  toxic  bodies  enter  the  circulation  and  cause  fever, 
but  the  microorganisms  are  killed  and  we  can  no  longer  vaccinate  with 
the  contents  of  the  now  yellow  pustule;  two  or  three  da3rs  more,  the 
struggle  is  over,  but  the  antibodies  remain  a  long  time.  Let  us  now 
revaccinate,  and  a  different  series  of  events  takes  place,  for  in  the  mean- 
time the  body  has  become  educated  and  instead  of  waiting  some  days 
before  attacking  the  colony  of  microorganisms  in  the  skin,  starts  the 
attack  at  once.  In  other  words,  there  is  an  immediate  reaction — a 
changed  power  of  reaction  or  anaphylaxis.  In  brief,  the  first  vaccina- 
tion has  sensitized  the  tissues,  so  that  they  respond  at  once  upon  the 
second  vaccination. 

The  invading  microorganisms,  attacked  at  once,  are  soon  digested — 
they  are  given  no  chance  to  multiply,  and  little  toxin  is  formed.  This 
attractive  explanation  of  the  immunity  to  smallpox  or  cowpox,  developed 
by  von  Pirquet,  shows  that  the  prophylaxis  depends  upon  the  anaphylaxis. 

Other  Practical  Relations  of  Anaphylaxis. — In  addition  to  hay 
fever,  already  mentionedj  there  are  a  number  of  other  conditions  which 
find  their  best  explanation  as  examples  of  local  anaphylaxis.  This  in- 
cludes many  of  the  urticarias  and  sudden  vasomotor  disturbances  of 
the  mucous  membranes ;  various  forms  of  asthma  are  also  associated 
with  hypersusceptibility  to  foreign  substances.  Idiosyncrasies  with  re- 
gard to  articles  of  diet  belong  to  the  same  category.  Some  persons  are 
sensitized  to  pork,  others  to  eggs,  and  sensitization  to  sea-food  is  com- 
mon. Other  conditions  which  have  been  explained  in  whole  or  part  on 
the  theory  of  anaphylaxis  are  puerperal  eclampsia,  sympathetic  ophthal- 
mia, the  onset  of  labor,  the  crisis  in  pneumonia,  the  spasmophilic  dia- 
thesis, the  symptoms  attendant  on  the  rupture  of  the  cysts  in  echino- 


414  IMMUNITY 

coccus  disease,  etc.  The  anaphylactic  reaction  is  also  used  in  diagnosis, 
and  in  forensic  medicine  in  the  identification  of  blood  stains,  and,  linally, 
may  be  used  as  a  scientific  instrument  for  the  detection  of  minute 
amounts  of  protein. 

References. — Many  of  the  statements  contained  in  this  chapter  have 
been  taken  from  Emery's  splendid  book  upon  '"Immunity  and  Specific 
Therapy,"  which  is  recommended  to  the  reader  who  desires  a  more  ex- 
tended review  upon  the  subject.  Kolle  and  Wassermann's  "Handbuch 
der  Mikroorganismen"'  has  also  been  consulted,  as  well  as  Kraus  and 
Levaditi's  "Handbuch  der  Technik  und  ]\rethodik  der  Immunitats- 
forschung.''     These  volumes  also  contain  selected  bibliographies. 

The  current  literature  upon  immunity  will  be  found  in  the  Zeit- 
schrift  fur  Imniunitdtsforschungen. 

For  those  who  desire  to  dip  deeper  into  the  subject  the  original  ref- 
erence to  many  of  the  fundamental  studies  will  be  found  in  "Collected 
Studies  on  Immunity"  by  Ehrlich,  translated  by  Bolduan;  "Studies  on 
Immimity"  by  Bordet,  translated  by  Gay;  "Studies  in  Immunization" 
by  Wright,  and  "L'Immunite  dans  les  Maladies  Infectieuses"  by  Metch- 
nikoff,  translated  by  Binnie. 


CHAPTER    II 
HEREDITY    AND    EUGENICS 

Heredity  may  be  defined  as  the  genetic  relation  between  successive 
generations.  It  is  a  condition  of  all  organic  evolution.  Castle  defines 
heredity  as  organic  resemblance  based  on  descent. 

It  is  now  perfectly  evident  that  heredity  is  one  of  the  fundamental 
factors  in  preventive  medicine — which,  after  all,  is  the  true  sociology. 
It  is  well  known  to  students  of  biology  that  education  and  environ- 
ment have  but  a  limited  power  to  influence  imperfect  human  proto- 
plasm. 

One  of  the  best  protections  we  have  against  diseases  of  body  and 
mind  is  that  which  is  inherited  from  our  forebears.  The  whole  prob- 
lem of  improving  the  human  stock,  not  only  from  the  medical  view, 
but  from  the  broader  sociological  standpoint,  is  based  upon  the  breed- 
ing of  the  fit  and  elimination  of  the  unfit.  The  science  of  eugenics 
(normal  genesis),  therefore,  assumes  especial  importance  in  preventive 
medicine.  The  physician,  as  w-ell  as  the  sanitarian,  stands  impotent 
before  many  deplorable  conditions  both  in  the  individual  and  in  so- 
ciety at  large,  which  are  inherited  from  our  ancestors  and  are,  there- 
fore, incurable — but  largely  preventable.  We  are  interested  in  educat- 
ing the  present  generation  to  the  facts  of  eugenics  so  that  future  gen- 
erations may  have  that  best  of  all  birthrights — good  human  protoplasm. 

The  discoveries  of  Mendel  have  made  it  quite  clear  how  certain  char- 
acters are  inherited,  why  certain  characters  skip  a  generation  and  re- 
appear in  the  grandchildren,  and  why  it  is  that  certain  defects  are 
carried  from  generation  to  generation  through  many  centuries.^  The 
defects  transmitted  hereditarily  are  not  all  of  equal  practical  impor- 
tance. Thus,  it  makes  comparatively  little  difference  to  the  individual 
if  he  has  a  supernumerary  spleen,  an  extra  finger,  or  an  anatomical 
anomaly  of  the  liver.  The  defects  which  are  of  especial  importance 
both  to  the  individual  and  to  succeeding  generations  are  the   defects 

^  Mendel 's  work  has  not  only  made  it  possible  for  us  to  predict  with  precision 
whether  good  or  bad  traits  will  or  will  not  appear  in  the  future  offspring,  but 
also  to  foretell  with  mathematical  precision  in  what  proportion  certain  characters 
will  appear  and  reappear. 

415 


416  HEREDITY    AND    EUGENICS 

of  organization  of  the  nervous  system.  These  comprise  the  class  known 
as  defectives.  A  slight  defect  in  the  structure  of  the  brain  which 
would  be  unnoticed  in  the  lung,  bone,  or  musculature  may  render  the 
individual  vicious  instead  of  useful.  The  principal  factors  which  are 
believed  to  start  a  line  of  defectives  are  inbreeding,  syphilis,  and  al- 
cohol; also  nervous  or  physical  diseases,  mental  or  nervous  exhaustion, 
and  excesses  and  poisons  of  all  kinds.^ 

The  defective  individual  is  very  easily  recognized  when  the  condi- 
tion is  well  marked.  The  mental  abnormality  is  usually  accompanied 
by  prominent  physical  defects  known  as  the  stigmata  of  degeneration 
(Lombroso  and  Weismann).  An  unfortunate  side  to  this  problem  is 
that  degenerates  and  defectives  generally  are  not  only  irresponsible 
morally,  but  are  very  prolific.  They  lack  self-control  and  have  abnor- 
mal sexual  appetites.  Defectives  beget  defectives,  and  thus  insanity, 
nervous  diseases,  moral  and  physical  degeneracy  are  propagated.  The 
typical  degenerate  is  of  pOor  bodily  development;  the  brain  is  smaller 
than  normal,  with  convolutions  less  abundant,  and  less  fully  formed. 
He  has  a  degraded  physiognomy,  lacks  capacity  for  sustained  attention 
or  for  prolonged  thought,  is  cunning  rather  than  intelligent,  deficient 
in  moral  sense — in  all  points  resembling  the  stigmata  of  the  lower,  less 
developed  races  of  our  species.  The  whole  gives  the  impression  of  a 
reversion  to  a  lower  type. 

Prevention  of  Propagation  of  Defectives. — Four  methods  have  been 
proposed  to  prevent  the  propagation  of  defectives:  (1)  education;  (2) 
legislation;   (3)  segregation;  (4)  surgery. 

Education. — Education  directed  toward  the  defective  is  a  failure, 
for  he  is  incapable  of  profiting  by  the  lessons.  The  education  of  the 
better  class  of  the  community  is  indirectly  helpful  in  calling  attention 
to  the  situation  as  being  largely  preventable,  and  to  the  necessity  and 
means  for  controlling  it. 

Eestrictive  Legislation. — Eestrictive  legislation  is  a  praiseworthy 
effort,  but  has  signally  failed  as  a  preventive  measure,  for  the  evident 
reason  that  it  only  adds  illegitimacy  to  degeneracy,  and  thus  the  chil- 
dren enter  on  life's  battle  doubly  handicapped.  Minnesota  has  a  law 
providing  that  within  the  bounds  of  the  state  no  marriage  shall  be 
permitted,  either  party  to  which  is  epileptic,  imbecile,  feeble-minded, 
or  afflicted  with  insanity,  unless  the  woman  be  over  forty-five.  Michigan, 
Delaware,  Connecticut,  Indiana,  New  Jersey,  and  North  Dakota  have 
also  passed  laws  for  the  purpose  of  preventing  marriage  among  de- 
fectives. 

Segregation. — Segregation  would  be  an  ideal  and  humane  method 

^  The  real  cause  or  method  of  origin  of  defective  characters  that  are  trans- 
mitted hereditarily  is  no  better  understood  than  the  origin  of  "sports"  or  muta- 
tions. 


PEEVENTION  OP  PROPAGATION  OF  DEFECTIVES    417 

of  eliminating  those  who  are  incapable  of  having  normal  offspring.  The 
segregation  of  all  degenerates  and  defectives  would  be  an  enormous 
and  impractical  task.  Further,  the  great  difficulty  is  to  detect  the  un- 
fit individual  who  starts  a  strain  of  defectives  and  degenerates.  It  is 
evidently  a  hopeless  task  to  know  where  to  draw  the  line  between  the 
fit  and  the  unfit,  so  that  for  the  present  we  must  be  satisfied  to  enforce 
restrictive  measures  upon  only  those  who  are  evident  and  well-marked 
examples.  Insane  asylums,  homes  for  epileptics,  reformatory  schools, 
as  well  as  special  hospitals  and  institutions  for  advanced  cases  must  not  be 
regarded  as  preventive  measures  in  the  true  sense,  for  such  segregation 
provides  care  and  comfort  as  a  terminal  measure;  that  is,  it  is  usually 
a  last  resort.  Frequently  defectives  propagate  their  kind  before  and 
sometimes  after  they  are  segregated. 

Surgery. — Surgery  has  been  proposed  as  a  means  of  controlling 
the  propagation  of  defectives.  This  is  done  either  by  severing  the 
vas  deferens  or  the  Fallopian  tube.  At  the  Indiana  Reformatory  Dr. 
Sharp  carries  out  the  law  ^  of  that  state  providing  for  the  sterilization 
of  defectives.  The  operation  of  vasectomy  consists  of  ligation  and  re- 
section of  a  small  portion  of  the  vas  deferens.  The  operation  is  very 
simple  and  easy  to  perform.  It  may  be  done  without  an  anesthetic, 
either  local  or  general.  As  performed  by  Dr.  Sharp  it  requires  about 
three  minutes,  and  the  subject  returns  to  his  work  immediately,  suf- 
fering no  inconvenience  and  in  no  way  hampered  in  his  pursuit  of  life, 
liberty,  and  happiness,  but  is  effectively  sterilized.  In  456  cases  Dr. 
Sharp  has  had  no  unfavorable  symptoms.  The  operation  is  performed 
as  follows:  After  cleansing  the  scrotum  with  soap  and  water,  fol- 
lowed by  alcohol,  the  spermatic  cord  is  grasped  between  the  thumb  and 
index  finger  of  the  left  hand.  The  vas  deferens  is  detected,  firmly 
held  and  fixed  with  a  pair  of  bullet  forceps.  It  is  then  exposed  by  a 
small  incision  and  drawn  through  the  scrotum  wound  by  means  of  a 
tenaculum.  It  is  stripped  of  all  membranes  and  the  accompanying  ar- 
tery ligated  above  and  severed,  care  being  taken  to  cut  away  any  por- 

^  The  Indiana  law  reads  as  follows : 

Whereas,  Heredity  plays  a  most  important  part  in  the  transmission  of  crime, 
idiocy,  and  imbecility; 

Therefore,  Be  it  enacted  by  the  General  Assembly  of  the  State  of  Indiana, 
That  on  and  after  the  passage  of  this  act  it  shall  be  eompulsoiy  for  each  and 
every  institution  in  the  State,  entrusted  with  the  care  of  confirmed  criminals, 
idiots,  rapists,  and  imbeciles,  to  appoint  upon  its  staff,  in  addition  to  the  regular 
institutional  physician,  two  (2)  skilled  surgeons  of  recognized  ability,  whose  duty 
it  shall  be,  in  conjunction  with  the  chief  physician  of  the  institution,  to  examine 
the  mental  and  physical  condition  of  such  inmates  as  are  recommended  by  the 
institutional  physician  and  board  of  managers.  If,  in  the  judgment  of  this 
committee  of  experts  and  the  board  of  managers,  procreation  is  inadvisable  and 
there  is  no  probability  of  improvement  of  the  mental  and  physical  condition  of 
the  inmate,  it  shall  be  lawful  for  the  surgeons  to  perform  such  operation  for  the 
prevention  of  procreation  as  shall  be  decided  safest  and  most  effective.  But  this 
operation  shall  not  be  performed  except  in  cases  that  have  been  pronounced  unim- 
provable.    ... 


418  HEREDITY    AND    EUGENICS 

tion  of  the  vas  deferens  that  may  have  been  damaged  in  the  manipula- 
tion. This  is  done  in  order  that  the  end  next  to  the  testicle  may  not 
become  closed.  It  is  very  important  that  the  testicular  end  shall  re- 
main open,  in  order  that  the  secretion  of  the  testicle  may  be  emptied 
around  the  vessels  of  the  pampiniform  plexus  and  there  be  absorbed, 
for  it  is  through  this  process  that  the  body  receives  the  tonic  etfect  of 
the  internal  secretion.  Further,  if  the  testicular  end  of  the  vas  defer- 
ens is  closed,  there  is  likely  to  be  cystic  degeneration  of  the  testicle. 
The  retraction  of  the  muscle  closes  the  skin  wound  and  no  stitch,  col- 
lodion, or  adhesive  plaster  is  needed.  There  is  no  diminution  of  the 
sexual  power  or  pleasure.  The  discharge  at  the  orgasm  is  but  slightly 
decreased. 

The  operation  in  the  female  is  more  difficult,  but  if  carefully  done 
no  more  hazardous.  The  Fallopian  tubes  are  reached  through  a  median 
incision  and  ligated  near  the  uterus  and  severed  beyond  the  ligature. 

Opinions  vary  greatly  concerning  the  proper  use  of  sterilizing  crim- 
inals, insane,  degenerates,  and  defectives  generally.  There  is  no  doubt 
concerning  its  effectiveness. 

Sterilization  is  a  measure  which  contains  great  potential  possibili- 
ties for  abuse  and  injustice.  It  probably  will  never  receive  general 
acceptance  on  account  of  the  difficulty  of  determining  upon  whom  the 
operation  shall  be  done.  Even  in  perfectly  clear  cases,  such  as  the  in- 
sane, the  epileptic,  or  the  high  grade  degenerate,  the  harm  has  often 
been  done  before  the  operation  is  decided  upon. 

Statistics  of  Defectives. — The  large  number  of  defectives  and  unfit 
in  our  country  may  be  gleaned  from  the  following  figures. 

The  last  census  report  for  the  United  States  gives  data  relative  to 
the  dependents  and  defectives  in  institutions;  the  number  not  in  in- 
stitutions can  only  be  guessed  at.  Kellicott  gives  the  following  ap- 
proximate numbers  in  our  country  to-day : 

Insane  and  feeble-minded,  at  least 200,000 

Blind    100.000 

Deaf   and   dumb    100,000 

Paupers  in  institutions 80,000 

Prisoners 100,000 

Juvenile  delinquents  in  institutions 23,000 

The  number  of  persons  cared  for  in  hospitals,  dispensaries,  "homes" 
of  various  kinds  in  the  year  1904  was  in  excess  of  two  million. 

\\'e  have  to  support  about  half  a  million  insane,  feeble-minded,  epi- 
leptic, blind,  and  deaf;  80,000  prisoners,  and  100,000  paupers,  at  a  cost 
of  $100,000,000  per  year.  A  new  plague  affecting  4  per  cent,  of  the 
population  and  costing  this  vast  treasure  would  instantly  attract  uni- 


DEGENERATE    FAMILIES  419 

versal  attention.  We  have  become  so  used  to  crime^  disease,  and  de- 
generacy that  we  take  them  as  necessary  evils.  "That  many  of  them 
were  so  in  the  world's  ignorance  is  granted;  that  they  must  remain  so 
is  denied." 

Statistical  studies  seem  to  indicate  a  rapid  (at  least  an  unneces- 
sary) increase  of  the  unfit,  defective,  insane,  criminal,  and,  on  the 
other  hand,  a  slow  increase,  or  even  a  decrease  (?),  of  the  fit,  normal, 
or  gifted  stocks.  It  is  plain  to  the  student  of  eugenics  how  such  con- 
ditions account  for  the  rise  and  fall  of  nations. 

The  United  States  census  of  1880  reported  40,942  insane  in  hos- 
pitals and  51,017  not  in  hospitals;  a  total  of  91,959  known  insane.  In 
1903  it  was  estimated  that  there  was  a  total  of  180,000  in  the  United 
States.  Thus,  the  ratio  of  known  insane  in  the  total  population  was 
225  per  100,000  in  1903,  as  compared  with  183  per  100,000  in  1880. 
These  figures  must  not  be  taken  as  an  index  of  the  increase  of  insanity 
in  the  population  at  large — for  institutional  care  has  been  growing 
much  more  popular  during  the  past  decade,  especially  since  more  hu- 
mane methods  have  been  adopted.  Further,  the  classification  of  insan- 
ity now  includes  man)^  cases  that  were  formerly  little  noticed.^ 

The  comparatively  large  and  increasing  numbers  of  defectives  and 
weaklings  among  the  civilized  races  compared  with  wild  animals  may 
be  accounted  for  by  the  fact  that  atavism  and  reversion  are  more  fre- 
quently met  with  in  artificially  cultivated  strains,  such  as  civilized 
man;  and  the  further  fact  that  our  charitable  and  philanthropic  efforts 
foster  and  even  favor  the  unfit. 

Deg-enerate  Families. — A  careful  study  has  been  made  of  the  records 
of  several  families  in  which  the  mating  of  unfit  individuals  has  begotten 
a  swarm  of  unfit  descendants. 

^  A  special  census  of  the  insane  confined  in  institutions  -was  taken  by  the 
Bureau  of  the  Census  in  1910,  and  it  was  found  that  187,454  patients  were  con- 
fined in  hospitals  for  the  insane  in  the  continental  United  States. 

While  the  population  of  the  United  States  increased  about  11  per  cent,  in 
the  interval  between  1904  and  1910,  the  population  in  insane  asylums  increased 
about  25  per  cent.  The  number  of  insane  in  asylums  per  100,000  population  in- 
creased from  186.2  in  1904  to  203.8  in  1910.  The  number  of  persons  annually 
committed  to  hospitals  for  the  insane  per  100,000  population  increased  from 
61.5  in  1904  to  65.9  in  1910.  If  these  ratios  are  accepted  as  representing  insanity 
rates,  it  would  appear  that  the  number  of  persons  becoming  insane,  in  a  com- 
munity comprising  100,000  persons,  was  greater  by  4.4  in  1910  than  it  was  in 
1904.  It  must  be  remembered,  however,  that  these  figures  include  only  the  insane 
who  are  committed  to  hospitals.  As  to  the  number  of  cases  of  insanity  not 
resulting  in  commitments  to  hospitals  the  census  has  no  data.  It  is  entirely 
possible  that  the  increase  in  the  number  of  commitments  per  100,000  population 
is  not  due  to  any  considerable  degree  to  an  increased  prevalence  of  insanity,  but 
simply  to  the  extension  of  this  method  of  caring  for  the  insane.  It  is  a  change 
which  might  result  from  an  increase  in  the  number  of  institutions  of  this  class 
and  from  the  increasing  disposition  on  the  part  of  the  public  to  resort  to  such 
institutions.  In  this  connection  it  may  be  noted  that  the  number  of  institutions 
for  the  insane  reported  by  the  census  increased  from  328  in  1904  to  372  in 
1910,  an  increase  of  about  13  per  cent.  The  average  number  of  inmates  per 
institution  increased  from  458  in  1904  to  504  in  1910. 


420 


HEREDITY    AND    EUGENICS 


traced  from  the  five  daughters 


^    I 


One  of  the  best  known .  families  of  this  type  is  the  so-called  Jukes 
family  of   New  York  State  investigated  by  Dugdale.     This  family  is 

of  a  lazy  and  irresponsible  fisherman 
boi-n  in  1720.  In  five  generations  the 
descendants  of  Jukes  numbered  about 
1,200  persons,  including  nearly  200  who 
married  into  it.  Tlie  liistories  of  5-40 
of  these  are  well  known,  and  about  500 
more  are  partly  known.  Some  300 
died  in  infancy.  Of  the  remaining  900, 
310  were  professional  paupers  living  in 
almshouses  (a  total  of  2,300  years)  ; 
440  were  physically  wrecked  by  their 
own  diseased  wickedness;  more  than 
half  of  the  women  were  prostitutes; 
130  were  convicted  criminals;  60  were 
habitual  thieves;  7  were  murderers. 
Not  one  had  even  a  common  school 
education ;  only  20  learned  a  trade,  and 
10  of  these  learned  it  in  State's  prison. 
The  descendants  of  Jukes  in  five  gen- 
erations have  cost  New  York  State 
ever  one  million  and  a  quarter  dollars, 
^^  \\\  "^    and  the  cost  is  still  going  on. 

Probably  the  most  complete  family 
liistory  of  this  kind  ever  worked  out  is 
that  of  the  "Familie  Zero,"  a  Swiss 
family  whose  pedigree  has  been  studied 
by  Jorger.  In  the  seventeenth  century 
this  family  divided  into  three  lines. 
Two  of  these  have  ever  since  remained 
valued  and  highly  respected  families, 
while  the  third  has  descended  to  the 
depths.  This  third  line  was  established 
by  a  man  who  was  himself  the  result 
of  two  generations  of  intermarriage, 
the  second  tainted  with  insanity.  He 
was  of  a  roving  disposition,  and  in  the 
Valla  Fontana  found  an  Italian  vagrant 
wife  of  vicious  character.  Their  son 
inherited  fully  the  parental  traits  and  himself  married  a  member  of  a 
German  vagabond  family — Marcus.  This  marriage  sealed  the  fate  of 
their  hundreds  of  descendants.  The  pair  had  seven  children,  all  char- 
acterized by  vagabondage,  thievery,  drunkenness,  mental  and  physical 


Q^' 


5 


DEGENEEATE    FAMILIES  421 

defects,  and  immorality  (Kellicott).  How  much  of  this  is  due  to 
heredity  and  how  much  to  environment  will  be  discussed  presently. 

Another  interesting  example  of  the  same  type  has  been  described 
by  Poellmann.  This  family  was  established  by  two  daughters  of  a 
woman  drunkard  who  in  five  or  six  generations  produced,  all  told,  834 
descendants.  The  histories  of  709  of  these  are  known.  Of  the  709 
107  were  of  illegitimate  birth,  64  were  inmates  of  almshouses,  162 
were  professional  beggars,  164  were  prostitutes,  and  17  procurers,  76 
had  served  sentences  in  prison,  aggregating  116  years,  7  were  condemned 
for  murder. 

Dr.  Henry  H.  Goddard  ^  has  investigated  and  compiled  the  results 
of  his  work  on  the  heredity  of  a  most  remarkable  family,  the  Kallikak 
family.  During  the  Revolutionary  days,  the  first  Martin  Kallikak  (the 
name  is  fictitious),  descended  from  a  long  line  of  good  English  ancestr}^, 
took  advantage  of  a  feeble-minded  girl.  The  result  of  their  indulgence 
was  a  feeble-minded  son.  This  son  married  a  normal  woman.  They  in 
turn  produced  five  feeble-minded  and  two  normal  children.  Practically 
all  of  the  descendants  of  these  defectives  have  been  traced,  as  well  as 
those  of  the  two  normals. 

From  both  normal  and  defective  descendants  of  this  union  came  a 
long  line  of  defective  stock.  There  were  480  in  all.  Of  these  thirty- 
Six  were  illegitimate,  thirty-three  sexually  immoral,  twenty-four  con- 
firmed alcoholics,  and  three  epileptics.  Eighty-two  died  in  infancy, 
three  were  criminal,  eight  kept  houses  of  ill  fame,  and  143  were  dis- 
tinctly feeble-minded.  Only  forty-six  were  found  who  were  apparently 
normal.  The  rest  are  unknown  or  doubtful.  But  the  scion  of  the  good 
family  who  started  this  long  line  of  delinquent  and  defective  progeny 
is  also  responsible  for  a  strain  of  an  entirely  difi^erent  character.  After 
the  Revolutionary  War  was  over,  he  married  a  Quaker  girl  of  good 
ancestry  and  settled  down  to  live  a  respectable  life  after  the  traditions 
of  his  forefathers.  From  this  legal  union  with  a  normal  woman  there 
have  been  496  descendants.  All  of  these  except  two  have  been  of  normal 
mentality.  The  exceptions  were  cases  of  insanity,  presumably  inherited 
through  marriage  with  an  outside  strain  in  which  there  was  a  consti- 
tutional psychopathic  tendency.  In  all  the  496  there  is  not  an  instance 
of  feeble-mindedness.  The  offspring  descended  from  this  side  of  the 
house  have  universally  occupied  positions  in  the  upper  walks  of  life. 
They  have  never  been  criminals  or  ne'er-do-wells.  On  the  other  hand, 
there  has  not  been  a  single  instance  of  exceptional  ability  among  the 
descendants  of  the  first  Martin  Kallikak  and  the  feeble-minded  girl. 
Most  of  these  descendants  have  failed  to  rise  above  the  dead  level  of 


^ ' '  The  Kallikak   Family,   a  Study  in  the   Heredity   of  Feeble-mindedness, ' ' 
New  York,  Macmillan  Company,   1912. 
29 


422  iEIEREDITY    AND    EUGENICS 

mediocrity;  indeed,  most  of  them  have  fallen  far  below  even  this 
minimum  standard. 

The  fact  that  tlie  descendants  of  both  the  noniial  and  the  feeble- 
minded mother  have  been  traced  and  studied  in  every  conceivable  en- 
vironment, and  that  the  respective  strains  have  always  been  true  to 
type,  tends  to  confirm  the  belief  that  heredity  has  been  the  determining 
factor  in  the  formation  of  their  respective  characters.  In  the  cities 
the  descendants  of  the  legal  marriage  with  the  normal  woman  are 
physicians,  lawyers  and  prominent  business  men,  while  the  descendants 
of  the  feeble-minded  mother  are  almost  invariably  found  in  the  slums. 
In  the  rural  districts  the  descendants  of  the  normal  mother  and  her  con- 
sort are  wealthy  and  influential  farmers,  while  the  other?  never  rise 
above  the  rank  of  farm  laborers  and  shiftless  men  and  women  who  are 
unable  to  subsist  without  the  aid  of  charity.  Many  representatives  of 
the  defective  branch  are  inmates  of  almshouses,  while  there  are  no 
paupers  at  all  among  the  normal  descendants. 

In  many  ways  this  study  of  Goddard's  far  outweighs  in  importance 
the  famous  comparison  by  Dr.  Winship  of  the  Jukes  and  Edwards  fam- 
ilies. In  that  case  the  simple  fact  was  demonstrated  that  a  good  family 
like  that  of  the  illustrious  Jonathan  Edwards  had  given  rise  to  innu- 
merable examples  of  the  highest  intellectual  and  moral  worth,  whereas 
the  criminal  Jukes  for  seven  generations  contributed  nothing  to  the 
common  good  and  cost  the  state  of  Xew  York  large  sums  of  money. 
But  tlie  Jukes  family  and  the  Edwards  family  had  no  ancestor  in 
common.  Their  environment  was  totally  different  and  they  lived  in 
entirely  separate  communities.  Although  from  sociologic  and  economic 
points  of  view  the  history  of  the  Jukes  family  and  its  comparison  with 
that  of  the  family  of  Jonathan  Edwards  has  great  value,  it  is  of  but 
scant  scientific  importance  as  compared  with  that  of  the  Kallikak  family, 
for  here  a  natural  object-lesson  in  eugenics  shows  unmistakably  the 
manner  in  which  after-coming  generations  from  a  given  mating  receive 
the  characteristics  of  the  dominant  strain,  which  in  the  elder  (illegiti- 
mate) Kallikak  line  was  the  inferior  strain,  with  only  a  debased  and 
enfeebled  heritage  to  hand  on.^ 

In  contrast  to  these  we  have  the  descendants  of  the  families  of 
Wedgwood,  Darwin,  and  Galton.  the  Edwards  family  and  the  Ward 
family.  These  three  noted  families  contained  a  large  number  of  states- 
men, jurists,  professors,  physicians,  officers  in  the  army  and  navy,  prom- 
inent authors  and  writers,  and  occasionally  men  and  women  of  genius. 
They  show  a  long  line  of  usefulness  in  every  department  of  social  prog- 
ress, and  not  one  of  them  ever  has  been  convicted  of  a  crime. 

How  much  of  this  is  due  to  heredity  and  how  much  to  environment 
are  debatable  questions.     Students  of  biology  are  convinced  that  heredity 

'J.  A.  M.  A.,  Oct.  26,  1912,  LIX,  17,  p.  1545. 


EUGENICS 


423 


plays  the  major  role  in  the  lives  of  the  individuals  in  the  above-men- 
tioned families.  In  how  far  such  extreme  instances  as  those  given  above 
represent  the  rule  or  exceptions  will  require  much  additional  data  and 
long  years  of  study  to  determine. 

EUGENICS 

The  science  of  eugenics  has  been  defined  as  "the  science  of  being 
well  born."     According  to  Galton,  "eugenics  is  the  study  of  the  agen- 


h/£DCWOOD 


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C ALTON 

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^  shows  a  -man  of  scientific  ability  ;  |P  shows  a  man  of  scicnlific  ability,  who  is  also  a 

Fellow  of  the  Royal  Society  ;  Q)  shows  five  other  children,  and  so  on. 

Fig.  58. — History  (Condensed  and  Incomplete)  of  Three  Markedly  Able 
Families   (After  Whentham)  (Kellicott) . 

cies  under  social  control  that  may  improve  or  impair  the  racial  quali- 
ties of  future  generations  either  physically  or  mentally." 

The  aim  of  eugenics  is  to  increase  the  number  of  best  specimens 
in  each  class;  that  done,  leave  them  to  work  out  their  common  civiliza- 
tion in  their  own  way.  It  also  aims  to  leave  a  good  heritage  to  the 
next  generation  and  to  repress  the  propagation  of  the  vicious  and  de- 
fective classes. 

The  success  of  eugenics  depends  almost  entirely  upon  our  knowl- 
edge of  heredity  and  sociology.  Therefore,  the  fundamental  principles 
of  heredity  should  be  familiar  to  all  students  of  preventive  medicine. 

The  present  movement  started  in  1865  when  Francis  Galton  showed 
that  mental  qualities  are  inherited,  just  as  are  physical  qualities,  and 


424  •  HEREDITY   AND    EUGENICS 

pointed  out  that  this  opened  a  way  to  an  improvement  of  the  race  in 
all  respects.  The  student  sliould  read  Galton's  work  on  "Hereditary 
Genius,"  published  in  18G9,  when  he  again  emphasized  definitely  the 
possibility  and  desirability  of  improving  the  natural  qualities  of  the 
lunnan  race.  The  word  "eugenics"  was  coined  in  1883  in  his  "In- 
quiries Into  the  Human  Faculty." 

There  is  no  doubt  concerning  the  desirability  of  breeding  better 
human  stock,  but  how  this  may  be  accomplished  practically  is  a  difh- 
cult  question.  The  program  of  the  eugenist  is  perplexing  and  compli- 
cated. To  follow  the  theoretical  extremists  would  require  a  social  revo- 
lution— a  change  from  the  present  method  of  haphazard  nuiting.  The 
threshold  of  the  subject  has  scarcely  been  passed,  and  we  must  bear 
in  mind  that  some  of  the  striking  men  of  genius  from  whom  the  world 
has  greatly  profited  have  been  individuals  whom  the  student  of  genetics 
would  regard  as  degenerates  or  defectives.  Eugenics  does  not  mean 
free  love,  nor  does  the  eugenist  recommend  Burbanking  the  human  race 
to  produce  great  physical  strength,  beauty,  endurance,  mental  or  moral 
j)ower.  One  point  only  in  the  program  is  perfectly  clear,  and  that  is  that 
a  check  should  be  placed  upon  the  propagation  of  the  crop  of  defectives 
by  means  already  pointed  out. 

The  known  facts  of  heredity  and  the  study  of  eugenics  nuike  us 
examine  more  critically  some  of  the  directions  which  preventive  medi- 
cine, including  philanthropy  and  social  uplift,  has  taken.  We  must  now 
ask  ourselves  the  question  whether  it  would  not  be  better  for  the  future 
generations  if  we  helped  the  fit  rather  than  the  weakling  and  the  unfit. 
These  are  problems  raised  by  Galton,  who  questions  whether  some  of  our 
charitable  efforts  are  well  balanced  and  well  directed. 

The  importance  of  eugenics  in  medicine  is  not  new.  For  a  while, 
however,  the  medical  sciences  lost  sight  of  heredity,  owing  to  the  ultra- 
materialistic  view  of  disease  which  became  the  vogue  as  a  result  of  the 
germ  theory.  A  neglect  of  the  personal  element  in  medicine  and  a 
wholly  impersonal  hygiene  were  laid  down  as  universally  applicable. 
Davenport  states :  "It  has  forgotten  the  fundamental  fact  that  all  men 
are  created  hound  by  their  protoplasmic  make-up  and  unequal  in  their 
powers  and  responsibilities." 

It  is  evidently  now  of  great  importance  to  collect  a  large  number 
of  pedigrees,  in  which  the  data  shall  be  stated  with  scientific  exactness 
and  in  minute  detail.  Such  a  mass  of  facts  may  then  be  studied  in  the 
light  of  our  present  knowledge  in  order  to  determine  in  how  far  the 
laws  of  heredity  apply  to  human  characters.  This  is  being  done  by  the 
Eugenics  Eecord  Office  at  Cold  Springs  Harbor,  New  York,  under  the 
patronage  of  the  Carnegie  Institution. 

Specifically,  the  Eecord  Office  seeks  pedigrees  of  families  in  which 
one  or  more  of  the  following  traits  appear:  short  stature,  tallness,  cor- 


PEINCIPLES    OF    HEREDITY  425 

pulency,  special  talents  in  music,  art,  literature,  mechanics,  invention, 
and  mathematics,  rheumatism,  multiple  sclerosis,  hereditary  ataxy, 
Meniere's  disease,  chorea  of  all  forms,  eye  defects  of  all  forms,  otosclero- 
sis, peculiarities  of  hair,  skin,  and  nails  (especially  red  hair),  albinism, 
harelip  and  cleft  palate,  peculiarities  of  the  teeth,  cancer,  Thomsen's 
disease,  hemophilia,  exophthalmic  goiter,  diabetes,  alkaptonuria,  gout, 
peculiarities  of  the  hands  and  feet  and  of  other  parts  of  the  skeleton. 

In  brief,  then,  the  aim  of  eugenics  is  through  heredity  to  give  the 
individual  the  greatest  of  all  birthrights,  viz.,  good  human  protoplasm, 
and  to  eliminate,  as  far  as  may  be  possible,  bad  human  protoplasm. 


PRINCIPLES    OF    HEREDITY 

For  a  clearer  understanding  of  the  hereditary  transmission  of  dis- 
ease, malformations,  and  defects  it  is  necessary  to  have  an  understand- 
ing of  the  principal  views  upon  organic  evolution  and  the  theories  of 
heredity.  The  student  of  preventive  medicine  should  especially  have 
a  clear  comprehension  of  MendeFs  work,  which  has  thrown  a  flood  of 
light  upon  the  problems  before  us.  Mendel  has  opened  new  vistas  in 
biology,  which  have  a  practical  bearing  upon  public  health  work.  It 
is  evidently  impossible  in  a  short  space  to  do  justice  to  such  large  sub- 
jects as  evolution  and  heredity,  and  the  student  is,  therefore,  referred 
to  the  authorities  given  at  the  end  of  this  chapter,  which  will  repay 
careful  study. 

Variation. — It  has  been  a  matter  of  common  observation  that  like 
tends  to  beget  like  rather  than  "like  begets  like,'^  for  there  is  a  ten- 
dency toward  new  departures. 

Two  distinct  sorts  of  divergences  may  appear  among  the  members 
of  a  single  family.  The  first  is  known  as  variation;  the  second  as 
mutation. 

By  variation  we  understand  those  slight  differences  which  invariably 
distinguish  all  the  members  of  ever}^  family.  They  consist  of  individ- 
ual variations  which  affect  every  part  and  every  character.  Such  dif- 
ferences are  also  known  as  fluctuating,  normal,  or  continuous  variations 
to  distinguish  them  from  abnormal,  definite,  or  discontinuous  varia- 
tions, which  are  more  properly  termed  mutations.  As  examples  of 
variation  in  man  we  may  cite  the  variations  in  size  or  stature,  color 
of  skin  and  eyes,  curliness  of  hair,  configuration  of  face,  etc. 

Darwin  lays  particular  emphasis  upon  the  importance  of  variation 
in  his  views  of  organic  evolution. 

Darwin's  Theory. — The  Survival  of  the  Fittest. — Darwin's 
views  ^  of  heredity  are  based  upon  his  theory  of  organic  evolution.     Two 

^Darwin:    "The  Origin  of  Species,"  "The  Descent  of  Man,"  etc. 


426  HEREDITY    AXD    EUGENICS 

separate  factors  are  primarily  concerned:  (1)  the  fact  of  fluctuating 
variation,  that  is,  that  no  two  members  of  the  same  family  ever  resemble 
one  another  exactly;  and  (2)  the  occurrence  of  a  struggle  for  existence 
between  organisms,  owing  to  the  geometric  rate  of  increase  of  living 
things.  From  these  two  facts  it  follows  that,  when  a  change  of  environ- 
ment takes  place,  certain  members  of  an  existing  species  will  be  some- 
what better  adapted  than  others  to  withstand  the  new  conditions,  and 
the  former  will  tend  to  survive  to  the  exclusion  of  the  latter.  Darwin 
assumes  that  during  a  long  series  of  generations  this  process  will  cause 
a  steady  change  in  the  character  of  the  species  in  the  direction  of 
better  adaptation  to  the  new  conditions.  In  other  words,  Darwin 
considers  that  an  accumulation  of  a  series  of  small  changes  due  to  the 
influence  of  environment  are  transmitted  hereditarily  through  natural 
selection. 

The  remarkable  effects  produced  in  the  case  of  domestic  animals  and 
plants  by  the  action  of  artificial  selection  greatly  influenced  Darwin's 
views  upon  the  selective  influences  which  exist  in  nature.  Darwin  be- 
lieved in  the  hereditary  transmission  of  acquired  characters  and  re- 
garded organic  evolution  as  proceeding  by  a  slow,  gradual,  or  continuous 
process.  There  can  be  no  doubt  but  that  natural  and  sexual  selection 
have  a  great  influence,  but  whether  suflBcient  to  originate  new  species 
or  even  new  specific  characters  is  a  question.  Now  that  the  transmis- 
sion of  acquired  characters  is  denied  by  students  of  heredity,  and  the 
fact  that  DeVries  has  actually  observed  new  species  arise  suddenly, 
Darwin's  theory  of  organic  evolution  and  the  origin  of  species  is  receiv- 
ing critical  examination. 

Darwin  firmly  believed  that  the  characters  of  organisms  can  be 
modified  by  selection,  and  he  made  this  the  foundation  stone  of  his 
theory  of  evolution.  The  brilliancy  of  the  mutation  theory  of  DeVries, 
coupled  with  his  great  service  to  biology  in  rediscovering  the  Mendelian 
laws,  has  somewhat  dazzled  our  eyes.  Castle  believes,  after  ten  years 
of  continuous  work  in  selection,  that  much  may  be  accomplished  by 
this  means  quite  apart  from  the  process  of  mutation,  and  considers 
that  the  work  of  DeVries  himself  argues  strongly  in  favor  of  this  idea, 
although  his  interpretation  of  it  is  adverse  to  selection.  From  the  evi- 
dence at  hand  we  must  conclude  that  Darwin  was  right  in  assigning 
great  importance  to  selection  in  evolution,  that  progress  results  not 
merely  from  sorting  out  particular  combinations  by  large  and  striking 
unit  characters,  but  also  from  the  selection  of  slight  differences  in  the 
potentiality  of  gametes  representing  the  same  unit  character  combina- 
tions. 

Mutation. — Mutations  comprise  definite  differences,  usually  of  con- 
siderable magnitude — differences  that  indicate  specific  characters  or 
the  beginning  of  new  species.     Such  differences  are  also  known  as  ab- 


PEINCIPLES    OF    HEEEDITY  427 

normal,  definite,  or  discontinuous  variations,  but  more  properly  they 
are  termed  mutations,  sometimes  "sports."  Mutations  may  be  either 
useful  or  harmful.  They  arise  spontaneously  and  may  be  transmitted 
hereditarily  in  accordance  with  Mendel's  law.  As  examples  of  muta- 
tions in  man  we  may  cite  albinism,  polydactylism,  brachydactylism,  etc. 

DeVries,  Bateson,  and  the  "mutationists"  are  convinced  that  muta- 
tion is  a  much  more  important  factor  in  the  origin  of  species  than 
variation,  as  understood  b}^  Darwin.  In  the  light  of  Mendel's  work 
mutations  appear  to  be  unit  characters  which  arise  "spontaneously" — 
in  some  instances  they  represent  recessive  characters  that  have  remained 
dormant  for  many  generations. 

DeVries — Discontinuous  Evolution.^ — The  observations  of  DeVries 
upon  the  evening  primrose  (CEnoihera  lamarcTcimia)  convinced  him  that 
species  may  arise  suddenly,  that  evolution  is  discontinuous  and  goes  by 
leaps  and  bounds  rather  than  by  the  slow  or  continuous  process  of  or- 
ganic evolution  described  by  Darwin. 

Mutation  is  the  term  applied  by  DeVries  to  express  the  process  of 
origination  of  a  new  species  or  a  new  specific  character,  when  this  takes 
place  by  the  discontinuous  method  at  a  single  step.  DeVries  believes 
that  this  is  the  most  important,  if  not  the  sole,  method  by  which  new 
species  or  specific  characters  arise.  To  those  who  are  convinced  that 
acquired  characters  are  not  inherited  the  explanations  of  Lamarck  and 
Darwin  have  always  been  incomplete.  Darwin  insisted  that  nature  does 
not  make  jumps  and  that  new  species  arise  slowly  through  the  action 
of  natural  selection  on  minute  variations — a  gradual  or  continuous  evo- 
lution.^ From  his  experiments  DeVries  concludes  that  when  selection 
is.  really  efficient  the  full  possible  effects  of  this  process  are  exhausted  in 
quite  a  small  number  of  generations,  and  that  then  the  only  further 
effect  of  selection  is  to  keep  up  the  standard  already  arrived  at.  De- 
Vries actually  obtained  quite  a  number  of  new  types  of  plants  which 
arose  suddenly  and  naturally.  When  they  made  their  appearance  the 
majority  of  the  new  types  came  true  to  seed.  With  regard  to  the  causes 
of  mutation  little  is  known,  unless  we  assume  that  they  represent  unit 
characters  which  have  long  remained  recessive. 

Weismann's  Views. — Weismann's  ^  views  are  based  largely  upon  his 
assumption  that  the  germ  plasm  is  distinct  from  the  body  and  that  ac- 
quired characters  are  not  inherited.  The  parent  is  composed  biologi- 
cally of  somatic  or  body  cells  which  are  mortal,  and  reproduction  cells 
or  germ  plasm  which  is  distinct,  continuous,  immortal.  The  germ 
cells  undergo  the  least  modification  from  their  original  condition.  In- 
deed, Weismann  believes  that  there  is  no  reason  for  supposing  that  they 

^Darwin,  however,  recognized  the  facts  of  mutations  or  "sports"  as  he 
called  them  and  dwelt  upon  their  importance. 

^Weismann.  A.:  "Essays  upon  Heredity,"  1889,  and  "The  Evolution 
Theory,"   1906.' 


428 


HEREDITY    AND    EUGENICS 


have  undergone  any  modification  at  all.  From  this  point  of  view  we 
may  consider  tlie  nature  of  a  given  series  of  animals  as  being  determined 
only  by  the  particular  series  of  cells  which  constitute  tlie  direct  an- 
cestry of  the  germ  cells  in  each  individual.  The  cells  which  make  up 
the  bodily  structure  may  be  regarded  as  the  result  of  so  many  offshoots 
which  come  to  an  end  at  the  death  of  the  organism  and  have  no  progeny 
of  their  own. 

The  minute  study  of  the  germ  cells  taken  in 
connection  with  modern  experimental  work  on  the 
methods  by  which  inheritance  takes  place  shows 
a  strong  tendency  to  confirm  TVeismann's  view,  so 
far  as  the  inheritance  of  distinct  and  definite  char- 
acters is  concerned. 

Wilson  ^  has  expressed  Weismann's  theory  as 
follows :  It  is  a  reversal  of  the  true  point  of  view 
to  reward  inheritance  as  taking  place  from  the 
body  of  the  parent  to  that  of  the  child.  The  child 
inherits  from  the  parent  germ  cell,  not  from  the 
parent  body,  and  the  germ  cell  owes  its  characters 
not  to  the  body  which  bears  it,  but  to  its  descent 
from  a  preexisting  germ  cell  of  the  same  kind. 
Thus,  the  body  is,  as  it  were,  an  offshoot  from  the 
germ  cell.  As  far  as  inheritance  is  concerned,  the 
body  is  merely  the  carrier  of  the  germ  cells  which 
are  held  in  trust  for  coming  generations.  Fig.  59 
illustrates  Wilson's  theory  of  inheritance  as  modi- 
fied by  Lock. 

Mendel's  Law. — We  are  indebted  to  Mendel  ^ 

Fig.  59. — Wilson's  The-  for  one  of  the  most  important  observations  of  biol- 
ORY  OF  Inheritance  ,,  ,    •  ^      .      •      ^     i.        -ii,        c 

Modified  by  Lock   °&5' — ^^^  most  important,  in  fact.  With  reterence 

(G,  germ    cells;   S,  to  heredity.    The  essential  factors  of  Mendel's  dis- 

covery  are:     (1)  unit  characters,  (2)  dominance, 

(3)  segregation.     By  a  unit  character  is  understood  any  characteristic 

of  an  individual  that  is  transmitted  from  parent  to  offspring  through 

^Wilson:     "The  Cell  in  Development  and  Inheritance,"  p.   13. 

^  Gregor  Johann  Mendel  was  born  July  22,  1822,  at  Heizendorf  in  Austrian 
Silesia.  In  1843  he  entered  the  Augustine  Convent  at  Altbrunn  as  a  novice,  and 
was  ordained  priest  in  1S47.  Mendel  was  a  teacher  of  natural  science  in  the 
Brunn  Eealschule  from  1853  to  1868,  when  he  was  appointed  abbot  of  his 
monastery. 

Mendel  published  only  the  results  of  his  work  upon  hybridization  with  peas 
and  a  few  of  his  experiments  with  Hieracium.  The  original  paper  on  "Hybridi- 
zation" was  published  in  the  Verh.  Naturf.  Fer.  in  Brunn,  Abthandlungen  IV, 
I860,  which  appeared  in  1S66;  the  paper  on  "Hieracium"  appeared  in  the  same 
journal,  VIII,  1869.  The  student  is  advised  to  read  "Mendel's  Principles  of 
Heredity"  by  W.  Bateson,  1909,  in  which  he  will  find  a  translation  of  these  two 
important  papers.  A  clear  exposition  is  also  given  by  R.  C.  Punnett  in  his  book 
entitled  "MendeUsm"  (1911). 


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PEIJTCIPLES    OF    HEEEDITY 


429 


successive  generations  and  which  conforms  to  the  following:  they 
are  usually  complementary.  When  parents  with  complementary 
unit  characters  unite,  it  is  found  that  one  character  predominates  over 
the  other.  This  is  known  as  dominance.  It  has  further  been  found  that 
the  unit  characters  contributed  by  the  respective  parents  do  not,  as  a 
rule,  blend,  but  remain  separate  or  distinct.  This  is  known  as  segrega- 
tion. The  principles  of  segregation  and  dominance  have  been  found  to 
apply  to  the  inheritance  of  many  characters  in  animals  and  plants.  It 
should  be  carefully  borne  in  mind  that  the  unit  characters  themselves 
are  not  transmitted  as  such  in  the  germ  cells.  Just  what  is  transmitted 
is  not  definitely  known.  It  is  quite  sure  that  the  only  thing  that  is 
inherited  in  the  germ  cells  is  something  which  determines  the  develop- 
ment of  the  unit  character.    This  something  is  called  a  determiner. 

The  essence  of  this  great  discovery  was  published  by  Mendel  in  a 
short  paper  in  1866.  By  some  extraordinary  chance  Mendel's  ob- 
servations were  entirely  lost  sight  of  until  the  same  facts  were  inde- 
pendently rediscovered  in  1899  by  DeYries,  working  in  Holland,  by 
Correns  in  Germany,  and  by  Tschermak  in  Austria. 

A  Schematic  Representation  of  AIendel's  Law 

D  R.  .  .  . P'— great-grandparental  generation. 

D  R. . .  .P- — grandparental  generation. 

D  R.  .  .  -P' — parental  generation. 


D(R) 


F' — first  filial  (hybrid)  generation. 


2DD 

Pure  dominants 


DD       IDD 


2D(R) 
Impure  dominants 


IRR  F- — second  filial 

Pure  recessives       (inbredj  genera- 
tion. 


2D(R) 


IRR        RR 


DD        DD       IDD    2D(R)     IRR       RR 


RR 


F' — third    genera- 
tion. 


F* — fourth   gener- 
ation. 


D  and  R  represent  complementary  unit  characters,  D  the  dominant  charact_er, 
and  R  the  recessive  character.  D(R)  represents  a  dominant  with  the  recessive 
character  unexpressed  but  potentially  present.  DD  means  pure  dominants,  and 
RR  pure  recessives. 

Mendel's  law  may  best  be  understood  from  a  concrete  illustration. 
One  of  the  simplest  cases  is  that  of  the  heredity  of  color  in  the  Andalu- 
sian  fowl,  which  has  been  so  clearly  described  by  Bateson. 


430  HEREDITY    AND    EUGENICS 

There  are  two  established  color  varieties  of  this  fowl :  one  with  a 
great  deal  of  black  and  one  that  is  white  with  some  black  markings  or 
splashes.  For  convenience  we  may  refer  to  these  as  the  black  and  white 
varieties  respectively.  Each  of  these  breeds  true  by  itself.  Black  mated 
with  black  produce  none  but  black  offspring.  White  mated  with  white 
produce  none  but  white  offspring.  Crossing  black  and  white,  however, 
results  in  the  production  of  fowls  with  a  sort  of  grayish  color  called 
"blue"'  by  the  fancier,  though  in  reality  it  is  a  fine  mixture  of  black 
and  white.  If  we  continue  to  breed  succeeding  generations  from  these 
blue  hybrid  fowls  we  get  tlirec  different  colored  forms.  Some  will 
be  blue,  like  the  parents,  some  black,  like  one  grandparent,  some  white, 
like  the  other  grandparent.  Further,  these  different  colors  appear  in 
certain  definite  proportions  among  the  three  classes  of  descendants. 
Of  the  total  number  of  the  immediate  offspring  of  the  hybrid  blues,  ap- 
proximately one-half  will  be  blue,  like  the  parents,  approximately  one- 
fourth  black,  and  one-fourth  white,  like  each  of  the  grandparents. 
Thus,  black  bred  together  produce  only  blacks;  the  white  similarly 
produce  only  whites;  the  blues,  on  the  other  hand,  when  bred  together 
produce  a  progeny  sorting  into  three  classes,  and  in  the  same  propor- 
tion as  that  produced  by  the  blues  of  the  original  hybrid  generation. 
The  fact  that  the  black  grandchildren  and  the  white  grandchildren  re- 
spectively breed  true  is  a  very  important  fact.  In  this  illustration  no 
race  of  the  hybrid  blue  character  can  be  established,  for  the  blues  al- 
ways produce  blacks  and  whites  as  well  as  blues  (see  diagram). 


t?  t7t? 


Fig.  60. — Diagram  Showing  the  Course  of  Color  Heredity  im  the  Andalusian 
Fowl,  in  Which  One  Color  Does  Not  Completely  Dominate  Another.  P,  paren- 
tal generation.  The  offspring  of  this  cross  constitute  Fi,  the  first  filial  or  hybrid  gen- 
eration. F2,  the  second  filial  generation.  Bottom  row,  third  filial  generation.  (Kel- 
licott.) 

Another  instance  which  illustrates  the  phenomenon  of  dominant  and 
recessive  characters  as  well  as  segregation  is  here  given.  If  black  and 
white  varieties  of  guinea  pigs  are  crossed  the  offspring  are  all  black, 


PEmCIPLES    OF    HEEEDITY  431 

like  one  parent;  that  is,  when  black  and  white  characters  are  brought 
together  in  the  guinea  pig,  these  do  not  appear  to  blend  into  gray  or 
"blue,"  as  in  the  case  of  the  Andalusian  fowl,  but  one  character  alone 
appears.  The  black  seems  to  cover  up  or  wipe  out  the  white.  The 
black  color  is,  therefore,  said  to  be  dominant  and  the  white  recessive. 
The  white  character,  however,  has  not  disappeared,  for  when  the  black 
offspring  are  crossed  together  the  progeny  falls  into  two  groups :  some 
black  and  some  white,  't'hree-fourths  of  the  progeny  are  black;  that  is, 
they  resemble  the  hybrid  form  and  at  the  same  time  one  of  the  grand- 
parents, while  the  remaining  fourth  resemble  the  other  white  grand- 
parent. Some  of  these  blacks  will  breed  true  and  are,  therefore,  known 
as  homozygotes.  Some  of  the  blacks  contain  a  mixture  of  the  black 
and  white  characters  and  are,  therefore,  known  as  heterozygotes.  The 
hereditary  transmission  of  the  color  character  in  these  two  illustrations 
through  the  germ  cell  is  shown  in  the  accompanying  diagram. 

^  <•     CD 


CO  CDCD 


Fig.  61. — Diagram  Showing  the  Course  of  Color  Heredity  in  the  Guinea-pig,  in 
Which  One  Color  (Black)  Completely  Dominates  Another  (White)  .  Refer- 
ence letters  as  in  Fig.  60.      (Kellicott.) 

Unit  characters  may  either  be  positive  or  negative;  that  is,  they 
may  be  due  to  the  presence  or  absence  of  "something"  in  the  germ 
cell  or  sperm  cell.  This  something,  known  as  a  determiner,  is  a  force, 
a  molecular  structure  or  an  enzyme  (?)  in  the  nuclear  matter  of  the 
germ-plasm.  Thus,  the  determiner  in  the  case  of  pigment  is  not  the  pig- 
ment itself,  but  something  that  activates  pigment  production.  These 
determiners  are  transmitted  in  the  germ  plasm  and  are  the  only  things 
that  are  truly  transmitted.  The  determiner  may  be  either  in  the  ovum 
or  the  sperm. 

An  hereditable  character  may  be  due  to  the  presence  or  absence  of 
a  determiner  in  the  germ  plasm  of  both  parents.  When  a  character  is 
due  to  the  presence  of  a  determiner  it  is  called  positive,  when  due  to 
the  absence  of  a  determiner,  negative.  Thus,  a  brown  eye  depends  on 
a  determiner  that  produces  the  brown-colored  pigment,  while  the  blue 
eye  depends  upon  the  absence  of  such  a  determiner.     It  is  not  always 


433  HP]KKI)ITY    AND    EUGP]NICS 

easy  to  anticipate  whether  a  given  character  is  positive  or  negative. 
For  instance,  long  hair  in  Angora  cats,  sheep,  or  guinea  pigs  is  ap- 
parently not  due  to  a  factor  added  to  short  hair,  but  rather  to  an 
absence  of  a  determiner  that  stops  growth  in  short-haired  animals. 

One  of  the  most  important  conclusions  from  Mendel's  observations 
is  that  the  different  inherited  traits  act  independently;  that  is,  they 
do  not  blend.  In  other  words,  the  definitely  hereditable  characters 
act  as  independent  units  that  are  without  any  apparent  relation  to 
other  peculiarities  of  the  individual  concerned.  Furthermore,  these 
units  do  not  interfere  witli  each  other.  It  follows  that  all  the  unit  char- 
acters of  an  individual  are  to  be  regarded  as  mutually  independent  as- 
semblages. This  is  the  doctrine  of  unit  characters.  According  to  this 
doctrine,  each  individual  is  of  dual  origin,  paternal  and  maternal,  and 
each  individual  is  made  up  of  a  mosaic  of  inherited  characters,  some 
of  which  may  be  dominant, ,  others  recessive.  The  idea  of  unit  char- 
acters capable  of  being  inherited  independently  of  one  another  is  one 
of  the  most  important  conceptions  which  has  been  added  to  our 
knowledge  of  heredity.  We  now  know  from  the  phenomenon  of  segre- 
gation what  constitutes  purity  in  a  strain  of  animals  or  plants;  that 
is,  purity  does  not  depend  upon  the  length  of  time  during  which  a  race 
has  exhibited  a  constant  character,  for  a  strain  of  absolute  purity  may 
arise  from  the  second  generation  of  a  cross.  Mendel's  law  has  not  only 
explained  many  facts  in  heredity,  but  also  has  important  practical 
bearing  in  the  improvement  of  the  breeds  of  cultivated  plants  and  do- 
mestic animal.-. 

Atavism  and  Reversion. — Atavism  (from  atavus,  a  grandfather)  is 
the  inheritance  of  properties  not  manifest  in  either  parent,  but  pres- 
ent in  the  grandfather  or  some  relatively  recent  ancestor.  Mendel's 
observations  upon  recessive  characters  now  make  plain  some  of  the 
phenomena  known  as  atavism.  According  to  Castle,  atavism  or  rever- 
sion to  an  ancestral  condition  can  be  completely  explained  by  the  Men- 
delian  principles.  It  is  nothing  more  or  less  than  the  reassertion  of 
recessive  unit  characters  that  have  long  been  overshadowed  by  dominant 
characters.  It  seems  that  recessive  characters  may  not  be  lost,  no  mat- 
ter how  long  they  remain  latent  or  dormant. 

The  term  "atavism"  is  sometimes  employed  to  mean  any  reversion- 
ary condition,  whether  favorable  or  unfavorable,  while  the  term  "re- 
version" means  a  return  in  the  offspring  to  a  lower  type,  usually  of 
some  remote  ancestor.  The  degenerations  which  run  in  families  may 
be  instances  either  of  atavism  or  reversion,  or  mutation. 

Darwin's  classical  experiment  illustrating  reversion  consisted  in 
crossing  a  barbed  fan-tail  female  pigeon  with  a  barbed  spot  male  and 
producing  offspring  hardly  distinguishable  from  the  wild  Shetland 
species  of  blue-rock  pigeon  (Colomba  livia).    This  is  a  case  of  reversion. 


PRINCIPLES    OF    HEREDITY  433 

in  which  an  artificially  bred  and  highly  specialized  race  quickly  re- 
covered characters  which  had  been  lost  during  many  generations.  A 
foal  is  sometimes  born  with  a  few  stripes  on  its  forelegs,  as  if  remind- 
ing us  of  striped  wild  horses.  Highly  cultivated  and  specialized  flowers 
and  vegetables  have  a  tendency  to  revert,  and  sometimes  produce  forms 
hardly  distinguishable  from  their  wild  progenitors.  Reversion  is  due 
to  the  reassertion  ■  of  latent  ancestral  characters.  It  is  an  impelling 
hereditary  force  which  must  be  taken  into  account.  True  reversion  may 
arise  in  pure  bred  races,  but  is  much  more  frequent  as  the  result  of 
hybridization. 

The  facts  of  reversion  and  atavism  are  of  peculiar  interest  to  man, 
for  the  reason  that  the  human  species  has,  through  unconscious  selec- 
tion and  conscious  effort,  improved  the  race  to  its  present  point  of 
superiority.  Whether  civilized  man  to-day  is  superior  to  ancient  races 
may  be  doubted,  but  the  fact  is  plain  that  civilization  is  breeding  an 
artificial  and  highly  civilized  strain  that  shows  artificial  departures  from 
primitive  stock. 

It  is  well  known  that  the  high  bred  and  "fancy"  races  of  the  do- 
mesticated animals  show  a  marked  tendency  to  reversion  or  deteriora- 
tion of  type.  •  Likewise,  the  human  race  shows  the  same  tendency  to 
revert  to  types  resembling  its  forebears.  The  present  level  attained  by 
the  more  highly  civilized  races  can  only  be  maintained  by  a  continua- 
tion of  that  struggle  for  improvement,  progress,  and  desire  for  per- 
fection which  is  an  inborn  characteristic  and  an  essential  element  of 
progress.  Owing  to  the  artificial  position  to  which  the  human  race 
has  brought  itself,  it  becomes  necessary  to  continue  the  struggle — to 
stand  still  means  rapid  deterioration.  Some  of  the  stigmata  of  degen- 
eration and  hereditary  defects  may  be  accounted  for  by  this  natural 
tendency  on  the  part  of  an  artificially  nurtured  standard  to  slip  back- 
ward. 

G-alton's  Law  of  Filial  Regression. — Filial  regression  has  nothing  to 
do  with  reversion.  The  law  of  filial  regression  concretely  stated  is  that 
offspring  are  not  likely  to  differ  from  mediocrity  in  a  given  direction 
so  widely  as  their  parents  do  in  the  same  direction.  There  is  a  contin- 
ual tendency  to  sustain  a  specific  average  or  a  stock  average. 

Let  us  take  a  simple  instance  from  Professor  Karl  Pearson's  "Gram- 
mar of  Science."  Suppose  a  group  of  fathers  with  a  stature  of  72 
in. :  the  mean  height  of  their  sons  is  70.8  in. — a  regression  toward  the 
mean  height  of  the  general  population.  On  the  other  hand,  fathers 
with  a  mean  height  of  66  in.  give  a  group  of  sons  of  mean  height 
68.3  in. — again  nearer  the  mean  height  of  the  general  population.  The 
"regression"  works  both  ways — there  is  a  leveling  up  as  well  as  a  level- 
ing down.  "The  father  with  a  great  excess  of  the  character  contributes 
sons  with  an  excess^  but  a  less  excess  of  it;  the  father  with  a  great 


434  HEREDITY    AXD    EUGENICS 

defect  of  the  character  contributes  sons  with  a  defect,  but  less  of  it" 
(Thompson). 

THE  CELL  IN  HEREDITY 

Each  parent  (male  and  female)  is  composed  biologically  of  somatic 
or  body  cells,  which  are  mortal,  and  germ  plasm  which  is  distinct,  con- 
tinuous, immortal.  The  development  and  embryology  of  the  germ  and 
sperm  cells  are  of  particular  interest  to  the  student  of  heredity. 

The  view  has  gained  ground  and  general  acceptance  that  the  nucleus 
is  the  chief  or  exclusive  bearer  of  the  hereditable  characters;  that  is, 
the  female  nuclear  material  transmits  the  characters  of  tlie  mother 
and  her  forebears  and  the  male  nucleus  those  of  the  father  and  his  fore- 
bears to  the  offspring. 

Cells  divide  and  multiply  in  two  ways :  ( 1 )  by  direct  division  or 
amitosis,  and  (2)  by  indirect  division  or  mitosis.  Direct  division  oc- 
curs more  frequently  than  is  usually  suspected.  The  process  appears 
to  be  a  very  simple  one;  the  nucleus  divides  without  any  preliminary 
arrangement  of  its  structure,  the  cytoplasm  is  constricted,  and  presently 
we  have  two  cells  in  place  of  one.  Indirect  division  or  mitosis  appears 
to  be  the  natural  mode  of  cell  development.  The  chromatin,  which  is 
the  deeply  staining  matter  in  the  nucleus,  rearranges  itself  from  its 
"resting"  stage.  After  a  complicated  process  the  nuclear  matter  forms 
itself  into  a  long  cylindrical  thread  known  as  the  linene  thread.  This 
then  divides  into  links  or  chromosomes.^  The  chromosomes  are  of  spe- 
cial interest,  for  they  are  believed  to  carry  the  hereditable  traits. 

In  amitotic  division  each  chromosome  is  divided  in  half  longitu- 
dinally, as  a  stick  might  be  split  up  the  middle,  and  after  a  very  com- 
plex process  the  halves  of  each  split  chromosome  migrate  to  opposite 
poles.  Then  each  centrosome  attracts  a  group  of  chromosomes  con- 
sisting of  just  one-half  of  the  original  chromatin  material.  Each  group 
then,  in  orderly  fashion,  rounds  itself  into  a  new  nucleus,  and  the  body 
of  the  cell  (the  c}i;oplasm)  constricts  across  the  equatorial  plane,  and 
two  cells  are  formed. 

Everv'  species  of  plant  or  animal  has  a  fixed  and  characteristic 
number  of  chromosomes  which  regularly  recurs  in  the  division  of  all 
of  its  cells  and  in  all  forms  arising  by  sexual  reproduction  the  number 
is  even.  Thus,  in  some  of  the  sharks  the  number  of  chromosomes  is 
36,  in  certain  gastrapodes  it  is  32 ;  in  the  mouse  and  salamander, 
the  trout,  the  lily,  24;  in  the  worm  Saggita,  18;  in  the  ox  and  guinea 
pig,  16;  in  man  the  number  was  formerly  stated  as  16,  now  24.     In 

^  For  a  full  understanding  of  cell  division  the  student  is  referred  to  one  of 
the  standard  text-books  upon  Cytology,  or  Minot  's  ' '  Embryology ' ' ;  also,  to  E.  B. 
Wilson's  "The  Cell  in  Development  and  Inheritance,"  2d* Ed.,  1900. 


THE    CELL    m    HEEEDITY  435 

crustaceans  the  number  of  chromosomes  may  be  as  high  as  168.  In 
a  tew  insects  the  females  have  in  their  body  cells  one  chromosome  in 
addition  to  the  number  possessed  by  the  males.  This  has  been  inter- 
preted as  bearing  upon  the  determination  of  sex. 

Van  Beneden  in  1885  discovered  the  important  fact  that  the  nu- 
cleus of  the  ovum  and  the  nucleus  of  the  spermatozoon  which  unite 
in  fertilization  contain  each  one-half  of  the  number  of  chromosomes 
characteristic  of  the  body  cells. 

As  both  the  germ  and  sperm  cells  contain  only  half  the  number  of 
chromosomes,  a  reduction  must  take  place  in  the  liistory  of  these  cells; 
in  fact,  alike  in  the  history  of  the  germ  cell  and  in  the  history  of  the 
sperm  cell,  there  is  a  parallel  reduction  in  the  number  of  chromosomes 
to  one-half.  This  reduction  appears  to  be  a  preparation  of  the  repro- 
duction cells  for  their  subsequent  union,  and  a  means  by  which  the 
number  of  chromosomes  is  held  constant  in  the  species. 

In  sexual  reproduction  each  centrosome  attracts  a  group  of  chromo- 
somes, half  of  which  are  of  paternal  origin  and  half  of  maternal  origin. 
This  is  interpreted  as  meaning  that  the  paternal  and  maternal  chromo- 
somes that  unite  to  form  the  new  zygote  probably  carry  the  heredi- 
table  characters. 

The  gist  and  meaning  of  the  whole  process  to  the  student  of  hered- 
ity is  the  precisely  equal  partition  of  the  maternal  and  paternal  con- 
tributions, so  that  each  of  the  daughter  cells  has  a  nucleus  half  from 
the  mother  and  half  from  the  father. 

Although  the  ovum  is  much  larger  than  the  spermatozoon,  each 
contributes  equally  so  far  as  the  amount  of  nuclear  matter  is  concerned ; 
the  new  individual  is  dual  in  its  origin,  and  the  offspring  is  a  double 
creature  and  retains  its  duality  to  its  dying  day,  and  transmits  it  to 
succeeding  generations. 

Professor  E.  B.  \Yilson  states  the  generally  accepted  opinion  some- 
what as  follows:  As  the  ovum  is  much  larger  it  is  believed  to  furnish 
the  initial  capital — including,  it  may  be,  a  legacy  of  food  yolk — for 
the  early  development  of  the  embryo.  Erom  both  parents  alike  comes 
the  inherited  organization  which  has  its  seat  (according  to  most  biolo- 
gists) in  the  readily  stainable  chromatin  rods  of  the  nuclei.  From  the 
father  comes  a  little  body,  the  centrosome,  which  organizes  the  ma- 
chinery of  division  by  which  the  egg  splits  up  and  distributes  the  dual 
inheritance  equally  between  the  daughter  cells. 

The  ovum  may  be  stimulated  to  maturation  without  the  sperm 
cell  (parthenogenesis).  When  this  happens  individuals  are  produced 
similar  to,  but  not  as  vigorous  as,  the  normal  types.  The  sperm  cell 
similarly  is  able  to  develop  without  the  nuclear  matter  of  the  egg.  In 
other  words,  the  o^iim  and  the  sperm  each  contain  potential  factors 
for  the  new  individual.     As  we  have  already  seen,  in  accordance  with 


436  HEREDITY    AND    EUGENICS 

Weismann's  theory,  that  the  germ  plasm  is  independent  of  the  hody  and 
is  continuous;  tlierefore,  ac(iuired  characters  not  affecting  the  germ 
plasm  are  not  inlierited  in  accordance  with  this  conception. 

Foreign  bodies  carried  along  by  either  the  germ  or  sperm  cells  are 
not  instances  of  true  heredity;  therefore,  in  tlie  present-day  con- 
ception of  heredity  it  is  not  possible  for  a  microbic  disease  to  be  trans- 
mitted hereditarily,  even  though  the  microorganism  is  contained  in 
either  the  germ  or  the  sperm.  Thus,  hens  may  be  caused  to  lay  col- 
ored eggs  by  feeding  the  hen  with  anilin  dyes.  Anaphylaxis  is  an 
example  of  a  transmitted  property,  but  the  substance,  whatever  it  is, 
seems  to  be  carried  along  with  the  maternal  germ  cell  as  a  foreign 
body.  In  the  case  of  syphilis,  the  Treponema  paUlduin  may  l)e  carried 
along  by  the  germ  or  sperm,  and  the  disease  is  said  to  be  transmitted 
hereditarily,  but,  strictly,  the  microorganism  is  carried  as  a  foreign  body 
and  not  as  a  unit  character  or  constituent  pait  of  the  nuclear  matter. 

BIOMETRY 

Statistical  methods  applied  to  biology  have  been  termed  biometry 
by  Professor  Karl  Pearson.  Francis  Galton's  book  on  "Natural  In- 
heritance" is  a  pioneer  in  the  subject,  and  embodies  a  lucid  introduction 
to  the  statistical  study  of  variation  and  inheritance.  The  health  offi- 
cer must  be  familiar  with  statistical  methods  not  only  in  their'  applica- 
tion to  biology,  but  as  they  relate  to  vital  statistics.  The  health  officer 
who  lacks  the  quantitative  view  or  who  fails  to  grasp  the  statistical 
values  of  the  facts  and  factors  in  preventive  medicine  works  under  a 
decided  handicap.  The  sanitarian  who  is  ignorant  of  statistical  methods 
must  necessarily  grope  in  the  dark.  Efficiency  and  economy  in  public 
health  work  depend  not  alone  upon  a  knowledge  of  the  biological 
sciences,  but  also  upon  a  correct  sense  of  proportion.  The  statistical 
method  is  a  strong  lever  which  makes  for  sane  administration,  economy 
in  expenditure,  efficiency  of  effort;  in  short,  successful  results. 

Statistics  deal  with  groups  rather  than  with  individuals.  It  must 
be  understood  that  the  average  of  a  group  may  represent  something 
quite  different  from  any  individual  which  the  group  contains.  Also  a 
group  may  contain  individuals  of  very  diverse  natures.  In  collecting 
statistical  material  the  data  must  be  gathered  without  any  preconceived 
ideas  and  without  neglecting  any  members.  In  this  respect  statistical 
methods  differ  from  biological  methods,  which  require  careful  discrimi- 
nation of  data. 

The  quantitative  determination  of  a  character  may  be  made  by  various 
methods,  as  by  counting  or  by  measurement. 

The  statistical  method  may  be  illustrated  by  a  simple  model,  such 
as  that  suggested  by  Galton.     This  is  a  modification  of  the  familiar 


BIOMETRY 


43? 


bagatelle  board  covered  with  glass  and  arranged  as  shown  in  Fig.  63. 
A  fimnel-shaped  container  at  the  top  of  the  board  is  filled  with  peas 
or  similar  objects.  Below  this  is  a  regular  series  of  obstacles  symmetri- 
cally arranged^  and  at  the  bottom  of  the  board  is  a  row  of  vertical  com- 
partments  also  arranged  symmetrically  with  reference  to  the  chief  axis 
of  the  whole  system.  If  we  allow  the  peas  to  run  through  the  funnel 
and  fall  among  the  obstacles  into  the  compartments  below,  we  find  that 
their  distribution  will  follow  certain  lav.^s  capable  of  precise  mathe- 
matical  description.      The   distribution  of   the   peas  may  be   predicted 


^ 

■^ 

\ 

X 

S 

s^ 

^ 

<•  i 

7 

.  1 

Fig.  62. — Model  to  Illtjsthate  the  Law  of  Probability  or  "Chance."  A,  Peas 
held  in  container  at  top  of  board.  B,  Peas  after  having  fallen  through  the  obstruc- 
tions into  the  vertical  compartments  below.  The  curve  connecting  the  tops  of  the 
columns  of  peas  is  the  normal  probability  curve. 

with  fair  accuracy.  The  middle  compartment  will  receive  the  most; 
the  compartments  next  the  middle  somewhat  fewer;  those  further  from 
the  middle  still  fewer ;  and  the  end  compartment  fewest.  If  we  connect 
the  top  of  each  column  of  peas  by  a  curved  line  we  get  a  curve  known 
as  the  "normal  frequency  curve."  A  curve  of  the  same  essential  char- 
acter would  result  from  plotting  the  dimensions  of  a  thousand  cobble- 
stones, the  deviation  from  the  bull's  eye  in  a  target  shooting  contest, 
or  by  plotting  the  variability  of  a  biologic  character,  such  as  the  stature 
or  strength  of  men,  the  spread  of  sparrows'  wings,  the  number  of  rays 
on  scallop  shells,  or  of  ray  flowers  of  daisies. 

While  from  the  above  law  of  probability  we  know  quite  definitely 
30 


438 


HEREDITY    AND    EUGEXICS 


wliat  tlie  general  distribution  of  the  peas  will  be,  we  do  not  know  at 
all  the  future  position  of  any  single  pea.  Of  this  we  can  speak  only  in 
terms  of  probability.  The  chances  are  very  high  that  it  will  fall  in 
one  of  the  three  middle  com})artments,  very  low  that  it  will  be  one  of 
the  extreme  compartments.  The  chances  are  equal  that  any  individual 
pea  will  fall  above  or  below  the  aveiage  or  middle  position.  We  there- 
fore see  that  in  any  group  there  are  many  more  individuals  near  the 
average  than  there  ai-e  in  the  classes  removed  from  the  average,  and 
the  farther  the  removal  of  a  class  from  the  average  the  smaller  the 
numbei'  of  individuals  in  that  class;  hence,  we  have  the  important  fact 
in  statistical  methods  that  an  individual  may  belong  to  a  group  with- 
out representing  it  fairly.  In  order  to  get  a  correct  idea  of  the  whole 
group  we  must  know  first  to  what  extent  deviation  in  each  direction 


Q         M         Q' 

Fig.  63. — Normal  Curve.     (Lock.) 


occurs  above  and  below  the  group  average;  and,  second,  the  average 
amount  by  which  each  individual  of  the  group  deviates  from  this  group 
average;  that  is,  we  must  know  the  amount  of  variability  as  well  as 
tlie  extent  of  the  greatest  divergence  from  the  average.  Hence,  we  have 
the  following  definitions  and  corollaries : 

The  mode  of  a  normal  curve  is  the  longest  perpendicular  which  can 
be  drawn  from  the  base  line  to  meet  the  curve  itself,  ]\I,  Fig.  ()3.  The 
normal  curve  is  symmetrically  on  either  side  of  the  mode;  that  is  to 
say,  two  perpendiculars  drawn  from  the  base  to  the  curve  on  either  side 
of  the  mode  and  at  the  same  distance  from  it  will  l)e  e(|ual  in  length. 

The  median  is  a  perpendicular  line  which  divides  the  area  of  the 
curve  into  two  equal  halves.  In  dealing  with  a  symmetrical  curve  the 
position  of  the  mode  is  identical  with  that  of  the  median. 

The  mean  or  average  of  all  the  values  from  which  the  curve  is  con- 
structed is  the  foot  of  the   median.     In  any  actual  case  obtained  by 


BIOMETEY  439 

practical  methods  the  position  of  the  mode,  the  median,  and  the  mean 
will  only  be  approximately  the  same  because  such  a  curve  is  never 
perfectly  symmetrical. 

The  quartile  is  the  distance  from  the  median  to  a  perpendicular 
line  extending  from  the  base  of  the  curve  at  such  a  distance  from  the 
median  that  it  divides  the  area  inclosed  by  the  median,  the  base,  and 
half  the  curve  into  two  equal  parts.  An}^  given  curve  will  have  two 
quartiles,  one  on  either  side  of  the  median.  They  are  shown  at  Q 
and  Q'.     (Fig.  63.) 

A  variate  is  one  of  the  separate  numerical  values  from  which  a 
curve  of  variability  can  be  constructed.  The  accuracy  of  the  statistical 
method  is  usually  proportionate  to  the  number  of  variates  out  of  which 
the  curve  is  built.  The  ,biometrician  usually  deals  with  some  such 
number  as  1,000  variates.  The  total  number  of  variates  is  represented 
by  the  area  inclosed  by  the  curve,  and  it  will  be  seen  that  half  the  total 
number  of  variates  falls  between  the  two  quartiles  and  half  outside  of 
them. 

A  class  may  be  defined  as  a  group  of  variates  all  of  which  show  a 
particular  value  or  a  value  falling  between  certain  limits. 

The  frequency  of  a  class  is  the  number  of  variates  which  it  contains. 

The  amount  of  variation  shown  by  a  particular  group  of  variates 
is  measured  by  the  degree  of  slope  of  the  curve.  A  flat  curve  indi- 
cates greater  variability  and  a  steep  curve,  denotes  less  variability. 

The  standard  deviation  of  a  normal  curve  is  the  measure  of  vari- 
ability and  is  more  often  used  than  the  quartile  and  is  expressed  shortly 
as  ff.  The  value  of  C  is  found  by  multiplying  the  square  of  the  devi- 
ation of  each  class  from  the  mean  (or  mode)  by  the  frequency  of  the 
class,  adding  together  the  series  of  products  so  obtained,  di^dding  this 
number  by  the  total  number  of  variates,  extracting  the  square  root  of 
the  result,  and  multiplying  by  the  number  of  units  in  the  class  arranged. 

The  coefficient  of  variahilitij  is  a  purel}'  abstract  number  obtained 
by  dividing  the  standard  deviation  by  the  magnitude  of  the  mean  in 
any  particular  case  and  multiplying  the  result  by  100. 

The  probable  error  arises  from  the  circumstances  that  half  the  total 
number  of  variates  lies  outside  the  limits  of  the  quartile  and  half  within. 
The  probable  error  of  any  statistical  determination  is  obtained  b}'  find- 
ing a  pair  of  values  lying  one  above  and  one  below  the  true  value  re- 
quired. For  further  details  regarding  properties  of  normal  cur^'CS  the 
student  is  directed  to  Davenporfs  "Statistical  Methods  with  Special 
Eeference  to  Bioloo-ical  Variation."' 


440  HEREDITY   AND    EUGENICS 

HEREDITY  VERSUS  ENVIRONMENT 

How  much  oi  our  physical  and  meutal  makeup  is  due  to  heredity 
(nature)  and  how  much  to  environment  (nurture)  is  one  of  the  much- 
discussed  problems.  It  seems  evident  to  students  of  biology  that  by 
far  the  overwhelming  factor  in  our  organization  is  set  and  definitely 
fixed  at  our  birth.  Heredity  appears  to  be  the  overshadowing  influence 
of  first  and  prime  importance.  Herbert  Spencer  well  said  that  "in- 
herited constitution  must  ever  be  the  chief  factor  in  detennining  char- 
acter." Environment  may  influence  the  individual,  but  apparently  has 
small  and  slow  power  of  propagating  itself  for  good;  great  and  rapid 
power  for  evil.  That  is,  the  hereditary  transmission  of  acquired  char- 
acters is  denied,  but  the  transmission  of  defects  of  organization,  such 
as  insanity,  deaf  mutism,  the  consequences  of  syphilis,  alcoholism, 
and  other  vices,  are  fully  recognized.  Atavism,  reversion,  and  muta- 
tions must  not  be  regarded  as  instances  of  the  hereditary  transmission 
of  acquired  characters  in  the  biological  sense.  The  tendency  of  the 
artificially  bred  strains  of  the  civilized  human  races  to  revert  and  de- 
teriorate has  already  been  emphasized. 

Despite  the  teachings  of  biolog}'  we  are  convinced  that  life  is  in- 
exorably conditioned  by  its  environment.  Jordan  states  that  "among 
the  factors  ever}where  and  inevitably  connected  with  the  course  of 
descent  of  any  species  variation,  heredity,  selection,  and  isolation  must 
appear;  the  first  two  innate,  part  of  the  definition  of  organic  life;  the 
last  two  extrinsic,  arising  from  the  necessities  of  environment,  and  not 
one  of  these  can  find  leverage  without  the  presence  of  the  others."  In 
the  present  state  of  our  knowledge,  while  we  are  convinced  that  hered- 
ity plays  the  major  role,  we  are  by  no  means  prepared  to  deny  the 
influence  of  environment. 

IMMUNITY  GAINED  THROUGH  INHERITANCE 

Immunity  to  disease  is  either  natural  or  acquired.  Natural  immu- 
nity is  inherited  through  successive  generations  of  a  species  or  a 
race.  Acquired  immunity,  like  other  acquired  characters,  is  probably 
not  inlierited  as  a  "unit  character"  in  the  sense  of  Mendel.  Thus, 
there  has  been  little  variation  in  our  natural  power  to  resist  most  in- 
fections, such  as  tuberculosis,  yellow  fever,  plague,  smallpox,  cholera, 
tetanus,  measles,  scarlet  fever,  diphtheria,  and  so  on  through  a  long 
list,  although  these  diseases  have  doubtless  afflicted  the  human  species 
through  untold  ages.  The  fluctuating  virulence  of  some  infections  is 
a  matter  of  common  knowledge,  and  is  doubtless  due  to  many  factors. 
In  a  few  well-known  instances  a  certain  amount  of   tolerance   or  re- 


IMMUNITY    GAINED    THEOUGH    INHERITANCE       441 

sistance  has  been  gained  and  perhaps  transmitted  through  succeeding 
generations  by  a  process  of  the  survival  of  the  fittest.  Thus,  syphilis 
is  much  less  virulent  now  than  it  was  during  the  great  pandemic  of 
the  sixteenth  century.  The  resistance  which  the  natives  enjoy  to  ma- 
laria in  badly  infected  quarters  of  the  globe  is  largely  acquired  as  a 
result  of  early  infections,  and  this  increased  resistance  is  perhaps  partly 
transmitted  by  a  weeding  out  of  the  very  susceptible  (see  chapter  on 
Immunity). 


CHAPTER   III 

THE    HEREDITARY    TRANSMISSION    OF    DISEASE 

We  are  now  prepared  to  discuss  more  in  detail  the  hereditary 
transmission  of  disease.  The  question  whether  disease  is  ever  trans- 
mitted hereditarily  or  not  rests  somewhat  upon  our  conception  of  dis- 
ease; that  is.  whether  it  is  an  entity,  a  process,  or  a  "unit  character." 
The  process  itself,  of  course,  cannot  be  transmitted,  but  the  potentiality 
of  it  may  be  involved  in  some  peculiarity  in  the  organization  of  the 
germ  plasm.  This  may  be,  and  often  is,  transmitted  through  succes- 
sive generations.  In  the  limited  sense  in  which  the  word  "heredity" 
is  used  in  biology  and  in  the  limited  sense  in  which  the  word  "disease" 
is  used  in  pathology,  there  may  be  no  inherited  diseases,  but  this  ap- 
pears to  be  a  quibble  of  words  or  a  matter  of  definitions.  While  we 
are  not  familiar  with  the  intimate  processes  concerned,  we  are  certain 
that  many  abnormal  conditions  of  mind  and  body  are  transmitted. 
Some  of  them  follow  the  Mendelian  principles. 

Formerly  a  large  number  of  diseases  were  regarded  as  transmissible, 
but  the  list  has  been  revised  and  restricted  as  a  result  of  recent  studies. 
The  reappearance  of  a  diseased  condition  in  successive  generations  does 
not  prove  that  it  has  been  transmitted  or  even  that  it  is  transmissible. 
This  mistake  has  been  made  with  tuberculosis  and  other  infections. 

Lack  of  completeness  vitiates  most  of  the  statistics  bearing  on 
heredity  in  relation  to  human  diseases.  Even  in  the  case  of  clearly  in- 
herited diseases  there  are  very  few  pedigrees  sufficiently  complete  for 
the  study  of  the  applicability  of  Mendelian  and  other  laws  of  heredity. 

Sometimes  the  disease  itself  is  not  transmitted,  but  a  tendency  to 
the  disease  is  transmitted.     This  will  be  discussed  again. 

Some  unit  characters  as  well  as  certain  diseases  are  transmitted 
hereditarily,  but  limited  to  one  sex;  that  is,  the  disease  or  condition 
appears  in  one  sex  only,  although  transmitted  by  the  other.  The  best 
example  of  a  sex-limited  disease  is  hemophilia,  which  affects  males  al- 
most exclusively,  but  is  transmitted  through  the  normal  female.  Color- 
blindness is  also  transmitted  hereditarily,  but  is  sex-limited,  as  it  af- 
fects males  almost  exclusively. 

This  remarkable  sort  of  inheritance,  known  as  sex-limited  inheritance, 
443 


GENEEAL    CONSIDERATIONS  443 

occurs  when  the  male  parent  is  characterized  by  the  absence  of  some 
character  of  which  the  determiner  is  typically  lodged  in.  the  sex  (x) 
chromosome.  A  striking  feature  of  this  sort  of  heredity  is  that  the 
trait  ajDpears  only  in  males  of  the  famih',  but  is  not  transmitted  by 
them;  it  is  transmitted,  however,  through  normal  females  of  the  family. 
Examples  of  this  sort  of  heredity  occur  in  hemophilia,  color-blindness, 
also  in  multij^le  sclerosis,  atrophy  of  the  optic  nerve,  myopia,  ichthyosis, 
and  muscular  atrophy.  The  explanation  is  the  same  in  all  cases  of 
sex-limited  heredity.  The  abnormal  condition  is  due  to  the  absence  of 
a  determiner  from  the  male  sex  chromosome. 

The  diseases,  defects,  and  conditions  believed  to  be  transmitted 
hereditaril}'  are  discussed  in  the  following  pages.  Some  of  these  dis- 
eases, malformations,  and  defects  of  organization  follow  Mendel's  law. 
It  is  probable  that  other  diseases,  tendencies,  and  characters  are  trans- 
missible, but  the  subject  has  only  recently  been  placed  u]3on  a  scientific 
basis,  and  it  will  require  careful  and  prolonged  observation  to  estab- 
lish the  facts.  It  is  often  difficult  to  determine  whether  the  disease 
itself  or  a  tendency  to  the  disease  has  been  transmitted  in  any  particu- 
lar case,  and,  further,  it  is  often  difficult  to  decide  whether  an  individ- 
ual has  inherited  or  acquired  his  affliction. 

The  transmissible  defects  which  are  of  principal  concern  to  the 
human  species  are  the  defects  of  organization  of  the  central  nervous 
system.  It  is  important  to  remember  that  the  defects  of  the  nervous 
system  do  not  necessarily  propagate  just  the  same  defects  in  the  suc- 
ceeding generations.  Thus,  an  epileptic  does  not  necessarily  beget 
epileptics;  epilepsy,  insanity,  degeneracy,  color-blindness,  and  other  stig- 
mata may  arise  as  the'  result  of  deficiencies  of  various  kinds  in  the 
forebears. 

Defects  such  as  harelip,  cleft  palate,  cervical  fistula,  spina  bifida, 
etc.,  are  not  true  instances  of  hereditary  transmission  of  specific  char- 
acters. They  rather  represent  an  inherited  deficiency  in  developmental 
vigor.  These  defects  for  the  most  part  represent  the  failure  of  parts 
to  unite  during  embryological  development;  in  other  words,  the  failure 
of  embryological  clefts  to  close  normally.  Such  deformities,  as  well  as 
clubfoot,  web  fingers,  and  other  acquired  or  congenital  deformities  or 
disfigurations,  are  not,  as  a  rule,  transmitted. 

Some  practical  problems  of  great  importance  arise  from  our  knowl- 
edge  of  the  hereditary  transmission  of  disease  and  defects.  A  man  or 
woman  who  intends  marrying  is  now  more  than  justified  in  carefully 
examining  the  personal  and  medical  histories  of  the  family  of  his  or 
her  intended  mate.  It  is  not  only  possible  to  foretell  the  color  of  the 
eyes,  the  nature  of  the  hair,  and  other  Mendelian  characters  in  the 
future  offspring,  but  it  is  also  possible  to  foretell,  with  mathematical 
precision,  the  chances  of  transmitting  defects,   such   as   insanity,   epi- 


■iU      THE  HEREDITARY  TRAXSMISSIOX  OF  DISEASE 

lepsy,  degeneracy,  deaf-mutism,  color-blindness,  migraine,  and  other 
nervous  disorders,  as  well  as  hemophilia,  polydactylism,  brachydactylisra, 
albinism,  and  other  stigmata.  In  any  doubtful  case  it  may  be 
well  to  consult  a  student  of  heredity,  for  it  is  possible  to  foretell 
with  precision  in  certain  cases  which  cbaracters  will  and  wliieh  will 
not  be  transmitted. 

To  illustrate  the  precision  with  which  the  characters  of  offspring 
may  be  predicted  in  the  best  studied  cases,  we  need  only  refer  to  the 
color  of  the  eyes.  Two  parents  with  pure  blue  eyes  will  have  only 
blue-e3'ed  offspring,  for  they  both  lack  the  brown  pigment  which  de- 
termines the  color  of  the  iris.  Similarly,  if  the  hair  of  parents  be 
flaxen,  this  may  be  taken  as  evidence  of  the  absence  of  a  hair-pigment- 
determiner  in  the  germ  plasm,  and  the  offspring  will  have  flaxen  hair. 
For  the  same  reason  parents  with  lack  of  curliness  or  waviness  of  hair 
will  have  only  straight-haired  children. 

In  determining  whether  transmissible  characters  are  apt  to  reappear 
in  successive  generations  or  not  we  must  know  whether  these  characters 
are  positive  or  negative,  that  is,  whether  they  are  due  to  the  presence 
or  absence  of  determiners.^ 

Inbreeding  may  be  hazardous,  for  reasons  that  are  well  understood. 
Tlie  marriage  of  cousins  will  be  evidently  hazardous  if  the  objection- 
able hereditary  characters  are  dominant,  for  in  this  case  the  danger  is 
plain ;  if  the  characters  are  recessive  the  danger  is  specially  unfortunate, 
l)ecause  of  unexpected  outcroppings  in  the  offspring.  Inbreeding  tends 
to  secure  homozygous  combinations,  and  this  brings  to  the  surface 
latent  or  hidden  recessive  characters.  Crossbreeding  brings  together 
differentiated  gametes  which,  reacting  on  each  other,  produce  offspring 
of  greater  vigor.  On  the  other  hand,  continued  crossbreeding  only  tends 
to  hide  inherent  defects,  not  to  exterminate  them;  inbreeding  only  tends 
to  bring  them  to  the  surface,  not  to  create  them.  It  is  not,  therefore, 
correct  to  ascribe  to  inbreeding  by  intermarriage  the  creation  of  bad 
racial  traits,  but  only  their  manifestation.  Further,  a  racial  stock 
which  maintains  a  high  standard  of  excellence  under  inbreeding  is 
certainly  one  of  great  vigor  and  free  from  inherent  defects    (Castle). 

The  variety  of  the  product  of  consanguineous  marriage  is  well 
brought  out  when  we  compare  localities.  Thus,  consanguinity  on 
Martha's  Vineyard  results  in  11  per  cent,  deaf  mutes  and  a  number 
of  hermaphrodites;  in  Point  Judith,  13  per  cent,  idiocy  and  7  per  cent, 
insanity;  in  an  island  off  the  Elaine  coast  the  consequence  is  "intellec- 
tual dullness";  in  Block  Island,  loss  of  fecundity;  in  some  of  the 
"Banks"  off  the  coast  of  Xorth  Carolina  suspiciousness  and  an  inability 

'  We  do  not  yet  know  all  the  unit  characters  in  man,  and  it  is  impossible 
to  foretell  which  of  them  are  due  to  positive  determiners  and  which  to  the 
absence  of  such. 


TENDENCY    TO    A    DISEASE  445 

to  pass  beyond  the  third  or  fourth  grade  of  school;  in  a  peninsula  on 
the  east  coast  of  Chesapeake  Bay  the  defect  is  dwarf ness  of  stature;  in 
George  Island  and  Abaco  (Bahama  Islands)  it  is  idiocy  and  blind- 
ness (G.  A.  Penrose,  1905).  There  is  thus  no  one  trait  that  results 
from  the  marriage  of  kin;  the  result  is  determined  by  the  specific  de- 
fect in  the  germ  plasm  of  the  common  ancestor. 

The  Microbic  Diseases. — It  seems  a  confusion  of  thought  to  the 
student  of  heredity  to  speak  of  the  inheritance  of  any  microbic  disease. 
At  one  time  the  hereditary  transmission  of  microbic  diseases  was  gen- 
erally believed.  Now  we  know  that,  in  the  true  sense  of  the  term,  no 
infectious  disease  is  transmitted  hereditarily — for  even  in  the  case  of 
syphilis  the  Treponema  pallidum  is  carried  in  the  germ  or  sperm  as  a 
foreign  body.  Tuberculosis  at  one  time  was  considered  as  transmitted, 
but  we  now  know  that  this  occurs  so  seldom  that  the  popular  pam- 
phlets are  entirely  justified  in  denying  it  entirely.  Children  are  some- 
times born  with  smallpox,  measles,  and  other  infections;  these  are  not 
true  instances  of  heredity,  but  cases  of  congenital  transmission. 

Congenital  Transmission. — Prenatal  infection  is  not  a  true  in- 
stance of  inheritance.  Microbic  diseases  may  be  acquired  by  infection 
through  the  placenta  during  the  fetal  period.  The  placenta  is  a  bet- 
ter filter  for  some  infections  than  for  others.  Thus,  anthrax  and  tu- 
berculosis of  the  mother  are  rarely  transmitted  to  the  fetus,  while  there 
is  great  liability  in  the  case  of  syphilis.  The  fetus  in  utero  may  take 
smallpox,  measles,  and  other  infections,  but  these  instances  are  more 
properly  spoken  of  as  congenital  than  inherited. 

We  must  remember  that  to  be  inherited  on  the  part  of  the  offspring 
or  transmitted  on  the  part  of  the  parents  biology  includes  only  those 
characters  or  their  physical  bases  which  were  contained  in  the  germ 
plasm  of  the  parental  sex  cells  (Martins)  ;  or,  as  Verco  says,  "what 
operates  on  the  germ  after  the  fusion  of  the  sex  nuclei,  modifying  the 
embryo,  or  even  inducing  an  actual  deviation  in  the  development,  can- 
not be  spoken  of  as  inherited.  It  belongs  to  the  category  of  early  ac- 
quired deviations  which  are,  therefore,  frequently  congenital." 

Hereditary  Transmission  of  a  Tendency  to  a  Disease. — While  the 
disease  itself  may  not  be  transmitted,  a  tendency  to  a  disease,  known 
as  a  diathesis,  may  be  transmitted  through  successive  generations.  A 
person  may  inherit  a  small  bony  structure,  a  poor  musculature,  "weak" 
lungs,  susceptible  mucous  membranes,  an  abnormal  amount,  distribu- 
tion, or  development  of  lymphoid  structures,  etc.  In  fact,  we  are  not 
air  born  equal,  and  most  persons  have  some  vulnerable  structure  or 
organ  which  is  commonly  spoken  of  as  their  "weak  point."  In  many 
cases  this  locus  minoris  resistentice  is  inherited  as  a  defect  in  structure 
or  function. 

Davenport  has  collected,  the  health  records   and  other  charaqteris- 


44(;      TlIK  HEKEDITAUY  TKAxNSMlSSlON  OF   DISEASE 

tics  furnislied  for  over  two  hundred  rainilies  by  members  of  the  fam- 
ilies concerned.  He  finds  certain  definite  facts  in  the  behavior  of  some 
of  the  commoner  diseases.  As  an  example  of  the  inheritance  of  a  gen- 
eral weakness  in  an  organ  he  cites  the  case  of  the  mucous  membranes. 
Thus,  in  one  family  the  principal  diseases  to  wliich  there  was  liability 
were  located  in  the  mucous  membranes  of  tlie  nose,  tliroat,  and  bronclii. 
In  another  family  tlie  center  of  susceptibility  was  more  specific,  being 
nearly  confined  to  the  nose  and  throat.  In  another  family  the  weak- 
ness was  in  the  ear;  in  another  the  lungs;  in  another  the  skin;  in  one 
family  the  kidneys  were  the  seat  of  incidence,  etc. 

The  examination  of  the  health  pedigrees  of  a  number  of  families 
impresses  one  by  the  fact  that  the  incidence  of  disease  is  not  always 
haphazard,  for  in  any  large  family  the  various  causes  of  death  do  not 
occur  in  the  proportions  given  in  the  census  table  for  the  population 
as  a  whole. 

Tuberculosis. — We  know  that  tuberculosis  is  never  transmitted  hered- 
itarily, and  is  seldom  contracted  congenitally.  The  reason  that  tu- 
berculosis runs  in  a  family  is  twofold:  (1)  an  inherited  predisposition 
to  the  disease,  and  (2)  increased  chances  of  infection.  Just  what  the 
tendency  or  predisposition  is  is  not  well  understood.  We  do  know, 
however,  that  the  predisposition  is  not  so  great  but  that  it  may  be 
overcome;  tlie  infection  may  be  avoided  and  the  disease  prevented. 

It  is  now  perfectly  plain  that  the  principal  reason  why  tuberculosis 
runs  in  families  is  the  close  association  between  the  infected  and  well 
members  of  the  family,  which  increases  the  chances  of  infection  and  re- 
infection. 

All  persons  inlierit  more  or  less  powers  of  resisting  tuberculosis. 
The  inborn  imnmnity  is  not  marked  in  any  case;  in  some  individuals 
it  is  quite  feeble.  The  border  line  between  immunity  and  susceptibility 
to  tuberculosis  in  the  human  species  is  delicately  balanced  and  may 
readily  be  overturned   (see  page  135). 

Syphilis. — Syphilis  and  the  consequences  of  syphilis  are  transmitted 
from  parent  to  offspring — '"even  unto  the  third  and  fourth  generation." 
Strictly  speaking,  and  in  accordance  with  the  present-day  conception 
of  heredity,  it  may  not  be  proper  to  speak  of  syphilis  as  a  true  in- 
stance of  heredity,  but  whatever  the  definition  of  words  may  be  the 
facts  are  plain.  The  reason  that  the  student  of  biology  refuses  to  re- 
gard syphilis  as  well  as  other  microbic  diseases  as  true  instances  of 
heredity  is  that  the  Treponema  pallidum  is  transmitted  in  the  germ 
plasm  as  a  foreign  body,  and  not  as  a  unit  character.  The  transmission 
of  syphilis,  therefore,  does  not  obey  Mendel's  law.  It  must  be  remem- 
bered that  while  syphilis  itself  is  not  a  true  instance  of  hereditary  trans- 
mission, the  consequences  of  syphilis  may  descend  as  inherited  defects 
through  many  generations.     Syphilis  may  be  transmitted  in  three  ways ; 


SYPHILIS  4:4:7 

(a)  from  the  father  (sperm  inheritance)  ;  (b)  from  the  mother  (germ 
inheritance);  (c)  placental  transmission  (congenital).  Osier  sum- 
marizes the  hereditary  transmission  of  syphilis  as  follows : 

(a)  Paternal  Transmission  {Sperm  Inheritance). — This  is  the  most 
common  form — in  which  the  father  is  infected,  the  mother  being  healthy. 
The  Treponema  pallidum  has  not  yet  been  found  in  the  sperm  cell,  but 
we  do  not  know  its  life  phases,  and  from  what  we  do  know  of  the  life 
history  of  syphilis  it  seems  probable  that  all  the  sperm  cells  are  not 
infective.  A  syphilitic  father  may  beget  an  apparently  healthy  child, 
even  when  the  disease  is  fresh  and  full-blown.  On  the  other  hand, 
in  very  rare  instances  a  man  may  have  had  syphilis  when  young,  un- 
dergo treatment,  and  for  years  present  no  signs  of  disease,  and  yet  his 
first  born  may  show  very  characteristic  lesions.  The  closer  the  beget- 
ting to  the  primary  sore  the  greater  the  chance  of  infection.  A  man 
with  tertiary  lesions  may  beget  healthy  children.  As  a  general  rule,  it 
may  be  said  that  with  judicious  treatment  the  transmissive  power  rarely 
exceeds  three  or  four  years. 

(b)  Maternal  Transmission  {Germ  Inheritance) . — While  the  father 
may  not  be  affected,  in  a  large  number  of  instances  both  parents  are 
diseased,  the  one  having  infected  the  other,  in  which'  case  the  chances 
of  fetal  infection  are  greatly  increased.  Heredity  through  the  mother 
alone  is  much  more  fatal  to  the  offspring  than  paternal  heredity.  It 
is  a  remarkable  and  interesting  fact  that  a  woman  who  has  borne  a 
syphilitic  child  is  herself  immune,  and  cannot  be  infected,  though  she 
may  present  no  signs  of  the  disease.  This  is  known  as  Beaumes'  or 
Colles'  law,  and  was  thus  stated  by  the  distinguished  Dublin  surgeon: 
"That  a  child  born  of  a  mother  who  is  without  obvious  venereal  symp- 
toms, and  which,  without  being  exposed  to  any  infection  subsequent  to 
its  birth,  shows  this  disease  when  a  few  weeks  old,  this  child  will  in- 
fect the  most  healthy  nurse,  whether  she  suckle  it,  or  merely  handle 
and  dress  it ;  and  yet  this  child  is  never  known  to  infect  its  own  mother, 
even  though  she  suckle  it  while  it  has  venereal  ulcers  of  the  lips  and 
tongue."  In  a  majority  of  these  cases  the  mother  has  received  a  sort 
of  protective  inoculation,  without  having  had  actual  manifestations  of 
the  disease.  A  child  showing  no  taint,  but  born  of  a  woman  suffering 
with  syphilis,  may  with  impunity  be  suckled  by  its  mother  (Prof eta's 
law). 

(c)  Placental  Transmission. — The  mother  may  be  infected  after 
conception,  in  which  case  the  child  may  be,  but  is  not  necessarily,  born 
syphilitic.  If  the  infection  is  late  in  pregnancy,  after  the  seventh 
month,  the  child  usually  escapes. 

Osier  and  Churchman  state  that  syphilitics  may  marry  with  safety 
after  they  have  undergone  three  years  of  thorough  treatment  and  have 
been  without  symptoms  at  least  one  year  after  treatment  has  ceased, 


448      THE  HEREDITARY  TRAXSMTSSTOX  OF  DISEASE 


Cancer.— It  will  probably  be  a  long  time  before  the  final  word  can 
be  said  concerning  the  influence  of  heredity  in  cancer.  At  present 
there  is  no  proof  that  heredity  plays  a  part  in  the  causation  of  can- 
cer, but  trustworthy  conclusions 
are  not  possible  in  the  present 
incomplete  state  of  our  knowl- 
edge upon  the  subject. 

Leprosy. — Leprosy  was  for- 
merly regarded  as  one  of  the 
inherited  infections.  Leprosy  is 
not  transmitted.  The  children 
of  lepers  born  out  of  leper  dis- 
tricts, in  England  or  the  United 
States,  for  example,  never  in- 
herit it.  The  disease  is  con- 
tracted after  birth,  as  tuberculo- 
sis and  other  microbic  diseases 
are  contracted. 

Deaf -mutism. — Deaf-mutism 
is  due  to  a  great  variety  of  causes, 
but  in  different  individuals  of 
the  same  family  the  chances  are 
large  that  it  is  due  to  the  same 
defect.  This  defect  is  frequent- 
ly recessive,  that  is,  hidden  in 
the  normal  children.  Two  such 
normal  children  who  are  cousins 
but  from  deaf-mute  stock  tend 
to  have  about  one-fourth  of  their 
offspring  deaf-mutes.  The  pro- 
portion of  congenital  deaf  off- 
spring is  thrice  as  great  among 
cousin  marriages  as  among 
others.  The  conclusions  of  Fay, 
based  on  extensive  statistics, 
deserve  to  be  widely  known. 
"Under  all  circumstances  it  is 
exceedingly  dangerous  for  a  deaf 
person  to  marry  a  blood  rela- 
^  five,  no  matter  whether  the  rela- 

tive is  deaf  or  hearing,  nor  whether  the  deafness  of  either  or  both  or 
neither  of  the  partners  is  congenital,  nor  whether  either  or  both  or 
neither  have  other  deaf  relatives  besides  the  other  partner." 

Albinism. — Albinism  belongs  to  a  class  of  cases  resulting  from  the 


COLOR-BLINDNESS  449 

absence  of  a  character  or  quality — in  this  instance  the  absence  of  a  pig- 
ment determiner.  Two  albino  parents  have  only  albino  children.  Nor- 
mal offspring  of  an  albino  and  a  pigmented  parent  may  transmit  the 
albinic  condition. 

Albinism  is  an  extreme  case  of  blondeness,  all  pigment  being  absent 
from  skin,  hair,  and  eyes.  The  method  of  inheritance  resembles  that 
of  eye  color.  When  both  parents  lack  pigment,  all  offspring  are  like- 
wise devoid  of  pigment.  When  one  parent  only  is  an  albino  and  the 
other  is  unrelated,  then  the  children  are  all  pigmented.  Wlienever 
pigmented  parents  have  albino  children,  the  proportion  of  the  albinos 
approaches  the  ideal  and  expected  Mendelian  proportions — 25  per  cent. 
Davenport  points  out  that  albinos  may  avoid  albinism  in  their  offspring 
by  marrying  unrelated  pigmented  persons.  Pigmented  persons  belong- 
ing to  albinic  strains  must  avoid  marr3dng  cousins,  even  pigmented 
ones,  because  both  parents  might,  in  that  case,  have  albinic  germ  cells 
and  produce  one  child  in  four  albinic.  Albino  communities,  of  which 
there  are  several  in  the  United  States,  are  inbred  communities,  but  not 
all  inbred  communities  contain  albinos. 

Color-blindness,  or  Daltonism. — Color-blindness,  or  daltonism,  is  a 
condition  probably  not  localized  in  the  eyes,  but  due  to  some  defect 
in  the  central  nervous  structure.  It  is  transmitted  hereditarily.  Color- 
blindness is  much  commoner  in  men  than  in  women.  A  color-blind 
man,  however,  does  not  transmit  color-blindness  to  his  sons,  but  only 
to  his  daughters.  The  daughters,  however,  are  themselves  normal,  pro- 
vided the  mother  was,  yet  the  daughters  transmit  color-blindness  to 
half  their  sons.  A  color-blind  daughter  could  be  produced  apparently 
only  by  the  marriage  of  a  color-blind  man  with  a  woman  who  trans- 
mits color-blindness,  since  the  daughter,  to  be  color-blind,  must  have 
received  this  unit  character  from  both  parents,  whereas  the  color-blind 
son  receives  the  character  only  from  his  mother;  that  is,  the  condition 
is  sex-limited. 

Color-blindness  is  apparently  due  to  a  defect  in  the  germ  cell — 
absence  of  something  normally  associated  there,  with  an  X-structure 
which  is  represented  twice  in  women,  once  in  men. 

The  following  interesting  family  history,  studied  by  Horner,  shows 
the  hereditary  persistence  of  color-blindness  and  its  transmission  to 
male  offspring  through  normal  females. 


450      THE  HEREDITARY  TRANSMISSION  OF  DISEASE 
M 


M 


M 


M 


M 

J 


M 


M       M 


I 
F 

I 
M 


F 
M 


^ 


MMFFM     MMF 


I 
M 


F    F 


M=Male. 

F=Female. 

Bold-faced  type^=Color-blind  subjects. 

The  folkwing  pedigree  of  a  family  containing  color-blind  members 
was  worked  out  by  Dr.  Rivers  among  the  Todas,  an  Indian  tribe: 


M 

1 

F 

^', 

M 

F     F 

1 

F 

1            1 
F         M 

1 

F      F      M       M        M 

.    1                  1 

MMF 

M  F 

M 

F 

M  F    F 

1  1  1  1  1  1  1 
M  M  M  M  M  M    I 

M     M 

Hemophilia. — Hemophilia  is  a  condition  in  which  the  blood  does 
not  coagulate  properly,  and  those  having  this  condition  may  bleed  to 
death  from  minute  wounds.  It  is  transmitted  hereditarily  and  is  largely 
confined  to  males,  although  transmitted  by  normal  females.  It  is  one 
of  the  best  instances  of  an  hereditable  character,  sex-limited. 


M 


M 


M 


M 


I      I      I     I     !     I     I     I     I     I  I  I      I      I      I      I        I      I      I      I      I      I 

MFFMMMFMMF        F         MMMFM    FMMFMM 


M 

7 


I       I    I        I    I  I 


I    I 


MF  MF        MFMFMF         FMFMF        FMF      MF 

(Bold-faced  type  indicates  bleeders.) 


PtETIXITIS    PIGMEXTOSA  451 

The  foregoing  case,  given  by  Klebbs,  is  instructive  in  showing  how 
the  tendency,  though  transmitted  through  daughters,  finds  expression 
only  in  the  males,  and  in  illustrating  first  a  diffusion  and  then  a  wan- 
ing of  the  peculiarity   (Thompson). 

GrOut.- — It  is  known  that  gout  runs  in  families,  but  just  what  the 
predisposition  is  that  favors  this  condition  of  deranged  metabolism  is 
not  known.  During-  four  centuries  one  family  history  showed  that 
out  of  535  gouty  subjects  309  had  a  family  taint — about  60  per  cent. 
In  another  family  out  of  156  cases  140  had  a  family  taint^ — about  90 
per  cent.  Statistics  show  that  in  from  50  to  60  per  cent,  of  all  cases 
the  disease  existed  in  the  parents  or  grandparents.  It  seems  clear  that 
some  predisposing  factor  may  be  transmitted  hereditarily,  but  in  any 
individual  case  it  is  not  always  plain  how  much  is  due  to  heredity  and 
how  much  to  environment. 

Brachydactylism. — A  typical  example  of  an  abnormality  is  that  of 
brachydactylism,  or  short-fingeredness,  a  condition  in  which  each  digit 
comprises  only  two  phalanges — the  fingers  are  all  thumbs.  This  con- 
dition seems  to  be  due  to  an  inhibition  of  the  normal  growth  process, 
that  is,  normality  implies  entire  absence  of  the  determiner  that  stops 
the  growth  of  the  fingers  in  the  brachydactyl.  Thus,  a  brachydactyl 
person  married  even  to  a  normal  person  will  beget  100  per  cent,  or 
50  per  cent,  abnormals,  according  to  circumstances;  but  two  parents 
who,  though  derived  from  brachydactyl  strains,  altogether  lacking  the 
determiner  which  inliibits  the  growth  of  the  fingers  may  have  only 
normal  children. 

According  to  Punnett,  brachydactylism  is  a  good  example  of  a 
simple  Mendelian  case.  It  behaves  as  a  simple  dominant  to  the  normal; 
that  is,  it  depends  upon  a  factor  which  the  normal  does  not  contain. 
The  recessive  normals  cannot  transmit  the  affected  condition  whatever 
their  ancestry.  Once  free,  they  always  remain  free,  and  can  marry 
other  normals  with  full  confidence  that  none  of  their  children  will  show 
the  deformity. 

Polydactylism. — Polydactylism  is  a  condition  in  which  there  are 
supernumerary  fingers  or  toes.  This  is  a  defect  which  may  be  trans- 
mitted through  successive  generations. 

Myopia. — Myopia  can  hardly  be  called  a  disease  in  the  strict  sense, 
being  rather  a  structural  defect  in  the  focusing  power  of  the  optical 
apparatus.  It  seems  that  the  structural  peculiarity  which  leads  to 
short-sightedness  is  transmitted. 

Cataract. — Bateson  and  others  have  collected  pedigrees  in  which 
cataracts  run  in  families.  Presenile  cataract  especially  appears  to  be 
transmitted  hereditarily. 

Retinitis  Pigmentosa. — Eetinitis  pigmentosa  is  a  degenerative  disease 
of  the  retina  which  is  transmitted  hereditarily.     Normals   may  carry 


45-3       THE    HEREDITARY  TRANSMISSION  OF  DISEASE 

the  disease,  so  that  two  normal  cousins  from  retinitis  stock  may  have 
offspring  with  retinitis.  A  large  percentage  of  cases  of  retinitis  come 
from  consanguineous  marriages. 


Diabetes  Mellitus. — Hereditary  influences  seem  to  play  an  impor- 
tant role  in  diabetes  mellitus,  for  cases  are  on  record  of  its  occurrence 
in  many  members  of  the  same  family.     Thus,  out  of  104  cases  of  dia- 


EPILEPSY  453 

betes  mellitiTS  22  had  a  famil}^  taint — about  20  per  cent.  iTaunyn  ob- 
tained a  history  of  diabetes  in  35  out  of  201  private  cases^  but  in  only 
7  of  157  hospital  cases. 

Orthostatic  Albuminuria. — Orthostatic  albuminuria  occurs  in  boys 
more  commonly  than  girls.  These  are  often  the  children  of  neurotic 
parents,  and  have  well-marked  vasomotor  instability.  Defects  or  pe- 
culiarities in  the  filtering  apparatus  in  the  kidneys  may  arise  as  a 
germinal  variation  and  be  handed  on  from  generation  to  generation. 
Under  conditions  which  may  mean  nothing  to  normal  subjects  this 
defect  in  the  kidney  may  find  expression  in  active  disease.  In  this  case, 
as  in  gout,  it  may  not  be  proper  to  speak  of  the  disease  itself  being 
transmitted  hereditarily,  but  the  tendency  to  deviate  is  so  transmitted. 

Alcoholism. — It  is  a  common  observation  that  among  the  offspring 
of  drunkards  are  many  cases  of  unhealthy,  insane,  and  criminal  types. 
The  disastrous  results  may  be  manifested  by  nervous  disorders, 
varying  from  hyperexcitability  to  dementia;  or  as  debility  and  lack 
of  developmental  vigor  expressed,  for  instance,  in  infantilism,  want 
of  control,  imbecility,  or  as  structural  abnormalities,  especially  of 
the  head  and  brain.  The  results  are  so  varied,  they  suggest  that 
what  is  inherited  is  general  rather  than  specific.  Thus,  the  offspring 
of  alcoholic  parents  are  not  necessarily  predisposed  in  any  one  particu- 
lar direction,  except  that  the  nervous  system  is  most  liable  to  be  af- 
fected. They  may  be  epileptic,  idiotic,  insane,  etc.  On  the  other  hand, 
it  is  necessary  to  recognize  that  what  may  be  inherited  is  not  the  re- 
sult of  alcoholism,  but  rather  the  predisposition  which  led  the  parent 
to  become  alcoholic.  This  is  clearly  illustrated  in  cases  where  the 
parent  did  not  acquire  the  alcoholic  habit  until  after  the  children  were 
born.  Clouston  observes  that  "it  is  not  the  craving  for  alcohol  that  was 
inherited,  but  a  general  psychopathic  constitution  in  which  the  alcoholic 
stimulus  is  an  undue  stimulus  and  the  mental  control  deficient."  (See 
page  301.) 

Epilepsy. — Brown-Sequard  showed  conclusively  that  artificially  in- 
duced epilepsy  in  the  guinea  pig  is  transmissible.  The  statistics  col- 
lected for  man  give  from  9  to  over  40  per  cent,  of  cases  in  which 
heredity  is  an  important  predisposing  cause.  Gowers  gives  35  per  cent, 
for  his  cases.  In  the  Elwyn  cases  32  of  the  126  gave  a  family  history 
of  nervous  derangement  of  some  sort,  either  paralysis,  epilepsy,  marked 
hysteria,  or  insanity. 

Chronic  alcoholism  in  the  parents  is  also  regarded  as  a  potent  pre- 
disposing factor  in  the  production  of  epilepsy.  Echeherria  has  analyzed 
572  cases  bearing  upon  this  point,  and  divided  them  into  3  classes,  of 
which  257  cases  could  be  traced  directly  to  alcohol  as  the  cause,  126 
cases  in  which  there  were  associated  conditions,  such  as  syphilis  and 
traumatism,  189  cases  in  which  alcoholism  was  probably  the  result  of 
31 


454       THE    HEREDITARY  TRANSMISSION  OF  DISEASE 

the  epilepsy;  Figures  equally  strong  are  given  by  Martin,  who,  in  150 
insane  epilepticsr  found  S3  with  a  marked  history  of  paternal  intem- 
perance.    Of  the  126  Elwyn  cases  in  which  the  family  history  of  this 


point  was  carefully  investigated,  a  definite  statement  was  found  in  only 
4  of  the  cases  (Osier). 

Huntington's  Chorea.— Huntington's  chorea  is  frequently  inherited. 
The  disease  is  known  as  chronic  hereditary  chorea.    It  was  described  by 


INSANITY  455 

L3?on  in  1863,  who  traced  the  disease  through  five  generations.  Hun- 
tington in  1872  gave  the  three  salient  points  in  connection  with  the 
disease,  viz.:  (1)  its  hereditary  nature;  (2)  association  with  psychical 
troubles;  and    (3)    late  onset  between  the  thirtieth  and  fortieth  year. 

Huntington's  chorea  is  a  typical  dominant  trait.  The  normal  con- 
dition is  recessive;  in  other  words,  the  disease  is  due  to  some  positive 
determiner.  Persons  with  this  dire  disease  should  not  have  children, 
but  the  members  of  normal  branches  derived  from  the  affected  strain 
are  immune  from  the  disease.  This  disease  forms  a  striking  illustra- 
tion of  the  principle  that  many  of  the  rarer  diseases  of  this  country 
can  be  traced  back  to  a  few  foci,  even  to  a  single  focus ;  certainly  in  this 
case  many  of  the  older  families  with  Huntington's  chorea  trace  back  to 
the  New  Haven  colony  and  its  dependencies  and  subsequent  offshoots 
(Davenport). 

Friedreich's  Disease — Hereditary  Ataxia. — This  disease  resembles 
locomotor  ataxia,  although  differing  from  it  in  several  essential  par- 
ticulars. It  begins  in  childhood  and  usually  occurs  in  a  family  having 
other  members  of  the  family  affected  with  the  same  disease.  There 
are  curious  forms  of  incoordination  and  loss  of  knee-jerk,  early  talipes 
equinus,  scoliosis,  nystagmus,  and  scanning  speech.  The  affection  lasts 
for  many  years  and  is  incurable.  In  1861  Friedreich  reported  six  cases 
of  this  form  of  ataxia  in  one  family.  Since  then  it  has  usually  been 
observed  to  be  a  family  disease,  and  is,  therefore,  assumed  to  be  trans- 
mitted hereditarily.  The  eugenic  teaching  in  this  affection,  according 
to  Davenport,  is  that  normally  all  the  affected  fraternities  should  marry 
only  outside  the  strain.  Whether  all  cases  of  ataxic  offspring  of  one 
normal  parent  are  derived  from  consanguineous  marriage  is  still  un- 
certain and  warrants  hesitation  in  advising  the  marriage  of  any  ataxic 
person. 

Imbecility,  Defectives,  and  Delinquents. — Davenport  believes  that 
imbecility  is  due  to  the  absence  of  some  definite  simple  factor,  on 
account  of  the  simplicity  of  its  method  of  inheritance.  Two  imbecile 
parents,  whether  related  or  not,  have  only  imbecile  offspring.  Daven- 
port states  that  there  is  no  case  on  record  where  two  imbecile  parents 
have  produced  normal  children. 

Dr.  H.  H.  Goddard,  of  the  Training  School  for  Feeble-Minded,  at 
Vineland,  N.  J.,  has  studied  the  ancestry  of  children  in  the  Vineland 
institution  and  has  found  almost  without  exception  a  history  of  feeble- 
mindedness for  several  generations.  Dr.  Goddard's  remarkable  study 
of  the  Kallikak  family  has  already  been  referred  to.  In  this  instance 
he  traced  the  ancestry  of  a  22-year-old  girl  through  about  1,100  individ- 
uals as  far  back  as  the  Eevolutionary  War.  Similar  studies  are  being 
carried  out  in  other  institutions  and  always  with  similar  results. 

Insanity. — Insanity   is   a   general   term   comprising  many   different 


456       THE    HEREDITARY  TRANSMISSION  OF  DISEASE 

conditions.     No  general  statement  can,  tlierefore,  be  made  except  that 
certain  forms  of  insanity  are  undoubtedly  transmitted  through  succes- 

'ft 

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sive  generations.     Mental  diseases  are  rare  in  persons  free  from  ances- 
tral taint,  except  as  the  result  of  wounds  or  toxic  influences. 

Practically  all  the  statistics  accumulated  on  insanity  have  limited 
value  to  the  student  of  heredity,  because  they  do  not  give  numerical 
records  of  the  sane  members  of  the  families  of  the  insane  (see  page  298). 


KEFEEENCES  457 

REFERENCES 

Lock,  R.  H. :  '"Variation,  Heredity,  and  Evolution,"  1910. 

Huxley,  T.  H. :  "Collected  Essays,"  Vol.  2,  1899. 

Lamarck,  J.  B. :  "Philosophic  Zoologique,"  1809. 

Darwin,  Chas. :  "The  Origin  of  Species,"  6th  Edition,  1872. 

Weismann,  A. :  "Essays  Upon  Heredity,"  1889 ;  "The  Variation 
Theory,"  1906;  "The  German  Plasm:  A  Theory  of  Heredity"  (trans- 
lated by  W.  N.  Parker  and  H.  Pionnfeld,  1893). 

Galton,  F.:  "Xatural  Inheritance,"  1889;  "Hereditary  Genius," 
1869;  "English  Men  of  Science,"  1874;  "Inquiries  Into  Human  Faculty 
and  Its  Development,"  1883;  "Xatural  Inheritance,"  1889;  "Eugenics: 
Its  Definition,  Scope,  and  Aims,"  1905. 

Davenport:  "Statistical  Methods,"  1904;  "Heredity  in  Eelation  to 
Eugenics,"  1911. 

Pearson,  K. :  "The  Grammar  of  Science,"  2d  Edition,  1900. 

Bateson,  W. :  "Materials  for  the  Study  of  Variation,"  1894;  "Men- 
del's Principles  of  Heredity,"  1909. 

DeVries,  H. :  "Die  Mutationstheorie,"  1901;  "Species  and  Varieties: 
Their  Origin  by  Mutation,"  1905. 

Wilson,  E.  B. :  "The  Cell  in  Development  and  Inheritance,"  2d 
Edition,  1900. 

Thompson,  J.  A.:  "Heredity,"  1908. 
Castle,  William  E. :  "Heredity,"   1911. 

The  Proceedings  of  the  Roy.  Soc.  of  Medicine,  1909,  Vol.  II :  "The 
Influence  of  Heredity  on  Disease,"  with  Special  Eeference  to  Tubercu- 
losis,  Cancer,  and  Diseases  of  the  Nervous  System. 

Punnett,  E.  C. :  "Mendelism,"  1911. 


SECTION  III 
FOODS 

CHAPTER    I 
GENERAL    CONSIDERATIONS 

Foodstuffs  fall  naturally  into  two  great  divisions:  (1)  those  de- 
rived from  the  animal  kingdom,  and  (2)  from  the  plant  kingdom. 
The  animal  foods  are  much  more  apt  to  convey  infections  or  to  pos- 
sess injurious  properties  than  foods  derived  from  plant  life.  Of  the 
animal  foods  meat  and  milk  are  the  chief  offenders.  Water  ordinarily 
is  not  classed  as  a  food,  and  is  discussed  in  a  separate  chapter. 

The  increase  of  food  poisoning  and  the  increase  of  diseases  caused 
by  infected  foods  are  more  apparent  than  real.  The  subject  is  better 
understood,  and  cases  are  now  recognized  and  reported  that  were  for- 
merly misinterpreted.  The  hygienic  conscience  of  the  people  has  been 
aroused,  and  a  demand  has  been  established  for  clean,  fresh,  wholesome 
foodstuffs.  The  separation  of  the  producer  and  the  consumer  and  the 
demands  of  large  cities  have  made  these  sanitary  reforms  eminently 
necessary.  The  pure  food  laws,  the  meat  inspection  act,  the  milk  or- 
dinances, and  the  local  surveillance  over  markets,  provision  shops, 
dairies,  etc.,  are  all  part  of  the  general  movement  to  obtain  a  reason- 
ably decent  and  safe  food  supply. 

People  should  be  educated  to  demand  flesh  from  healthy  animals, 
cut  up  and  handled  in  a  careful  manner  by  butchers  free  from  dis- 
ease, and  to  demand  garden  truck  grown  in  clean  dirt  and  not  in  soil 
polluted  with  human  excrement.  Food  must  be  guarded  in  trans- 
portation and  purveyed  in  markets  and  shops  so  as  to  be  protected  from 
flies,  rats,  dust,  and  unnecessary  human  contact. 

The  prophylactic  and  therapeutic  uses  of  food  are  growing  subjects. 
It  is  only  necessary  to  point  out  the  importance  of  diet  in  the  preven- 
tion and  treatment  of  tuberculosis,  diabetes,  nephritis,  arteriosclerosis, 
gout,  rheumatic  affections,  disorders  of  metabolism,  dyspepsia,  gastric 
ulcer,  infantile  diarrheas,  and  many  other  affections.  The  proper 
amount  and  quality  of  food  is  one  of  our  important  preventive  measures. 
458 


GENEKAL    CONSIDEEATIONS  459 

Food  may  affect  health  in  a  great  variety  of  ways: 

(a)  Foods  may  be  naturally  poisonous,  as  in  the  case  of  certain 
mushrooms,  some  fish,  or  the  alkaloids  in  various  species  of  plants. 

(b)  Poisonous  substances  may  develop  in  the  food  as  a  result  of 
bacterial  activity,  as  sausage  poisoning  (botulism).  In  this  class  are 
also  included  the  so-called  ptomains  or  putrefactive  poisons. 

(c)  Foods  may  convey  foreign  or  accidental  poisons.  This  class 
includes  mostly  the  metallic  poisons  and  chemicals  added  as  adulterants, 
as  lead,  copper,  arsenic,  formaldehyde,  sulphites,  etc. 

(d)  Foods  may  contain  animal  parasites,  such  as  trichina  and  tape- 
worms. These  infections,  as  a  rule,  occur  as  ante-mortem  infections 
in  the  animal.  Plant  foods  may  carry  the  eggs  or  larvas  of  various 
animal  parasites. 

(e)  Foods  may  contain  vegetable  parasites.  Both  animal  and  vege- 
table foods  may  convey  bacteria  pathogenic  for  man.  The  harmful 
varieties  are  more  often  found  upon  animal  foods  than  upon  vegetable 
foods.  The  food  animals  may  be  infected  before  death,  or  the  meat 
may  become  infected  while  it  is  being  cut  up  or  handled.  The  best 
example  in  this  class  is  paratyphoid  infection,  sometimes  called  meat 
poisoning;  also  typhoid  bacilli  in  oysters,  or  on  celery,  etc. 

(f)  Foods  may  contain  special  poisons,  as,  for  example,  solanin  in 
sprouted  potatoes,  or  ergot  in  rye. 

In  this  class  are  also  included  spoiled  corn  and  its  relation  to  pel- 
lagra. 

(g)  Food  may  be  injurious  as  a  result  of  abnormality  of  amount 
or  composition  of  diet.  Thus,  an  excess  of  food  predisposes  to  obesity 
and  perhaps  to  arteriosclerosis  and  diseases  of  the  liver  and  kidneys. 
An  insufficient  amount  undermines  health.  A  monotonous  diet,  espe- 
cially of  polished  rice,  leads  to  beri-beri;  lack  of  organic  acids  induces 
scurvy;  defective  alimentation,  especially  a  deficiency  of  lime  salts,  pre- 
disposes to  rickets.  Highly  spiced  and  stimulating  diets  are  irritating 
both  to  the  digestive  tube  and  the  organs  of  excretion.  An  excess  of 
fats  produces  a  condition  resembling  acidosis,  particularly  in  children. 
An  unbalanced  ration  long  continued  is  apt  to  be  harmful.  Thus,  an 
excess  of  protein  induces  putrefactive  changes  with  its  dangers  of  auto- 
intoxication. Eating  when  fatigued,  or  improper  mastication,  are  causes 
of  indigestion.     Drinking  too  little  water  is  a  common  dietetic  error. 

(h)  Finally,  foods  may  not  be  poisonous  in  themselves,  but  may  be 
harmful  to  persons  who  lack  ability  to  digest  them  or  lack  the  mechan- 
ism by  which  they  may  be  assimilated.  Thus,  certain  forms  of  pro- 
tein habitually  produce  symptoms  resembling  anaphylaxis  in  persons 
who  are  sensitized.  This  occurs  most  commonly  with  sea  food,  but 
also  takes  place  with  strawberries,  eggs,  and  other  forms  of  protein. 


460  GENEEAL    CONSIDERATIONS 


THE  USES  OF  FOOD 

Tlie  two  ultimate  uses  of  all  food  arc  to  supply  the  body,  (1)  with 
materials  for  growth  or  renewal,  and  (2)  with  energy  or  the  capacity 
for  doing  work.  The  potential  energy  received  in  a  latent  form  stored 
in  the  various  chemical  combinations  in  foods  is  liberated  as  kinetic 
or  active  energy  in  two  chief  forms,  heat  and  motion.  Force  is  the 
manifestation  of  energy,  and  the  force  developed  by  a  healthy  man  may 
be  measured  in  foot  pounds.  A  foot  pound  is  the  amount  of  energy 
expended  or  force  required  to  lift  mechanically  a  weight  of  one  pound 
to  a  height  of  one  foot. 

The  work  of  an  average  man  is  calculated  at  about  2,000,000  foot 
pounds  per  diem  (R.  H.  Thurston).  This  may  exceptionally  be  in- 
creased to  3,000,000  foot  pounds.  Ordinarily  less  than  one-fifth  of  the 
total  energA^  of  the  body  is  expended  in  motion,  and  more  than  four- 
fifths  in  heat  production. 

The  total  intake  of  energy  into  the  body  is  derived  from  food  plus 
the  oxygen  of  the  inspired  air.  The  total  output  of  energy  is  computed 
from:  (1)  the  heat  of  combustion  of  the  unoxidized  ingredients  of  the 
urine  and  feces;  (2)  the  energy  liberated  as  body  heat,  and  (3)  the 
energy  of  external  muscular  work,  or  the  work  of  the  voluntary  muscles 
(Thompson). 

Whether  alimentary  substances  are  burned  outside  of  the  body  or 
oxidized  within  the  body,  the  resulting  waste  products  are  similar.  No 
substance  is  a  good  food  unless  it  fulfills  two  conditions,  viz. :  easy  as- 
similation and  complete  combustion.^ 

Two  methods  may  be  emplo^^ed  to  study  the  energy-producing 
power  of  food  in  the  body:  (1)  a  careful  and  prolonged  study  of  sub- 
jects who  are  allowed  to  follow  their  usual  vocations,  but  whose  food 
and  excreta  are  carefully  measured  and  analyzed;  (2)  the  shorter 
method  of  enclosing  a  man  for  a  brief  period,  not  exceeding  a  few  days, 
in  a  cabinet  known  as  a  calorimeter. 

The  unit  of  measurement  is  the  calorie,  which  is  the  amount  of 
heat  required  to  raise  one  kilogram  of  water  from  0°  to  1°  C.  This 
equals  3,100  foot  pounds,  or  approximately  the  heat  required  to  raise 
the  temperature  of  one  pound  of  water  4°  F.  Fuel  value  is  a  term 
denoting  the  total  number  of  calories  derived  from  a  gram  or  pound 
of  any  given  food  substance  if  it  is  completely  combusted  within  the 
body.  The  fuel  values  are  calculated  for  a  given  food  by  the  factors 
of  Rubner  as  follows: 

^  It  is  not  sufficient  to  know  merely  the  amount  anrl  caloric  value  of  the  coal 
fed  to  a  furnace,  and  subtract  therefrom  the  amount  of  unconsumed  ash.  We 
must  know  how  much  of  the  heat  generated  has  been  utilised. 


CLASSIFICATION    OF    FOODS  461 

4.5  calories  per  gram  of  either  protein  or  carbohydrate. 
9.3  calories  per  gram  of  fat. 

Atwater  and  Br3^ant  compute  the  food  factors  as  4  calories  per  gram 
for  proteins  and  carbohydrates  and  8.9  for  fats,  in  a  mixed  diet.  C.  F. 
Langworthy  gives  the  fuel  value  of  the  three  chief  classes  of  nutrients 
as  follows: 

1  pound  of  protein  yields 1,860  calories 

1  pound  of  fats    4,220  calories 

1  pound  of  carbohydrates   1,860  calories 

From  a  chemical  standpoint  foods  are  oxidized  or  burned  to  simpler 
compounds  during  the  process  of  digestion  and  metabolism  within  the 
body.  Food  is,  therefore,  fuel.  The  oxygen  to  feed  the  flame  is  mainly 
furnished  by  the  inspired  air,  hence  active,  breathing  of  pure  fresh  air 
is  essential  and  one  of  the  best  stimuli  for  complete  metabolism.  It  is 
the  common  experience  of  all  persons  that  digestion  and  the  utilization 
of  foods  are  favorably  promoted  by  life  in  the  open  air. 


CLASSIFICATION  OF  FOODS 

Foods  may  be  classed  in  various  ways.  Thompson  divides  them 
into  four  groups,  according  to  (1)  their  physical  properties,  (2)  their 
source,  (3)  their  composition,  and  (4)  their  function,  or  the  role  which 
they  perform  in  the  animal  body. 

Physical  Properties. — Foods  are  classed  in  accordance  with  their 
general  physical  properties  first  into  solid,  semisolid,  and  liquid  foods; 
secondly,  into  fibrous,  gelatinous,  starchy,  oleaginous,  crystalline,  and 
albuminous  foods.  Foods  are  also  classed  as  foods,  beverages,  and  con- 
diments. 

Sources. — Foods  may  be  classed  as  to  their  source  primarily  into 
(a)   animal  and  (b)   vegetable  foods. 

Animal  foods  consist  of  meat,  fowl,  fish,  shellfish,  crustaceans,  in- 
sects and  their  products  (honey),  eggs,  milk  and  its  products,  animal 
fats,  gelatin. 

The  vegetable  foods  are  subdivided  into  cereals,  vegetables  proper, 
fruits,  sugar,  gums,   vegetable  oils  and  fats. 

Composition  and  Function. — The  simplest  chemical  classification 
possible  is  that  advocated  by  Liebig,  who  was  the  first  to  suggest  a 
really  scientific  definition  of  foods.  He  grouped  all  foods  into  two 
classes :  nitrogenous  and  non-nitrogenous.  Each  of  these  classes  con- 
tains food  materials  from  both  the  animal  and  vegetable  kingdoms, 
although  the  majority  of  the  animal  substances  belong  to  the  nitroge- 


462  GENERAL    CONSIDERATIONS 

nous  and  the  majority  of  the  vegetable  substances  to  the  non-nitrogenous 
group. 

Nitrogenous  foods  contain  proteins  and  include  gelatinoids  and  al- 
buminoids, substances  wliich  resemble  albumin.  They  consist  chiefly 
of  the  four  elements :  carbon,  oxygen,  hydrogen,  and  nitrogen,  to  which 
a  small  proportion  of  sulphur  and  phosphorus  is  usually  joined.  The 
nitrogenous  foods  were  regarded  by  Liebig  as  containing  plastic  ele- 
ments; that  is,  they  are  essentially  tissue  builders  or  flesh  formers. 
The  non-nitrogenous  group  Liebig  called  respiratory  or  calorifacient 
foods,  because  their  function  in  the  body  is  largely  to  furnish  fuel  to 
maintain  animal  heat.  It  is  now  knowTi  that  the  non-nitrogenous  foods 
supply  energy  for  muscular  action,  hence  they  are  also  called  force 
producers,  to  distinguish  them  from  the  nitrogenous  or  tissue  builders. 
This  is  a  convenient  distinction,  but  it  must  not  be  held  too  absolutely, 
for  in  certain  conditions  the  tissue  builders  are  used  as  force  and  heat 
producers  as  well. 

Foods  are  now  ordinarily  classed  as:  (1)  nitrogenous;  (2)  starchy; 
(3)  oily,  and  (4)  condimental.  Examples  of  nitrogenous  foods  are 
lean  meat,  the  white  of  eggs,  or  the  casein  in  milk.  The  gluten  of 
wheat  and  the  zein  of  corn  are  also  typical  nitrogeneous  constituents. 
Peas  and  beans  contain  large  percentages  of  nitrogenous  matter.  The 
nitrogenous  or  protein  substances  build  and  repair  tissue,  and  to  a  less 
extent  serve  as  fuel  to  yield  energy  in  the  forms  of  heat  and  muscular 
power. 

The  starchy  or  carbohydrate  foods  are  represented  by  the  cereals, 
the  tubers,  such  as  potatoes,  the  sugars  of  the  cane,  beet,  fruits,  etc., 
and  glycogen  in  flesh. 

Fats  or  oily  foods  are  represented  by  butter,  olive  oil,  cotton-seed 
and  other  oils,  the  fat  of  meat,  the  oil  of  nuts  and  seeds.  All  vege- 
tables contain  more  or  less  oily  substances.  The  fats  as  well  as  the 
carbohydrates  serve  as  fuel  to  yield  energy  in  the  form  of  heat  and 
muscular  power. 

Mineral  matter  or  ash  performs  an  important  service  in  forming 
bone  and  assisting  in  digestion  and  metabolism.  These  substances  are 
ordinarily  not  classed  as  foods;  however,  life  cannot  be  maintained 
without  them. 

Among  the  condiments  are  classed :  spices,  such  as  pepper,  mustard, 
cinnamon,  cloves,  etc. ;  also  coffee,  tea,  and  alcoholic  beverages. 

THE  AMOUNT  OF  FOOD 

Excessive  Amounts. — The  amount  of  food  required  varies  greatly 
with  conditions.  In  civilized  communities,  where  cooking  is  a  fine  art, 
the  number  and  variety  of  food  preparations  are  so  great  that  the  ap- 


THE    AMOUNT    OF    FOOD  463 

petite  is  often  stimulated  beyond  the  requirements  of  the  system,  and 
consequently  more  food  is  eaten  than  is  necessary  or  desirable  to  main- 
tain the  best  bodily  health  and  vigor.  Gluttony  results  in  overdevelop- 
ment and  overwork  of  the  digestive  apparatus;  the  stomach,  and  bowels 
become  enlarged;  the  liver  is  engorged,  and  a  predisposition  is  estab- 
lished to  degenerative  changes,  fatty  heart,  etc.  The  quantity  of  food 
required  to  maintain  the  body  in  vigor  varies  with  the  climate  and 
season,  clothing,  occupation,  work,  and  exercise,  the  state  of  individual 
health,  age,  sex,  and  body  weight. 

Both  overeating  and  overdrinking  may  be  temporary  or  chronic. 
When  chronic  it  may  lead  to  such  diseases  or  diatheses  as  obesity,  gout, 
lithemia,  oxaluria,  or  the  formation  of  renal,  vesical,  and  hepatic  cal- 
culi. It  is  very  certain  to  cause  congestion  of  the  liver  and  the  con- 
dition known  as  "biliousness,"  in  which  the  stomach  and  intestines 
are  engorged,  constipation  results,  the  tongue  is  heavily  coated,  the 
bodily  secretions  are  altered  in  composition,  the  urine  especially  be- 
comes overloaded  with  salts,  the  liver  becomes  congested,  and,  finally, 
the  nervous  and  muscular  systems  are  affected,  which  result  in  the  pro- 
duction of  headache  and  feelings  of  fatigue,  lassitude,  drowsiness,  and 
mental  stupor. 

Insufficient  Food. — Starvation  or  asitia  is  a  term  which  technically 
applies  to  the  lack  of  sufficient  food  for  the  maintenance  of  the  body, 
while  inanition  means  the  lack  of  the  assimilation  of  food  by  the  tis- 
sues. When  food  is  completely  withheld,  life  cannot  be  prolonged  be- 
yond six  or  ten  days  in  the  majority  of  instances.  Professional  fasters 
have  gone  41  days  without  anything  but  water.  If  food  is  withheld 
suddenly,  the  sensation  of  hunger  gradually  increases,  becomes  extreme, 
lasts  for  two  or  three  days,  and  slowly  disappears.  It  is  accompanied 
by  a  gnawing  pain  in  the  epigastrium,  which  is  relieved  on  pressure. 
The  pain  may  disappear,  but  it  is  followed  by  a  sensation  of  extreme 
weakness  or  faintness,  which  is  both  local  in  the  stomach  and  general 
throughout  the  body.  Even  though  the  pain  disappears,  the  sensation 
of  hunger  may  occasionally  reassert  itself,  when  all  food  is  withheld, 
until  death,  or  until  the  subject  becomes  insane  or  unconscious. 

Hunger  is  not  always  a  reliable  guide  to  the  need  of  the  system 
for  food.  Some  dyspeptics  are  always  hungry  and  eat  more  than  they 
can  digest.  A  habit  of  rapid  eating  does  not  satisfy  the  sensation  of 
hunger.  More  food  may  be  taken  than  is  necessary,  because  it  has  not 
had  time  to  meet  the  needs  of  the  system  before  the  meal  is  over.  Can- 
non has  shown  that  the  sensations  of  hunger  come  and  go  rhythmically, 
appearing  synchronously  with  the  contractions  of  the  empty  stomach. 

The  statement  is  frequently  made  that,  when  starvation  occurs  upon 
a  large  scale,  affecting  a  community  with  famine,  pestilence  is  sure  to 
accompany  it.     Thus,  disease  has  often  been  rampant  in  Ireland  when 


464  GENERAL    CONSIDERATIONS 

the  potatoes  have  failed,  and  in  India  when  the  grain  supply  has  given 
out.  j\Iuch  of  the  illness  which  occurred  in  the  early  history  of  the 
Crimea  was  coincident  with  insufticient  food,  and  it  is  stated  that  in 
the  middle  ages  the  ravages  of  pestilential  diseases,  such  as  typhus, 
smallpox,  plague,  etc.,  were  always  worse  in  times  of  general  starva- 
tion. The  history  of  epochs  of  famine  in  siege  or  otherwise  is  always 
accompanied  by  outbreaks  of  violence,  for  hunger  begets  ill  temper,  vice, 
and  crime.  This  has  occurred  of  late  years,  notably  in  Athens,  Flor- 
ence, and  London,  and  in  Paris  during  the  Commune.  There  is,  how- 
ever, no  very  definite  relationship  between  famine  and  epidemics.  The 
depressed  vitality  caused  by  insufficient  food  does  not  account  for  epi- 
demics of  plague,  smallpox,  relapsing  fever,  typhus  fever,  and  other 
pestilential  diseases,  sometimes  called  famine  fevers.  The  reasons  for 
this  have  been  discussed  under  Immunity. 

Unbalanced  Diets. — Unbalanced  diet  may  produce  anemia  from  lack 
of  meat  or  other  food;  scurvy  from  lack  of  fresh  fruits  and  vegetables, 
with  preponderance  of  salty  meat  and  fish;  rickets  and  marasmus  from 
an  excess  of  amylaceous  and  lack  of  animal  food,  necessary  salts,  etc. ; 
a  form  of  acidosis  from  too  much  fat,  especially  in  babies;  acne  or 
eczema  from  food  too  rich  in  carbohydrates  or  fats;  constipation  from 
too  nutritious  and  concentrated  diet;  and  gout  from  various  dietetic 
errors.  Unbalanced  diets  are  responsible  for  a  long  list  of  affections, 
a  type  of  which  is  beri-beri,  caused  by  a  monotonous  diet  consisting 
chiefly  of  unpolished  rice. 

Salts  in  the  Diet. — Common  organic  or  vegetable  acids,  such  as 
citric  from  lemons  and  oranges,  tartaric  from  grapes,  malic  fi'om  apples, 
etc.,  usually  exist  in  combination  with  the  bases,  calcium,  sodium,  potas- 
sium, etc.,  when  derived  from  fresh  vegetables  and  fruits.  They  are 
indispensable  articles  of  food,  for  when  absorbed  they  form  carbonates, 
which  aid  in  maintaining  the  alkalinity  of  the  blood.  Prolonged  de- 
privation of  them  may  result  in  scurvy.  Lack  of  sufficient  potash  salts, 
especially  potassium  carbonate  and  chlorid,  is  also  a  factor  in  producing 
scurvy,  and  the  condition  is  intensified  by  the  excessive  use  of  common 
salt. 

If  calcium  phosphate  is  deficient  in  the  food  of  the  young,  growing 
infant,  the  bones  are  poorly  developed  and  so  soft  that  they  yield  to 
the  strain  of  the  weight  of  the  body  and  become  bent,  as  occurs  in 
rickets. 

Lack  of  inorganic  salts  in  the  food  impoverishes  the  coloring  matter 
of  the  red  blood  corpuscles  on  which  they  depend  for  their  power  of 
carrying  oxygen  to  the  tissues,  and  anemia  and  other  disorders  result. 
An  ash-free  diet  soon  causes  serious  symptoms. 

Longworthy  gives  the  following  as  the  estimated  amount  of  mineral 
matter  required  per  man  per  day: 


ADIJLTEEATIO^T    OF    FOOD  465 

Phosphoric  acid  (P2O5) 3  to  5         grams 

Sulphuric    acid    (SO,).^ 2  to  3.5 

Potassium   oxid    2  to  3  " 

Sodium  oxid -i  to  6  " 

Calci-um   oxid    < 0.7  to  1.0 

Magnesium   oxid    0.3  to  0.5  " 

Iron    0.006  to  0.012      " 

Chlorid    6  to  8 

ADULTERATION    OF    FOOD 

.  Adulteration  of  food  consists  of  a  large  number  of  practices,  some 
of  which  are  fraudulent,  others  technical  in  nature.  Some  forms  of 
adulteration  are  injurious  to  health,  but  for  the  most  part  they  have 
an  economic  rather  than  a  sanitary  significance.  Foods  may  be  adul- 
terated in  a  variety  of  ways :  by  the  removal  of  nutritive  substances ; 
by  the  addition  of  injurious  substances;  by  the  fraudulent  substitution 
of  cheaper  articles ;  by  misbranding ;  or  by  the  sale  of  food  that  is  filthy, 
decomposed,  or  putrid. 

Prior  to  the  passage  of  the  Pure  Food  and  Drugs  Act  in  1906  a  very 
large  percentage  of  the  food  sold  in  the  United  States  was  found  to 
be  adulterated  in  one  way  or  another.  Thus,  at  the  Agricultural  Ex- 
periment Station  in  Kentucky  -10  per  cent,  of  727  samples  were  adul- 
terated; at  the  Connecticut  Agricultural  Experiment  Station  41.5  per 
cent,  of  574  samples  of  spices  were  found  adulterated,  and  over  25  per 
cent,  of  coffee  samples  were  adulterated  (1899).^ 

Among  the  common  adulterations  mav  be  mentioned  the  followina:: 
cotton-seed  oil  is  sold  as  olive  oil;  honey  may  contain  glucose;  cocoa 
and  chocolate  are  frequently  adulterated  with  both  starch  and  sugar; 
coffee  is  extensiveh'  adulterated  with  caramel,  pea-meal,  chickorv,  and 
saccharose  extracts;  lard  is  mixed  with  cheaper  fats  or  cotton-seed  oil; 
saccharin  is  substituted  for  cane  sugar;  cereals  give  bulk  and  weight 
to  sausages ;  gypsum  or  bran  is  added  to  flour ;  barium  sulphate  to 
powdered  sugar,  flour  or  turmeric  or  corn  meal  to  mustard.  Oleomar- 
garin  is  sold  as  butter;  distilled  and  colored  vinegar  is  sold  as  cider 
vinegar;  ground  spices  are  adulterated  with  cocoanut  shells,  rice, 
flour,  and  ashes;  water,  sugar,  and  tartaric  acid  is  sold  as  lemonade; 

^  In  Massachusetts  the  State  Board  of  Health  began  to  examine  foods  for . 
adulteration  in  1883.  It  was  then  found  that  between  60  and  70  per  cent,  of  all 
foods  examined  were  adulterated.  As  a  result  of  official  surveillance  the  per- 
centages fell  in  a  few  years  to,  approximately,  15  per  cent,  and  have  remained 
between  10  and  20  per  cent,  since.  This  does  not  mean  that  from  10  to  20  per 
cent,  of  all  foods  found  on  the  market  are  adulterated,  for,  to  a  great  extent, 
samples  are  collected  from  suspicious  sources,  so  that  the  ratio  of  adulteration 
of  foods  analyzed  in  the  laboratory  is  higher  than  that  of  the  same  foods  sold 
on  the  market. 


466  GENERAL    CONSIDERATIONS 

wines  and  liquors  are  sometimes  adulterated  with  alum,  baryta,  caus- 
tic lime,  salicylic  acid,  and  hematoxylin.  Terra  alba,  kaolin,  and  vari- 
ous pigments  are  sometimes  added  to  candies;  gum  drops  are  largely 
made  with  petroleum  paraffin  products ;  much  of  the  nuiple  sugar  for- 
merly sold  was  made  from  glucose  and  coloring  matters. 

A  food  is  considered  adulterated  in  accordance  with  tlie  Food  and 
Drugs  Act  of  June  30,  1906:  (1)  "If  any  substance  has  been  mixed 
and  packed  with  it  so  as  to  reduce  or  lower  or  injuriously  affect  its 
quality  or  strength."  This  is  the  simplest  form  of  adulteration,  and  a 
good  example  is  the  addition  of  water  to  milk.  Cocoa  shells  are  some- 
times mixed  with  cocoa  or  chocolate.  Glucose  and  caramel  are  added 
to  maple  sugar;  talc  to  flour. 

(2)  "If  any  substance  has  been  substituted  wholly  or  in  part  for 
the  article."  As  illustrations  we  have  the  substitution  of  cotton-seed 
oil  or  corn  oil  for  olive  oil;  glucose  or  saccharin  for  sugar;  cereals, 
which  cost  about  five  cents  a  pound,  for  meat,  which  averages  fifteen 
cents  a  pound,  in  sausage.  Apple  cores  and  parings  are  frequently 
used  as  a  substitute  for  currants  and  other  fruits  in  jellies. 

Saccharin  is  several  hundred  times  sweeter  than  sugar  and  compara- 
tively cheap.  It  has,  therefore,  been  used  as  a  substitute  for  sugar  as 
a  sweetening  agent  in  the  inferior  qualities  of'  ginger  ale,  and  to  some 
extent  in  canned  corn,  peas,  etc.,  as  well  as  in  candies  and  other  articles. 
Saccharin  is  a  chemical  obtained  from  coal  tar  and  is  without  food 
value;  it  is  not  entirely  harmless.  The  Referee  Board  reports  that 
"the  continued  use  of  saccharin  for  a  long  time  in  quantities  over  0.3 
of  a  gram  per  day  is  liable  to  impair  digestion;  and  the  addition  of 
saccharin  as  a  substitute  for  cane  sugar  reduces  the  food  value  of  the 
sweetened  product  and  hence  lowers  its  quality."  Saccharin-containing 
foods  are  therefore  regarded  as  adulterated  within  the  meaning  of  the 
Food  and  Drugs  Act. 

(3)  "If  any  valuable  constituent  of  the  article  has  been  wholly  or 
in  part  abstracted."  Skimming  milk  is  a  good  illustration  of  this  part 
of  the  law,  or  the  abstraction  of  cocoa  butter  from  chocolate.  There  is, 
however,  no  objection  to  abstracting  valuable  or  nutritive  substances 
provided  the  label  properly  announces  the  facts;  thus,  skimmed  milk 
or  cocoa  are  legitimate  foods.  So  also  the  caffein  may  be  taken  out  of 
coffee  and  sold  as  caffein-free  coffee.  The  essential  oils  are  sometimes 
extracted  from  cloves  or  other  spices,  which  are  siibsequently  ground 
and  used  as  an  adulterant  with  unextracted  spice. 

(4)  "If  it  is  mixed,  colored,  powdered,  coated,  or  stained  in  any 
manner  whereby  damage  or  inferiority  is  concealed."  This  is  a  very 
frequent  form  of  adulteration,  and,  as  a  rule,  is  undesirable  and  some- 
times injurious.  Substances  used  to  color  foods  are  usually  considered 
in  three  classes:    (1)   mineral  dyes,   (2)    vegetable  dyes,    (3)   anilin  or 


ADULTERATION    OF    FOOD  467 

coal-tar  dyes.  The  principal  mineral  d3'es  are :  copper  sulphate,  oxid  of 
iron,  and  potassium  nitrate.  Copper  STilphate  is  used  to  give  a  green 
color  to  peas,  pickles,  and  similar  foods.  The  copper  probably  unites 
with  the  albuminous  matter  to  form  new  compounds  which  have  a 
bright  green  color.  The  oxid  of  iron  and  also  sulphites  are  used  upon 
meat  to  give  it  a  red  color;  potassium  nitrate  will  also  give  a  bright 
red  color  to  meat.  Many  vegetable  dyes  are  used,  such  as  annate  (the 
juice  of  the  Bixa  orellana,  a  South  American  tree),  which  is  used  to  color 
butter.  Carrot  juice  is  also  used;  turmeric  in  mustard;  and  logwood  in 
wines.  The  coal-tar  dyes  have  largely  replaced  the  vegetable  and  min- 
eral pigments  in  foods,  on  account  of  their  brilliant  color  and  cheap- 
ness. They  are  used  in  sausages,  confectionery,  jellies  and  jams,  meats, 
flavoring  extracts,  etc.  The  artificial  coloring  of  food  is  a  false  stand- 
ard and  serves  no  useful  purpose.  WHien  the  coloring  matter  is  used 
to  conceal  damage  or  inferiority  the  practice  is  indefensible,  as  when 
spoiled  meats  are  made  to  look  bright  red  and  fresh,  or  when  oleomar- 
garin  is  colored  in  order  to  imitate  butter  and  sold  as  such.  Flour 
may  be  bleached  with  nitrogen  peroxid,  thus  giving  an  inferior  grade 
the  appearance  of  first  quality  flour.  The  NOo  is  produced  by  electric 
action  and  nitrites  in  appreciable  quantities  remain  in  the  fiour.  Fruits 
are  bleached  by  exposure  to  sulphur  fumes,  which  leaves  objectionable 
sulphur  compounds.  Candies  and  chocolate  are  often  coated  with  gum 
bezoin  or  shellac. 

(5)  "If  it  contains  any  poisonous  or  other  added  deleterious  in- 
gredient which  may  render  such  article  injurious  to  health."  This 
section  of  the  law  is  intended  to  include  adulterants,  such  as  formal- 
dehyde, sulphites,  arsenic,  hydrofluoric  acid,  lead,  salicylic  acid,  borax 
and  boracic  acid,  as  well  as  any  other  injurious  substance.  Most  of  the 
storm  center  of  the  opposition  to  the  Pure  Food  Law  is  centered  around 
this  paragraph,  owing  to  the  difficulty  of  deciding  in  certain  instances 
whether  small  amounts  of  benzoic  acid  or  benzoates,  boric  acid  or 
borates,  are  injurious  to  health  or  not.  These  substances  are  discussed 
more  in  detail  under  chemical  preservatives. 

(6)  "If  it  consists  in  whole  or  in  part  of  a  filthy,  decomposed,  or 
putrid  animal  or  vegetable  substance  or  any  portion  of  an  animal 
unfit  for  food,  whether  manufactured  or  not,  or  if  it  is  the  product  of 
a  diseased  animal  or  one  that  has  died  otherwise  than  by  slaughter." 
Examples:  oysters  contaminated  with  sewage;  eggs  known  as  "rots  and 
spots";  animals  which  have  died  otherwise  than  by  slaughter;  figs  con- 
taining an  excessive  quantity  of  worms  and  worm  excrement.  This 
paragraph  of  the  law  has  caused  much  discussion,  especially  the  mean- 
ing of  the  word  "decomposed."  This  question  is  considered  more  in 
detail  under  the  paragraph  "Decomposed  Foods." 

Misbranding. — The  term  "misbranding"  is  specifically  defined  in 


468  GENERAL   COXSl DERATIONS 

the  Food  and  Drugs  Act  and  provides  for  all  possible  conditions  of 
fraud,  mislabeling,  imitation,  substitution,  and  other  forms  of  decep- 
tion. Misbranding  is  regarded  as  a  form  of  adulteration  under  the 
Food  and  Drugs  Act.  The  practices  of  misbranding  under  any  cir- 
cumstances are  so  evidently  fraudulent  or  dishonest  that  they  cannot 
be  justified  on  any  score  and  are  wholly  condemned.  It  is  true  that 
many  instances  of  misbranding  do  not  directly  affect  health,  except  in 
so  far  as  they  deceive  the  consumer;  that  is,  he  is  purchasing  at  a  high 
price  an  article  which  contains  less  nutritive  value  than  claimed  for  it. 
An  honest  label  which  correctly  states  the  character,  origin,  amount,  and 
the  constituent  parts  of  an  article  is  as  much  a  desideratum  in  food 
products  as  it  is  in  commercial  articles  of  all  kinds.  Honest  labeling  is 
the  heart  and  soul  of  the  pure  food  movement. 


DECOMPOSED   FOODS 

Decomposition  is  defined  as  natural  decay.  In.  this  sense  all  or- 
ganic substances,  both  animal  and  vegetable,  living  or  dead,  are  decom- 
posed, for  decomposition  and  recomposition  occur  as  a  constant  feature 
of  life's  processes.  At  the  moment  of  death  recomposition  ceases,  while 
decomposition  continues.  In  one  sense  the  hardest  rocks  decompose 
or  disintegrate;  bicarbonate  of  soda  decomposes  in  the  presence  of  an 
acid,  and  many  substances  decompose  in  the  presence  of  oxygen,  es- 
pecially when  heated.  In  other  words,  while  decomposition  is  usually 
the  result  of  bacterial  activity  in  organic  substances,  it  may  also  take 
place  as  the  result  of  physical,  chemical,  or  electrical  agencies.  The 
word  "decomposition"  is  not  used  in  this  technical  sense  in  the  Pure 
Food  and  Drugs  Act ;  there  it  has  the  meaning  of  the  word  used  in 
ordinary,  every-day  parlance.  Just  where  technical  decomposition  ceases 
and  objectionable  decomposition  begins  is  often  difficult  to  determine. 
Decomposition  may  be  objectionable  either  to  the  senses  or  to  health. 
We  purposely  permit  many  of  our  foods  to  decompose  before  they  are 
used.  Thus,  meats  hang  three  days  or  longer  in  order  to  render  them 
more  tender  and  to  improve  their  flavors.  During  this  time  decom- 
position takes  place  with  the  production  of  acids.  Some  persons  prefer 
meats  when  highly  decomposed  or  gamy.  Bread,  cheese,  butter,  butter- 
milk, sauerkraut,  vinegar,  cider,  and  many  other  foods  are  products 
of  decomposition.  The  line  must,  therefore,  be  drawn  between  decom- 
position that  is  objectionable  and  decomposition  that  is  technical.  It  is 
difficult  to  draw  the  line  at  decomposition  that  is  objectionable  to  the 
senses,  for  a  cheese  regarded  as  a  delicacy  by  one  person  may  be  highly 
objectionable  to  another.  The  principal  point,  then,  for  consideration 
is  the  decomposition  that  is  harmful  to  health. 


DECOMPOSED    FOODS  •  469 

Fermentation  and  Putrefaction. — The  question  is  further  compli- 
cated when  we  consider  that  tliere  are  very  many  kinds  of  decomposi- 
tion. Two  main  groups  are  recognized:  (1)  fermentative  decomposi- 
tion, and  (2)  putrefactive  decomposition.  Even  the  Pure  Food  Law 
distinguishes  between  foods  that  are  decomposed  and  foods  that  are 
putrid.  Fermentative  decomposition  refers  to  the  breaking  down  of 
carbohydrates  with  the  formation  of  acids  (lactic,  acetic,  butyric), 
alcohol,  carbon  dioxid,  ■  etc.  Putrefactive  decomposition  refers  to  the 
breaking  down  of  nitrogenous  substances,  usually  with  the  production 
of  alkalinity.  The  end  products  of  putrefaction  are  ammonia,  nitrates, 
carbon  dioxid,  etc.,  all  simple,  stable,  inorganic  compounds  which,  in 
ordinary^  concentration,  are  not  poisonous.  It  is  then  the  intermediate 
cleavage  products  of  putrefaction  and  the  end  products  of  fermentation 
that  may  be  poisonous.  The  question  of  decomposition  is  still  further 
complicated  by  the  fact  that  there  are  very  many  different  kinds  of 
fermentation  and  of  putrefaction.  Each  particular  microorganism 
breaks  down  organic  matter  in  a  specific  and  limited  sense.  Ordinarily 
these  processes  result  from  a  combination  of  bacteria  or  symbiosis,  in 
which  aerobic  and  anaerobic  organisms  each  play  a  part.  As  a  rule, 
putrefaction  does  not  take  place  in  the  presence  of  fermentation.  In 
this  sense  carbohydrates  protect  nitrogenous  matter;  further,  the  prod- 
ucts of  fermentation  are  much  less  poisonous  than  some  of  the  products 
of  putrefaction. 

"Ptomain"  Poisoning. — Ptomains  are  secondary  cleavage  products 
of  protein  putrefaction.  A'aughan  defines  a  ptomain  as  an  organic 
chemical  compound,  basic  in  character,  and  formed  by  the  action  of 
bacteria  on  nitrogenous  matter.  On  account  of  their  basic  properties 
ptomains  resemble  the  vegetable  alkaloids  and  are,  therefore,  called 
putrefactive  alkaloids.  They  are  sometimes  called  "animal"  alkaloids, 
but  this  is  a  misnomer,  for  they  also  are  formed  in  the  putrefaction 
of  vegetable  matter. 

The  term  "leukomain"  is  used  to  cover  the  same  or  similar  basic 
substances  which  result  from  tissue  metabolism  within  the  body;  that 
is,  leukomains  are  produced  in  the  living  body,  ptomains  in  dead  or- 
ganic matter. 

The  great  majority  of  ptomains  are  not  poisonous  or  less  toxic 
than  the  corresponding  ammonia  compound.  Ptomains  include  sub- 
stances which  are  chemically  very  different.  The  classification  is  not 
a  scientific  one,  and  is  gradually  being  abandoned.  In  fact,  most  cases 
of  so-called  ptomain  poisoning  are  really  infections  with  microorganisms 
belonging  to  the  parat}q3hoid  group. 

The  products  produced  during  the  various  stages  of  protein  putre- 
faction resemble  the  chemical  products  produced  during  the  stages  of 
protein  digestion.  Putrid,  or  putrefying,  organic  matter  is  not  neces- 
32 


470  GENERAL    CONSIDEKATIOXS 

sarily  poisonous  or  even  harmful.  There  is  a  time  when  decomposing 
meat  or  cheese  or  other  nitrogenous  substance  reaches  the  height  of  its 
toxicity,  then  gradually  declines,  and  finally  becomes  inactive.  The 
terminal  products  of  putrefaction,  or  even  the  later  stages,  while  highly 
oifensive  to  the  taste  and  smell,  may  be  quite  harmless.  Therefore, 
cheese,  if  toxic,  is  most  poisonous  when  green ;  that  is,  during  the  inter- 
mediate stages.  Meat,  if  toxic,  is  most  poisonous  from  the  fourth  to 
the  eleventh  day  of  putrefaction.  The  poisonous  properties  of  other 
foodstuffs  have  a  similar  relation  to  the  stage  of  putrefaction.^ 

Chemically,  ptomains  are  ammonia  substitution  compounds;  two- 
thirds  of  them  contain  only  carbon,  hydrogen,  and  nitrogen.  Those 
having  oxygen  in  their  composition  are  the  more  poisonous.  Most 
ptomains  are  inert  or  are  no  more  poisonous  than  the  corresponding 
ammonia  salts.  In  composition  they  show  a  predominance  of  the 
amin  radicle  (NH,).  Of  the  bases  containing  oxj^gen,  most  of  them 
are  trimethylamins  [(CH3)3N].  It  was  Brieger  who  pointed  out  that 
a  certain  quantity  of  oxygen  is  necessary  for  the  formation  of  poison- 
ous bases.  These  poisonous  bases  appear  about  the  seventh  day  of 
putrefaction  and  then   disappear. 

The  decomposition  products  of  putrefaction  have  long  been  studied 
by  chemists.  All  the  studies  made  before  bacterial  activity  was  under- 
stood are  now  only  of  historical  interest.  The  distinguished  physician, 
Panum,  was  the  first  to  demonstrate  positively  the  chemical  nature  of 
the  poisons  formed  in  putrid  flesh.  He  obtained  an  aqueous  extract 
which  retained  its  poisonous  properties  after  boiling  eleven  hours. 
Panum  studied  these  poisonous  substances  by  intravenous  injections 
upon  dogs.  These  observations  have  been  abundantly  confirmed,  but 
so  far  it  is  doubtful  whether  anyone  has  succeeded  in  isolating  the 
poisonous  substances  in  a  pure  state. 

In  1886  Bergmann  and  Sehmiederberg  obtained  sepsin  from  putrid 
flesh  and  from  decomposing  bodies.  This  substance  was  obtained  in 
needle-shaped  crystals,  and  small  doses  injected  into  dogs  caused  vom- 
iting and  bloody  diarrhea.  It  was  then  believed  that  the  putrid  poison 
of  Panum  had  been  isolated  and  was  identical  with  sepsin.  Further 
investigation,  however,  showed  that  this  was  not  the  fact.  Selmi,  an 
Italian,  added  valuable  information  to  the  study  of  this  question,  and, 
what  is  probably  more  important,  gave  an  impetus  to  the  study  of  the 
chemistry  of  putrefactive  changes.  Selmi  was  the  first  to  suggest  the 
name  ptomain;  he  showed  that  there  are  a  great  number  of  alkaloid- 
like substances   among  the   products   of   putrefaction.      Some   of   these 

^  It  seems  that  advanced  decomposition  favors  the  destruction  of  the  poison- 
ous substances  formed  earlier  in  the  process;  it  is  further  known  that  most  of 
the  pathologic  microorganisms  die  during  active  fermentative  or  putrefactive 
changes. 


DECOMPOSED    FOODS  471 

may  be  extracted  with  ether  from  an  alkaline  solution,  some  with  ether 
from  an  acid  solution,  some  with  chloroform  from  either  an  acid  or 
alkaline  solution,  and  some  with  amylic  alcohol,  and  after  all  these 
extractions  there  yet  remain  alkaloidal  bodies  in  the  putrid  infusion. 
This  gives  us  an  indication  of  the  great  number  of  ptomains.  We  long 
remained  ignorant  of  the  chemistry  of  these  substances  until  Nencki 
in  1876  made  the  first  ultimate  analysis  and  determined  the  empiric 
formula  for  ptomains.  In  1871  Lombroso  showed  that  an  extract  from 
moldy  corn  produced  tetanic  convulsions  in  animals.  This  observation 
was  part  of  Lombroso's  long  struggle  to  discover  the  chemical  substance 
responsible  for  pellagra.  In  1885  Vaughan  detected  in  poisonous  cheese 
an  active  agent  to  which  he  gave  the  name  tyrotoxicon.  However, 
Vaughan  afterward  admitted  that  this  is  not  the  substance  most  com- 
monly found  in  poisonous  cheese,  though  the  names  tyrotoxicon  poison- 
ing and  ptomain  poisoning  remain  in  popular  parlance.  Brieger  kept 
the  name  ptomain,  but  applied  it  to  those  basic  substances  only  that 
were  produced  in  the  life  processes  of  bacteria.  He  classed  under  the 
head  of  ptomains  a  great  number  of  poisons  which  he  succeeded  in 
isolating  from  putrid  flesh,  decomposed  fish,  rotten  cheese,  decomposed 
glue,  cadavers  in  various  stages  of  decomposition,  from  poisonous  mus- 
sels, etc.  Since  these  a  long  list  of  basic  substances  or  ptomains  have 
been  described.^  As  before  pointed  out,  the  great  majority  of  them 
are  not  poisonous,  or  slightly  so.  The  list  includes  a  variety  of  sub- 
stances which  are  chemically  very  different.  The  classification  is  not 
a  scientific  one,  and  is  gradually  being  abandoned.  Even  at  the  time 
of  Brieger's  investigations  it  was  found  necessary  to  distinguish-  be- 
tween poisonous  and  non-poisonous  ptomains,  and  on  this  account  the 
term  toxine  was  adopted — a  distinguishing  name  for  poisonous  products 
of  bacterial  activity. 

The  best  known  poison  which  has  been  isolated  in  an  approximately 
pure  state  from  decomposing  nitrogenous  material  is  sepsin.  Much 
work  has  been  done  upon  this  substance  by  Schmiederberg  and  recently 
by  Faust,  who  obtained  sepsin  in  a  purified  state  in  sufficient  quanti- 
ties carefully  to  study  its  action  and  composition.  Faust  obtained 
the  crystals  from  putrefied  yeast  and  blood;  25  milligrams  of  the  sul- 
phate introduced  intravenously  will  kill  a  large  dog  in  two  hours. 

Sepsin  has  the  following  chemical  structure: 

NH2  OH     OH     NH2 

CH,— CH3— CH— CH— CH2 

Dihydroxypentamethylenediamin. 

*  See  Vaughan  and  Novy :   ' '  Cellular  Toxins. ' ' 


472  GENERAL   CONSIDERATIONS 

Sepsin  is  very  unstable.  It  is  rendered  inactive  at  60°  C.  for  a 
short  time,  and  is  readily  converted  into  cadaverin  or  pentamethylene- 
diamin.     The  chemical  structure  of  cadaverin  is : 

NH2  NH2 

I  I 

CH,— CH3— CH3— CH3— CH2 

Pentamethylenediamin. 

Cadaverin  is  one  of  the  best  known  of  the  ptomain  group.  Its 
presence  indicates  that  the  putrefactive  process  at  one  time  contained 
sepsin  which,  by  reduction,  has  been  changed  into  cadaverin. 

Putrescin  is  another  diamin.  which  almost  invariably  occurs  together 
with  cadaverin.  to  which  it  is  closely  related.  It  was  first  described 
by  Brieger  in  1S85,  and  has  been  obtained  from  putrefying  internal 
numan  organs,  herring,  mussels,  etc.  It  is  recognizable  on  the  fourth 
day  of  putrefaction,  and  appreciable  quantities  appear  by  the  eleventh 
day.  It  is  still  present  after  two  or  three  weeks.  Baummann  in  1888 
showed  the  rational  formula  to  be 

NH,  NH2 

.         I  I 

CH2 — ^1113 — CII3 — CHj 

Tetramethylenediamin. 

Putrescin  is  a  homolog  of  cadaverin  and  appears  in  putrefaction 
before  that  substance. 

The  more  the  question  of  ptomains  is  studied  the  less  do  they  ap- 
pear concerned  in  cases  of  food  poisons.  It  is  now  clear  that  most,  if 
not  all,  cases  of  so-called  ptomain  poisoning  are  nothing  more  nor  less 
than  acute  infections  with  B.  paratyphosus,  B.  enteritidis,  B.  choJercB 
suis,  and  other  microorganisms  belonging  to  this  group.  A  number 
of  bacteria  ordinarily  harmless  are  capable,  under  certain  conditions, 
or  in  overwhelming  numbers,  of  producing  acute  gastrointestinal  dis- 
turbances. Some  of  these  microorganisms  and  their  effects  are  discussed 
more  particularly  under  Meat  Poisoning. 

Less  is  known  concerning  the  decomposition  of  the  fats.  It  is  quite 
possible  that  some  of  these  substances  may  be  exceedingly  poisonous. 
Thus,  while  cholin  in  itself  is  not  very  toxic,  Hunt  has  shown  that 
acetyl-cholin  is  one  hundred  thousand  times  more  poisonous.  Cholin 
is  a  base  widely  distributed  in  nature;  it  is  found  in  the  yolk  of  eggs, 
in  bile,  brain  substance,  fat,  seeds,  and  other  substances.  It  can  also 
be  prepared  from  pure  lecithin,  which  is  a  fatty  body  normally  pres- 


PEESERVATION    OF    FOODS  473 

ent  in  brain  substance,  yolk  of  eggs,  and  perhaps  all  cells.  Milk,  for 
example,  contains  about  one  per  cent,  of  lecithin.  The  lecithin  may 
be  readily  decomposed  by  bacterial  action  perhaps  to  cholin  and  cholin 
salts.  While  acetyl-cholin  has  never  been  demonstrated  in  milk,  it  is 
possible  that  this  or  similar  poisons  may  be  produced  in  decomposing 
foodstuffs. 

PRESERVATION  OF   FOODS 

The  preservation  of  meat,  milk,  vegetables,  and  other  perishable 
foods  is  one  of  the  most  important  questions  we  have  to  deal  v^ith  in 
the  whole  range  of  hygiene.  Fermented  and  decayed  foods  must  be 
looked  upon  with  suspicion.  The  proper  preservation  of  foodstuffs 
involves  not  only  the  art  of  keeping  them  "fresh"  and  wholesome,  but 
also  keeping  them  so  that  they  will  not  lose  their  nutritive  value.  Fi- 
nally, foodstuffs  must  be  joreserved  so  that  they  will  not  acquire  injurious 
properties.  The  preservatives  ordinarily  in  use  are:  cold,  drying,  salt- 
ing, smoking,  canning,  preserving,  and  chemical  treatment. 

Practically  all  these  methods  have  long  been  in  use.  The  only 
modern  innovation  in  the  preservation  of  foods  is  in  the  perfection  of 
the  old  processes,  based  upon  our  knowledge  of  antiseptics  and  germi- 
cides. Heat  and  cold  represent  old  family  methods  which  have  been 
extended  and  improved  in  the  modern  canning  and  cold  storage  indus- 
tries. The  drying  of  fruits,  fish,  and  meats  is  a  practice  of  very  ancient 
origin.  The  use  of  salt  doubtless  antedates  all  historical  records.  Sugar 
either  alone  or  with  acetic  acid  in  the  form  of  vinegar  and  with  vari- 
ous spices  is  an  old  contrivance  and  well  known  everywhere.  The  ap- 
plication of  creasote  obtained  crudely  from  the  smoke  of  incompletely 
burned  wood  is  the  ancient  forerunner  of  some  of  the  modern  packing 
processes. 

Concerning  the  value  and  legitimacy  of  these  old  family  methods 
there  is  comparatively  little  difference  of  opinion;  salt  meat  is  not  as 
good  as  the  fresh  article;  dry  apples  do  not  make  the  best  apple  pie; 
chipped  beef  is  not  an  adequate  substitute  for  a  fresh  steak.  However, 
it  is  absolutely  necessary  to  preserve  food  in  some  way  in  order  to 
tide  over  the  winter  or  the  dry  seasons,  to  furnish  food  to  people  living 
and  working  in  desert  and  arid  regions,  and  to  feed  the  hordes 'of  peo- 
ple massed  together  in  great  cities.  It  would  be  impossible  to  main- 
tain the  large  population  of  a  modern  metropolis  if  it  were  dependent 
upon  a  daily  supply  of  fresh  food  materials. 

The  art  of  preserving  foods  depends  upon  the  science  of  bacteriol- 
ogy. A  more  complete  knowledge  of  the  causes  of  decomposition  and 
methods  by  which  they  may  be  prevented  has  enabled  us  to  perfect 
the  crude  and  primitive  methods  that  have  been  in  use  from  time  im- 


474  GENERAL   CONSIDERATIONS 

memorial,  so  that  it  is  now  possible  to  preserve  certain  foods  practi- 
cally indefinitely  without  in  any  way  injuring  their  nutritive  value  or 
seriously  interfering  witli  their  appearance  and  taste. 

The  chief  harm  has  come  from  the  blind  use  of  chemical  germi- 
cides, without  regard  for  their  harmful  properties.  The  simplest  and 
cheapest  way  to  preserve  food  is  by  adding  one  of  these  chemicals,  and 
the  method  was,  therefore,  seized  upon  by  alert  men  whose  chief  in- 
terest was  of  the  pecuniary  kind.  The  question  was  to  find  the  small- 
est percentage  of  a  chemical  which  would  prevent  the  decay  of  some 
particular  food  product,  trusting  to  luck  that  the  preservative  used 
might  prove  harmless  to  the  consumer.  Often  these  chemicals  were 
added  with  a  liberal  hand;  further,  it  was  soon  found  that  chemical 
preservatives  could  be  used  to  preserve  food  products  for  the  market 
from  materials  already  so  decayed  as  to  be  unsalable  in  their  original 
condition. 

The  National  Pure  Food  and  Drugs  Act  of  1906  was  passed  largely 
to  meet  this  situation.  This  law  considers  any  food  which  contains 
some  "added  poisons  or  other  deleterious  ingredient  which  may  render 
such  article  injurious  to  health"  as  adulterated.  To  Harvey  W.  Wiley 
belongs  the  credit  of  inducing  Congress  to  pass  this  legislation  against 
opposition  and  for  an  aggressive  administration  that  proved  useful  in 
bringing  the  whole  question  prominently  before  the  public. 

Cold. — Cold  must  be  regarded  by  the  sanitarian  as  an  antiseptic 
rather  than  a  germicide.  Low  temperatures  kill  few  bacteria,  but  pre- 
vent the  growth  and  multiplication  of  most  of  them.  Even  the  anti- 
septic properties  of  cold  are  not  as  marked  as  they  were  once  believed 
to  have  been. 

Some  bacteria  grow  and  multiply  at  low  temperatures,  even  at  0°  C. 
In  1871  Burdon-Sanderson  was  the  first  to  show  that  freezing  does  not 
kill  bacteria.  Von  Frisch  demonstrated  that  subjecting  a  putrefying 
solution  to  a  temperature  of — 87°  C.  for  some  hours  did  not  efl'ect 
sterilization.  Lcidy  in  1848  showed  that  water  derived  from  melted 
ice  contained  not  only  living  infusoria,  but  also  rotifers  and  worms. 
Pictet  and  Young  found  that  anthrax  and  symptomatic  anthrax  cul- 
tures were  not  killed  after  an  exposure  of  108  hours  to  — 70°  C.  Later 
MacFayden  proved  that  the  temperature  of  liquid  air  does  not  kill 
bacteria;  he  subjected  cultures  to  temperatures  of  — 315°  F.  Ehrlich 
has  recently  shown  that  cancer  cells  kept  cold  will  live  and  remain 
virulent  for  at  least  two  years. 

While  no  microorganism  pathogenic  for  man  will  grow  and  multiply 
at  the  low  temperatures  of  the  refrigerator,  there  are  a  number  of 
saprophytic  bacteria  and  molds  that  develop  abundantly  at  tempera- 
tures as  low  as  0°  C.  Milk,  meat,  eggs,  and  other  products  kept  in 
cold  storage  at  or  near  the  freezing  point  may  show  a  notable  increase 


PEESERVATION    OF    FOODS  475 

in  the  number  of  bacteria.  A  number  of  tests  made  in  my  laboratory 
showed  that  in  the  case  of  milk  these  low-temperature  microorganisms 
belong  mainly  to  the  putrefying  and  proteolytic  group.  They  produce 
an  alkaline  reaction  in  the  milk  and  a  bitter  taste.  Whether  they  are 
capable  of  forming  poisonous  products  at  these  low  temperatures  is 
doubtful. 

For  the  most  part  pathogenic  bacteria  withstand  freezing  tempera- 
tures. They,  however,  suffer  a  quantitative  reduction  when  frozen  (see 
Ice  and  the  effects  of  freezing  upon  bacteria,  page  887).  Most 
animal  parasites  die  in  cold  storage;  a  few,  however,  survive.  The 
time  in  which  the  material  has  been  refrigerated  is  an  important  fac- 
tor. Just  as  water  becomes  safer  by  storing  it,  so  with  foods,  but  cold 
storage  foods,  while  safer,  cannot  be  entirely  relied  upon.  Thus,  cold 
appears  not  to  affect  trichina.  Tcenia  saginata,  the  beef  tapeworm,  dies 
in  twenty-one  days,  and  Tcenia  solium,  the  pork  tapeworm,  may  live 
more  than  twenty-nine  days  in  cold  storage. 

Fortunately,  cold  causes  a  quantitative  reduction  in  the  number  of 
harmful  bacteria,  even  though  it  does  not  produce  complete  steriliza- 
tion. The  element  of  time  here  plays  an  important  role,  as  most  of 
the  surviving  pathogenic  microorganisms  soon  die.  From  a  sanitary 
standpoint  the  protection  afforded  by  refrigeration  is  reassuring,  al- 
though not  perfect. 

The  best  temperature  at  which  foodstuffs  may  be  kept  must  be  de- 
termined for  each  case.  Some  substances,  such  as  meat  and  poultry, 
are  better  preserved  when  actually  frozen;  others,  such  as  shell-eggs  or 
milk,  are  materially  injured  by  freezing.  In  any  event,  the  tempera- 
ture of  the  icebox  should  not  rise  above  7°  C.  At  this  tempera- 
ture bacterial  growth  does  not  entirely  cease,  although  very  markedly 
hindered.  Few  household  refrigerators  reach  this  temperature  or 
maintain  it  for  any  length  of  time — either  through  faulty  construction 
or  on  account  of  insufficient  ice.  Often  the  icebox  is  placed  in  a  sunny 
corner,  or,  for  convenience,  near  the  kitchen  stove.  The  doors  of  the 
ice  chest  frequently  do  not  fit  well,  which  results  in  needless  waste 
and  imperfect  refrigeration.  A  study  of  household  refrigerators  dis- 
closes the  fact  that  the  temperature  is  often  15°  C.  and  higher.  Such 
conditions  make  good  incubators,  favoring  bacterial  growth.  The  ne- 
cessity for  scrupulous  cleanliness,  aeration,  and  dryness  in  all  refriger- 
ating devices  needs  only  be  mentioned. 

In  ordinary  refrigerating  plants  moisture  condenses  on  the  sur- 
face of  the  objects  exposed.  In  the  case  of  meat  this  moisture  dissolves 
some  of  the  proteins,  extractives, .  and  salts,  and  makes  a  perfect  cul- 
ture medium  for  bacteria  and  molds.  In  the  case  of  meats  it  is,  there- 
fore, better  to  hang  them  in  a  current  of  dry,  clean  air,  in  order  to 
desiccate  the  surface,  before  they  are  placed  in  the  refrigerator.     The 


476  GENERAL    CONSIDERATIONS 

dried  surface  delays  the  inward  growth  of  the  inevitable  bacterial  con- 
tamination upon  the  surface. 

Articles  of  food  may  be  kept  in  a  satisfactory  condition  in  cold 
storage  for  a  very  long  time.  The  time  varies  with  the  article  and 
its  condition  when  placed  in  storage,  also  with  the  temperature  and 
other  factors.  A  striking  illustration  of  the  great  preserving  power 
of  low  temperatures  occurred  several  years  ago  in  Northern  Siberia. 
In  consequence  of  a  great  landslide  on  the  banks  of  the  Kolyma,  the 
head  of  a  mammoth  became  exposed  and  was  so  well  preserved  that 
even  the  fleshy  trunk  remained.  It  is  said  that  famished  wolves  and 
half-starved  natives  began  to  eat  of  the  flesh.  The  Russian  government 
sent  Dr.  Hertz  to  rescue  what  remained.  The  mammoth  had  re- 
mained in  cold  storage  perhaps  thousands  of  years.  Some  of  the  soft 
parts  are  now  preserved  in  the  Museum  at  St.  Petersburg.  This  must 
not  be  taken  as  justification  of  prolonged  storage  or  the  "cornering" 
of  foods  for  economic  gain  in  mammoth  cold  storage  warehouses. 
While  meat,  poultry,  eggs,  and  vegetables  may  be  kept  in  a  satisfactory 
condition  for  months  and  transported  over  seas,  cold  storage  need  not 
be  unduly  prolonged.  In  any  case,  the  consumer  is  entitled  to  know 
whether  the  article  is  fresh  or  stored,  and  the  time  it  has  been  in  cold 
storage.     These  facts  should  be  stated  upon  the  label  or  stamp. 

During  the  past  few  years  cases  of  so-called  "ptomain"  poisoning 
have  been  attributed  to  the  ingestion  of  cold  storage  poultry.  It  is 
supposed  that  the  undrawn  condition  stimulates  decomposition  during 
cold  storage.  Laws  have,  therefore,  been  passed  in  certain  states  re- 
quiring poultry  to  be  drawn  before  being  placed  in  cold  storage.  It  is 
claimed,  on  the  other  hand,  that  the  undrawn  fowl  keep  better — it  is 
certain  that  they  weigh  more,  which  is  an  advantage  to  the  dealer.  The 
disadvantage  of  drawing  fowl  by  the  ordinary  method  is  that  the  car- 
cass becomes  contaminated  with  the  intestinal  contents  and  putrefactive 
processes  are  hastened.  This  question  was  investigated  by  the  Massa- 
chusetts State  Board  of  Health,  and  the  conclusion  was  reached  that 
it  made  practically  no  difference  whether  the  fowl  were  drawn  or  not, 
but  that  they  must  be  perfectly  fresh  when  placed  in  cold  storage. 
Poultry  is  kept  below  0°  C,  at  which  temperature  no  noticeable  change 
occurs.  It  was  found  that  cold  storage  fowl  are  even  less  contaminated 
with  bacteria  than  freshly  killed  birds  that  have  hung  for  a  few  days. 
However,  the  cold  storage  animals,  when  removed  from  the  refrigera- 
tor, decompose  more  quickly  than  the  fresh. 

Contrary  to  what  might  be  expected,  drawn  poultry  decomposes 
more  rapidly  after  removal  from  cold  storage  than  undrawn.  This  is 
because  in  the  process  of  drawing  the  intestines  are  broken  below  the 
gizzard  and  the  carcass  becomes  badly  contaminated  with  intestinal 
bacteria.     If  the  entire  alimentary  canal,  esophagus,  crop,  gizzard,  and 


PEESEKVATION    OF    FOODS  477 

intestines  are  removed  intact,  and  with  due  care  to  prevent  bacterial 
contamination,  the  bird  is  practically  safe  from  putrefaction.  In  case, 
therefore,  poultry  is  drawn  before  it  is  placed  in  cold  storage,  the  draw- 
ing should  be  done  with  bacteriological  care. 

From  a  sanitary  standpoint,  then,  refrigeration  is  one  of  the  best 
methods  of  preserving  foodstuffs.  The  advantages  of  cold  as  a  preserva- 
tive are  that  it  neither  adds  any  constituent  to  the  food  nor  takes  away 
any  constituent  from  the  food.  Cold  imparts  no  new  taste,  nor  does  it 
seriously  alter  the  natural  flavor.  It  does  not  diminish  its  digestibility 
nor  cause  a  loss  of  nutritive  value.  The  material  is  left  in  approxi- 
mately its  original  condition.  Cold  may,  therefore,  be  regarded  as 
one  of  the  simplest  and  best  antiseptics  we  have  for  the  preservation 
of  foods.  It  is  now  almost  universally  applied  to  prevent  decomposition 
and  decay.  The  housewife  uses  it  to  keep  food  in  cold  cellars,  deep 
wells,  and  the  like.  During  the  last  fifty  years  the  use  of  ice  for  the 
purpose  of  refrigeration  has  become  commonplace.  Fresh  and  whole- 
some food  may  now  be  transported  to  the  tropics,  and  the  sustenance 
of  large  communities  in  insular  and  arid  regions  is  made  possible 
and  pleasurable  through  the  preserving  use  of  cold. 

Drying. — Drying,  desiccation,  or  evaporation  is  a  favorite  and  primi- 
tive method  of  preserving  meats,  fruits,  vegetables,  and  various  food 
materials.  Dryness  furnishes  ideal  antiseptic  conditions.  Microorgan- 
isms must  have  moisture  to  grow  and  multiply.  Most  pathogenic  micro- 
organisms soon  die  when  dried,  hence  the  process  has  a  decided  sani- 
tary advantage.  Further,  dried  fruits,  vegetables  or  meats  are  rarely 
eaten  raw,  and  the  cooking  is  a  further  sanitary  safeguard. 

The  effectiveness  of  drying  as  a  food  preservative  depends  upon 
the  thoroughness  with  which  the  process  is  carried  out.  It  is  not  so 
well  adapted  to  meats  as  to  vegetables  and  fruits.  Dried  meats  lose 
their  natural  flavor,  which  may  be  replaced  with  others  less  real.  All 
sorts  of  organic  foodstuffs,  even  the  most  decomposable,  such  as  milk, 
eggs,  or  meat,  may  be  dried  and,  if  kept  dry,  they  will  keep  in  a  satisfac- 
tory state  almost  without  limit  of  time. 

Theoretically  dryness  is  not  a  complete  safeguard,  for  the  reason 
that  a  few  microorganisms  survive,  particularly  bacterial  spores.  Despite 
this  slight  limitation,  it  is  more  than  reasonably  safe  and  an  entirely 
satisfactory  procedure.  Practically  the  only  change  in  dried  foods 
is  the  loss  of  moisture,  which  may  readily  again  be  supplied.  Dryness 
has  the  great  advantage  in  that  no  added  chemical  or  added  preserva- 
tive process  is  necessary;  further,  dried  foods  are  quite  as  nutritious 
and  usually  quite  as  digestible  as  the  fresh  articles,  although  not  quite 
as  savory. 

Dried  Meat. — In  the  dry  climates  of  South  America  and  on  our 
western    plains   meat   is   cut   into   thin   strips,    suspended   in   the    air. 


478  GENERAL   CONSIDERATIONS 

and  exposed  to  direct  sunlight.  In  a  short  time  the  moisture  disap- 
pears and  the  hard  dry  pieces  keep  indefinitely,  or  as  long  as  they  are 
kept  dry.  The  meat  retains  a  fair  degree  of  palatability  and  practi- 
cally all  of  its  nutrient  properties.     This  is  known  as  jerked  beef. 

Dried  beef  is  also  prepared  by  first  treating  the  meat  with  condi- 
ments and  then  drying  it  artificially.  Chipped  beef  or  dried  beef  is 
prepared  in  this  manner,  except  that  the  meats  are  often  smoked  as  well 
as  salted  and  desiccated,  so  that  in  their  method  of  preparation  more 
than  one  method  of  preservation  is  employed. 

Powdered  meats  are  prepared  by  complete  desiccation,  and  such 
products  are  found  upon  the  market  as  a  finely  ground  powder.  Meat 
powders  are  made  not  alone  from  fresh  meats  in  their  natural  state, 
but  are  also  prepared  after  more  or  less  artificial  digestion. 

Dried  Fruits. — Dried  apples  are  taken  as  a  type  of  dried  fruits 
and  vegetables.  The  apples  may  be  dried  naturally  by  cutting  them 
into  convenient  sizes  and  exposing  them  to  the  action  of  the  sun.  This 
is  more  a  domestic  than  a  commercial  industry.  When  apples  are 
dried  by  this  simple  process  they  darken  and  become  unattractive  in 
appearance.  This  is  due  to  the  oxidizing  action  of  the  enzymes  when 
exposed  to  the  air.  When  properly  prepared  the  dried  apple  has  its 
moisture  content  reduced  to  approximately  30  per  cent,  or  less. 

In  order  to  prevent  the  darkening  of  the  surface  during  the  long 
exposure  necessary  to  secure  the  proper  degree  of  evaporation,  apples 
are  usually  subjected  to  the  fumes  of  burning  sulphur.  The  sulphur 
dioxid  acts  as  a  bleaching  agent  and  the  sulphurous  and  sulphuric 
acids  retained  in  the  apple  act  as  preservatives.  Apples  treated  with 
sulphur  fumes  are  less  likely  to  decay  or  become  infected  with  molds 
than  a  similar  product  not  exposed  to  sulphur  fumes.  The  process 
is  objected  to  from  the  standpoint  of  health,  for  the  reason  that  the 
sulphurous  acids  and  sulphites  are  admittedly  injurious  to  health.  The 
Department  of  Agriculture  found  that  approximately  half  of  the  evapo- 
rated fruits  purchased  on  the  open  market  had  been  treated  with  sul- 
phur fumes.  In  order  to  obtain  a  satisfactory  dried  product  it  is  of 
some  importance  that  the  fruits  be  selected,  so  as  to  reject  all  imper- 
fect, rotten,  or  infected  specimens. 

Evaporated  apples  is  a  term  applied  to  apples  dried  artificially  in- 
stead of  being  exposed  to  the  sun's  heat.  The  process  is  rapid  and 
satisfactory,  and  has  no  sanitary  objections. 

Dried  Eggs. — Eggs  are  broken  out,  mixed  and  dried  by  spreading 
the  mass  in  a  thin  film  in  shallow  pans  or  upon  a  broad  revolving  belt; 
the  water  is  abstracted  by  exposure  to  a  current  of  warm  dry  air.  The 
egg  substance  may  also  be  dried  by  forcing  it  through  small  orifices 
under  a  high  pressure  into  a  drying  chamber  so  adjusted  as  to  tempera- 
ture and  size  as  to  secure  the  desiccation  of  the  minute  particles  of  egg 


PEESEEVATION    OF    FOODS  479 

spray  before  they  fall  to  the  bottom.  Egg  substance  thoroughly  dried 
keeps  satisfactory  in  almost  any  climate.  It  retains  all  the  nutritive 
value  in  the  original  egg. 

Dried  Milk. — Milk  must  be  dried  quickly  and  at  a  comparatively 
low  temperature  in  order  to  obtain  a  successful  product.  It  must  be 
dried  quickly  in  order  that  it  will  not  spoil  during  the  process,  and 
the  temperature  must  not  be  high  enough  to  coagulate  the  lactalbumin, 
otherwise  the  addition  of  water  would  not  restore  the  milk  to  its  former 
homogeneous  state.  Milk  is  sometimes  dried  in  a  very  thin  film  on 
metal  plates;  sometimes  in  vacuo.  In  this  way  the  milk  can  be  re- 
duced to  a  dry  state  in  a  very  short  time  and  without  reaching  a  tem- 
perature sufficiently  high  to  produce  physical  changes.  Another  method 
of  drying  milk  consists  in  atomizing  it  under  pressure  and  projecting 
it  into  a  warm  chamber,  the  temperature  of  which  is  so  regulated  that 
the  fine  particles  are  completely  deprived  of  their  water  before  they 
reach  the  bottom  of  the  vessel.  The  milk  is  thus  reduced  almost  at 
once  to  a  fine  powder.  Dried  milk  when  mixed  with  water  is  practically 
restored  to  its  original  condition.  Milk  powder  should  be  either  kept 
in  a  cool  place  or  sealed  in  air-tight  packages  in  order  to  prevent  the 
fat  becoming  rancid.  Dry  powdered  milk  properly  cared  for  will  keep 
almost  indefinitely.  Since  practically  88  per  cent,  of  milk  is  water, 
there  is  a  decided  economic  gain,  so  far  as  the  handling  and  transporta- 
tion are  concerned.  Powdered  milk  should,  of  course,  be  made  from 
milk  derived  from  healthy  cows  handled  under  sanitary  conditions  and' 
free  from  infection.  The  milk  may  be  pasteurized  before  it  is  reduced 
to  a  powder.  Powdered  milk  is  finding  an  increasing  and  legitimate 
field  of  usefulness  for  cooking,  household  purposes,  and  even  as  a 
beverage  for  adults.  It  should,  however,  not  be  depended  \ipon  for 
infant  feeding. 

Salting'  and  Pickling. — The  preservation  of  meat  with  brine  or  com- 
mon salt  is  one  of  the  oldest  processes  known.  The  brine  should  con- 
tain from  18  to  25  per  cent,  of  salt.  For  red  meats  a  little  potassium 
nitrate  is  often  added;  this  salt  has  slight  antiseptic  properties,  but 
brings  out  the  red  color.  In  the  processes  of  salting  some  of  the  meat 
protein,  bases,  and  extractives  are  dissolved  out  and  the  fibers  become 
hardened;  the  nutritive  value  and  digestibility,  therefore,  is  somewhat 
diminished. 

Pickling  includes  preservation  of  food  in  brine,  vinegar,  weak  acids, 
and  the  like.  These  substances  have  antiseptic  and  also  feeble  germi- 
cidal properties,  depending  upon  their  concentration. 

PicJcled  meats  are  prepared  by  soaking  meat,  especially  pork,  in  a 
brine  made  of  common  salt,  though  other  substances,  such  as  sugar, 
vinegar,  and  spices,  are  often  added.  Chemical  preservatives  are  some- 
times added  to  the  brine.     Those  most  frequently  used  are  sulphite  of 


480  GEXEKAL    COXSIDEEATIONS 

soda  or  boric  acid.  With  proper  methods  these  added  chemical  anti- 
septics are  not  necessary.  The  vinegar  which  is  employed,  or  acetic 
acid,  may  be  injected  into  the  carcass  before  it  is  cut  up.  When  the 
arteries  are  filled  with  vinegar  in  this  way  it  rapidly  permeates  to  all 
parts  of  the  meat  and  acts  as  an  excellent  and  unobjectionable  preserva- 
tive in  cases  where  an  acid  taste  is  desired.  It  is  stated  that  carcasses 
which  have  been  injected  with  vinegar  are  easily  preserved  and  require 
far  less  salt  and  other  condimental  substances  than  when  not  so  treated. 
The  process  has  no  sanitary  objections. 

Trichina  die  after  a  prolonged  period  of  pickling.  Cysticerci  are 
killed  in  21  days'  exposure  to  25  per  cent,  brine.  Many  pathogenic 
bacteria  die  in  brine  of  this  concentration,  but  the  salt  must  be  looked 
upon  as  an  antiseptic  rather  than  a  germicide;  that  is,  it  prevents 
growth  rather  than  kills  the  bacteria  that  are  present.  From  a  sanitary 
standpoint  there  is  some,  though  slight,  danger  of  conveying  infection 
in  foods  that  have  been  improperly  salted  or  pickled.  Attention  is 
called  to  the  fact  that  the  cases  of  botulism  studied  by  von  Ermengen 
were  caused  by  a  ham  kept  in  brine  under  conditions  favoring  anaerobic 
growth. 

Decomposition  may  also  be  arrested  by  the  use  of  syrups,  which  have 
an  entirely  similar  action  to  that  of  salt,  vinegar,  or  weak  acids;  that 
is,  a  strong  solution  of  sugar  will  prevent  gro^\i:h,  but  cannot  be  de- 
pended upon  to  kill  parasites.  However,  most  of  them  die  under  such 
conditions  in  the  course  of  time.  As  most  preserved  foodstuffs  are 
cooked  before  eaten,  there  is  small  danger  in  articles  prepared  by  these 
processes. 

Jellies  and  Preserves. — By  preserving  is  commonly  understood  the 
addition  of  a  large  amount  of  sugar.  The  principal  preserves  are  jel- 
lies, marmalades,  jams,  and  fruit  butters.  These  substances  are  en- 
tirely free  from  the  danger  of  conveying  infection,  not  only  on  account 
of  the  antiseptic  action  of  the  sugar,  but  for-  the  further  reason  that 
they  are  always  cooked  in  preparation.  Jellies  are  frequently  adulter- 
ated by  the  substitution  of  apple  stock.  Apples  contain  a  large  num- 
ber of  pentose  bodies  which  favor  jellification.  A  common  method  of 
manufacturing  jelly  for  the  trade  has  been  to  use  a  stock  of  apple 
juice  or  cider,  or  a  preparation  made  from  the  cores,  skins,  and  re- 
jected portions  of  the  apple  at  evaporating  factories,  or  from  whole 
rejected  apples.  This  stock  is  used  as  a  common  base  for  the  manu- 
facture of  jellies  of  different  kinds.  Apple  juice  used  as  a  substitute 
for  other  fruit  juices  in  the  making  of  preserves  is  a  common  fraud 
and  an  adulteration,  according  to  the  Food  and  Drugs  Act,  unless 
plainly  stated  upon  the  label.  Phosphoric  acids  and  other  acids  are 
added  to  jellies  to  enable  jellification  to  take  place  with  the  use  of  less 
fruit  and  more  water.     Jellies  are  also  adulterated  with  artificial  color- 


PRESERVATION"    OF    FOODS         '  4^1 

ing  matter,  particularly  the  coal-tar  dyes.  Artificial  flavors  which  closely 
resemble  the  particular  flavor  desired  are  sometimes  employed.  The 
chemical  preservatives  most  frequently  added  to  jellies  and  preserved 
fruits  are  salicylic  acid,  benzoic  acid,  or  benzoate  of  soda. 

Smoking. — The  smoking  of  fish,  beef,  hams,  and  other  food  products 
consists  mainly  in  rapid  drying  plus  the  germicidal  action  of  certain 
substances  in  the  smoke.^  The  meat  or  fish  is  exposed  to  the  smoke 
of  a  smoldering  wood  fire  of  oak,  maple,  or  hickory,  usually  after  a 
preliminary  salting.  The  articles  so  exposed  become  dry  and  impreg- 
nated with  pyroligneous  products — acetic  acid  and  creasote,  formalde- 
hyde, and  other  germicidal  substances.  The  penetration  is  only  par- 
tial. 

An  artificial  or  quick  method  of  smoking  meat  is  to  brush  the 
pieces  or  dip  them  in  pyrolignic  acid  at  definite  intervals,  and  finally 
dry  in  the  air.  The  effects  of  the  smoking  do  not  penetrate  very  far; 
therefore,  in  sausages  of  generous  diameter  putrefaction  often  occurs 
in  the  interior.  Smoked  sausage  may,  therefore,  be  dangerous,  as  far 
as  various  parasites  and  the  products  of  decomposition  are  concerned, 
and  the  same  is  true  of  smoked  ham  and  other  meats  exposed  in  large 
pieces.  As  smoked  meats  are  often  eaten  raw,  the  occasional  survival 
of  parasites  in  such  products  has  some  sanitary  significance. 

Canning. — The  process  of  canning  is  practically  synonymous  with 
sterilization  and  is,  therefore,  one  of  the  best  sanitary  safeguards  we 
have  against  parasites  and  the  injurious  products  of  putrefaction  in 
foodstuffs.  The  process  of  canning  was  discovered  by  M.  Appert  of 
Paris  in  1804,  long  before  the  days  of  bacteriology.  Appert  found  that 
meats  and  other  foods  in  sealed  vessels  would  usually  keep  indefinitely 
if,  after  being  sealed,  they  were  kept  for  an  hour  in  boiling  water.  He 
improved  the  process  in  1810  by  introducing  a  method  of  sealing  the 
cans  after  the  heating  process  had  driven  out  the  air  and  replaced  it 
with  steam,  so  that  when  cool  a  vacuum  is  formed.  For  all  practical 
purposes  this  is  the  universal  method  of  canning  to-day,  except  that 
now  the  cans  are  given  a  second  heating,  after  an  interval  of  a  day,  in 
order  to  permit  the  germination  of  spores  and  the  destruction  of  all 
spore-bearing  bacteria.  In  other  words,  canning  is  a  practical  applica- 
tion of  the  well-known  laboratory  method  of  fractional  sterilization. 

The  objection  is  sometimes  raised  that  the  contents  of  the  can  are 
improperly  sterilized  and  that  the  surviving  spores  germinate  at  the 
first  opportunity  and  cause  decomposition.  Fortunately,  an  improperly 
sterilized  can  of  food  tells  its  own  story,  and  the  gaseous  products  of 
putrefaction  may  even  burst  the  tin  or  leave  the  food  in  such  condition 
that  when  the  can  is  opened  it  would  be  so  offensive  to  the  sense  of 

^  The  process  was  probably  accidentany  discovered  in  connection  witli  crude 
attempts  to  use  artificial  heat  for  drying  purposes. 


482  GENERAL    CONSIDERATIONS 

smell  that  no  one  would  use  it.  The  process  of  canning  fortunately 
does  away  with  the  necessity  of  using  chemical  preservatives  of  any 
kind.  The  proper  authorities  should  be  authorized  to  prohibit  the  can- 
ning of  foodstuffs  that  have  already  undergone  perceptible  decomposi- 
tion, or,  if  not  injurious  to  health,  they  should  be  labeled  '"second 
quality."  The  law  should  require  that  tlie  (juantity  contained  within 
the  can  and  the  date  on  which  it  was  put  up  as  well  as  the  amount 
should  be  stamped  in  the  tin.  This  phase  of  the  question  is  perhaps 
more  of  economic  than  of  hygienic  importance,  but  will  be  required  in 
time  as  surely  as  the  present  law  now  requires  honest  labeling  in  other 
particulars. 

Sometimes  scraps  or  inedible  portions  of  diseased  or  deca3'ed  meats 
are  canned  and  the  flavor  disguised.  This  cannot  be  too  severely  con- 
demned if  sold  as  first  quality. 

Before  meats  are  canned  they  are  first  parboiled  for  eight  to  twenty 
minutes,  in  order  to  secure  the  shrinkage  before  the  meat  is  placed 
in  the  can.  In  the  parboiling  there  is  a  certain  loss  of  fat,  soluble 
mineral  matter,  meat  bases,  and  water.  However,  the  shrinking  of  the 
meat  concentrates  it,  as  far  as  nutritive  value  is  concerned,  and,  there- 
fore, compensates  for  the  loss.  The  parboiled  meat  is  then  placed  in 
the  tin  and  a  small  quantity  of  the  soup  liquor  added.  The  cans  are 
closed  and  soldered  and  then  placed  in  autoclaves  and  subjected  to 
steam  under  pressure.  Usually  a  small  hole  is  left  in  the  can  in  order 
to  permit  the  exit  of  air  and  gases.  This  is  sealed  off  at  once  after 
heating.  The  cans  are  then  subjected  to  a  second  heating  at  225°  to 
250°  F.  for  one  to  two  hours.  A  modified  process  consists  in  placing 
the  cans  upon  an  endless  conveyor  which  exposes  the  can  to  a  high 
temperature  in  an  oil  bath  a  sufficient  length  of  time  to  sterilize  the 
contents  at  one  exposure. 

In  Germany  tuberculous  and  trichinous  meat  is  sterilized  and  sold 
as  second  quality  meat  in  accordance  with  the  third  class  or  "freihank" 
meat  system.  There  is  no  known  sanitary  objection  to  this  practice, 
provided  the  sterilization  is  complete  and  the  label  represents  the  true 
nature  of  the  product. 

Canned  foods  are  sterile  foods  and,  therefore,  generally  safer  than 
fresh  foods.  Fresh  foods,  of  course,  are  to  be  preferred  to  those  that 
have  been  sterilized,  although  many  unsterilized  foods  are  more  dan- 
gerous in  the  fresh  state  than  after  they  have  been  exposed  to  a  high 
temperature.  The  process  of  canning,  discovered  by  Appert  and  af- 
terward perfected  through  the  work  of  Pasteur,  has  proven  of  ines- 
timable benefit  to  mankind.  It  enables  nourishing  food  of  a  perishable 
character  to  be  kept  and  transported  to  great  distances  and  to  be  used 
in  localities  where  fresh  foods  are  unobtainable.  Without  this  method 
of  preserving  foods  the  pioneer  and  the  explorer  would   be  seriously 


PEESEEVATIGN    OF    POODS  483 

handicapped.  Large  army  and  navy  maneuvers  would  be  materially 
impeded,  and  great  metropolitan  cities  would  be  impossible.  Wiley 
states  that  "the  winning  of  the  West  has  been  marked  by  the  debris 
of  the  rusty  can." 

Canned  foods  are  not  only  safe,  but  are  quite  as  nutritious  as  the 
original  articles.  The  process  permits  us  to  have  a  well-balanced  ra- 
tion throughout  the  year — irrespective  of  season.  The  canning  indus- 
try is  growing  to  enormous  proportions,  and,  on  account  of  the  great 
importance  of  the  process,  the  character  and  quality  of  foods  thus  pre- 
served should  be  wholly  above  suspicion,  and  no  adulteration  or  sophis- 
tication of  any  kind  permitted.  Every  can  should  be  plainly  stamped 
with  the  quantity  and  true  nature  of  its  contents  and  also  the  date 
when  it  was  first  sterilized. 

Concerning  the  character  of  the  container  Wiley  states:  "Much 
in  the  direction  of  securing  a  better  product  may  be  accomplished  by 
a  more  careful  selection  of  the  container.  The  common  method  of 
preserving  canned  goods  is  in  tin.  This  material,  as  well  known,  is 
placed  on  the  surface  of  sheet  iron  and  should  be  free  of  other  metals. 
Lead  especially  should  be  excluded  from  the  composition  of  the  tin  as 
far  as  possible.  In  spite  of  all  these  precautions,  however,  the  coating 
of  the  tin  is  sometimes  broken,  so  that  the  iron  itself  may  be  attacked, 
perforations  result,  and  the  package  of  goods  be  spoiled.  More  fre- 
quently, however,  the  erosion  of  the  tin  plate  occurs  over  widely  ex- 
tended areas,  introducing  into  the  contents  of  the  package  a  considerable 
quantity  of  tin  salts.  This  may  be  prevented  to  a  certain  degree  by 
coating  the  surface  of  the  tin  with  a  gum  or  varnish  which  is  not  acted 
upon  by  the  contents  of  the  package.  Glass  is  also  coming  into  more 
general  use,  and  if  it  could  be  secured  of  a  character  to  avoid  breakage 
it  would  be  possible  to  replace  to  a  considerable  extent  the  tin  packages 
now  in  such  common  use,  and  thus  prevent  the  introduction  of  soluble 
tin  salts  into  food.  In  this  case  the  glass  itself  should  be  free  of  lead, 
borax,  and  fluorids.  A  glass  package  is  now  coming  into  use  which  is 
tough  and  resistant  to  ordinary  causes  of  fracture.  Much  may  be  ex- 
pected from  progress  in  this  direction." 

Chemical  Preservatives. — Chemical  preservatives  are  nothing  more 
nor  less  than  antiseptic  substances;  that  is,  substances  which  restrain 
the  growth  and  development  of  bacteria  and  molds.  Chemical  preserva- 
tives in  the  proportions  commonly  used  may  have  little  or  no  germicidal 
action.  Such  substances  as  sugar,  salt,  vinegar,  vinegar  extract  of 
spices,  and  the  pyroligneous  products  in  wood-smoke  are  not  regarded 
as  "chemical"  preservatives,  but  as  "natural"  preservatives  or  condimen- 
tal  substances,  although  their  mode  of  action  is  precisely  the  same  as  the 
chemical  preservatives.  There  is  a  great  prejudice  against  the  use  of 
any  preservative  for  our  foods  if  this  preservative  is  a  "chemical"  or 


484  GENERAL    CONSIDERATIONS 

"drug,*'  whereas  no  objection  is  raised  to  the  same  substance  if  de- 
rived from  "natural"  sources.  Thus,  foods  exposed  to  a  smoldering 
wood-fire  become  impregnated  with  pyroligneous  acid,  which  includes 
ereasote,  acetic  acid,  and  probably  formaldehyde  and  other  8ul)stances 
having  antiseptic  properties.  This  method  of  food  preservation  is  not 
only  countenanced  by  the  law,  but  is  favored  on  account  of  the  savory 
result  and  the  antiquity  of  the  process. 

The  great  increase  in  the  use  of  chemical  preservatives  in  foods 
during  the  last  fift}'  years  is  owing  to  the  fact  that  this  is  the  cheapest 
and  surest  method  of  preservation,  thus  offering  a  convenient  method 
of  supplying  the  needs  of  large  communities  as  well  as  remote  places. 
The  question,  therefore,  has  an  economic  side  that  cannot  be  disre- 
garded. Here,  however,  wc  must  confine  ourselves  to  the  healtli  as- 
pect of  the  problem.  Fortunately  we  possess  two  efficient  and  wholly 
unobjectionable  processes  for  the  preservation  of  food,  viz.,  refrigera- 
tion and  sterilization  by  heat,  which  for  the  most  part  make  it  unneces- 
sary to  resort  to  the  use  of  chemical  preservatives.  One  of  the  most 
objectionable  uses  that  can  be  made  of  chemical  preservatives  or  any 
other  method  of  food  preservation  is  to  conserve  foods  which  are  so 
decayed  as  to  be  unfit  or  possibly  injurious  to  health  if  used  fresh. 
The  law  cannot  be  too  strictly  enforced  in  order  to  prohibit  the  use 
of  chemical  preservatives  and  condiments  used  to  disguise  such  foods, 
which  may  then  be  sold  at  high  prices  as  first  quality. 

Upon  general  principles  it  is  undesirable  to  add  a  chemical  sub- 
stance of  whatever  nature  to  food  for  the  purpose  of  preserving, 
coloring,  or  improving  its  appearance,  and  in  most  countries  this  prac- 
tice is  prohibited  by  law.  There  are,  however,  a  few  instances  in  which 
the  addition  of  some  chemical  preservative  in  minimal  amounts  seems 
harmless,  and  occasionally  even  desirable,  as,  for  example,  small  quan- 
tities of  benzoate  of  soda  in  catsup;  a  thin  film  of  gum  benzoin  as  a 
protective  coating  for  chocolate,  etc. 

No  sweeping  generalization  can  be  made  concerning  all  chemical 
preservatives.  Each  substance  must  be  considered  for  itself,  and  each 
substance  must  further  be  considered  in  relation  to  the  particular  food- 
stuff for  which  it  is  proposed.  It  may,  however,  be  stated  as  a  general 
rule  that  any  chemical  which  is  poisonous  in  large  amounts  should  be 
considered  as  poisonous  in  small  amounts  until  the  contrary  is  proven. 
In  other  words,  the  consumer  is  entitled  to  the  benefit  of  the  doubt. 
The  toxicology  of  various  food  preservatives  is  in  its  infancy  and  fre- 
quently presents  a  very  difficult  and  complex  problem.  Thus,  lead  in 
one  large  dose  is  not  particularly  harmful.  The  older  practitioners 
frequently  gave  twenty,  thirty,  and  more  grains  of  sugar  of  lead  (ace- 
tate of  lead)  for  diarrheal  affections.  Only  a  minute  portion  of  the 
lead  taken  in  one  large  dose  is  absorbed;  the  rest  is  quickly  eliminated. 


PRESERVATION    OF    FOODS  .      485 

However,  if  the  same  amount  of  lead  should  be  taken  in  small  sub- 
divided daily  doses,  it  would  be  absorbed,  retained  by  the  tissues,  and 
the  poisonous  action  would  be  cumulative,  so  that  serious  chronic  lead 
intoxication  would  result.  On  the  other  hand,  hydrocyanic  acid,  one 
of  the  most  poisonous  chemicals  known,  is  harmless  in  small  amounts, 
for  the  reason  that  when  introduced  into  the  body  it  meets  the  available 
sulphur  (HoS),  with  which  it  unites  to  form  a  sulphocyanid,  as  KSCN. 
The  potassium  sulphocyanid  is  not  poisonous,  and  it  has  been  shown 
experimentally  that  animals  are  able  to  withstand  larger  quantities  of 
hydrocyanic  acid  by  first  giving  them  substances  which  increase  the 
available  amount  of  sulphur  to  form  this  chemical  combination.  Ben- 
zoic acid  in  large  amounts  is  irritating  and  produces  well-defined  symp- 
toihs  of  poisoning ;  small  amounts  of  benzoic  acid  are  paired  in  the 
liver  and  eliminated  by  the  kidneys  as  hippuric  acid,  a  normal  and 
harmless  constituent  of  the  urine. 

The  point  at  issue  now  is  to  determine  which  of  the  chemical  sub- 
stances are  injurious  to  health.  In  the  present  transitional  state  of  our 
knowledge  it  is  not  possible  to  make  a  final  statement  concerning  all  or 
perhaps  any  one  of  them.  It  is  well  known  that  the  most  serious  poisons 
may  be  taken  in  minute  amounts  without  apparent  injury.  In  fact, 
many  medicinal  substances  in  the  pharmacopeia  are  very  poisonous,  but 
in  therapeutic  doses  may  be  quite  beneficial.  The  effect  of  the  con- 
tinued use  of  chemical  substances  in  small  amounts  will  require  long 
and  patient  observation  to  determine  whether  or  not  they  should  be 
permitted  as  food  preservatives.  Of  all  the  substances  so  far  brought 
forward,  the  least  harmful  is  benzoic  acid  and  benzoate  of  soda.  There 
can,  however,  be  no  defense  for  the  use  of  formaldehyde,  salicylic  acid, 
sulphites,  and  a  host  of  other  chemicals.  So  far  as  we  know  the  human 
organism  possesses  no  natural  mechanism  for  rendering  them  harmless. 

There  can  be  no  defense  for  the  use  of  chemical  preservatives  to  hide 
inferiority.  This  is  well  illustrated  in  the  case  of  bleaclied  flour.  The 
only  purpose  of  the  bleaching  is  to  make  the  flour  from  a  dark  wheat 
look  as  white  as  the  best  patent  flour.  It  was  recently  discovered  that 
this  "artificial  aging"  of  flour  may  be  accomplished  by  adding  nitrogen 
peroxid.  The  flour  absorbs  this  poisonous  gas  as  a  sponge  absorbs  water 
and  instantly  becomes  white.  Processes  of  this  kind  should  be  regarded 
as  a  common  fraud,  for  the  flour  is  not  improved  in  any  way  except  in 
appearance,  which  is,  after  all,  a  deception.  The  silly  process  of  modi- 
fying the  natural  colors  of  food  is  illustrated  in  the  use  of  copper  sul- 
phate to  give  peas  a  bright  green  hue,  and  the  use  of  anilin  dyes  in 
glucose,  jellies,  fruit  juices,  ices,  and  other  substances  to  imitate  the 
color  of  natural  flavoring  extracts.  "Natural"  colors,  such  as  caramel 
and  vegetable  substances,  are  also  frequently  used.  The  substitution  of 
cheap  chemicals  for  high-priced  natural  flavoring  extracts^  the  substitu- 
33 


486  GENERAL   CONSIDERATIONS 

lion  of  acetic  acid  or  even  mineral  acids  for  fj^enuine  vinegar,  the  sub- 
stitution of  saccharin  for  sugar,  the  paraffin  [)()iisliiiig  of  i-iee,  and  sim- 
ilar devices  are  nothing  but  common  fi'auds,  which  may  in  some  cases 
also  be  injurious  to  health. 

Benzoic  Acid  and  Benzoate  of  Soda. — Benzoic  acid  is  an  organic 
acid  contained  largely  (12  to  20  per  cent.)  in  gum  benzoin,  and  also 
in  balsam  of  Peru  and  balsam  of  Tolu.  It  is  obtained  from  gum  ben- 
zoin, from  the  urfne  of  herbivorous  animals,  and  artificially  from  toluen, 
by  treating  it  with  chlorin  and  heating  with  water  to  150°  0. 

The  storm  center  of  the  question  of  chemical  preservatives  in  this 
country  has  raged  about  the  use  of  sodium  benzoate.  Wiley  conducted 
experiments  upon  a  number  of  healthy  individuals  known  as  the  "poison 
squad."  These  men  were  given  rather  large  quantities  of  sodium  ben- 
zoate with  their  meals  and  the  result  seemed  to  be  an  impairment  of 
the  appetite,  disturbance  of  digestion,  and  other  injurious  effects  in 
certain  instances.  On  the  other  hand,  the  Referee  Board  appointed  by 
President  Roosevelt  and  consisting  of  Remsen,  Chittenden,  Long, 
Taylor,  and  Herter  found  that  moderate  quantities  over  a  period  of 
four  months  have  no  appreciable  influence  vipon  health. 

The  reason  why  benzoic  acid  in  moderate  amounts  is  believed  to  be 
harmless  is  that  the  body  possesses  a  special  mechanism  for  taking  care 
of  this  substance.  Many  of  our  ordinary  foods  contain  substances  which 
are  transformed  in  the  body  into  benzoic  acid.  Some  foods,  such  as 
cranberries,  contain  this  acid  in  notable  amounts.  Benzoic  acid  meets 
glycocoll  (one  of  the  decomposition  products  of  protein)  in  the  liver. 
Benzoic  acid  and  glycocoll  form  hippuric  acid,  a  normal  and  harmless 
constituent  of  the  urine.  We,  therefore,  know  that  the  human  organism 
is  prepared  to  take  care  of  and  render  harmless  a  certain  amount  of 
benzoic  acid;  we  know  that  this  mechanism  is  a  very  efficient  one,  and 
is  capable  of  taking  care  of  relatively  large  amounts  of  benzoic  acid. 

There  can  be  no  serious  objection  from  the  standpoint  of  health  to 
the  addition  of  0.1  per  cent,  of  sodium  benzoate  to  catsup,  on  account 
of  the  small  quantity  of  this  article  consumed  at  any  one  time,  and 
further  on  account  of  the  long  time  a  bottle  of  catsup  is  usually  kept 
after  it  is  opened  in  the  household.  There  is,  thus,  the  added  economic 
gain  of  preserving  the  catsup  until  it  is  all  consumed.  The  same  ob- 
ject may  be  obtained  by  the  use  of  a  sufficiently  strong  vinegar  extract 
of  spices,  but  the  question  may  be  asked  whether  the  aromatic  and 
preserving  substances  in  the  vinegar  extract  of  spices  may  not  be  more 
irritating  than  the  sodium  benzoate. 

Hoffman  and  Evans  ^  have  shown  that  ginger,  black  pepper,  and 
cayenne  pepper  fail  to  prevent  the  growth  of  microorganisms.  Nutmeg 
and  allspice  have  slight  antiseptic  properties,  but  only  for  a  very  few 

^Journal  of  Industrial  and  Engineering  Chemistry,  Nov.,  1911,  p.  835. 


PEESERVATION    OF    FOODS  487 

days.  Cinnamon,  cloves,  and  mustard,  on  the  other  hand,  have  very 
marked  antiseptic  powers  and  are  valuable  preservatives.  The  active 
antiseptic  constituents  of  mustard,  cinnamon^  and  cloves  are  the  aromatic 
or  essential  oils  which  they  contain. 

No  one  would  advocate  the  promiscuous  use  of  sodium  benzoate  in 
foodstuffs  generally.  Its  use  in  such  foods  as  cider  or  tomato  soup  may 
be  questioned  on  account  of  the  amounts  that  would  be  taken  in  such 
articles.  Further,  benzoate  of  soda  placed  in  an  acid  medium  becomes 
benzoic  acid.  It  is  difficult  to  know  where  to  draw  the  line,  and  the 
consumer  must  be  given  the  benefit  of  the  doubt,  but  the  evidence  seems 
fairly  well  established  that  in  the  case  of  benzoate  of  soda  small  amounts 
are  harmless. 

The  question  has  a  large  economic  significance  in  addition  to  its 
sanitary  aspect,  for  it  is  claimed  that  benzoates  as  well  as  other  chemical 
preservatives  permit  the  use  of  rotten  tomatoes,  skins,  and  undesirable 
food  which  otherwise  could  not  readily  be  preserved.  Benzoate  of  soda 
is  a  rather  feeble  germicide  at  best,  and  in  such  dilute  proportions  as 
0.1  per  cent,  has  little  antiseptic  power. 

BoEAX  AND  Boric  Acid. — Both  boric  acid  and  borax  are  only  mild 
antiseptics.  They  are  not  very  potent  germicides.  They  are  gen- 
erally used  together,  for  the  reason  that  the  combination  of  the  two 
is  more  efficient  than  ?ither  one  alone.  Locally  boric  acid  is 
not  very  irritating,  and  for  this  reason  it  has  been  extensively  used 
in  surgical  practice.  To  some  skins,  however,  it  is  very  irritating,  and 
cases  are  reported  of  its  absorption  from  wounds  and  cavities  when  used 
too  freely,  causing  depression  and  eruptions,  such  as  erythema  and 
urticaria.  Fatal  results  have  been  reported  in  a  few  cases  from  injecting 
the  solution  into  abscess  sacs,  and  from  washing  out  the  stomach  with  it. 

Boric  acid  and  borax  are  used  for  preserving  meats,  milk,  butter, 
oysters,  clams,  fish,  sausage^  and  other  foods.  For  meat  it  is  often 
mixed  with  salic^dic  acid  and  applied  externally.  For  milk  it  was  a 
common  practice  to  add  to  one  c|uart  of  milk  10  grains  of  a  mixture 
of  equal  parts  of  borax  and  boric  acid;  for  butter  the  amount  used  is 
about  one-tenth  of  an  ounce  to  the  pound. 

The  effect  of  small  amounts  of  boric  acid  and  borax  upon  healthy 
human  beings  has  been  extensively  studied  and  has  resulted  in  con- 
flicting testimony. 

On  one  hand  we  have  the  researches  of  Chittenden  ^  and  Liebreich  ^ 
with  dogs  fed  upon  articles  containing  borax  and  boric  acid.  To  say 
the  least,  in  both  series  the  digestion  of  the  food  was  not  notably  im- 
paired and  the  animals  gained  in  weight.  The  same  result  followed 
the  experiment  made  by  Liebreich  upon  rabbits  and  guinea  pigs.     No 

^American  Jour,  of  Physiology,  1898. 

^  Vierteljahresschrift  filr  gericht.  Med.,  1909,  also  Lancet,  Jan.  6,  1900. 


488  GENERAL   CONSIDERATIONS 

injury  appears  to  have  followed  the  administration  of  boric  acid  to 
pigs,  calves,  and  children  by  the  British  Commission.^  Tuniiicliffe  - 
made  experiments  from  which  he  inferred  that  neither  borax  nor  boric 
acid  affected  the  health  of  the  children  experimented  on.  Vaughan  and 
Veenboer  ^  conclude  that  in  the  small  amounts  required  for  preserving 
cream  and  butter,  and  tliat  used  as  an  external  dust  on  hams  and  ba- 
con, both  boric  acid  and  borax  are  unobjectionable  from  a  sanitary 
standpoint. 

On  the  otlier  hand,  the  experiments  made  by  H.  E.  Annette  *  led 
him  to  an  opposite  conclusion.  He  found  boric  acid  injurious  to  kit- 
tens, and  naturally  assumed  that  the  use  of  milk  containing  it  might 
be  hurtful  to  young  infants.  Foster  and  Schleuker  ^  found  that  albumin 
digestion  was  impaired  by  boric  acid,  which  also  produced  increased 
desquamation  of  the  intestinal  epithelium.  Doane  and  Price  ^  made 
experiments  on  calves  which  indicate  that  borax  and  boric  acid  in  milk 
retard  digestion  to  a  slight  extent. 

As  these  substances  are  not  normal  constituents  of  the  body,  nor 
are  they  normal  constituents  of  foods,  the  conservative  course  would  be  to 
avoid  their  use  until  satisfactory  evidence  has  been  adduced  that  they 
are  free  from  harm  in  the  amounts  commonly  used  for  preserving  food. 

FoRMALDEiiYDE. — Formaldehyde  has  been  and  still  is  used  exten- 
sively as  a  preservative  for  milk  and  other  articles  of  food.  Formalde- 
hyde in  large  quantities  is  exceedingly  irritating,  and  death  in  isolated 
instances  has  been  reported  from  the  swallowing  of  amounts  from  1  to 
3  ounces.  There  has  been  much  discussion  as  to  the  effect  of  the  small 
quantities  ordinarily  used  as  a  food  preservative.  Bliss  and  No^7■  ^ 
and  Halliborton  ^  have  sho^^^l  conclusively  that  small  quantities  of  for- 
maldehyde greatly  delay  the  digestion  of  proteins  by  the  gastric  and 
pancreatic  juices,  the  digestion  of  starch  by  the  pancreatic  juice,  and 
the  curdling  of  milk  by  rennet.  It  is  also  known  that  some  individuals 
are  especially  susceptible  to  the  effect  of  formalin,  small  quantities 
in  the  food  causing  dyspepsia  and  other  disturbances  of  digestion. 
Formaldehyde  unites  directly  with  protein  matter  to  form  new  com- 
pounds of  an  undetermined  nature.  Thus,  formaldehyde  added  to  egg 
albumin  prevents  its  coagulation  by  heat,  and  added  to  gelatin  pre- 
vents liquefaction.  It  hardens  tissues,  so  that  it  will  render  fish  and 
meat  tough  and  brittle,  even  in  proportions  as  dilute  as  1-5,000,  hence 

'  V ierteljahresschrift  fiir  gericht.  Med.,  1901. 
^Journal  of  Hygiene,  1901. 
^American  Medicine,  March   13,   1902. 

*  Lancet,  Nov.  11,  1899. 

°  Quoted  in  report  of  Kober  on  ' '  Milk  Preservatives, "  U.  S.  Senate  Com- 
mission,  1902. 

*  Bulletin  No.  86,  Maryland  Agricultural  Experiment  Station,  Sept.,  1902. 
'Jour,  of  Exp.  Medicine,  1899,  Vol.  IV.  p.  47.      ' 

'British  Medical  Jour.,  1900,  Vol.  II,  p.  1. 


PEESERVATION    OF    FOODS  489 

it  is  not  generally  applicable  as  a  food  preservative.  In  small  amounts 
it  delays  decomposition;  in  large  amounts  it  is  an  active  germicide.  Its 
use  in  milk  was  recently  advocated  by  no  less  an  authority  than  von 
Behring,  but  this  view  met  with  almost  unanimous  protest. 

There  can  be  only  one  opinion  concerning  the  use  of  formaldehyde 
in  foods,  and  that  is  absolute  condemnation  of  the  practice.  It  is  pro- 
hibited by  the  statutes  of  practically  all  nations  having  pure  food 
laws. 

Salicylic  Acid. — Individuals  differ  greatly  in  their  susceptibility 
to  salicylic  acid.  In  mild  cases  of  poisoning  with  this  substance  there 
is  a  feeling  of  fulness  in  the  head  with  roaring  sounds  in  the  ears, 
dimness  of  vision,  profuse  perspiration,  confusion,  and  dulness.  Large 
doses  of  the  acid  cause  intense  irritation  of  the  throat  and  stomach, 
leading  to  vomiting  and  difficulty  in  swallowing.  Later  there  may  be 
diarrhea.  Eczema  and  other  skin  eruptions  may  appear,  and  dimness 
of  vision  and  deafness  may  continue  for  some  time.  The  long-continued 
use  of  salicylic  acid  and  its  salts  has  led  to  a  form  of  chronic  poisoning 
in  which  the  chief  symptoms  have  been  loss  of  appetite,  diarrhea  al- 
ternating with  constipation,  irritation  of  the  kidneys,  skin  eruptions, 
and  mental  depression.  Such  results  are  said  to  have  followed  the  use 
of  articles  of  diet  preserved  with  salicylic  acid.  The  use  of  such  foods 
may  be  objectionable  in  the  case  of  aged,  feeble,  and  susceptible  per- 
sons. Salicylic  acid  and  the  salicylates  are  more  efficient  antiseptics 
than  boric  acid  or  borax,  but  they  are  not  used  extensively  on  account 
of  the  taste,  or  rather  the  tendency  to  cause  unpleasant  flavors.  They 
are  for  the  most  part  used  in  jams,  fruit  juices,  soda  water  syrups, 
cider,  wines,  and  other  sweet  preparations.  The  objection  to  the  use 
of  salicylic  acid  in  food  is  practically  unanimous  and  well  founded. 

Sodium  ISTiteate. — Sodium  nitrate  or  potassium  nitrate  (saltpeter) 
is  not  used  as  a  preservative,  but  as  an  indirect  coloring  matter.  It 
retains  and  accentuates  the  red  color  of  meat.  It  is  not  known  to  be 
harmful  in  the  small  quantities  in  which  it  is  commonly  employed,  but 
must  be  regarded  as  a  fraud  when  used  to  make  stale  meat  look  fresh. 

Potassium  Peemanganate  is  also  used  on  the  surface  of  meat  to 
destroy  decomposition.  This  may  be  detected  by  heating  a  knife  in 
hot  water,  plunging  it  into  the  meat,  and  withdrawing  it  quickly.  This 
brings  out  the  hidden  odors  of  putrefactive  changes. 

Sodium  Fluorid. — Sodium  fluorid  has  considerable  antiseptic  power, 
putrefaction  being  delayed  by  the  addition  of  1  part  to  500;  and  1  in 
200  arrests  completely  the  growth  of  bacteria.  The  fluorids  are  ab- 
sorbed from  the  alimentary  canal  and  are  excreted  by  the  urine,  but 
this  takes  place  very  slowly,  and  much  of  the  fluorid  is  stored  up  in 
the  body,  some  in  the  liver  and  skin,  but  most  in  the  bones  in  the 
form  of  calcium  fluorid.     Crystals  of  this  very  insoluble  salt  are  found 


490  GENERAL    COXSIDERATTONS 

in  masses  in  the  Haversian  canals,  which  increases  the  hardness  and 
brittlcness  of  the  bones. 

Sulphites. — Sulphites  act  as  antiseptics  and  also  preserve  tlie  red 
color  of  meats.  Sodium  sulphite  and  bisulphite  and  sulphurous  acid 
are  used  principally  upon  fresh  meats,  where  they  act  as  a  preservative 
and  as  a  retainer  of  color.  Sulphur  dioxid  is  also  much  employed 
for  the  bleaching  of  fruits.  Sulphites,  even  in  minute  amounts, 
interfere  with  the  action  of  ferments,  and  thus  influence  digestion. 
Free  sulphurous  acid  is  very  irritating.  Sodium  sulphite  is  very 
poisonous  when  injected  subcutaneously  or  intravenously.  Death  oc- 
curs by  paralysis  of  respiration.  Much  larger  quantities  are  tolerated 
by  the  mouth,  the  sulphite  being  slowly  absorbed.  The  greater  part  is 
converted  to  the  harmless  sulphate  during  and  after  absorption.  The 
quantities  ordinarily  used  in  preserved  food  cause  no  immediate 
symptoms,  even  when  continued  for  several  months.  If,  however,  the 
animals  are  killed  and  examined,  extensive  hemorrhagic  and  inflamma- 
tory lesions  are  found  in  various  organs.^  These  lesions  are  probably 
due  to  destruction  of  red  blood  cells  or  infarction.  Harrington  in  1904 
also  described  nephritic  changes.  In  1898  the  Imperial  Board  of  Health 
in  Germany  forbade  the  use  of  sodium  sulphite  in  food  on  account  of 
its  dangerous  properties,  and  it  is  also  forbidden  by  our  Federal  Pure 
Food  Act  of  1906. 

SoDiuii  Bicarbonate. — Sodium  bicarbonate  is  too  ineffective  as  a 
germicide  for  general  use  as  a  food  preservative.  It  is  sometimes  added 
to  milk  in  order  to  neutralize  the  excess  of  acid. 

Hydrogen  Peroxid. — Hydrogen  peroxid  is  perhaps  one  of  the  less 
dangerous  of  the  chemical  preservatives,  and  is  considered  by  some  to 
exert  no  deleterious  effect  whatever  in  the  quantities  commonly  used. 
It  is  used  for  the  preservation  of  wine,  beer,  and  fruit  juices,  and  also  in 
milk. 

Arsenic. — Arsenic  in  food  comes  from  a  variety  of  sources.  Glu- 
cose is  apt  to  contain  it,  especially  if  impure  acid  is  used  to 
hydrolize  starch  in  the  production  of  glucose.  This  was  the  source  of 
the  arsenic  in  the  beer  wliich  caused  the  epidemic  of  peripheral  neuritis 
several  years  ago  in  England.  Arsenic  may  also  contaminate  certain 
anilin  dyes  as  well  as  shellac,-  which  is  now  so  much  used  as  a  coating 
for  some  kinds  of  cheap  confectionery  and  bakers'  goods,  and  also  as  a 
varnish  on  receptacles  and  containers  of  various  kinds. 

The  use  of  preservatives  containing  lead,  arsenic,  or  other  substances 
known  to  be  poisonous  finds  no  advocates. 

^Kionka  and  Ebstein,  1902. 

-Smith,  B.  H. :  "The  Arsenic  Content  of  Shellac  and  the  Contamination  of 
Foods  from  This  Source,"  Cir.  91,  U.  S.  Dept.  Agr.,  Bureau  of  Chemistry, 
Washington,   1912. 


THE  PREPAEATIOX  OF  FOOD  491 


THE  PREPARATION  OF  FOOD 

Cooking. — Cooking  may  be  regarded  as  the  greatest  sanitary  in- 
novation ever  introduced  by  man  to  protect  himself  against  infection. 
The  heat  required  for  thorough  cooking  kills  all  forms  of  infection  and, 
therefore,  renders  food  safe,  so  far  as  these  dangers  are  concerned.  The 
heat  also  destroys  most  of  the  toxic  products  of  decay;  thus,  the  true 
bacterial  toxines  are  destroyed  at  temperatures  of  about  60°  C.  Foods 
may  sometimes  contain  heat-resisting  poisons.  Thus,  boiling  has  no 
effect  upon  muscarin,  the  poisonous  principle  in  certain  toadstools. 
Heat  also  does  not  destroy  a  poisonous  principle  sometimes  found  in 
mussels.  The  colon  bacillus  and  other  microorganisms  produce  ther- 
mostable substances  that  are  poisonous  when  injected  into  the  lower 
animals,  but  the  relation  of  these  heat-resisting  toxic  substances  to  food 
poisoning  in  man  is  not  at  all  understood.  It  is  highly  improbable 
that  foods  ordinarily  contain  heat-resisting  poisons  resulting  from  bac- 
terial decomposition. 

Trichina  die  at  65°  C. ;  cysticerci,  or  the  larval  stage  of  tapeworms, 
at  52°  C;  the  non-sporulating  bacteria  are  for  the  most  part  destroyed 
at  60°  C.  Food  thoroughly  cooked  throughout  will  always  reach  these 
temperatures,  but  much  meat  and  many  vegetable  food  substances  are 
preferred  rare  or  underdone,  and.  while  the  outside  of  a  large  piece  of 
meat  may  be  thoroughly  cooked  or  even  charred,  the  interior  may  be 
practically  raw  or  at  least  not  have  reached  the  temperature  necessary 
to  destroy  parasites. 

Meat  that  is  well  cooked  throughout  always  reaches  from  60° -70°  C 
on  the  inside.  It  should  be  remembered  that  heat  penetrates  a  large 
piece  of  meat  slowly.  For  example,  it  recjuires  II/2  hours  in  boiling 
water  for  the  temperature  to  reach  62°  C.  in  the  interior  of  a  piece 
of  meat  weighing  3I/2  pounds.  Meat  placed  in  a  cjuick  oven  or  broiled 
soon  forms  a  hard  coagulated  and  insulated  coating  that  retains  the 
juices,  but  retards  the  penetration  of  the  heat. 

Cooking  softens  the  connective  tissue  and  renders  meat  more  ten- 
der. The  bundles  of  fibrillffi  are  loosened  from  each  other,  the  albumin 
is  coagulated,  the  flavors  are  improved,  and  new  flavors  are  developed, 
all  of  which  enhances  its  digestibility. 

Metchnikoff  in  his  '^^new"  hygiene  dwells  upon  the  great  sanitary 
value  of  cooking.  Perhaps  no  other  single  factor  in  preventive  medi- 
cine protects  us  to  an  equal  degree  against  infection.  Metchnikoff 
believes  that  we  should  eat  nothing  in  its  raw  state.  This  seems  almost 
as  extreme  as  the  cult  which  proclaims  the  contrary. 

One  of  the  important  functions  in  the  preparation  of  food  is  to 
render  it  savory,  tender,  and  appetizing.     Foods  that,  appear  inviting 


493  GENERAL    CONSIDERATIONS 

aid  digestion  by  stimulating  the  secretion  and  flow  of  the  digestive 
juices.  Foods  that  are  rendered  soft  and  tender  are  more  readily  di- 
gested, but  it  should  not  be  forgotten  that  the  teeth  need  exercise  to 
keep  them  in  good  condition.  Tough  meats  may  be  pounded  to  separate 
the  connective  tissue  bundles,  or  may  be  chopped  or  minced  as  an  arti- 
ficial aid  to  mastication,  or  may  be  steeped  for  several  hours  in  fresh 
milk  or  sour  milk,  in  which  case  the  fibers  are  softened  through  the 
action  of  the  bacteria  and  their  enzymes.  In  the  case  of  vegetables, 
cooking  breaks  open  and  softens  the  cellulose  envelopes  and  fibers ;  the 
starch  grains  swell  and  burst,  and  the  insoluble  starch  is  converted  into 
soluble  starch  or  dextrine. 

Fermentation  is  of  great  use  in  the  preparation  of  foods.  The 
best  example  is  the  leavening  of  bread.  The  yeast  ferments  the  carbo- 
hydrates in  the  flour  with  the  production  of  carbon  dioxid  and  alcohol. 
The  carbon  dioxid  renders  the  bread  porous;  the  gas  is  held  within  the 
loaf  on  account  of  the  glutenous  property  of  the  protein  (gluten)  in 
the  flour.  Fermentation  is  an  adjunct  in  the  preparation  of  many 
other  foods  and  beverages,  such  as  cheese,  sauerkraut,  vinegar,  beer, 
wine,  cider,  etc. 

The  observations  of  Becker,  Grove,  and  others  concerning  the  heat 
of  cooking  are  practical  and  important  in  the  preparation  of  food.  Ex- 
posure to  steam  at  60°  to  70°  C.  for  a  long  time  has  the  advantage  of 
cooking  foods  thoroughly  throughout.  This  treatment  prevents  burning 
or  the  results  of  overheating;  the  juices  are  retained.  Tlie  process 
requires  little  or  no  attention.  Meat  is  thereby  rendered  tender  and 
juicy,  vegetables  thoroughly  soft,  and  the  starch  grains  are  all  opened. 
A  modification  of  this  method  is  found  in  the  fireless  cookers  now 
offered  for  sale  in  various  forms.  These  devices  consist  simply  of  a 
well-insulated  box.  The  food  is  first  heated,  then  placed  in  suitable 
compartments,  and  a  temperature  above  70°  C.  maintained  for  many 
hours. 

Certain  precautions  are  advisable  in  the  choice  of  pots  and  pans 
used  in  cooking.  Brass  and  copper  are  not  advisable,  and  if  used  must 
be  kept  scrupulously  clean.  Acid  foods  should  not  be  cooked  in  copper 
vessels,  and  milk  and  saccharin  substances  sliould  not  be  kept  in  cop- 
per containers  on  account  of  the  possibility  of  the  organic  acids  dis- 
solving the  copper.  Tin,  nickel,  and  aluminiumware  are  least  objec- 
tionable. Enameled  ware  is  entirely  satisfactory,  provided  it  does  not 
contain  lead. 

Methods  of  Cooking. — Much  depends  upon  the  method  of  cooking. 
The  principal  methods  in  ordinary  use  are:  roasting,  broiling,  boiling, 
frying,  and  stewing. 

Roasting  or  broiling  causes  considerable  shrinking,  due  mainly  to 
loss  of  water.     The  heat  coagulates  the  exterior  of  the  meat  and  thus 


THE    PKEPARATION    OF    FOOD  493 

prevents  the  further  loss  of  juices  and  drying  up.  In  order  to  obtain 
adequate  heating  of  the  meat  throughout  a  large  joint  without  burning 
and  drying  the  exterior,  it  is  necessary  to  baste  it  from  time  to  time 
with  hot  melted  fat.     This  also  helps  to  form  a  protective  coating. 

In  BOiLiXG  the  meat  is  placed  either  in  cold  or  hot  water,  depending 
upon  the  object  desired.  If  it  is  desired  to  maintain  the  flavors  within 
the  mass,  the  meat  should  be  plunged  into  boiling  water.  This  quickly 
coagulates  the  albumins  at  the  surface.  If  a  rich  broth  is  desired  the 
meat  should  be  placed  in  cold  water  and  gradually  heated.  In  this 
way  the  soluble  albumins  and  extractives  pass  out  into  the  surrounding 
water.  The  albumin  of  meat  begins  to  coagulate  at  134°  F. ;  the  con- 
nective tissue  is  changed  to  gelatin  and  dissolved  above  160°  F. 

Feting  consists  in  placing  meat  or  other  substances  into  very  hot 
fat,  lard,  or  vegetable  oil.  This  causes  a  speedy  coagulation  of  the 
surface  similar  in  all  respects  to  that  brought  about  in  the  process  of 
boiling.  The  flavors  and  juices  are  thereby  retained.  If  the  fat  is 
not  very  hot  it  will  penetrate  the  tissues  and  cause  the  meat  or  other 
substance  to  become  greasy  and  unpalatable.  Fried  substances  are 
apt  to  be  indigestible  on  account  of  the  large  amount  of  grease  that 
adheres  to  and  j^enetrates  into  them. 

In  STEAViNG  the  meat  is  cut  into  small  pieces  and  placed  in  cold 
water,  which  then  is  heated  slowly  to  about  180°  F.,  at  which  the  whole 
is  kept  for  several  hours.  If  heated  above  180°  F.  the  meat  becomes 
tough,  stringy,  unpalatable,  and  of  diminished  digestibility. 


CHAPTER    II 
ANIMAL    FOODS:     MILK 

The  animal  foods  used  by  man  are  not  of  great  variety  and  source. 
They  include  the  flesh  and  various  organs  of  the  herbivorous  animals, 
swine,  domestic  and  wild  fowl,  eggs,  fish,  shellfish,  insects  and  their 
products  (honey),  milk,  and  milk  products.  The  flesh  of  carnivorous 
animals,  except  that  of  fish,  is  unpalatable  and,  therefore,  undesirable 
as  a  food. 

The  most  important  animal  foods  from  the  standpoint  of  the  sani- 
tarian are  milk  and  meat. 

MILE 

Milk  is  responsible  for  more  sickness  and  deaths  than  perhaps  all 
other  foods  combined.  There  are  several  reasons  for  this:  (1)  bacteria 
grow  well  in  milk;  therefore,  a  very  slight  infection  may  produce  wide- 
spread and  serious  results;  (2)  of  all  foodstuffs  milk  is  the  most  diffi- 
cult to  obtain,  handle,  transport,  and  deliver  in  a  clean,  fresh,  and 
satisfactory  condition;  (3)  it  is  the  most  readily  decomposable  of  all 
our  foods;  (4)  finally,  milk  is  the  only  standard  article  of  diet  obtained 
from  animal  sources  consumed  in  its  raw  state. 

The  total  milk  production  in  the  L'nited  States  in  1911  was  ten 
billion  gallons.  One-quarter  of  tliis  is  consumed  as  milk  and  the  re- 
maining three-quarters  is  used  for  butter  and  cheese.  The  average 
per  capita  consumption  of  milk  in  the  United  States  is  0.6  of  a  pint 
daily.  More  milk  is  used  in  the  Xorth  than  in  the  South ;  very  little 
in  the  tropics,  and  practically  none  at  all  in  China,  Japan,  and  some 
other  countries.  About  16  per  cent,  of  the  average  dietary  in  the  United 
States  consists  of  milk  and  milk  products. 

Fresh  milk  products  may  be  quite  as  dangerous  as  the  milk  from 
which  they  are  made.  Milk  laws  which  ignore  milk  products  are  in- 
complete from  the  sanitary  side,  and  will  fail  to  accomplish  their  pur- 
pose from  the  economic  side. 

Milk  is  a  perfect  food  for  the  suckling.  It  contains  all  the  essen- 
tial elements  of  a  well-balanced  diet  for  the  adult,  and  at  prevailing 
494 


MILK  495 

prices  it  is  one  of  the  cheapest  of  the  standard  articles  of  diet.  Fur- 
thermore, it  is  readily  digestible  and  is  capable  of  a  great  variety  of 
modifications.  The  sanitarian,  therefore,  has  every  reason  to  encourage 
the  use  of  pure  milk  as  well  as  to  discourage  the  use  of  impure  milk. 

Composition. — Milk  is  the  secretion  of  the  mammary  gland.  In 
composition  it  is  exceedingly  complex,  consisting  chiefly  of  water; 
several  proteins  in  colloidal  suspension;  fats  in  emulsion;  sugar,  and 
a  number  of  inorganic  salts  in  solution;  also  enzymes,  as  well  as  anti- 
bodies, cells,  gases,  and  other  substances.  Milk  from  all  animals 
shoM^s  a  general  agreement  in  physical  properties  and  composition,  con- 
taining essentially  the  same  ingredients,  but  exhibiting  differences  in 
the  amounts  of  the  several  constituents. 

In  the  fresh  state  milk  is  a  yellowish  white,  opaque  fluid.  Cow's 
milk  has  a  specific  gravity  of  1.027  to  1.035 ;  it  freezes  at  a  temperature 
somewhat  lower  than  the  freezing  point  of  water  ( — 0.554°  C.) ;  the 
electrical  conductivity  is  43.8X10-4  for  cow's  milk,  and  22.6X10"^ 
for  human  milk.  In  other  words,  58  per  cent,  of  the  molecules  in  cow's 
milk  and  26  per  cent,  in  human  milk  are  dissociated.  The  specific 
heat  of  milk  containing  3.17  per  cent,  of  fat  is  0.9457.  The  coeffi- 
cient of  expansion  is  greater  than  that  of  water.  Milk  shows  no  maxi- 
mum of  density  above  1°  C. 

Freshly  drawn  milk  of  carnivorous  animals  is,  as  a  rule,  acid  in 
reaction.  This  is  probably  due  to  CO2  and  acid  phosphates.  Human 
milk  and  that  of  most  of  the  herbivora  are  slightly  alkaline;  cow's  milk 
has  been  described  as  amphoteric. 

Under  the  microscope  milk  is  found  to  contain  fat  globules  and  cells, 
as  well  as  bacteria,  debris,  and  other  objects. 

The  gases  dissolved  in  milk  ^  are  oxygen,  nitrogen,  and  carbon 
dioxid  (3  to  4  per  cent,  by  volume).  Oxygen  and  nitrogen  are  car- 
ried into  milk  mechanically  from  the  air  in  the  process  of  milking. 
Other  substances  found  in  milk,  but  in  small  quantities,  are  lecithin, 
cholesterin,  citric  acid,  lactosin,  orotic  acid,  and  ammonia. 

The  composition  of  cow's  milk  may  be  understood  from  the  scheme 
prepared  by  Lucius  L.  Van  Slyke,  given  on  page  496. 

Proteins. — The  three  proteins  constantly  found  in  milk  are  casein, 
lactalbumin,  and  lactoglobulin.  A  trace  of  fibrin,  mucin,  and  other 
proteins  sometimes  occurs. 

The  proteins  in  milk  of  a  given  species  are  quite  constant  both  in 
composition  and  amount;  it  is,  therefore,  not  necessary,  as  a  rule,  to 
make  a  special  analysis  for  them.  They  may  be  estimated  by  subtract- 
ing the  fat,  sugar,  and  ash  from  the  total  solids. 

Casein  is  a  highly  specialized  protein  found  in  the  secretion  of  the 
milk  glands  of  all  mammals,  but  nowhere  else  in  nature ;  it  is  a  nucleo- 

^  When  not  otherwise  specified,  in  this  section  milk  refers  to  cow 's  milk.. 


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MILK  497 

albumin,  and  as  such  contains  phosphorus.  It  is  soluble  in  water,  and 
by  virtue  of  its  property  as  an  acid  it  forms  soluble  salts  with  alkalies. 
There  are  two  series  of  casein  salts,  basic  and  neutral;  solutions  of  the 
latter  have  a  milky  appearance.  In  milk,  casein  is  found  dissolved  in 
the  form  of  a  neutral  calcium  salt,  which  accounts  in  part  for  the  white 
opalescent  appearance  of  milk.  Casein  exists  in  milk  in  the  form  of 
caseinogen,  that  is,  casein  in  combination  with  calcium  phosphate.  The 
caseinogen  is  held  in  solution  by  the  calcium  phosphate.  It  is  not 
coagulated  by  heat,  but  is  precipitated  by  acids,  for  the  reason  that 
acids  take  the  calcium  from  the  calcium  phosphate,  and  thus  throw 
the  casein  out  of  solution  as  a  curd.  This  flaky  or  lumpy  precipitate 
is  again  soluble  in  lime  water  and  dilute  alkalies.  Casein  is  also  thrown 
out  of  solution  by  rennin. 

Lactalhumin  is  very  similar  to  the  serum  albumin  of  the  blood,  but 
it  appears  to  differ  from  this  in  some  particulars.  It  coagulates  by 
heating  to  70°  C,  but  not  with  dilute  acids,  and  is  precipitated  by  a 
saturated  solution  of  ammonium  sulphate,  but,  like  all  other  albumins, 
is  not  precipitated  in  a  neutral  solution  of  sodium  chlorid  and  mag- 
nesium sulphate.  Lactalbumin  contains  sulphur  but  no  phosphorus. 
It  is  present  in  amounts  varying  from  0.2  to  0.8  per  cent.,  but  is  much 
more  abundant  in  colostrum. 

Lactoglohulin  occurs  in  milk  in  very  small  quantities,  merely  in 
traces,  while  colostrum  is  comparatively  rich  in  this  protein.  It 
coagulates  at  75°  C,  it  is  precipitated  in  the  same  way  as  serum  globu- 
lin, and,  like  serum  globulin,  is  insoluble  in  water,  but  is  soluble  to 
some  extent  in  weak  salt  solution. 

Fat. — The  fat  is  suspended  in  the  milk  serum  in  the  form  of  an 
emulsion.  The  droplets  or  globules  vary  in  size.  On  the  average  they 
are  smaller  in  milk  from  Holstein  than  from  Jersey,  Guernsey,  or  short- 
horned  breeds.  Under  the  microscope  some  of  the  fat  globules  seem  to 
have  an  albuminous  membrane,  but  this  interpretation  is  now  ques- 
tioned. The  fat  droplets  are  lighter  than  the  milk  serum,  hence  they 
rise  on  standing  (gravity  cream),  or  they  may  readily  be  separated  by 
centrifugal  force  (centrifugal  cream).  Cream,  or  top  milk,  does  not 
consist  of  fat  alone,  but  contains  all  the  constituents  of  the  milk;  it 
is  simply  milk  rich  in  fat.  Upon  shaking  the  fat  globules  gradually 
coalesce  into  larger  drops  and  lumps  to  form  butter. 

The  first  milk  drawn  from  the  udder  is  commonly  poor  in  fat. 
This  is  known  as  "fore"  milk.  The  middle  portion  contains  about  the 
average  percentage  of  fat,  and  the  last,  known  as  "strippings,"  is  al- 
ways the  richest  in  fat.  The  strippings  may  contain  as  much  as  9  or 
10  per  cent,  butter  fat. 

Heat  increases  the  viscosity  of  milk,  and  hence  hinders  the  rising 
of  the  fat  drops;  68°  C.  is  the  critical  temperature;  if  heated  above  this 


498  AXniAL    FOODS 

point  for  any  length  of  time  tlie  formation  of  the  cream  line  is  retarded 
or  prevented.  For  this  and  other  reasons  the  ricliness  of  milk,  there- 
fore, cannot  always  he  judged  by  tlie  deptli  of  the  cream  layer. 

Milk  fat  consists  of  a  mixture  of  dilferent  neutral  fats,  the  prin- 
cipal of  which  are  olein.  palmitin,  and  stearin.  These  are  neutral  tri- 
glycerids  of  tlie  corresponding  fatty  acids.  Besides  these  are  found  the 
triglycerids  of  miristic.  butyric,  and  caprylic  acids.  The  last  two  are 
volatile  and  give  to  butter  its  characteristic  odor  and  flavor.  The  com- 
position of  the  fat  is  subject  to  variation,  depending  upon  racial  or 
individual  peculiarities,  also  upon  the  character  of  the  food  and  other 
conditions. 

The  percentage  of  butter  fat  in  milk  has  long  been  one  of  the 
standards  by  which  milk  is  tested.  The  richness  of  milk  gaged  by 
the  amount  of  fat  it  contains  is  more  of  an  economic  than  a  sanitary 
question.  Milk  with  a  low  percentage  of  fat  from  Holstein  cows  is 
relatively  just  as  nutritious  a  food  as  richer  milk  from  Jersey  and 
Guernsey  cows;  even  skimmed  milk  containing  little  or  no  fat  is  a 
valuable  food.  The  problem  is  one  of  honest  labeling  and  the  market- 
ing of  various  grades  at  prices  corresponding  to  their  nutritive  con- 
tents. When  the  standard  for  butter  fat  in  milk  is  relatively  low,  say 
3.25  per  cent.,  it  is  a  temptation  for  dairy  men  to  remove  the  excess. 
This  is  a  fraudulent  practice  which  should  not  be  countenanced.  A  high 
fat  standard  encourages  the  breeding  of  better  cows;  requires  caution 
in  their  feeding  and  care,  and  puts  a  premium  upon  good  dairy  methods. 

In  normal  milk  the  larger  proportion  of  the  fat  droplets  agglutinate 
into  tiny  clusters  or  masses.  At  a  temperature  of  65°  C.  or  above  these 
clusters  are  broken  up  and  the  globules  are  more  homogeneously  dis- 
tributed throughout  the  liquid.  When  milk  is  subjected  to  a  pressure 
of  about  3,000  pounds  at  a  temperature  of  about  75°  C.  the  individual 
fat  globules  are  broken  up  into  fine  particles,  which  remain  as  a  uni- 
form and  permanent  emulsion  known  as  "homogenized  milk."  This 
process  applied  to  cream  increases  its  viscosity,  so  that  cream  contain- 
ing 20  per  cent,  butter  fat  appears  to  have  the  body  and  richness  of 
a  30  per  cent,  cream. 

Eesearches  of  Heubner.  Keller,  and  Czerny  show  that  the  fats  and 
not  the  proteins  are  the  cause  of  much  of  the  digestive  disturbances  in 
infants.  "Wlien  the  fat  is  excessive  in  amount  the  infant  at  first  seems 
to  thrive,  but  sooner  or  later  loses  weight  and  appetite,  and  shows  other 
sjTuptoms,  associated  with  stools  composed  largely  of  fat  soaps  and  of 
a  pale  gray,  hard,  and  dry  constituency.  The  alkaline  bases  are  so 
largely  drawn  upon  from  the  body  to  saponify  the  excessive  amount  of 
fat  in  the  intestines,  that  a  condition  resembling  acidosis  may  appear; 
furthermore,  fermentative  changes  take  place  in  the  intestines  and  the 
"catastrophe""  ensues. 


MILK 


499 


Fat  is  the  most  variable  constituent  in  milk.  The  amount  varies 
with  different  animals,  and  even  in  the  same  animal  from  time  to  time. 

Milk  Sugae^  or  Lactose. — Milk  sugar,  or  lactose  (CioHooOii),  is 
peculiar  to  milk;  it  is  found  nowhere  else  in  nature.  Its  formation 
is  not  understood.  Commercially,  milk  sugar  is  obtained  from  whey 
as  hard  rhombic  crystals,  which  have  a  slightly  sweet  taste  and  are 
soluble  in  six  parts  of  cold  water.  Lactose  is  readily  acted  upon  by 
microorganisms  and  reduced  to  glucose  and  galactose;  the  glucose  is 
further  changed  to  lactic  acid.  This  is  the  common  cause  of  sour 
milk  (see  The  Fermentation  of  Milk,  page  507). 

Lactose,  like  glucose,  reduces  Fehling's  solution  when  heated;  it  is 
dextrorotary.  When  heated  above  the  boiling  point  of  water  it  changes 
to  a  brownish  color  as  a  result  of  the  formation  of  lactocaramel. 

The  amount  of  lactose  in  milk  of  any  given  species  is  remarkably 
constant. 

Milk  Standards. — Milk  that  meets  standard  requirements  is  not  nec- 
essarily standard  milk.  The  legal  standards  are  minimum  requirements 
and  express  inferiority,  if  anything.  The  standards  are  the  lowest 
grades  that  the  law  will  permit.  There  are,  in  fact,  three  standards 
by  which  milk  should  be  judged:  (1)  the  chemical  standards;  (2)  bac- 
teriological standards;  (3)  standards  determined  by  inspection.  All 
three  are  necessary  for  the  satisfactory  control  of  the  milk  supply. 

The  principal  chemical  standards  are  those  for  butter-fat  and  total 
solids.  The  legal  requirements  for  the  butter-fat  and  total  solids  in 
milk  vary  somewhat  in  different  states,  as  shown  by  the  following  table : 


LEGAL  REQUIREMENTS 


Fat 
per  cent. 


SoHds 
not  fat  ^ 
per  cent. 


Total 

solids 

per  cent. 


3.0 


3.2 
3.25 


3.35 
3.5 


Idaho 

California,  Illinois,  New  Jersey,^  New 
York,^  Wisconsin 

Montana,  North  Dakota,  Ohio,  Porto  Rico .  .  . 

lowa,^  Michigan,!  Oklahoma^ 

Oregon,  Utah 

Association  of  Official  Agricultural  Chemists, 
Connecticut,  Georgia,  Indiana,  Ken- 
tucky, Maine,  Missoui'i,  North  CaroLLna, 
South  Dakota,  Tennessee,  Texas,  Virginia 

Washington ■ 

Massachusetts  ^ 

Hawaii  ^ 

District  of  Columbia,  Maryland  ^ 

Louisiana,  New  Hampshire 


8.0 


11.0 


8.5 

11.5 

9.0 

12.0 

9.5 

12.5 

9.0 

12.2 

8.5 

11.75 

8.75 

12.00 

8.8 

12.15 

8.0 

11.5 

9.0 

12.5 

9.5 

13.0 

1  These  states  marked  do  not  directly  specify  the  solids  not  fat.  The  figure 
given  in  such  cases  is  the  difference  between  the  required  total  solids  and  the  re- 
quired fat. 


500  ANIMAL    FOODS 

It  has  been  found  an  advantage  to  keep  the  butter-fat  standard  rela- 
tively high  and  the  total  solids  at  a  minimum  of  12  per  cent.  This 
allows  8.5  per  cent,  for  solids  not  fat,  such  as  the  proteins,  milk  sugar, 
and  inorganic  salts.  A  3.25  per  cent,  butter-fat  and  a  12  per  cent, 
total  solids  is  the  minimum  that  should  be  allowed. 

If  the  law  recognizes  a  low  standard  for  total  solids,  it  permits 
manipulation  of  the  milk,  such,  for  example,  as  adding  water.  It  also 
encourages  the  production  of  milk  from  inferior  cows.  High  standards 
encourage  good  dairy  methods,  require  good  feed,  and  place  a  premium 
upon  the  better  breeding  of  milch  cows. 

The  determination  of  fats  and  total  solids  is  used  to  detect  skim- 
ming or  watering;  however,  it  is  possible  to  skim  milk  or  water  it, 
within  limits,  without  the  possibility  of  detecting  it  through  the  fats 
and  total  solids. 

If  dependence  is  placed  upon  the  total  solids,  mistakes  may  also 
occur.  The  total  solids  represent  the  proteins,  fats,  sugar,  and  inorganic 
salts.  They  may  readily  be  tampered  with.  Thus  sugar  may  be  added 
to  replace  the  cream  tliat  is  taken  off. 

Ferments  or  "Life"  in  Milk. — ]\Iilk  contains  a  large  number  of  very 
active  ferments  or  enzymes.  These  substances  are  the  nearest  approach 
to  'life"  that  we  know  of  in  milk.  Milk  also  possesses  certain  other 
properties  common  to  blood  and  living  tissues,  but,  while  milk  may 
properly  be  regarded  as  a  vital  fluid,  it  possesses  none  of  the  funda- 
mental properties  of  life.  In  fact,  milk  begins  to  decay  the  moment 
it  is  drawn;  ofttimes  decomposition  begins  while  the  milk  is  still  within 
the  udder.  It  would,  therefore,  be  more  proper  to  regard  milk  as  a 
dead  fluid,  in  the  same  sense  that  shed  blood  is  dead. 

The  ferments  are  believed  to  be  important  to  the  infant,  and  this 
importance  has  been  emphasized  especially  since  the  introduction  of 
pasteurization,  for  the  reason  that  a  high  degree  of  heat  destroys  them. 
Some  of  the  ferments  in  milk  are  normal  constituents  of  that  secretion, 
while  others  are  produced  by  bacteria.  Many  tests  have  been  devised 
to  determine  the  kinds  and  activity  of  the  ferments  in  milk.  The 
tests  most  frequently  and  successfully  used  are  those  for  catalases  and 
reductases.  The  absence  of  ferments  in  milk  indicates  that  it  has  been 
heated.  The  presence  of  certain  ferments  gives  an  indication  of  the 
age  of  the  milk,  the  number  of  bacteria  it  contains,  and  also  lielps  to 
distinguish  between  fresh  normal  milk  and  pathologically  changed  milk. 

The  enz}Tnes  in  milk  are  the  following: 

Galactase. — Galactase  is  a  proteolytic  ferment,  similar  to  trypsin. 
It  was  found  by  Babcock  and  Russel  to  be  abundant  in  separator  slime. 
Ordinarily  galactase  by  itself  acts  too  slowly  to  cause  any  material 
change  in  the  proteins  in  the  short  intervals  which  elapse  between  the 
withdrawal  of  the  milk  from  the  animal  and  its  consumption  as  food. 


MILK  501 

Snyder  claims  that  this  enzyme  probably  assists  digestion,  in  that  when 
milk  is  used  in  a  mixed  diet  the  proteins  have  been  found  to  be  from 
4  to  5  per  cent,  more  digestible  than  when  milk  is  omitted  from  the 
diet. 

Laciohinase. — Hougardy  has  recently  shown  that  milk  contains  a 
ferment  or  a  kinase  similar  to  enterokinase.  Lactokinase  has  been 
found  to  accelerate  the  digestion  of  proteins  by  pancreatic  juice.  This 
property  is  destroyed  by  heating  the  milk  at  73°  to  75°  C. 

Lipase. — This  fat-splitting  ferment  was  found  in  milk  by  Marfan 
and  Gillet.  Human  milk  exhibits  this  property  to  a  higher  degree 
than  cow's  milk.  The  former  has  a  lipoMic  activity  of  20  to  30  on 
Harriot's  scale,  while  cow's  milk  shows  an  activity  of  only  6  to  8. 
Lipase  withstands  cold,  but  is  destroyed  by  heating  to  65°  C. ;  it  is 
monodialyzable  and  is  held  back  by  a  porcelain  filter.  It  probably 
hydrolyzes  the  higher  fats  of  milk,  at  least  to  some  extent,  and  may 
possibly  account  for  a  small  part  of  the  acidity  of  some  milk. 

Catalase. — Milk  contains  no  true  oxidases  or  oxidizing  ferments 
proper  (Kastle).  It  decomposes  hydrogen  peroxid  and  has  the  power 
of  effecting  the  oxidation  of  a  considerable  number  of  easily  oxidizable 
substances  in  the  presence  of  hydrogen  peroxid  or  ozonized  oil  of  tur- 
pentine. In  other  words,  milk  contains  catalase  and  peroxidase.  Cata- 
lase is  widely  distributed  among  animals  and  plants.  Jolles  has  pointed 
out  that  human  milk  decomposes  five  or  six  times  as  much  hydrogen 
peroxid  as  cow's  milk.  Considerable  importance  has  been  attached  to 
this  difference,  which  has  also  been  used  to  distinguish  human  milk 
from  cow's  milk.  Little  is  known  of  the  function  of  catalase.  Hy- 
drogen peroxid  is  probably  formed  in  both  animal  and  vegetable  tis- 
sues during  vital  activities.  The  catalase  would  destroy  it  and  thus 
prevent  its  accumulation  in  the  cell,  which  otherwise  would  destroy 
its  life. 

Peroxidases. — IMilk  contains  substances  capable  of  inducing  the 
oxidation  of  guaiacum  and  other  readily  oxidizable  substances  by  means 
of  hydrogen  peroxid  or  ozonized  oil  of  turpentine.  These  substances 
are  known  as  peroxidases.  The  peroxidases  are  destroyed  when  milk 
is  heated  to  80°  C.  The  color  reactions  for  these  ferments  are  a  con- 
venient test  to  determine  whether  milk  has  been  heated  beyond  a  cer- 
tain temperature  or  not.  The  interpretation  of  this  reaction  must, 
however,  be  guarded,  as  Gillet  and  Kastle  found  that  even  normal  fresh 
milks  vary  in  the  amount  of  peroxidases  which  they  contain. 

Reductases. — Eaw  milk  possesses  reducing  projDerties;  for  example, 
it  reduces  Schardinger's  reagent,  which  consists  of  a  solution  of  methy- 
lene blue  containing  small  amounts  of  formaldehyde. 

Diastase  (Amylase). — Bechamp  in  1882  isolated  from  milk  a  fer- 
ment which  liquefies  starch  and  converts  it  into  sugar  as  readily  as 
34 


502 


AMMAL    i-UUDS 


diastase.      These  observations   have  not   been  confirmed   by   recent   in- 
vestigation (Mora,  Van  De  Vekle,  and  Landtsheer,  or  Kastle). 

TiiEHMAL  Death  Point  of  Milk  Enzymes. — The  influence  of 
temperature  on  the  activity  of  milk  enzymes  is  very  much  like  enzymes 
from  other  sources.  All  of  this  great  group  of  substances  stand  in 
such  intimate  and  close  relation  to  the  vital  activities  of  the  cell  that 
all  those  conditions  and  influences  which  tend  to  destroy  the  one  tend 
also  to  destroy  the  other.  All  of  the  bacteria  in  milk  cannot  be  de- 
stroyed without  rendering  the  ferments  in  milk  inactive;  but  the  non- 
spore-bearing  bacteria  can  be  killed  without  appreciable  harm  to  the 
ferments,  for  in  general  the  ferments  have  a  higher  thermal  death  point 
than  such  bacteria.  The  activity  of  ferments  begins  to  be  influenced  at 
60°  C,  and  is  seriously  affected  at  70°  C;  at  80°  C.  they  are  destroyed. 
The  non-spore-bearing  bacteria  are  destroyed  at  60°  C.  It  is,  therefore, 
possible  to  destroy  all  the  serious  infections  in  milk,  so  far  as  man  is 
concerned,  without  influencing  its  "life,"  so  far  as  the  ferments  are 
concerned.  In  fact,  it  has  been  shown  that  milk  heated  to  60°  C.  in- 
creases the  activity  of  some  of  the  ferments,  notably  tlie  peroxidases. 

ENZYMES  IN  MILK  AND  THEIR  THERMAL  DEATH  POINTSi 


Galactase — Proteolylic  ferment 

70°  for  10  minutes  retards  its  action.  76°  for 
10  minutes  destro3\s  its  digestive  power. 
(Babcock  and  Russell.)  Not  weakened  at 
60°  for  one  hour,  (von  Freudenreich.) 
Withstands  65°  for  half  an  hour.  (Hippius.) 

Lactokinase — Accelerates  pancreatic 
digestion 

Destroj's  at  73°  to  75°  C.  for  haK  an  hour. 
Enfeebled  at  75°  for  20  minutes.     (Hon- 

gardy.) 

Lipase — Fat-splitting  ferment 

Destroys  at  70°  C.  (Harriot.)  Destroys  at 
65°  to  70°  C.  (Kastle  and  Loewenhart.) 
Withstands  60°  for  one  hour.     (Hippius.) 

Catalase — Decomposes  H2O2,  etc.  .  . . 

? 

Peroxidase  —  Oxidizes  guaiacum,  etc . 

Destroyed  at  79°  C.  (Marfan.)  Destroys 
at  76°  C.     (Hippius.) 

Reductase — A  reducing  ferment .... 

Existence  is  doubtful  in  Milk. 

Diastase — Converts  starch  into  sugar. 

Probably  does  not  exist  in  Milk.  Diastasein 
saliva  destroj'ed  at  65°  to  70°  C. 

Compiled  from  Kastle. 


"Leukocytes"  in  Milk. — A  large  number  of  cells  are  normally  pres- 
ent in  milk.  These  are  not  to  be  regarded  as  the  result  of  inflamma- 
tion, unless  they  have  the  characteristics  of  pus  "cells."  Those  found  in 
normal  milk  are,  for  the  most  part,  degenerated  epithelial  cells.  The 
number  of  cells  in  milk  is  greatly  increased  in  the  presence  of  garget; 
toward   the   end   of   lactation ;    on    approaching   calving   time ;    during 


MILK 


503 


periods  of  excitement,  and  various  other  factors.  A  leukocytic  content 
of  500,000  or  over  to  the  cubic  centimeter,  especially  in  a  mixed  milk, 
is  regarded  by  the  Boston  Board  of  Health  as  suggestive  of  some  in- 
flammatory condition  of  the  udder,  more  particularly  if  associated  with 
streptococci.  Such  milk  is  excluded  until  after  satisfactory  veterinary 
inspection  of  the  herd. 

Various  methods  have  been  proposed  to  count  the  number  of  cells 
in  milk   (see  Microscopic  Examination,  page  5.25). 

The  Excretion  of  Drugs  in  Milk. — The  following  drugs  taken  by 
the  mouth  have  been  found  in  the  milk  of  nursing  women:  aspirin, 
iodin,  mercury  (calomel),  arsenious  acid,  potassium  bromid,  and  prob- 
ably also  urotropin  (hexamethylamin),  salicylic  acid,  and  salicylates, 
ether,  antipyrin,  bromids.  and  many  others;  the  list  is  very  long.  It  is 
probable  that  opium,  all  volatile  oils,  purgative  salts,  and  rhubarb  are 
excreted  to  a  certain  extent  in  the  milk.  It  is  well  known  how  readilv 
the  flavor  of  cow's  milk  is  affected  by  turnips,  garlic,  wild  onions,  moldy 
hay  and  grain,  or  damaged  ensilage.  Fermented  distillery  waste  gives 
a  bad  flavor  and  may  also  cause  the  secretion  of  small  quantities  of 
alcohol  in  the  milk.  The  importance  of  these  facts  is  self-evident. 
Cows  in  pastures  sometimes  feed  on  poisonous  weeds,  and  these  poisons 
may  pass  into  the  milk.  In  the  production  of  certified  milk,  cows  are 
never  allowed  to  graze,  but  are  given  carefully  selected  feed.  Certain 
substances,  as  ensilage,  when  fed  to  cows,  cause  a  laxative  property  to 
appear  in  the  milk,  and  thus  it  is  possible  to  affect  the  baby  through 
the  feed  of  the  cow. 

The  Differences  Between  Cow's  Milk  and  "Woman's  Milk. — The  fol- 
lowing table  from  Eotch  summarizes  the  principal  points  of  differences 
between  cow's  milk  and  human  milk : 


Woman's  Milk  Directly  from  the  Breast 


Cow's  Milk,  Freshly  Milked 


Reaction,  amphoteric  (more  alkaline  than  acid) .  . 

Water,  87  to  88  per  cent 

Mineral  matter,  0.20  per  cent 

Total  solids,  13  to  12  per  cent 

Fats,  4.00  per  cent,  (relatively  poor  in  volatile 
glycerids) 

Milk  sugar,  7.00  per  cent 

Proteids.  1.50  per  cent 

Caseinogen,  M  to  3^  of  the  total  proteids 

WTiej'-products,  %  to  K  of  the  total  proteids.  .  . 

Coagalable  proteids,  small  proportionately 

Coagulation  of  proteids  by  acids  and  salts,  with 
greater  difRcuJty.    Cm-ds  small  and  floceulent .  . 

Coagulation  of  proteids  by  rennet,  does  not  coag- 
ulate readily ' 

Action  of  gastric  juice,  proteids  precipitated  but 
easily  dissolved  in  excess  of  the  gastric  juice . .  .  . 


Amphoteric      (more     acid     than 

alkahne) 
86  to  87  per  cent. 
0.70  per  cent. 
14  to  13  per  cent. 
4.00  per  cent,   (relativelj'  rich  in 

volatile  gh'cerids) 
4.75  per  cent. 
3.50  per  cent. 
2.66  per  cent. 
0.84  per  cent. 
Large  proportionately 
With  less  difficulty.      Curds  large 

and  tenacious 

Coagulates  readUy 
Proteids    precipitated    but     dis- 
solved less  readily 


504  ANIMAL   FOODS 

Tlie  differences  between  these  two  milks  are  greater  than  the  table 
indicates.  While  cow's  milk  may  be  modified  to  approximate  woman's 
milk  in  composition,  it  can  never  be  just  the  same  or  just  as  good  for 
infants. 

Cow's  milk  is  more  opaque  than  woman's  milk,  although  the  latter 
may  contain  a  greater  percentage  of  fat.  This  is  due  to  tlie  opacity  of 
the  calcium-casein,  which  is  present  in  greater  proportion  in  cow's 
milk.  Cow's  milk  is  faintly  acid  or  amphoteric  when  freshly  drawn, 
but  ordinarily  is  distinctly  acid  in  reaction  when  consumed.  Woman's 
milk  is  amphoteric  or  alkaline. 

There  is  three  times  as  much  protein  in  cow's  milk  as  in  woman's 
milk.  The  reason  for  this  is  obvious,  when  we  recall  that  the  ratio  of 
the  growth  of  the  calf  to  that  of  the  infant  is  about  as  two  to  one. 
Furthermore,  the  protein  in  cow's  milk  consists  chiefly  of  casein  (3.02 
per  cent.)  and  little  lactalbumin  (0.53  per  cent.),  while  woman's  milk 
contains  0.59  per  cent,  of  casein  and  1.23  per  cent,  lactalbumin.  The 
sugar  in  the  two  milks  varies  greatly  in  amount,  but  not  in  kind.  Cow's 
milk  contains  almost  four  times  the  amount  of  inorganic  salts  com- 
pared to  woman's  milk.  Of  more  importance,  the  salts  in  cow's  milk 
consist  mainly  of  the  calcium  and  magnesium,  while  those  in  woman's 
milk  consist  mainly  of  potassium  and  sodium  bases.  These  differences 
have  an  important  bearing  upon  infant  metabolism.  There  is  no  great 
difference  in  the  average  amount  of  fat  in  the  two  milks;  however,  both 
in  woman's  milk  and  in  cow's  milk  the  fat  is  the  most  variable  con- 
stituent. 

The  curd  from  cow's  milk  is  usually  tougher  and  in  larger  masses 
than  that  in  woman's  milk.  There  are  also  differences  in  the  antibodies, 
ferments,  etc. 

Classification  of  Milk. — From  a  public  health  standpoint  there  are 
only  two  kinds  of  milk — good  and  bad.  We  are,  however,  confronted 
with  a  complex  situation  which  has  resulted  in  various  schemes  for 
grading  milk  according  to  its  sanitar}^  quality  and  its  nutritive  value. 
Perhaps  the  most  practical  classification  has  been  advanced  by  the 
government,  viz.:  (1)  certified  milk;  (2)  inspected  milk;  (3)  market 
milk.  A  fourth  grade  known  as  "cooking  milk"  or  "milk  not  suitable 
for  drinking  purposes"  has  been  proposed,  but  has  not  met  with  favor 
except  from  the  economic  standpoint  in  large  cities. 

There  is  a  growing  tendency  to  classify  all  milk  into  raw  and  pas- 
teurized. This  is  the  most  satisfactory  classification  from  a  sanitary 
standpoint. 

Certified  Milk. — The  term  "certified  milk"  was  coined  by  Dr. 
Henry  L.  Coit  of  Newark,  N.  J.,  who  in  1892  formulated  a  plan  for  the 
production  of  clean,  fresh,  pure  milk  under  the  auspices  of  a  medical 
milk  commission.   The  term  "certified  milk."  then,  is  milk  of  the  highest 


MILK  505 

quality,  of  uniform  composition,  obtained  by  cleanly  methods  from 
healthy  cows  imder  the  special  supervision  of  a  medical  milk  commission. 

The  use  of  the  term  "certified  milk"  should  be  limited  to  milk 
produced  in  accordance  with  the  requirements  of  the  American  Asso- 
ciation of  Medical  Milk  Commissions.^  The  first  requisite  in  the  pro- 
duction of  certified  milk  is  to  enlist  the  cooperation  of  a  trustworthy 
dairyman  who  is  willing  to  enter  into  a  contract  with  the  medical  milk 
commission.  In  accordance  with  the  terms  of  this  contract,  the  dairy- 
man binds  himself  to  comply  with  the  specifications  set  forth  and  in 
return  his  milk  is  certified. 

The  dairies  are  subjected  to  periodic  inspections,  and  the  milk  to 
frequent  analyses.  The  cows  producing  certified  milk  must  be  free 
from  tuberculosis,  as  shown  by  the  tuberculin  test  and  physical  exam- 
ination by  a  qualified  veterinarian,  and  from  all  other  communicable 
disease,  and  from  all  diseases  and  conditions  whatsoever  likely  to  de- 
teriorate the  milk.  They  must  be  housed  in  clean,  properly  ventilated 
stables  of  sanitary  construction,  and  must  be  kept  clean  and  properly 
fed  and  cared  for.  All  persons  who  come  in  contact  with  the  milk 
must  exercise  scrupulous  cleanliness,  and  must  not  harbor  the  germs  of 
typhoid  fever,  tuberculosis,  diphtheria,  or  other  infections  liable  to  be 
conveyed  to  the  milk.  Milk  must  be  drawn  under  all  precautions  neces- 
sary to  avoid  contamination,  and  must  be  immediately  cooled,  placed 
in  sterilized  bottles,  and  kept  at  a  temperature  not  exceeding  50°  F. 
until  delivered  to  the  consumer.  Pure  water,  as  determined  by  chemical 
and  bacteriological  examination,  is  to  be  provided  for  use  throughout 
the  dairy  farm  and  dairy.  Certified  milk  should  not  contain  more  than 
10,000  bacteria  per  cubic  centimeter,  and  should  not  be  more  than 
twenty-four  hours  old  when  delivered. 

Inspected  Milk. — This  term  should  be  limited  to  clean,  fresh  milk 
from  healthy  cows,  as  determined  by  the  tuberculin  test  and  physical 
examination  by  a  qualified  veterinarian.  The  cows  are  to  be  fed,  wa- 
tered, housed,  and  milked  under  good  conditions,  but  not  necessarily 
equal  to  those  prescribed  in  the  production  of  certified  milk.  Scrupu- 
lous cleanliness  must  be  exercised  and  particular  care  be  taken  that 
persons  having  communicable  infections  do  not  come  into  contact  with 
the  milk.  This  milk  must  be  delivered  in  sterilized  containers,  and 
kept  at  a  temperature  not  exceeding  50°  F.  until  it  reaches  the  con- 
sumer. There  should  not  be  more  than  100,000  bacteria  per  cubic 
centimeter  of  inspected  milk. 

Market  Milk. — All  milk  that  is  not  certified  or  inspected  in  ac- 
cordance with  the  above  definitions,  and  all  milk  that  is  of  unknown 
origin,  is  classed  as  "market  milk,"  and  should  be  pasteurized. 

^See  annual  reports   of  this  Assoeiation. 


50() 


AX  1  MAI.    FOODS 


The  Decomposition  of  Milk, — ]\Iilk  spoils  in  various  ways  as  the  re- 
sult of  bacterial  «,n-o\vtli ;  the  kind  of  decomposition  depending  upon 
the  kind  of  bacteria  which  predominate.  Milk,  as  a  rule,  ferments,  but 
sometimes  it  putrefies.  In  the  former  case  the  main  change  takes  place 
in  the  carbohydrates;  in  the  latter  the  proteins  are  broken  down.  Tlie 
fermentation,  known  as  the  souring  of  milk,  is  accompanied  by  an  acid 
reaction  and  a  precipitation  of  the  casein.  Putrid  milk  turns  alkaline 
and  bitter,  owing  to  the  formation  of  peptones.  Sour  milk  is  regarded 
as  the  normal  form  of  decomposition,  because  it  is  the  usual  change 
and  is  not  harmful.  Putrid  milk  is  believed  at  times  to  contain  toxic 
substances ;  it  is  at  least  suspicious. 


Fig.  68. — Unsanitary  Surroundings  of  a  Cow  Barn. 

Sour  Milk — Lactic  Acid  Fermentation, — Milk  curdles  or  sours 
when  the  soluble  caseinogen  is  thrown  out  of  solution  and  precipitated 
as  casein.  The  caseinogen  exists  in  milk  as  a  complex  molecule  con- 
taining calcium  phosphate  loosely  bound  to  it;  it  also  contains  calcium 
as  part  of  the  molecular  complex.     The  formula  may  be  expressed  thus : 

Ca3(P04)2   (Ca.  Caseinogen) 


The  casein  is  held  in  solution  (colloidal  suspension)  by  the  calcium 
phosphate  and  other  solu])le  salts  of  calcium.  Any  chemical  reaction 
that  removes  tlie  calcium  ])hosphate  from  tliis  combination  causes  a 
precipitation  of  tlie  caseinogen  as  casein.  The  casein  may  be  precipi- 
tated by  various  substances,  such  as  rennin  or  acids.  In  the  normal 
curdling  or  souring  of  milk  the  casein  is  precipitated  by  lactic  acid 


MILK  507 

produced  through  the  action  of  bacteria  upon  lactose.     The  lactic  acid 
results  from  hydrolysis  of  the  lactose  as  follows : 

(lactose)  =  (galactose)-)- (glucose) 
CeH,30e=2C3He03 
(glucose)  =  (lactic  acid) 

The  bacteria  usually  concerned  in  the  souring  of  milk  are :  B.  acidi 
lactici  of  Hueppe,  B.  lactis  acidi  of  Leichmann,  Streptococcus  lactis  of 
Kruse,  B.  hulgaricus  of  Metchnikoff,  B.  aerogenes  capsulatus  of  Welch, 
B.  coli,  and  a  great  number  of  other  microorganisms  capable  of  fer- 
menting sugar  with  the  production  of  acid. 

Sour  milk,  obtained  from  clean  milk,  is  a  beneficial  food.  It  con- 
tains myriads  of  lactic  acid  bacteria.  MetchnikoS  has  recently  called 
attention  to  the  importance  of  a  normal  lactic  acid  flora  in  the  large 
intestines,  which  inhibits  putrefactive  processes  and  thereby  stands  guard 
against  autointoxication.  He  recommends  the  use  of  certain  bacteria 
in  sour  milk,  especially  B.  hulgaricus.  It  is  a  fallacy,  however,  to  sup- 
pose that  the  flora  of  the  large  intestines  may  be  materially  influenced 
through  ingestion  of  these  bacteria  by  the  mouth,  even  when  taken  in 
enormous  numbers,  as  in  sour  milk.  Perhaps  the  best  way  to  influ- 
ence the  bacteria  of  the  large  intestines  is  through  diet.  A  protein 
diet  favors  a  putrefaction  flora;  a  carbohydrate  diet  a  normal  flora. 
Kendall,  in  his  work  on  intestinal  bacteriology,  has  shown  that  carbo- 
hydrates spare  proteins;  that  is,  bacteria  do  not  ordinarily  break  down 
protein  in   the   presence   of   carbohydrates. 

Putrid  Milk — Alkaline  Putrefaction. — When  boiled  milk  is  al- 
lowed to  stand  at  room  temperature,  it  gradually  acquires  an  alkaline 
reaction,^  a  bitter  taste,  and  finally  curdles,  yielding  a  soft,  slimy  curd. 
On  further  standing  this  curd  is  peptonized  to  form  a  somewhat  clear 
fluid,  and  if  these  putrefactive  changes  are  allowed  to  proceed  for  a 
sufficient  length  of  time  a  semi-transparent  liquid  is  obtained,  having  no 
resemblance  to  milk.  In  this  form  of  decomposition  the  main  change 
occurs  in  the  protein  constituent  of  the  milk.  The  putrefactive  changes 
of  milk  are  undesirable  and  are  believed  sometimes  to  be  dangerous,  in 
that  toxic  substances  resembling  "ptomains"  may  be  produced.  The 
principal  cause  of  putrefaction  in  milk  is  the  spore-bearing  group  of 
bacilli,  belonging  to  and  resembling  the  hay  bacillus  and  also  the 
anaerobes. 

Slimy  or  Eopey  Milk. — Under  some  circumstances  certain  muci- 
laginous substances  develop  in  milk  through  abnormal  fermentation. 
Slimy  milk  has  been  obtained  of  such  viscosity  that  it  could  be  drawn 

^  Schorer  found  that  such  milk  becomes  less  acid  but  seldom  becomes  actually 
alkaline   in  reaction. 


508  ANIMAL    FOODS 

out  into  threads  ten  feet  in  lengtli,  and  of  such  thinness  as  to  he  scarcely 
visible.  In  Norway  such  milk  is  esteemed  a  delicacy;  in  this  country, 
however,  it  is  objectionable.  From  a  health  standpoint  ropey  milk  is 
not  injurious  unless  it  is  slimy  as  a  result  of  mucopurulent  materials 
caused  by  diseased  conditions  in  the  mammary  glands.  The  bacteria 
which  produce  ropey  milk  are  widely  distributed  in  nature.  Of  these 
B.  Jactis  viscosis  (Adametz)  is  the  commonest  organism  found  in  Eu- 
rope, and  a  similar  organism  occurs  in  this  country.  B.  lactis  viscosis 
is  very  hardy;  it  may  find  its  way  into  the  milk  through  the  water 
supply  of  the  dairy,  and  then  become  widely  diffused  and  difficult  to 
trace.  It  is  sometimes  very  troublesome,  but  may  be  eradicated  through 
cleanliness.  Sometimes  it  is  necessary  to  resort  to  disinfection.  Other 
organisms  producing  sliminess  in  milk  are  the  Micrococcus  freiiden- 
reichii,  two  forms  of  streptococci,  and  certain  of  the  lactic  acid  bacteria. 

Alcoholic  Fermentation  of  Milk. — This  is  an  abnormal  fermen- 
tation which  sometimes  occurs  as  a  result  of  yeasts,  aided  in  their  action 
by  certain  species  of  bacteria.  Alcoholic  fermentation  of  milk  seldom 
occurs  spontaneously,  but  may  be  induced  by  direct  inoculations  with 
certain  ferments,  such  as  those  employed  in  the  production  of  kumyss 
and  kefir. 

Kumyss  was  originally  made  from  mare's  milk;  is  now  made  from 
cow's  milk  by  the  addition  of  cane  sugar  and  yeast.  Kefir  is  a  similar 
beverage,  originating  in  the  Caucasus,  where  the  fermentation  is  car- 
ried out  in  leather  bottles  and  is  started  by  means  of  "kefir  grains" 
which  contain  yeast  and  various  microorganisms. 

Bitter  Milk. — Freshly  drawn  milk  sometimes  has  a  bitter  taste;  in 
other  instances  milk  acquires  such  a 'taste  on  standing  a  few  hours. 
The  former  is  due  to  improperly  feeding  the  cow  with  such  herbs  as 
lupines,  wormwood,  raw  Swedish  turnips,  cabbages,  etc.  The  latter 
case  is  due  to  the  growth  of  certain  bacteria  in  the  milk  after  it  is 
drawn.  The  condition  is  undesirable,  and  sometimes  causes  much 
trouble  for  the  dairyman,  but  it  has  no  particular  sanitary  significance. 
According  to  Conn,  it  is  a  micrococcus,  and  according  to  Weigmann  a 
bacillus,  that  has  the  power  of  ruining  the  taste  of  freshly  drawn  milk 
in  a  few  hours.  This  condition  should  be  distinguished  from  the  bit- 
ter taste  of  putrid  milk  above  noted. 

Colored  Milk. — Blue  milk  is  usually  due  to  the  Bacillus  cyanogenes. 
Such  milk  is  apparently  harmless.  Eed  milk  may  be  due  to  the  pres- 
ence of  blood  coming  from  an  injury,  or  acute  infection  of  the  udder. 
Sometimes  it  results  from  the  feeding  of  the  cow  on  plants  containing 
red  pigment,  such  as  the  madder  root.  A  red  color  may  also  be  pro- 
duced by  the  Bacillus  erythrogenes,  B.  prodigiosus,  and  sarcinge.  Red 
milk  caused  through  the  agency  of  bacteria  is  without  sanitary  sig- 
nificance. 


MILK  509 

Adulterations  of  Milk. — Shimming. — The  removal  of  part  or  all  of 
the  cream  and  selling  the  remaining  fluid  as  whole  milk  is  an  economic 
fraud,  and  has  no  reference  to  health,  except  that  the  milk  is  cor- 
respondingly lowered  in  nutritive  value. 

Vi'atering. — The  practice  of  watering  is  not  nearly  so  frequent  as 
formerly.  If  the  water  be  pure  it  must  be  regarded  more  as  a  fraud 
than  a  health  problem.  The  addition  of  water  to  milk  lowers  its  specific 
gravity,  raises  its  freezing  point,  and  lowers  its  index  of  refraction  and 
also  its  viscosity. 

TliicTcening  agents,  such  as  the  use  of  chalk,  calves'  brain,  and 
glycerin,  have  never  been  common  practices.  Gelatin  or  lime  is  some- 
times used  to  thicken  cream.  Cream  may  also  be  thickened  by  homo- 
genizing it.  Coloring  matter  is  sometimes  added  with  the  object  of 
concealing  skimming  or  watering  or  to  make  the  milk  look  richer. 
Annato,  a  vegetable  dye,  is  most  commonly  used;  orange  and  yellow 
azo  coal-tar  are  also  used.  Alkalies,  such  as  sodium  carbonate  or  bi- 
carbonate, are  occasionally  added  to  milk  to  reduce  its  acidity  or  to 
improve  its  taste  or  to  delay  curdling.  Sweet  substances,  such  as  sac- 
charin or  sugar,  are  occasionally  added  to  milk,  either  to  raise  the 
specific  gravity  and  thus  disguise  watering,  or  to  disguise  the  sour  taste 
of  milk  just  on  the  turn. 

Chemical  Preservatives. — Chemical  preservatives,  such  as  borax  and 
boracic  acid,  salicylic  acid,  benzoic  acid  and  benzoates,  potassium  bi- 
chromate, peroxid  of  hydrogen,  fluorids,  formaldehyde,  and  others, 
have  from  time  to  time  been  used  in  milk.  The  practice  of  adding  any 
chemical  preservative  to  milk  meets  with  the  unqualified  disapproval  of 
the  sanitarian.  Almost  all  countries  prohibit  the  use  of  such  foreign 
substances.  The  only  proper  preservatives  for  milk  are  cleanliness  and 
cold. 

Dirty  Milk — The  Dirt  Test. — Practically  all  milk  contains  more  or 
less  dirt.  For  the  most  part,  this  dirt  consists  of  cow  feces.  The  pres- 
ence of  dirt  may  best  be  determined  by  filtering  a  pint  of  milk 
through  a  little  disk  of  absorbent  cotton.  This  produces  a  stain  vary- 
ing in  intensity  from  a  yellowish  to  a  brownish  or  black  spot.  A 
Gooch  crucible,  a  Lorenz  apparatus,  or  simply  an  ordinary  funnel  may 
be  used  to  filter  the  milk.  Warm  milk  filters  much  more  readily  than 
cold  milk.  This  simple  test  is  one  of  the  most  practical  of  the  routine 
tests  used  for  the  public  health  control  of  milk  supplies.  The  intensity 
of  the  stain  and  the  amount  of  deposit  upon  the  cotton  is  a  tell-tale 
which  appeals  strongly  to  farmers  and  dairymen,  as  well  as  to  con- 
sumers. It  is  a  good  practice  to  send  these  disks  of  cotton,  with  a 
letter,  to  the  farmer,  showing  him  the  amount  of  dirt  contained  in  his 
milk. 

Bacteria  in  Milk. — As  a  rule,  milk  contains  relatively  and  actually 


510 


ANIMAL    FOODS 


more  bacteria  than  any  other  article  of  diet.  Milk  may,  in  fact,  con- 
tain more  bacteria  than  any  other  known  substance;  it  frequently  con- 
tains many  more  bacteria  than  are  found  in  sewage.  Mere  numbers, 
however,  need  not  alarm  us,  for  it  is  tlie  kind  tliat  most  concerns  us. 
By  universal  consent,  however,  milk  containing  an  excessive  number 
of  miscellaneous  bacteria  is  not  suitable  for  infant  feeding.  Were  milk 
a  transparent  food  the  enormous  growth  of  microorganisms  present  in 
average  market  milk  Avould  be  plainly  visible  to  the  naked  eye. 

The  bacteria  get  into  the  milk  from  a  number  of  different  sources. 
Some  of  them  are  in  the  milk  before  it  leaves  the  udder.  They  grow 
up  the  milk  ducts  into  the  milk  cistern;  hence,  the  fore-milk  contains 
more  than  the  "mid-milk  or  stri])pings.     It  is  practically  impossible  to 


Fig.  69. — Conditions  under  Which  It  Is  Difficult  to  Cleanse  and  Disinfect 
Milk  Bottles  and  Milk  Pails. 


obtain  sterile  milk  directly  from  the  teat  in  any  large  quantity.  As 
soon  as  the  milk  leaves  the  teat  it  receives  additional  contamination 
from  all  objects  with  which  it  comes  in  contact,  as  the  hands,  the  pail, 
the  dust  in  the  air,  etc.  Most  bacteria  get  into  milk  with  the  dirt 
that  falls  from  the  belly  and  udder  of  the  cow  during  milking. 

The  number  of  bacteria  in  milk  increases  every  time  it  is  handled 
or  exposed  in  any  way.  Separator  milk  contains  more  bacteria  than 
the  original  milk.  The  same  is  true  of  filtered  milk.  This  is  due  to 
the  fact  that,  while  some  of  the  visible  dirt  in  the  milk  is  taken  out, 
the  particles  are  broken  up  and  the  bacteria  disperse  throughout  the 
fluid. 

For  the  most  part  bacteria  do  not  pass  a  healthy  udder.  How- 
ever, we  can  place  no  trust  in  the  filtering  ability  of  the  mammary 


MILK  511 

gland.  It  is  known  that  the  virus  of  foot-and-mouth  disease,  which  is 
ultramicroscopic,  and  the  virus  of  malta  fever  {Micrococcus  meUtensis) , 
and  also  the  virus  of  milk  sickness  are  almost  constantly  found  in  the 
milk  of  affected  animals.  On  the  other  hand,  tubercle  bacilli  do  not 
pass  the  mammar};-  gland  unless  there  is  tuberculosis  of  the  udder. 

The  bacteria  in  milk  are  not  equally  distributed  throughout  the 
fluid.  There  are  more  bacteria  in  cream  than  in  the  underlying  skim 
milk — particularly  in  gravity  cream.  As  the  cream  rises  it  mechani- 
cally carries  the  bacteria  along  with  it,  very  much  as  a  snowstorm  sweeps 
the  atmosphere.  Milk  formulae  for  infant  feeding  are  often  made  of 
top  milk,  which,  however,  may  contain  5  to  100  times  the  number  of 
bacteria  per  cubic  centimeter  found  in  the  whole  milk.  In  twenty- 
six  samples  of  milk  Anderson  found  the  gravity  cream  contained  about 
four  times  as  many  bacteria  as  the  sediment  layer,  and  about  one- 
third  as  many  as  the  whole  milk.  Schorer  found  that  the  cream  from 
milk  of  high  bacterial  count  contained  several  thousand  times  as  many 
bacteria  as  the  underlying  skim  milk. 

Certified  milk  should  not  contain  over  10,000  bacteria  per  c.  c. ; 
inspected  milk  not  over  100,000,  and  market  milk  not  over  500,000. 
New  York  has  placed  the  limit  at  1,000,000  per  c.  c.  Even  this  stand- 
ard, however,  has  not  been  rigidly  enforced.  Boston  has  a  standard 
of   500,000;   Eochester   100,000. 

In  Washington  in  1908  the  average  bacterial  count  of  the  market 
milk  was  22,000,000  per  c.  c,  as  found  in  many  hundreds  of  samples 
of  the  city  supply.     In  1907  the  average  was  reduced  to  11,000,000. 

Excessive  numbers  of  bacteria  in  milk  indicate  that  it  is  dirty, 
old,  or  warm.  Any  one  or  any  combination  of  these  factors  favors  a 
rapid  growth  and  multiplication  of  the  bacteria  in  milk. 

Methods  for  determining  the  number  and  kind  of  bacteria  in  milk 
will  be  found  on  page  523. 

The  Germicidal  Property  of  Milk. — The  so-called  germicidal  prop- 
erty of  milk  has  been  much  misunderstood.  Judged  by  the  number  of 
colonies  that  develop  upon  agar  plates,  the  bacteria  in  milk  first  dim- 
inish, then  increase  in  number.  This  occurs  only  in  raw  milk  during 
the  first  8  or  12  hours  after  it  is  drawn.  Although  the  bacteria  seem- 
ingly decrease  in  numbers,  they  never  entirely  disappear.  After  this 
initial  decrease  there  is  a  continuous  and  rajDicl  increase,  until  the  milk 
contains  almost  infinite  numbers  in  each  cubic  centimeter.  This  power 
of  milk  to  restrain  the  development,  of  bacteria  lasts  from  6  to  21 
hours,  depending  upon  the  temperature  at  which  the  milk  is  kept.  When 
the  milk  is  kept  warm,  37°  C,  the  decrease  is  pronounced  within  the 
first  8  or  10  hours;  after  this  the  milk  has  entirely  lost  its  restraining 
action.  When  the  milk  is  kept  cool,  15°  C,  the  decrease  is  less  marked 
but  more  -  prolonged. 


512 


ANIMAL    FOODS 


The  decrease  in  the  niimher  of  bacteria  is  largely  apparent,  being 
fine,  at  least  in  part,  to  agglutination;  that  is,  the  bacteria  are  not 
killed,  they  are  simply  grouped  in  clusters;  this  is  proven  by  the  fact 
that  these  clusters  may  be  shaken  asunder.  The  germicidal  action  of 
milk  is  specific;  at  most,  is  feeble,  and  is  destroyed  if  the  milk  is 
heated  above  80°  C.  It  varies  in  dilferent  animals,  and  in  the  milk 
from  the  same  animal  at  different  times.  It  cannot  take  the  place  of 
cleanliness  and  ice,  but  may  be  taken  advantage  of  in  good  dairy  meth- 
ods. It  is  true  that  bacteria  develop  more  quickly  in  heated  milk  than 
raw  milk,  provided  the  raw  milk  is  fresh ;  it  should  be  remembered, 
however,  that  milk  that  is  a  day  old  no  longer  possesses  this  restrain- 
ing action.  The  germicidal  property  is,  therefore,  ordinarily  absent  in 
market  milk. 

Diseases  Spread  by  Milk. — The  diseases  most  commonly  conveyed 
through  milk  are :  tuberculosis,  typhoid  fever,  diphtheria,  scarlet  fe- 
ver, septic  sore  throat,  malta  fever,  foot-and-mouth  disease,  and  milk 
sickness,  also  some  of  the  summer  complaints  of  children,  and  the 
diarrheal  and  dysenteric  diseases  of  adults,  which  are  often  referable 
to  infected  milk.  When  all  the  facts  are  brought  together  they  make 
a  strong  indictment  against  milk.  Thus,  during  the  five  years,  1907-11, 
there  were  five  milk-borne  outbreaks  in  Boston,  causing  a  total  of  over 
4,000  cases  of  sickness. 


Year 


Milk-borne  Epidemics  in  Greater  Boston 


Cases 


1907 
1907 
1908 
1910 
1911 


Diphtheria 

Scarlet  fever 

Typhoid  fever,  about .... 

Scarlet  fever,  over 

"Septic  sore  throat,"  over 


72 
717 
400 

842 
2,065 


4,096 


As  a  rule,  milk  becomes  infected  from  human  sources,  sometimes 
on  the  farm,  sometimes  at  the  dairy,  sometimes  in  transportation,  and 
occasionally  in  the  household.  Sometimes  the  milk  becomes  infected 
as  a  result  of  disease  of  the  cow,  as  in  the  case  of  bovine  tuberculosis, 
malta  fever,  foot-and-mouth  disease,  streptococci,  etc. 

In  addition  to  the  specific  diseases,  milk  may  be  injurious  as  a 
result  of  other  causes.  Thus,  Le  Blanc  has  pointed  out  that  the  milk 
of  cows  in  heat  may  cause  gastrointestinal  disturbances.  The  toxic 
effects  of  milk  and  milk  products  of  nymphomanous  cows  are  even  more 
marked.  Milk  should  not  be  used  within  fifteen  days  of  parturition. 
The  requirement  for  certified  milk  is  placed  at  thirty  days  before  and 
fifteen  days  after.     Such  milk  is  apt  to  produce  diarrhea,  colic,  and 


MILK  513 

other  digestive  disturbances.  Milk  may  further  be  harmful  as  a  result 
of  such  diseases  as  mastitis  or  garget,  gastroenteritis,  septic  and  febrile 
conditions  of  the  cow.  Eecently  it  has  been  shown  that  contagious 
abortion  of  cows  is  due  to  the  Bacillus  abortus,  which  may  contaminate 
milk;  it  is  pathogenic  for  many  animals,  probably  including  man. 
Schroeder  and  Cotton  found  this  bacillus  in  8  out  of  27  samples  of 
market  milk  tested.     All  such  milk  should  be  excluded  or  pasteurized. 

Tuberculosis. — Bovine  tubercle  bacilli  get  into  milk  either  di- 
rectly as  a  result  of  tuberculosis  of  the  udder,  which  occurs  in  from 
1  to  3  per  cent,  of  all  tubercular  cows,  or  indirectly  through  cow 
manure.  In  the  latter  case  the  tubercle  bacilli  are  coughed  up,  swal- 
lowed, and  passed  in  the  feces.  Practically  all  market  milk  contains 
cow  feces.  Occasionally  milk  contains  tubercle  bacilli  of  the  human 
type  from  human  sources.  Tuberculosis  in  cattle  is  very  prevalent. 
The  "milk"  from  a  tuberculous  udder,  when  examined  under  the  micro- 
scope, may  contain  as  many  tubercle  bacilli  as  are  ordinarily  found  in 
tuberculous  sputum.  The  milk  from  a  tuberculous  udder  of  one  cow 
may  contain  sufficient  bacilli  to  infect  the  milk  of  25  or  30  cows.  In 
one  case  Ostertag  found  that  0.001  c.  c.  of  the  secretion  from  a  tuber- 
culous udder  was  sufficient  to  cause  tuberculosis  in  a  guinea  pig.  In 
such  a  case  a  child  would  receive  an  enormous  dose  in  a  gill. 

Tonney  examined  the  market  milk  of  Chicago  in  1910  for  the  pres- 
ence of  tubercle  bacilli.  In  10.5  per  cent,  of  144  samples  of  raw  milk 
he  found  tubercle  bacilli  in  sufficient  numbers  to  infect  guinea  pigs. 
Of  19  samples  of  pasteurized  milk  examined  none  contained  tubercle 
bacilli. 

Hess  in  1909  examined  107  samples  of  market  milk  in  Few  York 
City,  with  the  result  that  17  of  them,  or  16  per  cent.,  were  found  to 
contain  tubercle  bacilli. 

Anderson  examined  223  samples  taken  in  the  city  of  Washington, 
and  reported  16,  or  6.72  per  cent.,  as  positive.  The  tests  made  by 
the  Bureau  of  Animal  Industry  of  the  milk  in  Washington  disclosed 
7.7  per  cent,  infected.  Goler  reports  about  5  per  cent,  of  the  milk 
supply  of  Eochester,  N".  Y.,  infected. 

To  sum  up,  we  have  evidence  from  four  typical  American  cities. 
A  total  of  551  samples  of  milk  have  been  examined,  in  which  tubercle 
bacilli  were  found  in  46,  making  a  percentage  of  8.3.  This  may  be 
taken  as  the  average  percentage  for  the  entire  country. 

Professor  Delepine  found  that  the  milk  sent  by  rail  to  Manchester 
from  272  farms  contained  tubercle  bacilli  from  26,  or  9.5  per  cent. 
Wherever  these  investigations  have  been  carried  out  similar  and  some- 
times higher  results  have  been  obtained,  both  in  Europe  and  in  this 
country.  It  is  believed  that  the  figures  are  an  underestimate,  for  the 
methods  used  in  the  laboratory  are  not  sufficiently  delicate  to  detect 


514  ANIMAL    FOODS 

a  few  tubercle  l)aci]li  in  milk.  Unless  these  microorganisms  are  pres- 
ent in  considerable  numbers,  they  are  apt  to  escape  detection.  In  any 
event,  it  is  clear  that  the  common  market  milk  furnished  all  large 
cities  and  pr()l)ably  most  small  towns  very  often  contains  tubercle 
bacilli. 

The  frequency  with  which  tubercle  Ijacilli  are  found  in  butter  is 
shown  in  a  table  collected  by  Swithinbank  and  Newman.^  Of  4!)8  sam- 
ples tested  from  different  sources,  76,  or  15.2  per  cent.,  contained 
tubercle  bacilli. 

Schrocder  and  Cotton  ^  ha.ve  found  that  living  tubercle  bacilli  will 
retain  their  infective  properties  for  at  least  100  days  in  salted  butter 
when  kept  without  ice  in  a  house  cellar. 

Mohler,  Washburn,  and  Doane  found  tubercle  bacilli  to  live  a  year 
and  more  in  cheese  220  days  old.  In  these  experiments  the  cheese  was 
purposely  infected  and  fed  or  inoculated  into  guinea-pigs  at  various 
times. 

The  relation  of  bovine  tuberculosis  to  num  is  considered  on  page  124. 

Typhoid  Fevki;. — Of  milk-borne  epidemics,  typhoid  fever  takes  the 
lead.  Typhoid  bacilli  may  swarm  in  milk  without  altering  its  taste, 
odor,  or  appearance.  In  Washington  10  per  cent,  of  all  the  cases  of 
typhoid  fever  during  the  four  years  1907-10  were  traced  to  milk.  The 
milk  may  become  infected  by  a  convalescent,  a  carrier,  or  a  missed  case. 

Bolduan  estimates  that  from  300  to  400  cases  of  typhoid  fever  each 
year  come  in  contact  with  the  milk  supplied  New  York  City.  He  fur- 
ther states  that  "the  startling  total  of  90  to  120  typhoid  carriers  now 
probably  menace  th.e  milk  supply  of  this  city."  This  estimate  is  based 
upon  the  fact  that  about  200,000  persons  come  into  more  or  less  con- 
tact with  the  milk  from  over  40,000  dairy  farms  (see  Typhoid  Fever, 
page  89). 

Scarlet  Fever. — Milk-borne  outbreaks  of  scarlet  fever  are  some- 
times extensive  and  serious.  The  milk  is  practically  always  infected 
from  human  sources.  There  is  a  suspicion,  however,  that  sometimes 
streptococcal  infections  of  the  cow  may  reproduce  a  disease  resembling 
scarlet  fever  in  man   (see  Scarlet  Fever,  page  IGl). 

Diphtheria. — Diphtheria  bacilli  in  milk  usually  come  from  human 
sources,  either  cases  or  carriers.  In  a  few  instances  ulcers  upon  the 
teat  of  the  cow  have  become  infected  with  diphtheria,  and  the  bacilli 
are  thus  transferred  to  the  milk.  Such  an  occurrence,  however,  is  un- 
usual. As  a  rule,  diphtheria  outbreaks  caused  by  infected  milk  are  more 
limited  both  as  to  numbers  and  area  than  milk-borne  outbreaks  of 
typhoid  or  scarlet  fever  (see  Diphtheria,  page  14G). 

Septic   Sore  Throat. — The   first   milk-borne   outbreak   of  "septic 

^Bacteriology  of  Milk,  p.   221. 

-Bureau  of  Animal  Industry  Cir.  No.  153,  p.  38. 


MILK  615 

sore  throat"  recognized  in  this  country  occurred  in  and  about  Boston 
in  May,  1911.  Since  then  similar  outbreaks  have  occurred  in  Balti- 
more, Concord,  iST.  H.,  Chicago,  and  elsewhere.  The  infection  is  spread- 
ing. The  Boston  outbreak  was  carefully  studied  by  Winslow  and  is  so 
instructive  that  a  brief  account  of  it  is  given  below. 

Septic  sore  throat  due  to  infected  milk  is  well  known  in  Great 
Britain.  Swithinbank  and  JSTewman  state  that  a  year  never  goes  by 
in  which  there  are  not  outbreaks  of  sore  throat  or  tonsillitis  due  to  milk 
or  cream.  These  infections  appear  to  be  due  to  a  streptococcus,  several 
varieties  having  been  isolated  both  from  the  milk  and  the  throats  of 
the  patients.  It  is  assumed  that  the  infection  usually  gets  into  the  milk 
from  human  sources,  although  it  is  suspected  that  streptococci  elimi- 
nated by  diseased  udders  may  be  responsible  for  some  outbreaks. 

The  disease  often  presents  a  severe  clinical  type  and  may  result  in 
death.  Apparently  it  is  not  readily  communicable  from  person  to  per- 
son. The  inflammation  and  swelling  of  the  lymphoid  structures  of 
the  throat  and  of  the  mucous  membranes  are  more  severe  than  ordi- 
narily; edema  is  a  feature,  and  many  cases  present  pseudomembranous 
formation  and  other  indications  of  a  virulent  infection.  There  is  a 
sharp  febrile  reaction,  prostration,  and  sometimes  delirium.  The  dura- 
tion of  the  disease  may  be  prolonged,  and  complications  occur  in  about 
one-quarter  of  the  cases.  These  consist  mostly  of  enlarged  regional 
Ij^mph  nodes,  which  may  suppurate;  abscesses,  arthritis,  endocarditis, 
peritonitis,  erysipelas,  pneumonia,  pyemia,  acute  nephritis,  otitis,  and 
other  sequelae  indicating  the  invasion  of  the  blood  with  a  virulent  strep- 
tococcus. 

The  Boston  outbreak  in  1911  was  characterized  by  its  extraor- 
dinary virulence  and  comparative  immunity  of  children,  and  high 
mortality  among  the  aged  and  infirm.  In  this  outbreak  there  were  over 
2,000  cases  with  about  48  deaths.  One  of  the  features  of  special  in- 
terest was  that  the  milk  incriminated  had  always  been  a  particularly 
clean,  fresh,  and  satisfactory  supply.  It  was  obtained  from  tuberculin- 
tested  cows  under  veterinary  supervision,  and  the  milk  itself  subjected 
to  frequent  chemical  and  bacteriological  tests.  The  milk  was  bottled  at 
the  dairy,  the  bottles  were  sterilized,  and  many  extra  precautions  were 
taken  to  ensure  its  cleanliness.  For  28  3'ears  not  a  breath  of  suspicion 
was  attached  to  this  milk  until  this  catastrophe  occurred.  It  emphasizes 
the  lesson  that  raw  milk  is  apt  to  be  dangerous  milk,  and  our  only 
protection  against  these  particular  dangers  is  through  pasteurization.^ 

Milk  Sickness. — Slows  or  trembles  is  a  peculiar  disease  found 
in  the  central  part  of  the  United  States.  As  forests  are  cleared  and 
pastures  fenced  the  disease  becomes  less  frequent.     It  is  still  met  with 

^  For  a  more  detailed  study  of  this  and  other  milk-borne  outbreaks  see  The 
Milk  Question,  by  M.  J.  Eoseuau. 


516  ANIMAL    FOODS 

in  the  valley  of  the  Pecos  River,  New  Mexico,  in  parts  of  Tennessee 
and  North  Carolina.  The  virus  is  communicated  to  man  and  is  fre- 
quently fatal,  Nancy  Hanks,  the  mother  of  Lincoln,  died  from  the 
disease  in  1818  after  an  illness  of  a  week.  Little  is  known  of  the  cause 
of  milk  sickness.  Jordan  and  Harris  have  found  a  bacillus  associated 
with  the  disease  whicli  they  have  called  the  Bacillus  lactis  morhi. 

Milk  sickness  is  an  acute  non-febrile  disease  due  to  the  ingestion 
of  milk,  milk  products,  or  the  flesh  of  animals  suffering  from  a  disease 
known  as  trembles.  The  disease  is  characterized  by  great  depression, 
persistent  vomiting,  obstinate  constipation,  and  high  mortality. 

Malta  Fever. — Malta  fever  is  a  disease  primarily  of  goats;  sec- 
ondarily of  man.  The  infection  is  transmitted  from  goats  to  man 
through  milk  containing  the  Micrococcus  melitcnsis  (see  page  288). 

FooT-AND-MouTii  DISEASE. — Foot-and-mouth  disease  is  an  infection 
primarily  of  cattle  and  secondarily  of  man.  It  is  caused  by  a  filterable 
virus,  and  is  noteworthy  for  being  the  first  ultramicroscopic  virus  dis- 
covered by  Loeffler  and  Froesch  in  1898.  The  infection  is  transmitted 
to  man  through  the  ingestion  of  raw  milk,  buttermilk,  cheese,  or  whey 
from  diseased  cows.  Children  are  not  infrequently  infected  by  drink- 
ing unboiled  milk  when  the  disease  is  prevalent  in  tlie  neighborhood. 
In  man  the  disease  is  mild;  the  symptoms  resemble  those  observed  in 
animals;  there  is  fever,  sometimes  vomiting,  painful  swallowing,  heat 
and  dryness  of  the  mouth,  followed  by  an  eruption  of  vesicles  in  the 
buccal  and  mucous  membranes,  and  very  rarely  by  similar  ones  on  the 
fingers.  The  vesicles  are  about  the  size  of  a  pea;  they  soon  break, 
leaving  small  erosions,  which  rapidly  heal.  The  disease  is  seldom  fatal 
except  occasionally  in  very  weak  children. 

The  Character  of  Milk-home  Epidemics. — Milk-borne  epidemics 
usually  have  an  explosive  onset,  rise  to  a  peak,  and  decline  gradually. 
The  character  of  the  curve  depends  upon  the  amount  of  infection  in 
the  milk,  and  the  manner  of  its  distribution,  the  number  of  persons  who 
drink  it,  and  other  factors.  If  the  infection  in  the  milk  is  dilute  or 
attenuated,  the  disease  crops  out  among  a  few  susceptible  persons  who 
drink  it.  If  the  infection  is  concentrated  and  the  milk  is  widely  used, 
the  curve  of  the  outbreak  will  have  the  steeple-like  character  of  a  water- 
borne  epidemic.  The  length  of  the  epidemic  varies  with  the  period 
of  incubation  of  the  disease  and  with  the  length  of  time  the  milk  is 
infected.  The  number  of  people  involved  may  vary  from  a  few  to  a 
hundred  or  several  thousand.  Only  a  single  bottle  of  milk  may  be 
infected,  and  thus  convey  the  disease  to  only  one  person;  on  the  other 
hand,  many  gallons  of  mixed  dairy  milk  may  become  infected  and  pro- 
duce disease  in  many  hundred  persons.  As  a  rule,  milk  outbreaks  last 
a  comparatively  short  time,  and  extend  over  a  circumscribed  area,  as 
the  disease  follows  the  milk  route.     At  first  the  disease  occurs  almost 


MILK 


517 


exclusively  among  users  of  the  infected  milk.  Afterward  secondary 
cases  may  occur. 

The  disease  shows  a  special  incidence  among  milk  drinkers.  It  is 
interesting  to  note  that  sometimes  only  one  person  of  a  number  living 
in  the  same  house  is  attacked,  and  such  a  one  is  a  person  who  drinks 
the  milk  raw. 

Milk-borne  diseases  attack  those  living  under  the  best  sanitary  con- 
ditions. The  reason  for  this  is  that  such  people  drink  milk  more  freely 
than  the  poor.  Milk  outbreaks  among  the  well-to-do  are  unnecessary 
tragedies  to  the  sanitarian. 

Most  milk  outbreaks  show  a  greater  incidence  of  the  disease  among 
women  and  children,  who  are  usually  credited  with  drinking  more  milk 


Fig.  70. — A  Dabk,  Poorly  Ventilated  Cow  Shed,  Difficult  to  Keep  Clean. 


than  men.  There  is  apt  to  be  a  short  period  of  incubation,  probably 
on  account  of  the  concentration  and  large  amount  of  the  infection; 
however,  the  disease  often  runs  a  mild  course.  Multiple  cases  occur 
simultaneously  in  the  same  house.  Such  an  occurrence  is  very  sugges- 
tive to  the  epidemiologist,  and  frequently  gives  him  the  first  hint  of  an 
impending  milk  epidemic. 

Fresh  Milk  Products, — Cream,  butter,  buttermilk,  ice-cream,  sour 
milk,  fresh  cheese,  and  other  milk  products  may  convey  all  the  infec- 
tions contained  in  the  original  milk  from  which  they  are  prepared. 
It  is  known  that  tubercle  bacilli  pass  into  butter  and  may  live  there 
for  months.  It  has  also  been  demonstrated  that  infected  cream  may 
be  the  cause  of  typhoid  fever,  septic  sore  throat,  and  without  doubt 
diphtheria,  scarlet  fever,  and  other  milk-borne  diseases. 


518  ANIMAL    FOODS 

Milk  products  are  frequently  made  from  the  left-over  milk  or  milk 
otherwise  unsalable.  This  may  be  controlled  by  an  efificient  system  of 
inspection. 

The  infections  in  fresh  milk  products  may  be  guarded  against  by 
pasteurization.  It  is  comparatively  easy  to  pasteurize  cream,  for  the 
reason  that  it  may  be  heated  to  a  higher  temperature  than  is  the  case 
with  milk  without  materially  altering  its  physical  properties. 

For  so-called  tyrotoxicon  poisoning  due  to  cheese  see  section  on 
Ptomains. 

Inspection. — An  efficient  inspection  service  is  a  preventive  measure 
that  strikes  at  the  root  of  the  milk  problem.  A  good  inspection  service 
is  expensive,  but  is  worth  its  cost  in  providing  cleaner  and  better  milk. 
Inspection  has  its  limitations,  for  it  cannot  see  bacillus  carriers,  mild 
cases  of  disease,  and  cannot  be  on  hand  at  all  places  at  all  times.  No 
system  of  inspection  can  be  so  perfect  as  to  insure  milk  free  from 
infection  at  all  times. 

A  competent  system  of  inspection  will  help  the  farmer  very  much 
with  his  problems,  and  the  educational  value  of  such  a  system  is  one 
of  its  best  features.  The  score-card  system  is  an  essential  element  in 
a  successful  inspection  service. 

Inspection  is  particularly  helpful  in  tracing  the  source  of  infected 
milk  and  preventing  recurrences.  Another  important  element  in  any 
inspection  system  is  the  license  or  permit.  All  persons  producing  or 
handling  milk  should  obtain  a  license,  which  should  be  issued  only 
after  the  person  has  demonstrated  his  capacity  to  handle  milk  in  a 
safe  and  cleanly  manner. 

Pasteurization, — Pasteurization  as  applied  to  milk  consists  in  heat- 
ing it  for  a  short  period  of  time  at  a  temperature  below  the  boiling 
point,  followed  by  rapid  chilling.  In  the  language  of  the  kitchen,  pas- 
teurization means  parboiling.  To  the  sanitarian  pasteurization  has 
but  one  object,  viz.,  the  destruction  of  bacteria. 

Milk  heated  to  60°  C.  and  held  at  that  temperature  for  20  minutes 
will  kill  the  viruses  of  tuberculosis,  typhoid  fever,  scarlet  fever,  diph- 
theria, malta  fever,  dysentery,  foot-and-mouth  disease :  this  time  and 
temperature  will  also  kill  streptococci,  staphylococci,  and  practically  all 
non-spore-bearing  microorganisms  pathogenic  for  man.  To  provide  a 
factor  of  safety  it  is  advisable  in  commercial  practice  to  heat  milk  to 
65°  C.  for  a  period  of  30  or  45  minutes.  Heating  milk  to  this  tem- 
perature does  not  alter  its  taste,  odor,  or  digestibility,  does  not  inter- 
fere with  its  food  value,  and  has  the  great  advantage  of  preventing  much 
sickness  and  saving  many  lives. 

Pasteurization  is  not  the  ideal,  but  only  a  temporary,  expedient. 
It  is  the  simplest,  cheapest,  least  objectionable,  and  most  trustworthy 
method  of  rendering  infected  milk  safe.     Pasteurization,  however,  can- 


MILK  519 

not  atone  for  filth  and  should  not  be  used  as  a  redemption  process. 
A  pure  milk  is  better  than  a  purified  milk ;  however^  no  one  should  drink 
raw  milk  that  cannot  be  guaranteed  by  the  health  officer  as  safe  and 
free  from  danger.  Only  certified  milk  or  milk  of  equally  high  char- 
acter can  be  regarded  as  reasonably  safe  and  satisfactory  without  pas- 
teurization. Less  than  1  per  cent,  of  all  the  milk  found  upon  the 
market  comes  within  the  honor  class. 

Pasteurized  milk  must  be  handled  at  least  as  carefully  as  raw  milk. 
It  should  be  bottled  by  machinery  immediately  following  the  process, 
kept  cold,  and  delivered  promptly.  Pasteurized  milk  sours  as  a  result 
of  acid  fermentation,  just  as  raw  milk  does.  In  other  words,  the  tem- 
peratures recommended  do  not  destroy  nature's  danger  signal — the 
lactic  acid  bacteria. 

Pasteurization  is  not  proposed  as  a  substitute  for  inspection,  but 
as  an  adjunct  to  inspection.  Inspection  gives  us  cleaner  and  better,  but 
not  necessarily  safe,  milk.  Pasteurization  eliminates  the  dangers  in- 
spection cannot  see.  The  combination  of  inspection  and  pasteurization 
corresponds  in  all  respects  to  modern  methods  of  obtaining  a  safe  water 
supply  for  a  large  city.  The  watershed,  through  inspection,  is  kept 
clean,  but  the  water  is  filtered  or  purified  before  it  is  given  to  the  con- 
sumer. 

There  can  be  no  more  objection  to  the  heating  of  milk  for  the  use 
of  adults  and  children  above  the  age  of  three  years  than  there  is  to  the 
cooking  of  meat.  Infants  should  receive  breast  milk.  When  this  is 
not  possible  they  should  have  the  best,  freshest  cow's  milk  that  can  be 
obtained.  Whether  such  milk  is  to  be  pasteurized,  modified,  or  other- 
wise treated  will  vary  with  circumstances. 

Much  has  been  said  concerning  the  relation  of  scurvy  and  rickets 
to  pasteurized  milk.  This  is  still  a  disputed  point,  but  the  evidence 
seems  clear  to  me  that  these  two  diseases  bear  no  relation  whatever  to 
the  heating  of  the  milk.  Scurvy  may  readily  be  prevented  by  the  use 
of  a  little  orange  juice,  pineapple  juice,  or  the  juice  of  other  fresh 
fruits.  Eickets  is  a  disease  of  defective  alimentation,  which  cannot  be 
laid  to  the  door  of  pasteurization.  Pediatricians  now  almost  unani- 
mously recommend  pasteurization,  particularly  in  the  summer  time,  es- 
pecially for  those  infants  who  must  depend  upon  ordinary  market  milk 
or  milk  of  unknown  quality. 

Pasteurization  is  too  important  a  public  health  measure  to  leave 
to  individual  caprice.  The  process  should  be  under  official  supervision. 
Further,  pasteurized  milk  should  be  labeled  as  such  or  simply  "heated 
milk,"  stating  the  degree  of  heat  and  the  length  of  time,  and  the  date 
on  which  the  process  was  done. 

Pasteurization  is  sometimes  objected  to  because  it  does  not  destroy 
heat-resisting  toxines  which  are  supposed  to  be  in  milk.     The  occur- 


520 


ANIMAL   FOODS 


rence  of  such  poisons  is  a  mere  assumption.  Even  if  they  exist  in  milk 
they  would  be  in  the  raw  milk  as  well  as  in  the  heated  milk.  The 
true  exotoxins  are  all  killed  at  60°  C.  for  20  minutes. 

Theoretically  the  best 
place  to  pasteurize  milk  is 
in  the  home.  Practically 
the  best  place  is  at  some 
central  station,  where  it 
may  be  done  scientifically 
under  official  surveillance. 
Methods  of  Pasteur- 
ization.— There  are  three 
well-known  metliods  by 
which  milk  may  be  pas- 
teurized: (1)  the  flash 
method;  (2)  the  holding 
method;  (3)  in  the  bottle. 
The  flash  method  con- 
sists of  heating  the  milk 
momentarily  to  a  tempera- 
ture of  about  178°  F.  and 
cliilling  it  at  once.  This 
method  is  sometimes  in- 
correctly called  commercial 
pasteurization.  It  does  not 
give  uniform  results,  is 
not  entirely  reliable,  and  does  not  meet  with  the  approval  of  the  sani- 
tarian. The  method,  however,  is  rapid,  cheap,  and  is  much  in 
vogue. 

The  holding  method  consists  in  heating  the  milk  to  the  desired 
temperature,  say  65°  C,  and  then  holding  it  in  a  suitable  tank  or  series 
of  tanks  at  that  temperature  for  a  given  period  of  time,  say  30  or  45 
minutes.  This  method  has  proven  satisfactory  in  practice  under  com- 
mercial conditions. 

Pasteurization  in  the  hoitle  is  the  perfection  of  the  art.  It  is  the 
ideal  method,  because  the  danger,  however  slight,  of  recontamination 
is  entirely  eliminated.  In  order  to  pasteurize  milk  in  bottles  the  bottles 
must  be  well  sealed  with  a  crown  cork  and  cap,  or  equally  effective 
stopper.  The  bottles  containing  the  milk  may  either  be  immersed  in 
a  water  bath,  brought  to  the  proper  temperature,  held  there  a  sufficient 
length  of  time,  and  then  chilled;  or  the  methods  used  in  beer  pasteuriza- 
tion, such  as  the  Loew  pasteurizers,  may  be  used.  In  this  case  the 
bottles  are  subjected  to  a  spray  or  shower  of  heated  water. 

Freeman's  pasteurizer  for  heating  milk  in  individual  feeding  bottles 


Fig.  71.- 


-AuTOMATic  Temperature  Recorder  for 
Pasteurizers. 


MILK 


521 


in  the  home  is  most  serviceable.  The  modification  of  Mr.  Nathan 
Straus  is  shown  in  Fig.  72.     It  is  used  as  follows: 

After  the  bottles  have  been  thoroughly  cleaned  they  are  placed  in 
the  tray  (A)  and  filled  with  the  milk  or  mixture  used  for  one  feeding. 
Then  put  on  the  corks  or  patented  stoppers  without  fastening  them 
tightly. 

The  pot  (B)  is  now  placed  on  the  wooden  surface  of  the  table  or 
iloor  and  filled  to  the  supports  (C)  with  boiling  water. 


Fig.  72. — Straus  Home  Pasteurizer. 


Place  the  tray  (A)  with  filled  bottles  into  the  pot  (B)  so  that  the  bot- 
tom of  the  tray  rests  on  the  supports  (C),  and  put  cover  (D)  on  quickly. 

After  the  bottles  have  been  warmed  up  by  the  steam  for  five  minutes, 
remove  the  cover  quickly,  turn  the  tray  so  that  it  drops  into  the  water, 
replace  the  cover  immediately.  This  manipulation  is  to  be  made  as 
rapidly  as  possible  to  avoid  loss  of  heat.  Thus  it  remains  for  twenty- 
five  minutes. 

Now  take  the  tray  out  of  the  water  and  fasten  the  corks  or  stop- 
pers air-tight.  Cool  the  bottles  with  cold  water  and  ice  as  quickly  as 
possible,  and  keep  them  at  this  low  temperature  until  cold. 

Use  the  milk  from  the  bottles  and  do  not  pour  it  into  another 
vessel. 

The  milk  should  not  be  used  for  children  later  than  twenty-four 
hours  after  pasteurization. 

Emphasis  is  laid  on  the  fact  that  only  fresh,  clean  milk,  which  has 
been  kept  cold,  should  be  used. 


522  ANIMAL    FOODS 

The  Effect  of  Heat  upon  Milk.  — The  changes  produced  in  milk 
by  healing  depend  upon  the  degree  of  heat  and  the  length  of  exposure. 
Milk  heated  to  60°  C.  for  a  short  time  does  not  appreciably  affect  its 
chemical  and  pliysical  properties.  The  boiling  of  milk,  however,  pro- 
duces pronounced  changes.  In  the  main,  these  consist  of  a  partial  de- 
composition of  the  proteins  and  other  complex  nitrogenous  derivatives; 
diminution  of  the  organic  phosphorus  and  an  increase  of  inorganic 
phosphorus;  precipitation  of  the  calcium  and  magnesium  salts  and  the 
greater  part  of  the  phosphates;  expulsion  of  the  greater  part  of  the 
carbon  dioxid;  caramelization  or  burning  of  a  certain  portion  of  the 
milk  sugar,  causing  the  brownish  color;  partial  disarrangement  of  the 
normal  emulsion,  and  coalescence  of  some  of  the  fat  globules;  coagula- 
tion of  the  serum  albumin,  which  begins  at  75°  C. ;  the  ferments  are 
killed. 

Boiled  milk  has  a  cooked  taste  which  appears  at  about  70°  C.  This 
is  due  perhaps  to  the  decomposition  of  certain  of  the  proteins  in  the 
milk.  The  loss  of  certain  gases  also  alters  the  taste,  so  that  milk  heated 
in  closed  vessels  has  a  less  pronounced  flavor  than  if  heated  in  open 
vessels. 

Milk  heated  in  the  open  air  forms  a  pellicle  which  renews  if  it  is 
removed.  This  scum  forms  when  milk  reaches  about  60°  C.  It  con- 
sists of: 

Fatty  matter    45.42  per  cent. 

Casein   and    albuminoid 50.86  per  cent. 

Ash    3.72  per  cent. 

Milk  heated  in  closed  vessels  does  not  form  a  pellicle,  even  when 
the  temperature  reaches  the  boiling  point.  It  seems  that  this  pellicle 
is  due  mainly  to  the  drying  of  the  upper  layer  of  the  liquid. 

After  milk  has  been  heated  to  65°  C.  or  over  for  half  an  hour,  the 
cream  does  not  rise  well,  if  at  all,  owing  to  the  increase  in  the  vis- 
cosity of  the  fluid  in  which  it  is  emulsified.  The  clusters  of  fat  drop- 
lets which  are  agglutinated  into  masses  in  normal  milk  are  broken  down 
by  heating,  and  the  globules  are  more  homogeneously  distributed 
throughout  the  fluid. 

It  has  been  observed  that  cooked  milk  coagulates  with  rennin  more 
slowly  than  raw  milk.  This  effect  is  noted  often  at  temperatures  of 
80°  to  90°  C,  but  has  not  been  observed  in  milk  heated  to  60°  C.  for 
20  minutes.  The  curd  produced  by  rennin  coagulation  in  cooked  milk 
is  softer,  less  tough,  and  more  flocculent  than  that  produced  by  rennin 
coagulation  in  raw  milk.  This  is  believed  to  be  an  advantage  favoring 
the  digestibility  of  heated  milk.  Cooked  milk  is  said  to  be  constipat- 
ing. This  is  explained  by  the  fact  that  cooked  milk  contains  compara- 
tively few  bacteria  and  is,  therefore,  less  irritating  than  raw  milk. 


THE  BACTEEIOLOGICAL  EXAMIXATIOX  OF  MILK     523 

THE    BACTERIOLOGICAL    EXAMINATION    OF    MILK 

The  Number  of  Bacteria, — Xo  known  method  can  give  an  enumera- 
tion of  all  the  bacteria  in  milk.  Some  are  aerobes,  others  anaerobes; 
some  require  alkaline,  others  acid  media;  some  grow  best  at  room  tem- 
perature, others  only  at  blood  temperature;  and  some  grow  slowly  or 
not  at  all  upon  ordinary  media.  The  methods  in  use,  therefore,  are 
those  which  have  been  shown  by  experiments  to  give  the  highest  counts 
and  the  maximum  information  under  ordinary  conditions. 

For  the  sake  of  uniformity  methods  should  follow  the  report  of 
the  Committee  on  Standard  Methods  of  Bacterial  Milk  Analysis  of  the 
American  Public  Health  Association.^ 

The  samples  must  be  collected  and  kept  in  such  a  manner  as 
to  prevent  either  any  addition  of  bacteria  from  without  or  multiplica- 
tion of  the  bacteria  originally  present.  AYlienever  possible,  and  es- 
pecially in  the  selection  of  certified  milk  samples,  an  original  package 
should  be  taken,  placed  in  a  suitably  iced  case,  and  brought  at  once 
to  the  laboratory.  Samples  of  market  milk  may  be  collected  in  the 
same  manner  as  water  samples,  in  sterile,  wide-mouthed,  glass-stoppered 
four-ounce  bottles.  Care  should  be  taken  to  secure  a  sample  which  is 
thoroughly  representative  of  the  milk  to  be  examined.  This  may  be 
done  by  pouring  the  milk  back  and  forth  into  a  sterile  receptacle,  or 
shaking  the  milk  thoroughly  with  the  receptable  turned  upside  dov\-n. 
In  taking  samples  from  tanks  it  is  allowable  to  stir  thoroughly  with 
a  long-handled  dipper.  Generally  speaking^,  the  shorter  the  time  be- 
tween collection  and  examination  of  milk  samples  the  more  accurate 
will  be  the  results.  For  routine  work  the  attempt  should  be  made  to 
plate  within  four  hours  of  the  time  of  collection.  Too  much  stress 
cannot  be  laid  on  the  importance  of  keeping  the  samples  properly  iced 
during  this  interval.  They  should  be  kept  below  40°  F.,  but  care  should 
be  taken  that  they  are  not  frozen. 

The  standard  medium  for  routine  enumeration  of  bacteria  in  milk 
is:  agar,  1  per  cent.,  reaction  -{-1.0,  Fuller's  scale.-  Milk  should  al- 
ways be  diluted  before  plating,  for  the  reason  that  whole  milk  produces 
a  turbidity  of  the  agar,  and  because  the  bacteria  cannot  well  be  dis- 
persed without  diluting,  and  the  resulting  colonies  are  so  close  that  they 
interfere  with  each  other.  The  milk  is  diluted  in  the  proportion  of 
1-10,  1-100,  1-1,000,  1-10,000,  1-100,000,  or  1-1,000,000.  For  certified 
milk  1-100  dilution  should  be  used.  Ordinary  potable  water,  steril- 
ized, may  be  used  for  dilutions.  The  number  of  bacteria  present  may 
be  estimated  approximately  before  dilutions  are  made  by  direct  micro- 

^  America?^  Journal  of  PuhJic  Hygiene,  August,  1910,  Yl,  3,  p.   31c. 
^  .3]seulin   bile    salt,    agar,    lactose,    litmus    agar,    and   whey    agar    mav    also 
"be  used. 


524  ANIMAL    FOODS 

scopic  examination  of  a  properly  prepared  sediment.  Otherwise  it  is 
necessary  to  make  a  range  of  dilutions  therefrom,  selecting  for  record 
the  count  obtained  on  that  plate  Avhieh  yields  between  40  and  200 
colonies.  A  plate  containing  more  or  less  than  these  numbers  will  not 
give  reliable  results.  Porous,  earthenware  Petri  dish  covers  are  recom- 
mended as  superior  to  glass,  since  they  absorb  tlie  excess  of  moisture 
and  thus  help  prevent  spreaders.  Another  method  of  preventing  spread- 
ers is  to  invert  the  dishes  and  place  in  the  glass  cover  of  each  a  strip 
of  sterile  filter  paper  moistened  with  one  large  drop  of  glycerin. 

The  plating  should  always  be  checked  by  duplicate  controls,  and 
a  blank  plate  should  be  made  with  each  series  for  control  of  the  steril- 
ity of  the  agar,  water,  air,  Petri  dishes,  pipettes,  and  methods.  The 
plates  should  be  incubated  at  37°  C.  for  48  hours,  or  may  be  grown  at 
21°  C.  for  five  days.  Only  those  colonies  should  he  counted  which  are 
visible  to  the  naked  eye  or  may  be  seen  readily  by  a  low  power  lens. 
The  result  should  always  be  expressed  in  round  numbers.  It  is  mis- 
leading to  state  that  a  milk  contains  3,140,672  bacteria  per  c.  c.  This 
gives  a  false  and  exaggerated  notion  of  the  accuracy  of  the  method. 
At  best  the  results  are  only  an  average  approximation.  Results  should 
be  expressed  in  accordance  with  the  recommendations  of  the  Commis- 
sion on  Standards  of  the  New  York  Milk  Committee.^ 

The  Kinds  of  Bacteria. — We  still  lack  satisfactory  routine  methods 
for  determining  the  kinds  of  bacteria  found  in  milk.  If  the  plates  are 
made  with  gelatin  it  will  give  the  relative  proportion  of  liquefiers.  By 
the  use  of  Endo's  medium  or  lactose  litmus  agar  the  number  of  acid- 
producing  bacteria  may  be  determined.  The  number  of  fermenting 
organisms  may  be  estimated  by  planting  progressively  smaller  quanti- 
ties in  fermentation  tubes  containing  glucose  or  other  sugar;  or  by  the 
use  of  the  Wisconsin  curd  test.  The  presence  of  gas-producing  organ- 
isms in  abundance  usually  indicates  dirty  conditions  of  stables,  cows, 
or  containers. 

To  determine  the  number  of  proteolytic  bacteria  in  milk  place 
1  c.  c.  of  sterile  skim  milk  into  a  Petri  dish,  then  add  the  proper  dilu- 
tion of  milk  in  question,  and  finally  pour  in  molten  sugar-free  agar. 
Incubate  48  hours,  and  then  wash  the  surface  with  a  dilute  solution  of 
acetic  acid.  Count  the  number  of  colonies  surrounded  by  a  clear  zone, 
which  is  taken  to  represent  proteolysis  or  breaking  down  of  the  protein.^ 

Typhoid  bacilli  may  be  isolated  on  Endo's  medium,  and  diphtheria 
upon  Loeffler's  blood  serum.  Other  pathogens  require  special  technique 
applicable  to  each  case.  The  number  of  streptococci  in  milk  may  be 
estimated  by  the  direct  examination  of  stained  smears.  The  chains 
are  more  readily  counted  if  the  milk  is  first  incubated  at  37°  C.  for 

^Public  Health  Bcports,  Vol.  XXVII,  19,  May  10,  1912. 

*  Hastings:    Cent.  f.  Bakt.  u.  Parasitenk.,  Abt.  II,  Bd.  X,  p.  384, 


MICEOSCOPIC    EXAMINATION  525 

6  or  8  hours.  In  the  estimation  of  streptococci  only  the  longer  chains 
are  considered.  The  presence  of  streptococci  and  an  approximation 
as  to  their  number  may  also  be  determined  by  planting  the  milk  upon 
the  surface  of  blood  agar  and  studying  the  fine  dewdrop-like  colonies. 

A  few  streptococci  will  be  found  in  most  sediments  from  milk. 
They  are  seldom  found  to  any  great  extent  by  direct  microscopic  exam- 
ination of  clean  milk.  Occasionally  a  sample  will  be  found  crowded 
with  long  chains.  More  often  streptococci,  if  present,  are  in  the  form 
of  diplococci  or  very  short  chains.  The  common  interpretation  is  to 
regard  the  short  chain  varieties  as  probably  harmless,  while  long  chains 
are  regarded  as  more  apt  to  indicate  inflammatory  reactions.  A  milk 
containing  these  in  large  numbers  may  not  be  a  safe  article  of  diet. 

Euediger  points  out  that  Streptococcus  lacticus  can.  be  differentiated 
from  Streptococcus  pyogenes  by  means  of  blood  agar  plates.  Strepto- 
coccus pyogenes  produces  small  colonies  surrounded  by  a  large  zone  of 
hemolysis,  whereas  Streptococcus  lacticus  produces  green  or  grayish 
colonies  with  very  little  or  no  hemolysis. 

Streptococcus  lacticus  has  no  sanitary  significance,  as  it  is  found  in 
nearly  all  samples  of  clean,  soured,  or  fresh  milk,  and  very  often  in 
the  healthy  milk  ducts.  Streptococcus  pyogenes,  on  the  other  hand, 
seems  to  occur  but  rarely  in  milk,  and  is  indicative  of  the  existence  pf 
an  inflamed  condition  of  the  udder  of  the  cow  furnishing  the  milk. 

The  presence  of  Bacillus  cerogenes  capsulatus,  the  gas  bacillus  of 
Welch,  may  be  determined  by  heating  some  of  the  milk  to  80°  C.  for 
one  hour  and  then  incubating  the  sample  at  37°  C.  If  the  sample 
contains  this  microorganism  it  will  show  active  fermentation  with  gas 
production  within  24  hours  (sometimes  as  soon  as  6  hours),  with  the 
development  of  an  odor  of  butyric  acid. 

The  demonstration  of  tubercle  bacilli  in  milk  depends  upon  animal 
experimentation.  Guinea  pigs  are  injected  subcutaneously  with  5  c.  c. 
of  sediment  obtained  by  centrifuging,  or  with  cream,  or  both.  The 
guinea  pigs  that  do  not  die  in  two  months  are  tested  with  sufficient 
tuberculin  (0.  T.)  to  cause  the  death  of  the  tuberculous  animals  in  24 
hours.  Two  c.  c.  of  the  crude  tuberculin  is  injected  subcutaneously  for 
this  purpose. 

MICROSCOPIC    EXAMINATION 

There  are  three  methods  of  making  a  microscopic  examination  of 
milk  in  current  use. 

(1)  The  Stewart-Slack  Method. — Two  c.  c.  of  milk  are  placed  in 
a  glass  tube  closed  at  both  ends  with  a  rubber  stopper.  This  is  cen- 
trifuged  for  10  minutes  at  a  speed  of  from  2,000  to  3,000  revolutions 
per  minute.     The  sediment  upon  the  rubber  stopper  of  the  distal  end 


526  ANIMAL    FOODS 

of  the  tube  is  mixed  with  a  drop  or  two  of  water  and  spread  upon  a 
slide  in  a  thin  even  layer,  covering  a  space  of  about  four  square  centi- 
meters. This  is  dried  and  stained  with  methylene  blue.  The  micro- 
scopic examination  reveals  the  character  of  the  milk  as  judged  from 
the  approximate  number  of  pus  cells  and  presence  of  streptococci  in 
long  chains.  It  has  been  found  that  the  number  of  cocci,  bacilli,  or 
chains  in  the  1/12  oil  immersion  field,  multiplied  by  10,000,  gives  a 
rough  approximation  of  the  number  of  bacteria  in  a  cubic  centimeter 
of  the  whole  milk. 

The  results  of  this  method  vary  considerably  with  details  of  in- 
dividual manipulation,  with  the  speed  of  the  centrifugal  machine,  with 
the  time  allowed  for  centrifugation,  and  other  factors. 

(2)  The  Doane-Buckley  Method. — In  this  method  the  number  of 
leukocytes  are  counted  in  the  chamber  of  the  Zeiss  blood  counter,  which 
contains  just  0.0001  c.  c.  Ten  c.  c.  of  milk  is  centrifuged  at  2,000 
revolutions  per  minute  for  four  minutes.  The  fat  is  removed  with  a 
cotton  swab  and  again  centrifuged  for  one  minute.  The  fat  is  again 
carefully  removed,  for  any  appreciable  amount  of  fat  will  interfere 
with  the  counting.  The  supernatant  fluid  is  now  pipetted  off  and  two 
drops  of  a  saturated  alcoholic  solution  of  methylene  blue  are  added  to 
the  sediment,  which  is  thoroughly  mixed  and  warmed  in  boiling  water 
for  two  or  three  minutes,  which  favors  the  staining  of  the  cells.  The 
sediment  is  now  diluted  to  the  1  c.  c.  mark  with  water.  Some  of  this 
is  transferred  to  the  counting  chamber  and  the  number  of  cells  counted 
with  a  dry  lens.  The  number  of  cells  in  the  counting  chamber  multi- 
plied by  1,000  gives  the  number  per  c.  c.  in  the  milk. 

(3)  The  Prescott-Breed  Method.- — A  capillary  tube  is  prepared,  ar- 
ranged to  receive  a  rubber  bulb  at  one  end,  and  marked  carefully  to 
deliver  0.01  c.  c.  After  a  most  thorough  mixing  of  the  milk,  0.01  c.  c. 
is  removed  with  the  sterilized  pipette  and  spread  uniformly  over  a  square 
centimeter  on  an  ordinary  microscopic  slide.  It  is  allowed  to  dry  and 
is  fixed  with  methyl  alcohol,  after  which  the  fat  is  dissolved  from  it 
by  the  use  of  xylol.  The  smear  is  then  stained  either  with  methylene 
blue  or  preferably  with  one  of  the  blood  stains,  the  Jenner  stain  or 
Wright  stain  being  useful  for  this  purpose.  If  the  staining  is  so  deep 
as  to  make  the  specimen  too  opaque  for  proper  study,  it  is  slightly  de- 
colorized with  alcohol,  which  removes  the  stain  from  the  general  sedi- 
ment more  readily  than  it  does  from  the  bacteria  or  the  tissue  cells. 
The  stained  smear  is  studied  under  a  twelve-incli  immersion  lens.  The 
draw  tube  is  adjusted  so  that  the  field  of  the  microscope  covers  exactly 
15  millimeters,  and  under  these  circumstances  the  number  of  bacteria 
present  in  the  0.01  c.  c.  is  exactly  5,000  times  the  number  found  in  a 
microscopic  field.  The  counting  of  a  large  number  of  fields  (100 
fields)  and  averaging  the  results  multiplied  by  this  number  will,  there- 


CHEMICAL    A^TALYSIS    OF    MILK  527 

fore,  give  approximately  the  number  of  cells  or  bacteria  contained  in 
0.01  c.  c.  of  milk. 

CHEMICAL  ANALYSIS  OF  MILK 

Total  Solids. — The  total  solids  in  milk  consist  chiefly  of  the  fats, 
sugar,  proteins,  and  inorganic  salts.  The  United  States  standard  re- 
quires 12  per  cent,  of  the  milk  to  consist  of  total  solids,  8.5  per  cent, 
of  which  shall  be  solids,  not  fat,  and  3.25  per  cent.  fat.  In  some  states 
the  requirement  for  total  solids  is  as  high  as  13  per  cent.,  in  others 
11.5  per  cent. 

Determination  of  Total  Solids. — The  total  solids  may  be  determined 
either  by: 

(1)  The  use  of  Eichmond's  slide  rule. 

(2)  The  Babcock  asbestos  method. 

(3)  By  evaporation  and  direct  weighing. 

EiCHMOND^s  Slide  Eule. — This  is  a  device  by  which  the  total 
solids  may  be  determined  fairly  accurately  by  the  use  of  the  formula 
of  Hehner  and  Eichmond.  It  is  necessary  to  know  the  correct  specific 
gravity  and  the  amount  of  fat.  From  this  the  total  solids  is  deter- 
mined by  the  following  formula : 

T  S=(j)+1.2  F+.14 

in  which  T  S  equals  total  solids,  G  the  last  two  units  of  the  specific 
gravity  and  any  decimal.  Thus,  if  the  specific  gravity  is  1.0295,  G= 
29.5.  F  represents  the  percentage  of  fat.  In  using  the  slide  rule  the 
operation  is  conducted  in  two  stages.  First,  the  lactometer  reading 
is  corrected  for  temperature.  The  observed  lactometer  reading  is 
brought  opposite  the  60°  and  the  correct  lactometer  reading  read  off 
opposite  the  observed  temperature.  Second,  the  arrow  of  the  slide  is 
set  opposite  the  observed  percentage  of  fat,  and  the  total  solids  are  read 
off  opposite  the  corrected  specific  gravity  reading  on  the  scale  marked 
"specific  gravity."  The  results  obtained  by  the  use  of  Eichmond's  slide 
rule  agree  quite  closely  with  those  obtained  by  direct  weighing. 

This  formula  may  also  be  used  to  determine  the  percentage  of  fat 
provided  the  specific  gravity  and  total  solids  are  known. 

The  Babcock  Asbestos  Method. — The  milk  is  placed  upon  a  filter 
paper  cartridge  filled  loosely  with  freshly  ignited  woolly  asbestos,  sub- 
jected to  a  temperature  of  100°  C.  until  weight  is  constant,  and  then 
cooled  and  weighed.  The  gain  in  weight  represents  the  total  solids  of 
the  amount  of  milk  taken.  The  advantage  in  this  method  is  that  the 
cartridge  mav  then  be  slipped  into  the  Soxhlet  extraction  apparatus 
and  used  for  the  determination  of  fat. 

Weighing. — About  5  c.  c.  of  milk  are  weighed  in  a  tared  platinum 
dish,  evaporated  exactly  two  hours  on  a  steam  bath,  the  outside  wiped 


528  ANIMAL    FOODS 

dry.  and  then  cooled  to  constant  weight  in  a  desiccator.  The  weight 
of  the  residue  represents  the  total  solids  of  the  milk. 

Determination  of  Asii.-^The  platinum  dish  containing  the  total 
solid  residue  is  carefully  heated  in  the  flame,  avoiding  sjiattering  and 
heating  above  a  dull  red  glow.  When  the  residue  has  become  white,  or 
nearly  so,  it  is  cooled  in  a  desiccator  and  again  weighed;  the  difference 
between  the  final  weight  and  the  original  weight  of  the  empty  dish 
represents  the  amount  of  mineral  matter  in  the  amount  of  milk  taken. 
The  ash  is  saved  for  the  tests  for  boron  compounds,  carbonates,  and 
other  non-volatile  mineral  preservatives. 

Determination  of  Fats. — The  determination  of  the  quantity  of  but- 
ter fat  contained  in  milk  is  of  considerable  economic  importance  and  is 
included  as  a  routine  in  all  milk  laboratories.  There  are  several  methods 
by  which  the  fat  in  milk  may  be  accurately  determined. 

(1)  Babcock  Method. — The  Babcock  method  is  the  most  conveni- 
ent and  is  sufficiently  accurate  for  ordinary  purposes.  It  cannot  be 
carried  out  without  considerable  special  apparatus,  including  a  cen- 
trifuge, special  graduated  flasks  and  pipettes.  The  principle  of  this 
method  depends  upon  separating  the  fat  by  means  of  the  addition  of 
sulphuric  acid.  The  mixture  is  centrifugalized  so  that  the  fat  rises 
into  the  neck  of  the  specially  graduated  flask,  and  the  percentage  may 
be  read  off  directly.     The  method  is  carried  out  as  follows: 

In  the  special  graduated  flask  are  mixed: 

17.5  c.  c.  milk. 

17.0  c.  c.  of  sulphuric   acid    (specific  gravity   1.82-1.83). 

2  c.  c.  amyl  alcohol   (optional). 

The  acid  must  be  run  slowly  down  the  side  of  the  flask  under  the 
milk  and  the  whole  mixed,  without  splashing,  by  imparting  a  rotary 
motion  to  the  contents  of  the  bottle.  The  mixture  is  centrifugalized 
for  4  minutes;  boiling  water  is  then  added  until  the  liquid  rises  to  the 
bottom  of  the  neck  of  the  flask,  and  the  centrifugalization  is  repeated 
for  2  minutes.  Again  add  boiling  water  until  the  top  of  the  column 
is  near  but  safely  under  the  top  of  the  scale,  and  centrifugalize  a  third 
time  for  1  minute.  By  this  time  the  fat  in  the  neck  of  the  bottle 
should  be  clear,  yellow,  and  liquid.  The  length  of  the  column  of  fat 
is  considered  as  extending  from  the  bottom  of  the  line  of  contact  with 
the  liquid  below  to  the  top  of  the  meniscus  above.  The  length  of  the 
column  of  fat  is  measured  by  means  of  a  pair  of  dividers,  which  are 
first  adjusted  to  the  length  of  the  column  of  fat,  and  the  percentage 
read  by  touching  one  point  of  the  dividers  to  the  zero  mark  on  the 
scale,  when  the  upper  point  will  indicate  the  percentage  of  fat  in  the 
milk.     The  mixing  of  sulphuric  acid  with  the  milk  generates  consid- 


CHEMICAL    ANALYSIS    OF    MILK  539 

erable  heat,  which  should  be  maintained,  so  that  at  the  time  of  taking 
the  reading  the  contents  of  the  bottle  register  between  55°-60°  C. 
Care  should  be  taken  to  use  none  but  authoritatively  tested  and  guar- 
anteed bottles. 

(2)  The  Werxer-Schmidt  Method. — This  method  is  slower  than 
the  Babcock,  especially  when  many  samples  are  to  be  analyzed,  but  it 
can  be  done  with  improvised  apparatus  and  readily  procurable  ma- 
terials. Ten  c.  c.  of  milk  are  added  to  10  c.  c.  of  concentrated  liydro- 
chloric  acid  in  a  50-c.  c.  test  tube,  shaken,  and  boiled  until  dark  brown 
in  color.  The  mixture  is  then  cooled  in  water  and  30  c.  c.  of  washed 
ether  added,  the  stopper  inserted,  and  thoroughly  agitated.  When  the 
two  layers  have  separated  the  upper  layer  containing  the  ether,  and  dis- 
solved fat  may  be  withdrawn  by  means  of  a  pipette,  or  blown  out  with 
the  assistance  of  a  double  tube,  such  as  is  used  in  wash-bottles,  the 
delivery  tube  extending  into  the  ether  layer  almost  to  the  line  of  de- 
marcation between  the  ether  and  the  acid-milk  mixture.  The  ether  con- 
taining the  extracted  fat  is  transferred  to  a  weighed  flask.  The  ex- 
traction is  repeated  with  several  fresh,  smaller  portions  of  ether  (about 
10  c.  c).  and  the  whole  of  the  ether  used  is  collected  in  the  weighed 
flask.  The  ether  i&  then  distilled  off  or  permitted  to  evaporate  at  a 
low  temperature.  The  residuum  of  fat  is  heated  to  constant  weight  in 
an  air  bath,  cooled,  and  weighed.  Since  the  milk  is  measured  and  not 
weighed,  a  correction  must  be  made  accordingly. 

Example. — Amount  of  milk  used  equals  10  c.  c.  Specific  gravity  of 
sample  equals  1.029.  Weight  of  milk  used,  therefore,  equals  1.029X10, 
which  equals  10.29  grams.  The  weight  of  the  fat  found  equals  0.386 
gram.  Percentage  of  the  fat  in  the  original  milk  is  determined  from 
the  following  equation: 

10.29  :0.386::100:x 

x=3.97,  or  the  percentage  of  fat  in  the  original  milk. 

(3)  The  Soxhlet  Extraction  Method. — This  is  the  most  accu- 
rate method  for  determining  fats  in  milk  and  other  substances.  The 
principle  depends  upon  the  complete  extraction  of  all  the  fat  by  con- 
tinuous washing  with  ether.  The  only  error  in  this  method  consists 
in  the  fact  that  substances  other  than  fats  are  soluble  in  ether  and  are 
included  in  the  weight.  This  error  in  milk  is  negligible.  The  process 
requires  a  coil  of  thick  filter  paper  free  from  substances  soluble  in  ether 
and  alcohol,  and  a  Soxhlet  extraction  apparatus.  Instead  of  the  coil 
of  filter  paper  a  specially  prepared  cartridge  of  filter  paper,  which  fits 
loosely  within  the  cylinder  of  the  Soxhlet  apparatus,  may  be  used. 
^Yhen  the  cartridge  is  used  it  is  best  to  plug  its  open  end  with  ab- 
sorbent cotton,  in  order  to  prevent  the  escape  of  fine  particles  of  the 
contained  substance. 


530  ANIMAL    FOODS 

A  definite  weight  of  milk,  about  5  grams,  is  applied  to  the  coil  of 
filter  paper  or  cartridge,  in  one  of  two  ways.  A  small  beaker  containing 
the  required  amount  is  weighed  and  the  coil  is  placed  into  it  and  kept 
there  until  nearly  the  whole  has  been  absorbed.  The  coil  is  then  care- 
fully withdrawn  and  placed,  dry  edge  downward,  upon  a  sheet  of  glass. 
The  beaker  is  then  weighed  again,  and  the  loss  in  weight,  which  rep- 
resents the  amount  of  milk  absorbed,  is  noted.  Another  method  is  to 
weigh  the  beaker  containing  the  milk  and  a  small  pipette.  The  neces- 
sary amount  of  milk  is  then  transferred  to  the  coil  with  the  pipette, 
after  which  the  weight  of  the  beaker  and  pipette  containing  the  re- 
maining milk  is  noted.  The  difference  represents  the  weight  of  the 
milk  absorbed.  The  coil  or  cartridge  is  then  dried  in  an  air  bath  at 
100°  C.  for  an  hour  or  more,  when  it  is  ready  for  insertion  into  the 
extractor. 

The  three  separate  parts  of  the  Soxhlet  extraction  apparatus,  con- 
sisting of  the  flask,  the  cylinder,  and  the  condenser,  are  joined  together 
and  mounted  upon  a  water  bath  or  an  electrically  heated  plate.  Before 
the  operation  is  begun  the  exact  weight  of  the  flask  must  be  determined. 
The  ether  is  then  added,  and  as  it  volatilizes  the  vapor  passes  upward 
through  the  side  tube  into  the  extractor,  and  thence  to  the  condenser, 
where  it  falls  upon  the  substance  to  be  extracted.  As  the  process  con- 
tinues the  condensed  liquid  accumulates  in  the  cylinder  and  gradually 
rises  until  it  reaches  the  bend  of  tlie  siphon  in  the  cylinder  part  of  the 
apparatus.  When  full  the  siphon  acts  and  discharges  back  into  the 
flask,  until  the  entire  liquid  is  returned  to  its  starting  point.  During 
its  accumulation  in  the  cylinder  it  dissolves  the  fats  or  other  ether 
soluble  substances  which  are  carried  in  solution  into  the  flask.  The 
process  is  continued  until  this  siphoning  action  repeats  itself  again 
and  again  a^  long  as  is  necessary,  so  that  the  whole  of  the  extracted 
matter  is  finally  within  the  flask.  The  fat,  being  non-volatile,  remains 
in  the  flask  while  the  ether  is  revolatilized  and  sent  continually  on  its 
errand.  On  the  completion  of  the  process  the  ether  is  permitted  to  col- 
lect in  the  cylinder,  but  before  it  reaches  the  level  of  the  siphon  the 
flask  is  disjoined.  The  remaining  ether  is  expelled  cautiously  and  the 
flask  with  its  content  is  placed  in  an  air  bath  maintained  at  100°  C. 
and  dried  to  constant  weight.  The  increase  in  the  weight  of  the  flask 
represents  the  amount  of  matter  extracted. 

Example. — The  weight  of  milk  absorbed  by  the  filter  paper  was 
5.160  grams.  The  increase  in  the  weight  of  the  flask  was  0.161  gram. 
The  amount  of  fat  present  in  the  sample  is  then  obtained  by  the  fol- 
lowing equation : 

5.16:0.161::100:x 

xr:r3.20,  or  the  percentage  of  fat  in  the  milk. 


CHEMICAL    ANALYSIS    OF    MILK  531 

Determination  of  Milk  Sugar. — The  amount  of  lactose  in  milk  may 
be  determined  chemically  by  the  reduction  of  copper  sulphate  in  Fehling 
solution,  or  optically  by  means  of  the  polariscope. 

(1)  Method  by  Fehlixg's  Solution. — To  25  grams  of  milk  add 
0.5  e.c.  of  30  per  cent,  acetic  acid;  shake;  let  stand  3  minutes;  then 
add  100  c.  c.  of  boiling  water ;  again  shake ;  add  25  c.  c.  of  alumina 
cream;  again  shake,  and  let  stand  for  10  minutes;  filter  through  a  wet 
pleated  paper  filter  and  wash  the  residue  until  the  washings  and  filtrate 
total  250  c.  c,  representing  a  dilution  of  1-10  of  the  original  milk; 
this  dilutes  the  sugar  content  of  the  liquid  to  somewhat  less  than  0.5 
per  cent.  This  is  then  titrated  with  Fehling's  solution  in  the  usual 
manner,  namely:  fill  a  burette  with  sugar-containing  liquid,  place  10 
c.  c.  of  Fehling's  solution  (representing  0.067  gram  of  milk  sugar)  in 
a  flask,  and  heat  to  boiling.  Bun  in  the  liquid  from  the  burette  in  small 
portions,  maintaining  the  contents  of  the  flask  at  boiling  point  until  the 
liquid  in  the  flask  loses  its  original  blue  color,  which  marks  the  end 
point  of  the  reaction. 

Fehling's  solution  is  made  up  in  two  solutions:  1.  Dissolve  34.639 
grams  of  pure  sulphate  of  copper  in  distilled  water  and  dilute  it  to  a 
liter.  2.  Dissolve  173  grams  of  potassium  sodium  tartrate  (Eochelle 
salt)  in  distilled  water,  add  100  c.  c.  of  sodium  hydrate  solution  of 
1.393  specific  gravit}^,  and  dilute  the  mixture  with  distilled  water  to 
a  liter.  Equal  parts  of  solution  1  and  2  are  mixed  in  a  boiling-flask 
of  about  300  c.  c.  capacity.  The  amount  of  copper  contained  in  10  c.  c. 
of  solution  1  requires  for  its  reduction  0.050  gram  of  dextrose,  or  0.667 
gram  of  lactose. 

PoLAEiscoPE  Method. — The  polariscope,  the  quantities  used,  and 
the  factors  employed  in  the  polariscope  method  vary  with  different  types 
of  instruments.  Perhaps  the  most  satisfactory  is  the  Schmidt  and 
Haenzsch  half-shadow  type.  This  possesses  the  advantage  of  doing 
away  with  the  matching  of  colors,  and  hence  may  be  used  by  those  who 
are  color-blind,  and  even  with  those  having  normal  color  vision  it  gives 
the  most  satisfactory  results. 

To  70.65  grams  of  milk  add  an  excess  (3  c.  c.)  of  an  acid  nitrate 
of  mercury  solution  and  mix  thoroughly  by  shaking.  The  acid  nitrate 
of  mercury  solution  is  made  by  adding  one  part  of  weight  of  mercury 
to  two  parts  of  nitric  acid,  S.  G.  1.12,  and,  after  the  reaction  has  ceased, 
adding  an  equal  volume  of  distilled  water.  The  object  of  adding  the 
acid  nitrate  of  mercury  to  the  milk  is  to  remove  the  albumin  and  fat 
in  the  form  of  a  curd,  leaving  the  sugar  as  the  only  optically  active 
constituent  of  the  clear  serum.  The  milk  containing  the  acid  is  now 
diluted  to  102.5  c.  c.  with  distilled  water  and  again  thoroughly  mixed. 
Filter  through  a  dry  pleated  filter  and  take  the  polarimeter  reading 
without  delay  in  a  200-mm.  tube.     When  an  excess  of  acid  nitrate  of 


533  ANIMAL    FOODS 

mercury  is  added  to  the  sugar-containing  liquid  tlie  latter  quickl}'  be- 
gins to  decompose,  with  the  evolution  of  gas;  on  the  other  liand.  an 
excess  must  be  present  in  order  to  obtain  a  clear,  easily  filtered 
liquid. 

The  percentage  of  lactose  is  the  product  of  the  factor  0.0209  (this 
factor  is  applicable  to  these  conditions  only)  multiplied  by  the  number 
of  minutes  of  dextrorotation.  The  definite  directions  for  this  particu- 
lar kind  of  work  do  not  accompany  the  instrument  used.  The  factor 
should  be  determined  or  confirmed  by  comparing  with  lactose  solution 
of  known  strength.  Some  polarimeters  are  graduated  directly  in  sugar 
percentages  instead  of  degrees  and  minutes,  in  which  case  care  must 
be  taken  that  the  graduations  correspond  to  the  particular  form  of 
sugar  under  investigation,  or.  if  not,  that  a  suitable  correction  is  made. 

Determination  of  Proteins. — It  is  not  usual  to  estimate  the  proteins 
in  a  sanitary  analysis  of  milk,  since  different  specimens  of  milk  vary 
very  little  in  this  regard,  and  since  there  is  little  inducement  for 
sophistication,  as  far  as  the  proteins  are  concerned. 

(1)  Method  by  Difference. — If  we  know  the  weight  of  total 
solids  in  milk  and  subtract  therefrom  the  weight  of  the  fat,  ash,  and 
sugar,  the  difference  will  represent  the  proteins.  This  method  is  suffi- 
cient for  ordinary  purposes.  To  estimate  the  nature  of  the  various 
proteins  requires  special  skill  in  organic  analysis. 

(2)  Kjeldahl  Method. — The  milk  is  mixed  with  sulphuric  acid 
and  digested  in  a  flask  until  it  is  completely  charred  and  becomes  clear 
again.  The  residue  will  then  contain  all  of  the  nitrogen  in  the  form 
of  ammonium  sulphate,  which  is  determined  in  the  usual  way.  The 
total  nitrogen  multiplied  by  the  factor  6.38  gives  the  total  protein. 
The  method  is  carried  out  as  follows: 

Gunning  Modification. — An  accurately  weighed  amount  (about  5 
grams)  of  milk  is  placed  in  a  500-c.  c.  Kjeldahl  digestion  flask  and 
digested  with  10  grams  of  potassium  sulphate  and  15  c.  c.  of  concen- 
trated nitrogen-free  sulphuric  acid.  The  digestion  is  carried  out  over 
a  free  flame,  using  care  to  heat  gradually  at  first ;  the  process  is  con- 
sidered complete  when  the  liquid  becomes  clear  (about  2  hours).  The 
contents  of  the  flask  are  cooled  and  200  c.  c.  of  water  and  sufficient 
saturated  sodium  hydroxid  solution  to  neutralize  the  acid  and  to  make 
the  solution  strongly  alkaline  are  added.  The  nitrogen,  which  has  been 
converted  into  ammonium  sulphate,  is  now  distilled  through  a  block 
tin  tube  into  a  definite  amount  of  standard  acid,  and  tlie  acid  titrated 
back  with  standard  alkali,  using  cochineal  or  alizarin  as  indicator.  Tlie 
amount  of  nitrogen  can  be  calculated  from  the  results.  Total  nitrogen 
multiplied  by  6.38  gives  total  protein. 

Water. — Milk  is  still  frequently  sophisticated  by  the  addition  of 
water.     A  watered  milk  may  be  suspected  from  a  low  specific  gravity. 


CHEMICAL    ANALYSIS    OF    MILK  533 

or  may  be  detected  unerringly  by  the  index  of  refraction  of  the  milk 
serum. 

Eefractometer  Heading. — This  test  depends  upon  the  fact  that 
the  salts  dissolved  in  undiluted  milk  in  the  concentration  in  which  they 
exist  in  the  milk  seinim,  as  jDrepared  under  standard  conditions,  give 
a  reading  of  not  less  than  39  upon  the  scale  of  a  Zeiss  refractoiueter 
at  a  temperature  of  17.5°  C.  Distilled  water  gives  with  the  same  in- 
strument a  reading  of  15.     Milk  reading  below  39  is  certainly  watered. 

Eefractometer  reading  is  obtained  as  follows: 

The  milk  serum  is  prepared  by  adding  2  c.  c.  of  a  25  per  cent. 
acetic  acid  (S.  G.  1.035)  to  199  c.  c.  of  milk  at  about  20°  C.  and  mixing 
well.  Heat  the  mixture  to  70°  C.  Maintain  this  temperature  for  20 
minutes.  Cool  quickly  to  room  temperature  by  means  of  cold  water, 
and  filter  until  nearly  or  quite  clear.  Do  not  discard  the  curd,  as  it 
can  be  used  to  test  for  the  presence  of  artificial  colors.  The  refrac- 
tometer  reading  is  taken  with  the  filtrate  at  17.5°  C,  this  temperature 
being  maintained  by  means  of  a  large  body  of  water  at  the  same  tem- 
perature surrounding  the  milk  container. 

If  a  refractometer  is  not  at  hand  practically  the  same  information 
can  be  obtained  from  the  milk  serum  by  taking  its  sjaecific  gravity  with 
a  Westphal  balance  or  a  pycnometer. 

Reaction. — The  acidity  of  milk  is  determined  by  titration  with  a 
solution  of  sodium  hydroxid,  using  phenolphthalein  as  the  indicator. 

Take  50  c.  c.  of  milk  and  add  a  few  drops  of  alcoholic  phenolphtha- 
lein solution.  From  a  burette  run  in  0.1  normal  sodium  hydroxid 
solution  with  constant  stirring  until  the  pink  color  in  the  milk  per- 
sists about  15  seconds.  The  carbon  dioxid  in  the  atmosphere  fades  out 
the  phenolphthalein  color  by  converting  the  sodium  hydroxid  into  so- 
dium bicarbonate,  hence  the  determination  must  be  made  rapidly,  and 
a  rather  faint  but  not  very  permanent  pink  color  marks  the  end  point. 

The  acidity  of  milk  is  usually  expressed  in  terms   of  lactic  acid^ 

although  when  fresh  it  is  caused  by  other  organic  acids.     To  convert 

N 
the  amount  of  —  sodium  hydroxid  solution  necessary  to  neutralize  the 

acidity  in  50  c.  c.  of  milk  into  percentages  of  lactic  acid,  multiply  the 

number  of  cubic  centimeters  of  _  NaOH  by  0.018. 

10 
The  results  of  these  titrations  are  recorded  in  three  different  ways: 

(1)  In  this  country  the  calculations   are   reduced  to  terms   of   lactic 

acid.     Thus,  1  c.  c.  of  _  jSTaOH  neutralizes  0.02  gram  of  lactic  acid; 

(2)  in  degrees  of  acidity,  by  which  is  meant  the  number  of  cubic  cen- 
timeters of  „  XaOH  required  to  neutralize  100  c.  c.  of  milk;   (3)   in 

10  ^ 

36 


534  ANIMAL    FOODS 

German  degrees  of  acidity,  meaning  the  number  of  cubic  centimeters 
of  —  XaOH  per  100  c.  o.  of  milk.  For  transposition  purposes  the  fol- 
lowing equivalents  are  given: 

1  degree   (U.   S.)    of  acidity 0.009     per  cent,  lactic  acid 

1  degree   (German)    of   acidity.  ..  .0.0225  per  cent,  lactic  acid 
1  degree   (German)    of   acidity.  ..  .2.5°    (U.  S.)   acidity 

Eiihm  '  has  recommended  the  following  test  for  detection  of  begin- 
ning acidification  in  mixed  milks  of  two  or  more  cows:  Ten  c.  c.  of 
68  per  cent,  alcoliol  is  added  to  10  c.  c.  of  the  milk  to  be  tested.  If 
there  is  immediate  coagulation  the  acidity  is  above  8°.  More  advanced 
acidit}'  may  be  detected  b}'  boiling  a  small  amount  of  milk  for  a  few 
moments  in  a  test  tube.  Coagulation  appears  if  the  acidity  is  above 
10°.     These  are  convenient  tests  that  may  be  applied  at  the  dairy. 

Milk  has  a  variable  acidity  when  it  coagulates;  that  is,  when  it 
throws  its  caseinogcn  out  of  solution.  Milk  containing  about  0.225  per 
cent,  of  acid  will  coagulate  upon  heating.  This  may  be  prevented  by 
first  neutralizing  with  an  alkali,  such  as  sodium  carbonate.  The  amount 
of  acidity  in  a  particular  sample  of  milk  is  no  safe  criterion  as  to 
whether  it  will  coagulate  or  not  during  pasteurization.  This  can  only 
be  determined  with  certainty  by  first  testing  a  small  portion. 

Specific  Gravity. — The  specific  gravity  of  milk  is  taken  either  (1) 
with  the  lactodensimeter,  (2)  with  the  Westphal  balance,  or  (3)  upon 
an  ordinary  chemical  balance,  with  a  pycnometer. 

The  Quevenne  lactodensimeter  is  recommended  for  tlie  deter- 
mination of  the  specific  gravity.  It  is  made  like  an  ordinary  aerometer 
and  divided  into  degrees  which  correspond  to  a  specific  gravity  from 
1.014  to  1.040,  or  only  from  1.022  to  1.038,  since  by  the  latter  division 
a  greater  space  is  gained  between  the  difl^erent  degrees  without  unduly 
lengthening  the  instrument.  From  such  a  lactodensimeter  one  can  eas- 
ily read  off  four  decimal  places. 

The  milk,  the  specific  gravity  of  which  is  to  be  determined,  is  well 
shaken  and  poured  into  a  high-class  cylinder  of  suitable  diameter;  the 
lactodensimeter  is  dropped  in  slowly,  in  order  to  prevent  its  bobbing 
up  and  down.  (The  bulb  should  be  free  from  adhering  air  bubbles.) 
The  figuj-es  on  the  stem  are  the  second  and  third  decimals  of  the  num- 
bers of  the  specific  gravity,  so  that  34  is  to  be  read  1.034.  For  this 
examination  the  temperature  of  the  milk  must  be  15°  C.  (60°  F.)  :  if 
it  is  not,  the  specific  gravity  of  the  milk  at  15°  C.  must  be  calculated 
from  the  specific  gravity  found  and  from  the  temperature,  for  in  milk 
inspection  and  analysis  this  is  tlie  standard. 

lEiihin:  ZeitscJir.  f.  Fleisch  u.  Milrh-hyff.,  Vol.  XX,  1910. 


CHEMICAL    ANALYSIS    OF    MILK  535 

Westphal  Balance. — This  instrument  is  more  accurate  than  the 
lactometer.  It  is  in  equilibrium  when  the  sum  of  the  weights  equals 
the  specific  gravity  of  the  liquid. 

Taking  the  specific  gravity  of  the  whole  milk  does  not  of  itself  de- 
tect either  watering  or  skimming,  since,  if  these  practices  are  done 
artfully,  the  specific  gravity  of  the  milk  may  remain  unaltered.  The 
specific  gravity   of  normal  milk   serum  is   about   1.0387. 

Heated  Milk.— Milk  that  has  been  heated  above  79°  or  80°  C.  may 
be  detected  by  the  fact  that  the  enzymes  are  killed.  Several  methods 
are  used;  the  most  convenient,  perhaps,  is  Dupouy's  method.  A  few 
drops  of  a  freshly  prepared  solution  of  diamidobenzin  in  water  (1-4) 
and  a  little  hydrogen  dioxid  are  added  to  5  c.  c.  of  milk.  With  raw 
milk  a  coloration  appears,  while  with  milk  that  has  been  heated  to 
79°  C.  or  over  no  color  is  produced.  Other  tests,  such  as  the  Storch 
method  or  Arnold's  guaiac  method,  are  described  below  under  "Tests 
for  Enzymes."  A  test  for  heated  milk  has  recently  been  devised  by 
Frost  and  Eavenel,  who  find  a  difference  between  the  staining  of  the 
cells  when  subjected  to  an  aqueous  solution  of  safranin. 

Tests  for  Enzymes,  and  Their  Significance. — The  following  tests  are 
those  most  frequently  used: 

Catalase  Test. — Ten  c.  c.  of  the  milk  to  be  tested  is  mixed  with 
10  c.  c.  of  a  3  per  cent,  (by  volume)  hydrogen  peroxid.  The  mixture 
is  placed  in  a  Lobeck  tube  and  the  stopper  tightly  inserted.  Then  the 
tube  for  measuring  the  liberated  oxygen  is  filled  with  water  and  inserted 
into  the  perforated  stopper,  pushing  out  the  small  hard  rubber  button. 
The  mixture  of  milk  and  hydrogen  peroxid  is  immersed  up  to  the  stop- 
per in  a  water  bath  at  37°  C.  and  left  there  for  two  hours.  The  oxygen 
that  is  liberated  replaces  the  water  in  the  graduated  tube  on  which  the 
readings  are  made.  Larger  quantities  of  milk  (15  c.  c.)  and  less  hy- 
drogen peroxid  (3  c.  c.)  give  more  satisfactory  readings  for  pasteurized 
milk. 

According  to  Auzinger,  the  liberation  of  much  gas  by  this  test  oc- 
curs (1)  with  physiologically  changed  milk,  as  is  the  case  with  colos- 
trum and  with  milk  from  old  milkers;  (2)  in  the  case  of  pathologically 
changed  milk,  as  in  mastitis  and  other  febrile  diseases;  or  (3)  in 
milk  containing  a  large  number  of  bacteria.  The  test  for  catalase, 
therefore,  is  of  assistance  in  detecting  old,  bacteria-laden,  or  abnor- 
mal milk. 

Eeductase  Test. —  (1)  Sclimidt-Muller  or  Slow  Reductase  Test. — 
The  reagent  is  made  by  adding  195  c.  c.  of  distilled  water  to  5  c.  c.  of 
a  saturated  alcoholic  solution  of  methylene  blue  (zinc  chlorid  double 
salt).  This  reagent  should  be  boiled  every  day  before  using.  The 
test  is  made  by  adding  to  20  c.  c.  of  milk  in  a  test  tube  1  c.  c.  of  the 
reagent,  mixing,  sealing  with  melted  paraffin,  and  then  incubating  at 


536  ANIMAL    FOODS 

45°  C.  in  a  water  bath.  According  to  Kiihm/  fresh  milk  remains  blue 
for  12  hours  or  more,  and  "infected"'  milk  decolorizes  in  less  than  one 
hour.  Heductases,  according  to  Riihm,  are  increased  by  acid-forming 
bacteria,  but  not  by  alkaline  producers.  Auzinger,-  who  uses  0.5  c.  c. 
of  the  reagent  in  20  c.  c.  of  milk,  states  that,  on  holding  the  mixture 
at  38°  to  40°  C,  milk  not  decolorizing  in  seven  hours  contains  less 
than  100,000  bacteria  per  c.  c. ;  that  which  decolorizes  in  2  to  7  hours 
contains  100,000  to  300,000;  and  that  which  decolorizes  in  1/4  to  2 
hours  contains  300,000  to  20,000,000  bacteria  per  c.  c. 

(2)  Schardinger  or  Hastened  Reductase  Test. — The  reagent  is  made 
by  adding  190  c.  c.  of  distilled  water  and  5  c.  c.  of  formaldehyde  solu- 
tion to  5  c.  c.  of  saturated  alcoholic  solution  of  methylene  blue  (zinc 
chlorid  double  salt). 

The  test  is  made  by  adding  to  10  c.  c.  of  milk  2  c.  c.  of  the  reagent 
in  a  test  tube,  mixing  well,  sealing  with  melted  paraffin,  and  holding 
at  37°  C.  in  a  water  bath.  By  the  test,  according  to  Auzinger,^  good 
milk  reduces  the  color  in  8  to  12  minutes,  milk  rich  in  bacteria  reduces 
in  5  minutes  or  less,  and  when  colostrum  is  present  two  or  more  hours 
are  required. 

Of  the  two  reductase  tests,  according  to  Schardinger,^  reduction 
by  the  slow  method  is  due  to  ferments  produced  by  bacteria,  while  by 
the  hastened  method  reduction  is  due  to  the  natural  ferments  of  milk. 

The  slow  reductase  test  is  of  assistance  in  detecting  old  milk,  and 
the  hastened  reductase  test  offers  a  convenient  and  reliable  method  for 
detecting  and  testing  the  efficiency  of  pasteurization. 

Storch  Test. — This  test  is  made  by  adding  to  5  c.  c.  of  milk  one 
drop  of  0.2  per  cent.  HoO,  and  two  drops  of  a  2  per  cent,  solution  of 
paraphenylendiamin  and  thoroughly  mixing.  The  reagent  must  be 
freshly  made  at  least  every  two  weeks. 

WiLKiNSOX  AND  Peters  Test.'* — This  test  is  made  by  adding  to 
10  c.  c.  of  milk  2  c.  c.  of  a  4  per  cent,  alcoholic  benzidin  solution  and 
two  or  three  drops  of  acetic  acid,  then  mixing  well,  and  adding  2  c.  c. 
of  3  per  cent.  'RJd^. 

GuAiAC  Test.^ — The  reagent  is  made  by  adding  one  part  of  guaiac 
to  ten  parts  of  acetone.  To  make  the  test  several  drops  of  0.2  per  cent. 
H2O2  and  1  c.  c.  of  the  guaiac  solution  are  added  to  10  c.  c.  of  milk. 
The  reaction  appears. in  one  to  three  minutes. 

Bellei  Test. — The  test  is  made  by  adding  to  10  c.  c.  of  milk  3 
drops  of  1.5  per  cent,  aqueous  solution  of  ortol  and  two  drops  of  3 
per  cent.  HoO,. 

1  Euhm :   Zeit.  f.  FJ.  u.  MiJch-hyg.,  Vol.  XX,  1910. 

-Auzinger:  Ibid.,  Vol.  XX,  1910. 

^Schradinger:  Arch.  f.  Einderheilk.,  Bd.  58,  H.  5-6. 

*  Wilkinson  and  Peters:   Zeit.  Nahr.  u.  Genuszm.,  1908,  p.   172. 

^Arnold  and  Mentzel:   Milch  Zeit.,  1902,  p.  31. 


EEFERENCES  537 

The  Storch,  Wilkinson  and  Peters,  guaiac,  and  Bellei  tests  are  used 
primarily  to  detect  heating  above  70°  C,  and  are  of  little  practical 
value,  as  heating  to  such  high  temperatures  is  seldom  resorted  to  in 
this  country. 

REFERENCES 

Sommerfeld,  Paul:  "Handbuch  der  Milchkunde,"  J.  F.  Bergmann, 
Wiesbaden,   1909. 

Swithinbank,  Harold,  and  Newman,  George :  "Bacteriology  of  Milk," 
E.  P.  Button  &  Co.,  1903. 

"Milk  and  Its  Eelation  to  the  Public  Health,"  Hyg.  Lab.  Bull. 
No.  56,  U.  S.  P.  H.  &  M.  H.  S.    Various  authors. 

Eosenau,  M.  J.:  "The  Milk  Question,"  Houghton,  Mifflin  &  Co., 
1912. 

Savage,  Wm.  G. :  "Milk  and  the  Public  Health,"  Macmillan  &  Co., 
Ltd.,  London,  1912. 

Report  of  the  Commission  on  Milk  Standards,  N.  Y.  Milk  Com- 
mittee, Public  Health  Reports,  U.  S.  P.  H.  &  M.  H.  S.,  xxvii,  19, 
May  10,  1912. 

Barthel,  Chr. :  "Die  Methoden  zur  Untersuchung  von  Milch  und 
Molkereiprodukten."  Leipzig,  1911.  English  edition  translated  by 
Goodwin. 

Farrington  and  Woll:  "Testing  Milk  and  Its  Products,"  21st  edi- 
tion, Mendata  Book  Co.,  Madison,  Wis.,  1912. 


CHAPTER  III 

ANIMAL    FOODS:      MEAT,    FISH,    EGGS,    ETC. 

MEAT 

The  universal  consumption  of  meat  as  a  daily  article  of  diet  by 
civilized  man  is  of  more  recent  origin  than  is  generally  supposed. 
McCulloch  ^  states  that  "so  late  as  1763  the  slaughter  of  bullocks  for 
the  supply  of  the  public  markets  was  a  thing  wholly  unknown,  even  in 
Glasgow,  though  the  city  then  had  a  population  of  30,000."  In  the 
past  decade  or  two  the  consumption  of  meat  has  increased  enormously, 
especially  in  the  United  States  and  England,  owing  to  the  development 
of  cheap  refrigerator  processes,  canning,  and  increased  facilities  of  trans- 
portation. The  annual  per  capita  consumption  of  meat  has  almost 
doubled  during  the  past  half  century.  It  is  estimated  in  pounds  as  fol- 
lows : 

United   States    147 

England     100 

France    72 

Germany     64 

Russia    50 

Italy     24  2 

Structure  and  Composition  of  Meats.— Meat  is  composed  of  muscu- 
lar fibers,  and  the  structures  intimately  associated  with  them,  such  as 
connective  tissue,  blood  vessels,  nerves,  lymphatic  vessels,  and  more  or 
less  adipose  tissue. 

The  toughness  of  meat  is  due  to  the  thickness  of  the  walls  of  the 
muscle  tubes  and  excess  of  connective  tissue  which  binds  them  together, 
hence  the  flesh  of  young  domesticated  animals  is  usually  more  tender 
than  that  of  old  or  wild  animals. 

The  flavor  of  meat  varies  with  the  animal's  age,  its  food,  breed,  and 
condition  when  killed.  The  meat  of  male  animals,  excepting  pigs,  is 
usually  more  highly  flavored  than  that  of  females. 

Meat  contains  albuminoids  and  gelatinoids;  the  latter  through  ac- 

'  "Statistical  Account  of  the  British  Empire,"  Vol.  II,  p.  502. 
*  Thompson.     "Practical  Dietetics." 

538 


MEAT  539 

tion  of  hot  water  or  steam  are  converted  into  gelatin.  In  addition  meat 
contains  the  following  nitrogenous  substances:  syntonin,  myosin,  muscle 
albumin,  serum  albumin,  and  numerous  extractives,  such  as  creatin, 
creatinin,  xanthin,  hypoxanthin,  lactic  acid;  and  small  quantities  of 
inosit  and  glycogen. 

Meat  at  once  after  slaughter  has  an  alkaline  reaction,  is  tough, 
and  possesses  a  sweetish  and  rather  unpleasant  flavor.  Eigor  mortis 
soon  sets  in,  accompanied  by  the  following  changes :  the  reaction  of  the 
meat  turns  acid,  owing  to  the  development  of  sarcolactic  acid;  the  con- 
nective tissue  and  fibers  are  softened  as  the  result  of  autolytic  enzymes 
and  also  as  a  result  of  bacterial  action.  While  the  meat  becomes  more 
tender,  it  also  develops  pleasant  flavors.  It  is,  therefore,  not  advisable 
to  use  meat  at  once  after  slaughter,  but  it  should  be  allowed  to  hang 
at  least  two  or  three  days.  It  is  important  during  this  time  to  pre-' 
serve  the  meat  from  contamination  with  pathogenic  microorganisms 
and  to  retard  the  growth  of  the  saprophytes. 

Nutritive  Value  of  Meat. — The  nutritive  value  of  meat  depends 
mainly  upon  the  presence  of  proteins  and  fats.  Nitrogenous  extractive 
matters,  such  as  creatin,  xanthin,  etc.,  sometimes  called  meat  bases, 
are  formed  by  cleavage  of  the  proteins,  but  are  of  little  value  as  foods. 
These  nitrogenous  extractives  are  present  in  about  the  same  amount 
in  both  red  and  white  meats,  with  the  single  exception  of  venison, 
which  contains  the  least  amount. 

Meat  must  be  regarded  as  a  condensed  and  expensive  food.  For 
instance,  a  steak  that  costs  twenty-five  cents  a  pound  contains  over 
one-third  or  one-half  of  inedible  substances,  so  that  the  edible  portion 
really  costs  double  that  amount.  On  the  contrary,  when  a  pound  of 
flour  or  cereal  is  purchased,  the  price  of  which  is  perhaps  only  one- 
eighth  that  of  meat,  the  whole  of  it  is  edible. 

Beef  extracts  are  nothing  more  or  less  than  a  soup  or  soup  stock 
specially  prepared  from  beef.  They  first  became  generally  known 
through  the  researches  of  Liebig,  and  are  now  an  important  article  in 
commerce.  The  composition  of  the  ordinary  beef  extract  of  commerce 
contains  from  15  to  20  per  cent,  of  moisture,  from  17  to  23  per  cent, 
ash,  and  from  50  to  60  per  cent,  of  meat  bases.  These  meat  bases  are 
the  soluble  nitrogenous  contents  of  meat.  They  contain  only  a  trace 
of  soluble  albumin,  albumoses,  and  peptone.  The  chief  meat  bases 
which  form  the  principal  part  of  the  substance  are  creatin,  creatinin, 
.xanthin,  carnin,  and  carnic  acid.  It  is,  therefore,  evident  that  meat 
extracts  contain  little  nutritive  matter,  although  this,  being  in  a  state 
of  solution,  is  probably  more  readily  absorbed  than  a  similar  amount  of 
other  nutritives  in  the  form  of  ordinary  meat.  Wiley  properly  points 
out  that  the  claim  made  by  manufacturers  is  misleading,  in  that  one 
pound  of  extract  contains  the  nutritive  properties  of  many  pounds  of 


5-40  ANIMAL    FOODS 

meat.  Such  a  statement  is  absurd  upon  its  face,  and  should  not  be 
allowed  to  go  unchallenged.  These  extracts  may  be  useful  as  stim- 
ulants or  as  condiments,  or  as  a  means  of  speedily  introducing  a  sol- 
uble nutrient  in  the  case  of  disease,  where  it  is  extremely  important 
that  even  small  amounts  of  nutritious  material  should  enter  the  body. 

A  distinction  should  be  made  between  beef  extract  and  beef  juice. 
Beef  juice  is  obtained  by  strong  pressure  and  is  concentrated  in  vacuo 
to  the  proper  consistence,  or  it  may  be  used  freshly  prepared  in  the 
household. 

Sources  of  Meat. — The  principal  source  of  meat  is  from  cattle,  sheep, 
and  swine.  In  many  places  tlie  flesh  of  horses,  dogs,  and  cats  is 
eaten.  In  Germany  horses  and  dogs  are  slaughtered  and  reg- 
ularly inspected  for  human  food.  The  meat  of  these  animals  is  also 
•  used  in  other  countries  that  have  long  been  flesh  hungry.  There  is  no 
sanitary  objection  to  the  use  of  such  meat.  Horse  meat,  when  eaten 
in  ignorance  of  its  true  character,  makes  no  unpleasant  impression. 
In  Paris,  Vienna,  and  otber  cities  large  quantities  of  horses,  mules, 
and  donkeys  are  slaughtered  for  food.  Even  in  the  United  States  sev- 
eral thousand  liorses  are  slauglitered  and  officially  inspected  each  year 
with  other  food  animals.  It  was  formerly  difficult  to  distinguish  horse 
meat,  but  this  is  now  rendered  comparatively  easy  by  means  of  the 
specific  precipitins.     (For  this  test  see  page  400.) 

The  different  kinds  of  meat  may  be  detected  by  physical,  micro- 
scopical, chemical,  or  biological  tests.  Ordinarily  meats  from  different 
animals  ma}  be  distinguished  by  their  odor  or  taste.  Microscopically 
the  fibers  resemble  each  other  so  closely  that  this  test  is  not  to  be  re- 
lied upon.  Meat  varies  somewhat  in  chemical  composition  from  dif- 
ferent species,  from  different  animals  of  the  same  species,  and  even 
from  different  muscles  in  the  same  animal.  The  principal  difference 
in  the  chemical  composition  of  meats  from  animals  of  different  species 
consists  in  the  glycogen  and  fat  content.  Thus,  horse  meat  contains 
considerably  more  glycogen  than  beef.  The  glycogen  test,  however,  is 
not  reliable  because  it  may  be  changed  as  a  result  of  bacterial  action. 

The  fats  of  different  animals  have  different  physical  and  chemical 
characteristics.  The  fats  crystallize  in  different  forms  and  have  dif- 
ferent melting  points;  also  the  fatty  acids  derived  therefrom.  A  care- 
ful examination  of  the  fat,  therefore,  will  lead  to  an  approximate  de- 
gree of  knowledge  concerning  the  character  of  the  flesh  from  which  it 
has  been  derived.  For  instance,  lard  and  beef  fat  are  easily  distin- 
guished  from  each  otlier. 

The  Reco^ition  of  Spoiled  Meat. — The  recognition  of  spoiled  meat 
that  is  also  injurious  to  health  is  a  very  difficult  task.  Meat  that  is 
decomposed,  putrid,  or  offensive,  and  thus  objectionable  to  the  senses, 
needs  no  further  condemnation.     The  most  serious  infections  and  pois- 


MEAT  541 

ons  in  meat,  however,  do  not,  as  a  rule,  affect  its  appearance,  odor,  or 
taste,  or  do  so  so  slightly  as  readily  to  pass  unnoticed.  Certain  putre- 
factive changes  brought  about  by  bacterial  action,  which  give  the  high 
or  gamy  taste  so  much  prized  by  epicures,  appear  not  to  be  injurious. 
Dogs  and  other  carnivora  prefer  putrid  flesh. 

Meat  inspectors  are  usually  instructed  to  condemn  meat  that 
has  not  a  red,  fresh  appearance,  especially  if  it  has  become  brownish 
or  greenish.  The  meat  is  to  be  condemned  if,  upon  pressure,  much 
fluid  of  abnormal  color  or  alkaline  reaction  exudes;  if  the  fat  is  not 
yellow  and  firm,  especially  if  soft  and  gelatinous;  if  the  marrow  of 
the  femur  is  not  firm  and  rose-colored  and  has  become  soft  and  brown- 
ish. Spoiled  meat  under  the  microscope  shows  obscurity  of  the  cross 
striations  of  the  muscle  fibers  and  numerous  bacteria.  For  a  further 
discussion  of  this  subject  see  Meat  Inspection,  and  also  the  various  dis- 
eases which  render  meat  unsuitable  or  injurious  as  food. 

Prevention. — The  prevention  of  infections  and  jDoisoning  from  meat 
and  meat  products  depends,  first  of  all,  upon  the  health  of  the  ani- 
mal, next  upon  the  mode  of  death,  and  finally  the  methods  of  butcher- 
ing, preserving,  and  handling  the  flesh.  Careful  attention  to  every 
detail  is  necessary  all  along  the  line.  Cleanliness  approaching  surgi- 
cal methods  on  the  part  of  the  butcher  during  the  preservation,  trans- 
portation, and  preparation  of  the  meat  is  called  for.  A  careful  sys- 
tem of  meat  inspection  is  a  good  sanitary  safeguard.  Thorough  cooking 
is  the  most  important  protection  we  have  against  infection. 

Meat  should  never  be  eaten  raw,  even  where  there  is  a  carefully 
conducted  inspection  by  trained  experts.  Individual  cysticerci  (tape- 
worm larvae)  are  very  easily  overlooked,  and  one  is  enough  to  bring 
forth  a  tapeworm.  It  is  also  not  possible  to  examine  all  hogs,  par- 
ticularly those  slaughtered  in  country  districts,  for  trichina,  and  even 
where  this  is  done  with  care  the  method  does  not  afford  complete  pro- 
tection. It  should  further  be  remembered  that  some  of  the  more  se- 
rious bacterial  infections  do  not  alter  the  color,  taste,  or  appearance 
of  the  meat  in  any  way.  Eaw  meat  does  not  have  a  higher  nutritive 
value  than  cooked  meat,  and  is  no  more  easily  digested. 

Special  measures  of  prevention  will  be  discussed  under  each  infec- 
tion. 

Meat  Preservatives. — The  regulations  of  the  U.  S.  Department  of 
Agriculture  permit  the  addition  to  meat  or  meat  food  products  of  the 
following  substances:  common  salt,  sugar,  wood  smoke,  vinegar,  pure 
spices,  saltpeter,  benzoate  of  soda.  Only  such  coloring  matters  as  may 
be  designated  by  the  Secretary  of  Agriculture  may  be  used. 

The  adulterants  most  commonly  used  in  meats  are  saltpeter,  boracic 
acid,  borax,  sulphite  of  soda,  and  benzoic  acid. 


i42  ANIMAL    FOODS 


MEAT    INSPECTION 


The  necessity  for  a  careful  sanitary  control  of  our  food  is  growing 
greater  year  by  year  in  order  to  protect  the  consumer.  This  is  es- 
pecially necessary  in  the  case  of  animal  food  products,  especially  meat 
and  milk,  which  are  most  apt  to  carry  infections  and  are  the  most 
readily  decomposable.  The  necessity  for  this  inspection  is  accentuated 
by  the  fact  that  the  producer  and  the  consumer  are  often  separated  by 
great  distances,  and,  further,  there  are  several  middlemen  between  the 
two.  The  ignorance  or  greed  of  the  middleman  or  the  producer  may 
force  upon  the  consumer  meat  that  is  injurious  or  that  is  considerably 
below  value. 

The  danger  does  not  consist  alone  in  eating  infected  or  decayed 
animal  products;  the  mere  handling  of  flesh  of  some  animals  having 
had  anthrax  or  glanders  may  be  sufficient  to  transmit  infection  to  the 
butcher  or  housewife,  who  may  injure  themselves  in  cutting  the  meat. 
An  efficient  meat  inspection  system  is  not  only  of  advantage  to  man, 
but  is  the  means  of  detecting  and  preventing  disease  among  cattle,  sheep, 
and  swine.  A  sharp  outlook  at  the  slaughter  house  will  discover  the 
first  appearance  of  rinderpest,  foot-and-mouth-  disease,  Texas  fever,  or 
other  epizootic,  which  may  then  be  quickly  traced  to  its  origin  and 
nipped  in  the  bud. 

The  border  line  hc^tuccn  health  and  disease  is  ill-defined.  It  is 
doubtful  whether  any  animal  slaughtered  for  food  is  wholly  sound 
and  free  from  disease.  Parasitic  infections  among  the  lower  animals 
are  exceedingly  common.  Anyone  may  convince  himself  of  this  fact 
by  a  visit  to  a  slaughter  house,  for  there  he  will  see  that  many 
hogs  have  a  handful  of  round  worms  in  the  intestinal  tract;  most 
animals  have  one  or  more  species  of  intestinal  worms,  such  as  hook- 
worms, tapeworms,  and  many  protozoa,  but,  fortunately,  these  are 
for  the  most  part  not  dangerous  to  man.  Almost  every  hog  or  beef 
that  is  killed  contains  a  snrcosporidm,  a  small  parasite  that  inhabits 
only  the  muscles  of  these  animals  and  which  is  harmless  to  man.  It 
is,  therefore,  at  once  evident  that  the  line  in  meat  inspection  cannot 
be  drawn  between  health  and  disease,  but  aims  to  eliminate  those  dis- 
eases which  are  injurious  to  man  and  those  diseases  and  conditions 
which  render  the  meat  of  inferior  quality  or  otherwise  unfit  for  use. 
In  establishing  correct  principles  to  guide  a  meat  inspection  service 
sentiment  must  give  way  to  science.  The  killing  of  animals  and  the 
dressing  of  the  carcasses  is  not  a  kid-glove  business.  In  our  country 
much  good  meat  is  condemned  and  destroyed  according  to  law  as  a 
result  of  supersensitiveness.  When  meat  becomes  scarcer  and  prices 
higher  this  waste  will  be  checked  by  a  closer  adherence  to  a  sound 


MEAT  543 

application  of  pathology.  McCabe  estimates  that  the  value  of  the  car- 
casses or  parts  of  carcasses  destroyed  for  food  by  federal  inspection  dur- 
ing the  course  of  one  year  is  more  than  $3,500,000.  Dyson  places  the 
loss  at  about  three  million  to  three  and  a  half  million  annually. 

The  principles  of  meat  inspection  vary  in  different  countries,  de- 
pending upon  the  local  conditions.  Thus,  in  Germany  and  other  Eu- 
ropean countries,  which  have  long  had  a  scarcity  of  meat,  and  the 
people  are,  therefore,  flesh  hungry,  much  meat  is  passed  for  food  that 
would  here  be  condemned.  In  countries  where  meat  is  not  very  abun- 
dant it  is  even  necessary  for  the  officials  to  keep  a  sharp  watch  to 
prevent  the  people  from  eating  meat  known  to  be  injurious.  In  America 
our  attitude  is  very  different,  for  we  have  a  repugnance  even  against 
meat  known  to  contain  a  harmless  parasite.  The  records  of  the  sani- 
tary sciences  are  full  of  illustrations  of  the  consumption  of  meat  from 
animals  known  to  be  diseased. 

A  meat  inspection  service  should  have  for  its  object  first  of  all  the 
protection  of  the  consumer  against  diseased  or  other  injurious  quali- 
ties contained  in  the  meat.  This  should  be  accomplished  with  as  little 
waste  of  food  products  as  practicable,  and,  finally,  the  meat  should 
be  so  labeled  that  the  consumer  may  know  just  what  he  is  buying. 

The  Abattoir. — So  long  as  animals  are  permitted  to  be  slaughtered 
in  any  barn  or  cellar  it  is  impossible  to  exercise  a  proper  control  over 
meat  and  meat  products,  and  filthy  conditions  which  endanger  the 
public  health  will  prevail.  The  first  essential  of  a  good  meat  inspec- 
tion service  is  to  concentrate  all  slaughtering  in  large  central  sanitary 
abattoirs.  This  simplifies  the  inspection  and  sanitary  control,  and  is 
a  needed  measure  to  protect  the  consumer.  In  Germany  and  England 
public  abattoirs  have  been  established  which  belong  to  the  city.  These 
structures  are  built  thoroughly  of  brick  and  concrete,  and  they  are 
well  protected  against  rats.  They  are  situated  near  a  railroad,  so  as  to 
facilitate  transportation,  and  are  so  constructed  that  they  may  be  kept 
clean.  Each  person  who  wishes  to  slaughter  must  obtain  a  permit 
and  pay  rent.  In  the  entire  city  of  Paris  there  are  only  three  slaugh- 
ter houses.  The  erection  and  maintenance  of  sanitary  slaughter  houses 
is  one  of  the  needs  of  our  country,  especially  in  the  smaller  towns, 
and  until  this  reform  is  accomplished  we  shall  never  have  a  satisfac- 
tory solution  of  the  meat  problem. 

An  abattoir  must  be  especially  well  constructed  and  kept  clean. 
The  same  may  be  said  of  the  trucks,  drays,  and  all  objects  that  come 
in  contact  with  the  meat.  The  water-closets,  toilet-rooms,  and  dress- 
ing-rooms should  be  entirely  separated  from  the  departments  in  which 
the  carcasses  are  dressed  or  meat  products  handled  or  prepared.  At- 
tention must  be  paid  to  eliminate  all  sources  of  odor  that  may  con- 
taminate the  meat,  and  every  effort  must  be  made  to  keep  out  flies 


544  ANIMAL    FOODS 

and  other  vermin,  espeeiall}-  rats  and  mice.  Dogs  should  not  be  allowed 
around  slaughter  houses  on  account  of  the  danger  of  trichinosis  and 
other  parasites.  The  feeding  of  hogs  on  tlie  refuse  of  slaughter  houses 
should  not  be  permitted. 

The  employees  themselves  must  be  cleanh'  and  should  wear  clean 
outer  clothes  that  may  be  readily  laundered.  The  federal  regulations 
even  prescribe  that  employees  shall  pay  particular  attention  to  the 
cleanliness  of  their  boots  and  shoes.  It  is  just  as  important  to  wash 
the  hands  before  beginning  work,  and  to  be  particular  after  each 
visit  to  the  toilet  in  the  slaughter  house  or  butcher  shops,  as  it  is  in 
the  milk  industry.  Persons  with  tuberculosis  or  other  communicable 
disease  should  not  be  permitted  in  any  department  of  the  work  where 
the  meat  or  meat  products  are  handled  or  prepared  in  any  way.  It 
is  important  that  butchers  who  handle  a  diseased  carcass  should  thor- 
oughly cleanse  their  hands  of  all  grease  and  then  immerse  them  in 
a  good  disinfecting  solution.  Butchers'  implements  used  on  diseased 
carcasses  should  be  sterilized  in  boiling  water  or  strong  carbolic  acid 
or  formalin  solution  and  thoroughly  cleansed  before  they  are  again 
used.  The  federal  meat  inspectors  are  required  to  furnish  their  own 
implements  for  their  own  dissection  or  examination  of  diseased  car- 
casses or  unsound  parts.  The  precautions  required  in  an  abattoir  and 
butcher  shop  are  based  on  the  same  principles  necessary  in  a  surgical 
clinic.  Meat  that  falls  upon  the  floor  or  otherwise  becomes  soiled  is 
required  to  be  removed  and  condemned.  Inflation  by  air  from  the 
moutli  should  not  be  permitted,  though  inflation  by  mechanical  means 
is  allowed  by  the  federal  meat  inspection  regulations.  Only  good,  clean, 
and  wholesome  water  and  ice  should  be  used  in  the  preparation  of  the 
carcasses,  and  the  wagons  and  cars  and  all  surfaces  with  which  the 
meat  comes  in  contact  should  be  kept  clean  and  in  good  sanitary  con- 
dition. There  is  no  objection  to  the  use  of  the  skin  and  hoofs  of 
animals  condemned  for  tuberculosis  and  other  diseases  (except  anthrax) 
communicable  to  man,  provided  they  are  disinfected.  Each  skin  and 
hide  must  be  immersed  for  not  less  than  five  minutes  in  a  5  per  cent, 
solution  of  aqua  cresolis  compositus  or  a  5  per  cent,  solution  of  car- 
bolic acid  or  a  1-1,000  solution  of  bichlorid  of  mercury. 

Every  complete  abattoir  must  be  provided  with  a  retaining  room, 
a  condemned  room,  and  a  tank  room.  The  retaining  room  is  a  sep- 
arate compartment  set  apart  for  the  final  inspection  of  all  carcasses 
and  parts  which  the  inspector  desires  to  examine  more  carefully  at 
his  leisure.  The  retaining  room  must  be  large  enough  to  have  car- 
casses hang  separately,  furnished  with  abundant  light,  and  provided 
with  sanitary  tables  and  other  necessary  apparatus.  The  condemned 
room  must  be  securely  ratproof  and  be  under  the  lock  and  seal  of  the 
inspector.     The  object  of  this  room  is  to  contain   all  carcasses  and 


MEAT  645 

parts  of  carcasses  until  they  can  be  tanked  or  disposed  of  in  accord- 
ance with  instructions. 

All  condemned  carcasses  or  parts  of  carcasses  are  tanked  under 
special  requirements  in  an  official  abattoir.  Tanking  consists  in  expos- 
ing the  carcasses  to  steam  under  a  pressure  of  not  less  than  40  pounds, 
producing  a  temperature  of  228°  F.,  and  maintained  not  less  than  six 
hours.  This  effectively  renders  the  contents  of  the  tank  unfit  for  any 
edible  product.  In  the  absence  of  tanking  facilities  the  condemned  meat 
may  be  slashed  with  a  knife  and  then  denatured  with  crude  carbolic 
acid,  kerosene,  or  other  agent,  when  it  may  be  removed  to  some  other 
establishment  having  proper  tanking  facilities. 

Qualifications  of  a  Meat  Inspector.  ^ — A  corps  of  thoroughly  trained 
meat  inspectors  is  one  of  the  most  important  links  in  the  chain  of  an 
efficient  meat  inspection  system.  A  meat  inspector  should  be  a  quali- 
fied veterinarian,  having  special  experience  and  training  for  his  specialty. 
He  must  know  the  anatomy  of  the  various  food-producing  animals,  es- 
pecially cattle,  horses,  swine,  sheep,  and  also  fowl,  and  must  be  ac- 
quainted with  the  normal  parts  of  each.  He  must  be  able  to  distin- 
guish between  the  various  organs  of  the  various  species,  so  that  he 
cannot  be  imposed  upon  by  those  who  would  like  to  substitute  one 
for  another.  He  must  know  how  to  examine  animals  during  life, 
in  order  to  determine  whether  they  are  healthy.  He  must  know 
the  character  of  all  the  infectious  diseases  which  are  likely  to  pass 
through  the  district  where  he  is  situated.  The  government  recognizes 
that  it  requires  a  high  degree  of  skill  to  conduct  this  work,  and  it 
has,  therefore,  placed  the  meat  inspection  service  under  the  Civil  Serv- 
ice, and,  further,  will  admit  veterinarians  only  if  graduates  of  recog- 
nized veterinary  colleges.  In  addition  they  are  required  to  pass  a 
Civil  Service  examination. 

The  Freibank  or  Three-Class  Meat  System. — In  Germany  and  cer- 
tain other  European  countries  meats  are  divided  into  three  classes, 
viz.,  a  first  class,  including  meats  which  are  passed  for  unrestricted 
trade;  a  second  class,  or  Freibank  meats,  including  meats  which  are 
allowed  on  the  market  under  certain  restrictions;  and  a  third  class, 
including  meats  which  are  condemned  and  thus  excluded  from  the  food 
supply. 

The  federal  meat  inspection  system  of  our  country  is  essentially 
a  two-class  meat  system,  that  is,  meats  coming  to  inspection  are  either 
passed  for  unrestricted  trade  or  they  are  condemned  and  thus  excluded 
from  use  as  food. 

The  system  of  the  German  Freibank  and  the  compulsory  declara- 
tion of  the  condition  of  inferior  meats  are  very  old.  The  municipal  laws 
of  Augsberg  as  long  ago  as  1276  prescribed  that  inferior  meat  should 
not  be  sold  without  giving  notice  as  to  its  quality.     In  1404  the  mu- 


546  ANIMAL    FOODS 

nicipal  laws  of  Wimpfen  provided  that  the  Freihank  (from  tlie  German 
frei,  free,  here  in  the  sense  of  unconnected  or  separate,  and  hnnk,  a 
counter  or  stall)  should  be  situated  three  paces  away  from  the  regular 
counters.  The  Freihank  is,  therefore,  a  counter  which  is  free  or  sepa- 
rate from  the  counters  on  which  the  first  class  meats  are  sold.  The 
term  "Finnenhank"  is  sometimes  used  for  these  special  meat  stalls  be- 
cause measly  meat  or  "finneges  Fleisch"  especially  is  sold  at  these 
places.  This  system  of  the  Freihank  has  been  extended  quite  generally 
in  Germany  and  is  rapidly  extending  in  France,  Belgium,  Italy,  and 
other  European  countries.  Meat  from  tuberculous  animals,  from  ani- 
mals containing  cysticerci  (tlie  larval  stage  of  tapeworms),  trichinous 
meat,  and  meat  that  would  otherwise  be  injurious  if  eaten  raw,  but  is 
entirely  safe  as  far  as  these  infections  are  concerned  when  thoroughly 
cooked,  is  first  sterilized  by  steam  before  it  is  placed  upon  the  Freihank. 
It  has  been  the  more  or  less  general  axpericn-ce  that  the  introduction 
of  the  Freihank  system  has  at  first  been  met  with  by  prejudice  from 
various  sides,  but  it  is  also  the  experience  that  this  prejudice  gradu- 
ally wears  off,  and  that  in  some  places  the  demand  for  this  meat  be- 
comes greater  than  the  supply.  In  any  event,  no  large  quantity  of 
such  meat  should  be  sold  to  any  one  purchaser,  so  as  to  prevent  its 
being  used  to  any  great  extent  in  boarding  houses  and  restaurants. 

Emergency  Slaughter. — In  Germany  the  system  known  as  emergency 
slaughter  or  Nothschlachtung  has  developed  to  large  proportions.  Ani- 
mals that  are  sick  or  injured  are  killed,  examined,  and,  if  suitable  for 
food,  are  labeled,  inspected,  and  passed.  In  this  way  much  valuable 
foodstuff  is  saved  that  would  otherwise  be  lost.  It  is  said  that  over 
1  per  cent,  of  the  animals  killed  for  food  in  Germany  come  under  this 
emergency  rule.  There  is  also  a  certain  amount  of  what  may  be  termed 
emergency  slaughter  going  on  in  the  local  uninspected  slaughter  houses 
of  America,  but  it  is  not  countenanced  by  the  law,  and  is,  therefore, 
done  in  secrecy.  In  this  way  the  consumer  buys  inferior  meat  of  third 
or  fourth  quality  often  at  first  class  prices.  In  Germany  the  meat  of 
animals  killed  under  the  emergency  laws  is  so  labeled  and  sold  as  sec- 
ond quality. 

Methods  of  Slaughter.— In  slaughtering,  the  principal  indications 
are:  (1)  a  sudden  and  painless  death;  (2)  an  immediate  withdrawal 
of  the  blood;  (3)  removal  of  intestines  and  hair  or  hide;  (4)  im- 
mediate cooling.  Animals  should  be  kept  without  food  for  at  least 
12  hours  before  slaughter.  Sheep  and  hogs  are  usually  hung  by  the 
hind  feet  and  the  large  vessels  of  the  neck  dexterously  cut  with  a 
sharp  knife  and  with  a  single  motion  of  the  hand.  Cattle  are  usually 
first  stunned  by  a  blow  upon  the  head,  then  hung  up  by  the  hind  legs 
and  bled. 

The  Jewish  method  of  slaughtering  is  regarded   by  many  as  su- 


MEAT  547 

perior  to  any  other.  It  consists  in  cutting  all  the  large  vessels  of  the 
neck  with  one  cut  of  a  long,  keen  knife.  The  method  is  part  of  a 
ritual  which  includes  an  inspection  of  the  animal  and  its  organs  for  evi- 
dence of  disease,  according  to  the  Mosaic  laws.  This  is  the  oldest  sys- 
tem of  meat  inspection.  According  to  Dembo  ^  it  is  the  most  rational 
from  a  hygienic  standpoint,  since  the  animal  is  bled  rapidly  and  com- 
pletely, and  the  convulsive  movements  cause  the  meat  to  be  more  tender 
and  of  more  attractive  appearance.  Eigor  mortis  comes  on  more  quickly, 
and  the  meat  is,  therefore,  more  quickly  available  for  use,  and  also 
will  keep  several  days  longer  than  ordinarily. 

A  process  of  slaughtering  originating  in  Denmark  appears  to  have 
borne  the  test  of  trial  in  a  very  satisfactory  manner,  and  recommends 
itself  for  adoption  in  the  tropics,  where  meats  decompose  with  exceed- 
ing rapidity.  The  animal  is  shot  in  the  forehead  and  killed,  or  stunned, 
and  as  it  falls  an  incision  is  made  over  the  heart  and  the  ventricle 
is  opened  for  two  purposes:  to  allow  the  blood  to  escape  and  to  admit 
of  the  injection  of  a  solution  of  salt  through  the  blood  vessels  by  the 
aid  of  a  powerful  syringe.  The  process  requires  but  a  few  minutes, 
and  the  carcass  may  be  cut  up  at  once. 

The  common  methods  of  killing  fowl  intended  for  the  market  are 
either  by  bleeding,  by  dislocation  of  the  neck,  or  by  chopping  off  the 
head.  When  the  neck  is  stretched  and  dislocated  the  skin  remains 
unbroken  and  no  bruised  effect  is  produced,  but  most  of  the  blood  in  the 
body  drains  into  the  neck  and  remains  there.  In  killing  a  fowl  by  bleed- 
ing the  common  procedure  is  to  string  it  up  by  the  legs  with  the  head 
hanging  downward.  The  operator  then  gives  it  a  sharp  blow  with  a 
stick  on  the  back  of  the  head,  and  when  he  has  stunned  it  by  this  means 
he  inserts  a  sharp  knife  into  the  roof  of  the  mouth,  penetrating  the 
brain.  He  also  severs  the  large  vessels  of  the  throat  by  rotating  the 
knife,   and  the  bird  rapidly  bleeds  to   death. 

The  TJnited  States  Meat  Inspection  Law. — The  Federal  Meat  In- 
spection Law,  approved  June  30,  1906,  provides  for  the  inspection  of 
cattle,  sheep,  goats,  and  swine,  the  meats  or  meat  food  products,  which 
are  to  enter  into  interstate  or  export  trade.  It  is  administered  by  the 
Bureau  of  Animal  Industry  under  the  direction  of  the  Secretary  of  Agri- 
culture. It  should  be  remembered  that  the  Federal  Meat  Inspection 
Law  applies  only  to  meat  and  meat  products  sold  in  interstate  commerce 
or  for  export  trade,  and  does  not  apply  to  meats  butchered,  dressed, 
and  sold  within  the  state.  In  accordance  with  our  dual  form  of  gov- 
ernment, the  inspection  of  meat  that  is  slaughtered,  dressed,  and  sold 
within  the  borders  of-  a  single  state  is  left  entirely  to  the  authority  of 
that  state.     It  is  not  until  some  of  this  meat  passes  the  state  line  that 

*  Deutsche  VierteljaJiresscJirift  fiir  offentJiche  Gesundheitspflege,  XXVI, 
p.  688. 


548  ANIMAL    FOODS 

it  enters  interstate  traffic  and  comes  under  the  provisions  of  tlie  fed- 
eral law.  Some  of  the  states  have  passed  laws  similar  to  tlie  federal 
law  to  protect  their  own  citizens.  In  this  way  a  more  or  less  uniform 
method  of  meat  inspection  is  gradually  extending  throughout  the 
countr}'. 

The  federal  law  jirovidos  for  the  inspection  of  tlie  slaughter  houses, 
the  packing  houses,  the  moat-canning,  salting,  rendering,  or  similar 
estahlishments;  for  the  inspection  of  animals  before  and  after  they  are 
slaughtered  and  for  the  condemnation  and  destruction  of  diseased  car- 
casses or  parts  of  carcasses.  It  also  takes  cognizance  of  the  sanitary 
conditions  of  tlie  establishments  and  the  health  of  the  employees.  The 
carcasses  are  either  passed  and  labeled  "inspected  and  passed,"  or  con- 
demned in  whole  or  in  part  to  the  tank,  where  they  are  steamed  or 
immersed  in  strong  sulphuric  acid  and  reduced  to  inedible  grease. 

Ante-mortem  Inspection. — A  careful  ante-mortem  examination  or  at 
least  an  inspection  of  all  cattle,  sheep,  swine,  goats,  etc.,  about  to  be 
slauglitered  should  be  made  by  a  competent  veterinarian.  Any  animal 
showing  symptoms  of  or  suspected  of  being  infected  with  a  disease  or 
condition  which  would  probably  cause  its  condemnation  when  slaugh- 
tered should  be  set  aside.  These  animals  should  then  be  slaughtered 
separately  in  a  place  provided  for  this  special  purpose.  If  necessary 
the  temperature  of  the  animal  may  be  taken  in  the  ante-mortem  exam- 
ination, although  due  allowance  must  be  made  for  rise  in  temperature 
due  to  excitement  and  undue  exertion,  especially  in  hogs.  Animals 
commonly  termed  "downers"  or  crippled  animals  are  set  aside  and 
slaughtered  separately. 

Post-mortem  Inspection. — The  post-mortem  inspection  is  nothing 
more  or  less  than  a  well-conducted  autopsy.  The  head,  tongue,  tail, 
thymus  gland,  and  all  viscera,  and  also  the  blood  and  all  parts  used 
in  the  preparation  of  food  and  medicinal  products  should  be  retained 
in  such  a  manner  as  to  preserve  their  identity  until  the  post-mortem 
examination  is  completed.  It  is,  of  course,  impracticable  to  formu- 
late rules  to  cover  all  conditions  and  diseases,  and  much  must,  there- 
fore, be  left  to  the  judgment,  experience,  and  training  of  the  veteri- 
nary inspector  in  charge.  Carcasses  or  parts  of  carcasses  with  the 
following  diseases  or  conditions  are  condemned,  depending  upon  cir- 
cumstances: anthrax,  pyemia  and  septicemia,  vaccinia,  rabies,  tetanus, 
malignant  epizootic  catarrh,  hog  cholera  and  swine  plague,  actinomy- 
cosis, caseous  lymphadenitis,  tuberculosis,  Texas  fever,  parasitic  icterus, 
hematuria,  mange  or  scab,  trichinosis,  tapeworms,  infections  that  may 
cause  meat  poisoning,  icterus,  uremia,  and  sexual  odor,  urticaria,  mela- 
nosis, tumors,  bruises,  abscesses,  liver  flukes,  and  other  parasites,  emacia- 
tion from  anemia,  milk  fever,  and  railroad  sickness.  A  few  of  these 
diseases  deserve  brief  mention. 


MEAT  ■  549 

Tuberculosis. — Tuberculosis  is  exceedingly  cammon  in  cattle  and 
is  becoming  more  and  more  prevalent  among  hogs.  A  preponderating 
percentage  of  all  carcasses  condemned  as  unfit  for  food  is  so  condemned 
on  account  of  tuberculosis.  Thus,  about  0.5  per  cent,  of  all  hogs  slaugh- 
tered at  Boston  are  condemned,  but  of  these  over  95  per  cent,  are  con- 
demned for  tuberculosis.  Tuberculosis  is  important,  not  alone  because 
so  many  food-  animals  are  infected  with  it,  but  because  it  presents  a 
peculiarly  difficult  problem  for  the  meat  inspector.  The  fundamental 
thought  in  determining  whether  to  pass  or  condemn  meat  of  a  tuber- 
culous animal  is  that  it  should  not  contain  tubercle  bacilli,  and  should 
not  be  impregnated  with  toxiio  ■  substances  of  tuberculosis  or  associated 
with  septic  infection.-  If  the-il6si'oiis  are  localized  and  not  numerous,  if 
there  is  no  evidence  of  distribution  of  tubercle  bacilli  throughout  the 
blood,  and  if  the  animals  are  well  nourished  and  in  good  condition, 
there  is  no  reason  to  suspect  that  the  flesh  is  unwholesome,  and  it  is 
permitted  to  be  used  after  the  removal  of  the  infected  portions.  Just 
when  tuberculosis  should  be  considered  localized  or  generalized,  from 
the  standpoint  of  meat  inspection,  is  frequently  a  difficult  question  to 
determine.  Fortunately,  the  danger  from  this  source  is  not  very  great, 
as  tuberculosis  of  muscle  is  exceedingly  rare,  and  the  further  safeguard 
of  cooking  is  sufficient  to  kill  the  tubercle  bacilli,  provided  the  meat 
is  thoroughly  cooked  throughout.  The  relation  of  bovine  tuberculosis 
to  human  tuberculosis  has  been  discussed  on  page  124. 

Tuberculosis  of  cattle  shows  itself  in  four  primary  lesions:  (1)  the 
retropharyngeal  lymph  nodes,  (2)  the  lungs  and  associated  l3^mph 
nodes,  (3)  the  mesenteric  l3^mph  nodes,  and  (4)  the  liver.  From  the 
retropharyngeal  nodes  the  process  extends  to  the  cervical  lymph  nodes 
and  also-  to  the  anterior  mediastinal  IjTnph  nodes.  When  this  group 
of  glands,  alone  is  infected  the  disease  may  be  considered  as  localized. 
From  the  mesenteric  l}Tnph  nodes  the  infection  frequently  reaches  the 
peritoneum,  and  from  the  bronchial  hnnph  nodes  the  pleura.  The 
newly  formed  growth  in  the  peritoneal  or  pleural  cavities  may  be 
enormous  in  amount.  It  is  often  suspended  from  the  omentum  in  great 
grape-like  masses  (Perlsucht),  or  the  intestines  may  be  plastered  with 
tubercles.  In  these  cases  the  animal  otherwise  may  be  in  good  condi- 
tion ;  that  is,  the  disease  is  still  outside  .the  vital  organs  and  the  tu- 
bercle bacilli  have  not  invaded  the  blood  stream.  In  Germany  it  is 
permitted  to  cut  off  such  growth  and  allow  the  meat  to  go  into  con- 
sumption.    In  our  country  the  meat  of  such  animals  is  rejected. 

For  practical  purposes  it  is  necessary  to  formulate  definite  rules 
for  the  guidance  of  the  veterinary  inspector,  and  this  is  done  with 
minute  particularity  in  the  regulations  of  the  Bureau  of  Animal  In- 
dustry in  the  case  of  tuberculosis.  In  general,  if  the  tuberculous  le- 
sions are  limited  to  a  single  part  or  organ  of  the  body  without  evidence 


550  ANIMAL    FOODS 

of  recent  invasion  of  tubercle  bacilli  into  the  general  circulation,  the 
diseased  parts  are  removed  and  the  remainder  of  the  carcass  is  passed 
for  use.  If  the  animal  suffered  from  fever  before  it  was  killed  or  is 
cachectic,  anemic,  and  emaciated,  or  if  the  lesions  are  generalized, 
especially  if  they  exist  in  two  or  more  body  cavities,  or  if  the  lesions 
are  found  in  the  muscles,  intermuscular  tissues,  bones,  or  joints,  or  if 
the  lesions  are  multiple,  acute,  and  actively  progressive,  the  carcass  is 
condemned. 

AxTHRAX. — All  carcasses  showing  lesions  of  anthrax,  regardless  of 
the  extent  of  the  disease,  are  condemned  and  immediately  incinerated. 
This  includes  the  hide,  hoofs,  horns,  viscera,  fat,  blood,  and  all  portions 
of  the  animal.  The  killing  bed  upon  which  the  animal  was  slaughtered 
must  then  be  disinfected  with  a  10  per  cent,  solution  of  formalin,  and 
all  knives,  saws,  and  other  instruments  that  have  come  in  contact  with 
the  infection  must  be  boiled  or  otherwise  disinfected. 

Hog  Cholera  axd  Swine  Plague. — Carcasses  showing  well-marked 
and  progressive  lesions  of  these  diseases  in  more  than  two  of  the  or- 
gans (skin,  kidneys,  bones,  or  lymphatic  glands)  are  condemned.  If 
the  lesions  are  slight  and  limited  they  may  be  passed  and  the  meat 
used  for  food. 

Actinomycosis. — If  the  animal  is  in  a  well-nourished  condition  and 
the  disease  has  not  extended  from  a  primary  area  of  infection  in  the 
head,  the  head,  including  the  tongue,  is  condemned  and  the  remaining 
part  of  the  carcass  may  be  used,  but  if  the  disease  is  generalized  the 
entire  carcass  is  considered  unfit  for  human  use  and  condemned. 

Tapeworm  Cysts. — Carcasses  of  animals  affected  with  tapeworm 
cysts,  known  as  Cysticercus  hovis  and  Cysticercus  cellulosce,  are  ren- 
dered into  lard  or  tallow  unless  the  infection  is  excessive,  in  which 
case  the  carcass  is  condemned.  Carcasses  or  parts  of  carcasses  found 
infected  with  hydatid  cysts  (echinococcus)  may  be  passed  after  con- 
demnation of  the  infected  part  or  organ. 

Septic  and  Pyemic  Conditions. — All  carcasses  of  animals  so  infected 
that  consumption  of  the  meat  or  meat  food  products  thereof  may  give 
rise  to  meat  poisoning  should  be  condemned.  For  the  information  of 
the  inspector  the  following  conditions  are  specified:  (1)  acute  inflam- 
mation of  the  lungs,  pleura,  peritoneum,  pericardium,  or  meninges: 
(2)  septicemia  or  pyemia,  whether  puerperal  or  traumatic  or  without 
any  evident  cause;  (3)  severe  hemorrhagic  or  gangrenous  enteritis  or 
gastritis;  (4)  acute  diffuse  metritis  or  mammitis;  (5)  polyarthritis; 
(6)  phlebitis  of  the  umbilical  veins;  (7)  traumatic  pericarditis;  (8) 
any  other  inflammation,  abscess,  or  suppurating  sore  if  associated  with 
acute  nephritis,  fatty  and  degenerated  liver,  swollen  soft  spleen,  marked 
pulmonary  hyperemia,  general  swelling  of  the  lymphatic  glands,  and 
diffuse  redness  of  the  skin,  either  singly  or  in  combination. 


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552  ANIMAL    FOODS 

It  is  required  tliat,  immediately  after  the  slaughter  of  any  animal 
so  diseased  as  to  require  its  condemnation,  the  pl•emi^•cs  and  implements 
used  must  be  thoroughly  disinfected.  The  part  of  any  carcass  coming 
in  contact  with  the  carcass  of  any  diseased  animal  or  with  the  place 
where  such  animal  was  slaughtered,  or  with  the  implements  used  in 
tlie  slaughter,  before  thorough  disinfection  lias  been  accomplished, 
sliould  also  be  condemned.  These  infections  are  apt  to  give  rise  to 
meat-poisoning  in  those  who  eat  the  flesh  of  such  animals.  On  account 
of  the  importance  of  this  subject  it  will  be  discussed  separately. 

MEAT   POISONING 

Meat  poisoning  is  almost  always  due  to  the  presence  and  activity 
of  certain  bacteria  belonging  either  to  the  paratyphoid  or  the  hog  cholera 
group.  Tlie  meat  may  be  infected  as  a  result  of  disease  in  the  animal 
before  slaughter,  or  it  may  be  contaminated  post  mortem  from  soiled 
hands,  butcher's  tools,  rags,  paper,  dust,  or  other  objects  that  come  in 
contact  with  it.  Chopping  obviously  favors  the  spread  of  bacteria 
throughout  the  mass.  The  inward  growth  of  bacteria  is  greatly  ac- 
celerated if  the  meat  is  kept  warm.  This  may  be  prevented  to  a  certain 
extent,  or  at  least  delayed,  by  drying  the  surface  and  by  refrigeration. 

Animals  suffering  during  life  from  puerperal  fever,  uterine  inflam- 
mations, navel  infection  (in  calves),  septicemia,  septic  pyemia,  diarrhea, 
and  local  suppurations  are  apt  to  furnish  meat  containing  the  para- 
typhoid bacillus  or  closely  related  bacilli.  Such  meat  has  frequently 
given  rise  to  meat  poisoning.  The  bacilli  causing  meat  poisoning  may 
also  invade  the  tissues  of  the  animal  as  a  terminal  infection,  and  thus 
become  dangerous  to  man. 

In  1888,  while  investigating  a  large  outbreak  of  meat  poisoning, 
Gartner  isolated  from  the  suspected  meat  and  from  the  spleen  of  a 
patient  who  died  a  bacillus  which  he  called  "B.  enferitidis."  Ten 
years  later  Durham  in  England,  and  DeNobele  in  Belgium,  independ- 
ently isolated  from  cases  of  meat  poisoning,  and  also  from  the  meat, 
a  bacillus  closely  allied  to  Gartner's  bacillus. 

In  1896  Acharde  and  Bensaude  isolated  from  the  urine  of  a  case  of 
apparent  enteric  fever,  and  also  from  a  purulent  arthritis,  following  a 
similar  illness,  a  bacillus  which  they  called  the  "paratyphoid  bacillus.'' 
In  19.00-01  Schottmiiller  obtained  from  the  blood  of  patients  whose 
symptoms  were  those  of  enteric  fever  two  bacilli  resembling  the  para- 
typhoid bacillus  of  Acharde  and  Bensaude.  These  two  organisms 
were  named  by  Brion  and  Kaiser  "paratyphosus.  A"  and  "paratypho- 
sus  B." 

The  relationship  between  these  organisms  was  not  at  once  recog- 
nized, but  it  has  been  shown  during  the  last  few  years  that  they  are 


MEAT  553 

very  closely  allied  to  each  other,  and  also  to  the  hog  cholera  bacillus, 
B.  cholera  suis  ^  of  Salmon  and  Smith,  discovered  in  1885. 

In  fact,  these  bacilli  belong  to  a  group  of  organisms  which  has 
the  typhoid  bacillus  at  one  end  and  the  colon  bacillus  at  the  other. 
The  intermediate  forms  in  this  group  comprise  the  paratyphoid  bacilli, 
the  dysentery  bacilli,  the  hog  cholera  bacillus,  the  Bacillus  psittacosis 
(a  disease  of  parrots  communicable  to  man),  the  Bacillus  icteroides 
(once  associated  with  yellow  fever),  the  Bacillus  typhi  murium^  (the 
bacillus  of  mouse  typhoid,  the  type  of  all  the  bacterial  rat  viruses),  the 
Bacillus  enteritidis  of  Gartner  (associated  with  meat  poisoning  and 
diarrheal  diseases),  the  Bacillus  paracolon  of  Buxton,  the  Bacillus 
pseudotuberculosis  rodentium  of  Pfeiffer,  and  others.  The  organisms 
comprising  this  group  are  so  closely  related  that  it  is  often  difficult  to  de- 
termine where  specific  differences  begin  and  terminate.  This  group 
may  be  taken  as  a  beautiful  instance  of  missing  links,  and  a  study 
of  these  closely  related  organisms  excites  the  imagination  to  the  belief 
that  we  may  here  see  evolution  in  the  making. 

Bainbridge  ^  regards  meat  poisoning  and  paratyphoid  fever  as  dis- 
tinct diseases  caused  by  different  but  closely  allied  bacilli.  He  considers 
meat  poisoning  to  be  caused  by  the  Bacillus  enteritidis  or  B.  cholera 
suis,  while  paratyphoid  fever  is  caused  by  Bacillus  paratyphosus  A  or  B. 
Bainbridge  further  regards  paratyphoid  fever  as  spread  mainly  by 
human  bacillus  carriers,  and  not  as  an  infection  contracted  from  meat, 
whereas  meat  poisoning  in  his  opinion  results  from  the  consumption 
of  food  derived  from  infected  animals  or  food  that  is  contaminated 
after  slaughter.  Bainbridge  believes  that,  as  a  rule,  the  clinical  pic- 
ture is  quite  dissimilar,  paratyphoid  infection  resembling  typhoid  fever, 
while  meat  poisoning  usually  resembles  an  acute  gastroenteritis.  He 
admits,  however,  that  a  reversal  of  the  clinical  picture  sometimes  occurs. 
Much  further  work  will  have  to  be  done  before  the  subject  will  be 
entirely  clear. 

Eischer  divided  meat  poisoning  into  three  clinical  forms:  (1)  ty- 
phoidal,  (2)  choleraic,  (3)  gastroenteric.  The  chief  seat  of  attack  in 
true  meat  poisoning  is  the  gastrointestinal  canal;  the  local  irritation 
is  frequently  followed  by  a  general  bacterial  infection.  On  the  other 
hand,  sausage  poisoning  (Bacillus  hotulinus)  expends  its  chief  attack 
upon  the  nervous  system. 

Cases  of  meat  poisoning  vary  greatly  in  intensity  and  also  in  their 

^  This  microorganism  is  also  known  as  B.  suipestifer. 

^In  Japan  and  elsewhere  cases  of  poisoning  with  bacterial  rat  viruses  in 
man  have  been  reported.  Most  of  these  cases  were  caused  by  preparing  rice  in 
the  same  bowl  used  for  mixing  the  rat  virus. 

^  Bainbridge,  F.  A. :  "  The  Milroy  Lectures  on  Paratyphoid  Fever  and  Meat 
Poisoning."  The  Lancet,  March  16,  1912,  Vol.  I,  No.  XI,  p.  705,  and  two  suc- 
ceeding numbers. 


554  ANIMAL    FOODS 

clinical  picture.  The  period  of  incubation  in  the  acute  gastroenteric 
type  is  usually  short,  rarely  over  48  hours;  the  period  of  incubation 
ill  the  cases  resembling  typhoid  fever  is  generally  from  8  to  18 
days. 

The  symptoms  usually  caused  by  the  acute  form  of  gastroenteric 
meat  poisoning  are  severe  headache  with  rigor,  speedily  followed  by 
nausea,  diarrhea,  vomiting,  and  abdominal  pain.  In  some  severe  cases 
restlessness,  extreme  thirst,  and  nervous  symptoms,  such  as  cramp, 
become  prominent.  Coma  may  precede  death.  Fever  is  usually  pres- 
ent; the  temperature  may  reach  102°  to  103°  F.  As  a  rule,  the  tem- 
perature falls  to  normal  in  from  two  to  five  days,  and  the  symptoms 
subside.  The  total  duration  of  the  illness  rarely  exceeds  a  week,  but 
convalescence  is  often  delayed  by  general  muscular  weakness  or  by 
attacks  of  circulatory  impairment. 

Bainbridge  studied  forty  outbreaks  of  meat  poisoning  caused  by 
B.  cholera  suis  or  organisms  resembling  it.  In  twenty-eight  of  these 
the  bacillus  was  obtained  from  the  tissues,  twice  from  the  blood,  eight 
times  from  the  spleen  and  other  organs,  and  in  the  remainder  from 
the  stools.  In  twentj-one  cases  it  was  obtained  from  the  meat  which 
was  regarded  as  the  cause  of  the  outbreak.  The  illness  was  confined 
to  those  who  ate  the  meat,  though  not  every  one  who  partook  of  it 
was  ill. 

Outbreaks  caused  by  B.  enteritidis  of  Gartner,  B.  cholera  suis,  and 
their  congeners  are  frequent.  In  Germany  at  least  260  outbreaks  have 
been  recorded  during  the  years  1898  to  1908.  Although  Germany  is  pre- 
eminently the  home  of  meat  poisoning,  outbreaks  occur  from  time  to 
time  in  most  European  countries  and  in  America.  They  appear  to  be 
more  frequent  in  countries  in  which  uncooked  meat  is  eaten.  These 
outbreaks  are  more  apt  to  occur  in  summer,  when  the  bacteria  have 
better  chances  of  multiplying  within  the  meat. 

Hiibener  found  that  of  36  outbreaks  16  occurred  during  June,  July, 
and  August  and  30  between  May  and  October.  In  another  series  of 
27  epidemics  Sacquepee  found  that  11  occurred  in  June,  July,  and 
August  and  20  between  June  and  Xovember. 

The  meat  of  cows  and  calves  is  most  often  responsible  for  meat 
poisoning,  though  that  of  horses,  pigs,  and  goats  has  also  been  respon- 
sible. Dunham  says  that  no  known  case  has  come  from  mutton,  and 
that  the  pig  has  been  implicated  in  only  one  outbreak  which  has  been 
studied  bacteriologically.  This  is  of  particular  interest  to  bacteriol- 
ogists, on  account  of  the  similarity  between  the  hog  cholera  bacillus  and 
the  Bacillus  enteritidis. 

These  infections  are  not  only  conveyed  in  meat  and  meat  products, 
but  also  in  other  foods.  Many  an  instance  of  so-called  ptomain  poison- 
ing from  salads,  cream-puffs,  ice-cream,  etc.,  is  probably  nothing  but 


MEAT  555 

acute  infections  caused  by  one  of  the  bacteria  in  the  colon-typhoid 
group. 

Paratyphoid  Fever. — Paratyphoid  fever  both  clinically  and  etiologi- 
cally  is  a  first  cousin  of  typhoid  fever.  The  two  diseases  are  frequently 
indistinguishable  at  the  bedside.  It  needs  the  aid  of  the  laboratory 
to  differentiate  one  from  the  other.  Epidemiologically  paratyphoid 
fever  shows  marked  differences  from  typhoid  fever. 

Paratyphoid  is  a  world-wide  infection;  epidemic  outbreaks  occur, 
but,  as  a  rule,  are  of  limited  extent.  Paratyphoid  never  occurs  as 
great  epidemic  calamities,  such  as  have  been  frequently  observed  in 
water-borne  or  milk-borne  typhoid.  Paratyphoid  coexists  with  typhoid 
in  endemic  foci.  Thus,  in  Washington  somewhat  over  1  per  cent,  of 
all  the  cases  reported  as  typhoid  fever  were  shown,  upon  bacteriological 
examination,  to  have  been  paratyphoid.  In  India  the  proportion  is 
greater,  being  as  high  as  15  per  cent. 

The  paratyphoid  bacillus  closely  resembles  the  typhoid  bacillus  in 
its  cultural  and  morphological  characters.  The  principal  cultural  dif- 
ference between  the  two  is  that  the  paratyphoid  bacillus  ferments  dex- 
trose, whereas  the  typhoid  does  not.  They  also  vary  greatly  in  patho- 
genicity for  the  lower  animals.  Typhoid  cultures,  as  a  rule,  are  not 
very  pathogenic  for  the  lower  animals,  whereas  guinea  pigs  and  mice 
are  extraordinarily  susceptible  to  paratyphoid  cultures.  Most  strains 
will  kill  guinea  pigs  when  1/50  to  1/100  of  a  loop  is  injected  into  the 
peritoneal  cavity.  Babbits  are  also  susceptible;  birds  are  entirely  re- 
fractory; cattle,  dogs,  cats,  hogs,  sheep  show  a  high  degree  of  resistance 
to  paratyphoid  cultures. 

A  fundamental  point  of  difference  between  the  paratyphoid  and  the 
typhoid  organisms  is  that  they  each  have  specific  agglutinating  prop- 
erties. In  any  critical  case  this  difference  is  the  most  important  dis- 
tinguishing feature.  Care  must  be  taken,  in  using  agglutinins  in  dif- 
ferentiating these  closely  allied  species,  to  guard  against  confusion 
through  group  agglutinins,  and  also  to  keep  the  proagglutinoid  zone 
in  mind. 

The  paratyphoid  bacillus  is  a  small  rod  with  rounded  ends  and 
peritrichal  flagellse  resembling  the  typhoid  bacillus,  except  that  it  is 
more  actively  motile.  It  stains  readily  with  anilin  dyes,  decolorizes 
by  Gram's,  does  not  liquefy  gelatin,  has  no  spore,  and  is  a  facultative 
aerobe ;  it  clouds  bouillon  uniformly,  and  does  not  produce  indol.  Upon 
Endo's  medium  the  paratyphoid  colonies  are  pale,  moist,  translucent, 
with  a  bluish  cast,  quite  similar  to  typhoid  colonies. 

The  paratyphoid  bacillus  is  divided  into  several  subclasses.  These 
classes  vary  with  the  classifier.  Schotmiiller  in  1902  divided  them  into 
paratyphoid  A  and  paratyphoid  B.  In  the  same  year  Buxton  proposed 
that  paratyphoid  organisms  be   confined  to  those  producing  a  disease 


556  ANIMAL    FOODS 

resembling  typlioid.  while  paracolon  be  used  to  designate  those  organ- 
isms producing  gastrointestinal  disturbances.  We  now  hear  little  of 
the  paracolon  group.  Seiffert,  who  studied  the  question  in  Ehrlich's 
laboratory,  considers  two  groups,  viz.,  paratyphoid  A,  those  producing 
permanent  acidity  in  litmus  whey,  and  paratyphoid  B,  those  producing 
acidity  terminating  in  alkalinity  in  litmus  whey.  Group  B  also  pro- 
duces characteristic  lesions  when  injected  into  the  muscles  of  pigeons. 
The  group  known  as  paratyplioid  B  is  much  more  common  and  wide- 
spread than  type  A.  It  is  interesting  to  observe  that  the  agglutinins 
have  a  closer  relationship  between  paratyphoid  B  and  typhoid  than 
between  paratyphoid  A  and  typhoid,  although  type  B  seems  farther 
removed. 

The  paratyphoid  bacillus  may  be  found  in  the  blood  and  internal 
organs,  also  in  the  feces;  seldom  in  the  urine.  It  produces  a  continued 
fever  in  man  closely  resembling  typhoid  fever.  As  a  rule,  paratyphoid 
is  milder  than  typhoid.  Lentz  ^  gives  a  mortality  of  3.3  per  cent., 
against  typhoid,  which  is  about  9  per  cent.  Paratyphoid  infections 
frequently  manifest  themselves  as  an  acute  gastroenteritis,  having  a 
sudden  onset  with  vomiting,  chill,  and  diarrhea  and  a  sharp  rise  of 
temperature.  Between  these  acute  cases  and  the  typhoid  type  there 
are  all  grades  of  severity  and  several  clinical  varieties. 

Paratyphoid  fever  may  be  complicated  with  hemorrhages  from  the 
bowels,  bronchitis,  and  pneumonic  processes,  just  as  in  typhoid  fever; 
relapses  are  rare.  It  is  not  definitely  known  how  much  of  an  im- 
munity is  conferred  by  one  attack,  but  it  is  known  that  paratyphoid  does 
not  protect  against  typhoid,  nor  does  typhoid  protect  against  paraty- 
phoid. 

The  paratyphoid  bacillus,  although  it  contains  no  spore,  is  claimed 
to  have  a  higher  degree  of  resistance  to  heat  than  the  typhoid  bacillus. 
Thus,  Fischer-  found  that  an  exposure  to  70°  C.  for  10  to  20  minutes 
did  not  destroy  this  microorganism.  This  unusual  resistance  is  impor- 
tant, in  view  of  the  fact  that  the  bacillus  is  usually  conveyed  in  meat. 
As  a  rule,  the  inside  of  a  large  piece  of  meat  or  a  bulky  sausage  does 
not  reach  70°  C.  during  the  process  of  cooking. 

The  virus  enters  the  body  through  the  mouth  and  is  discharged  in 
the  feces.  The  intestinal  tract  of  man  must  be  regarded  as  the  great 
reservoir  for  paratyphoid  infection,  just  as  it  is  the  main  source  of 
typhoid.  The  paratyphoid  bacillus  does  not,  as  a  rule,  multiply  in 
nature,  except  in  meat,  and  perhaps  other  foodstuffs. 

The  paratyphoid  bacillus  does  not  necessarily  exist  in  the  tissues 
of  the  animal  at  the  time  of  its  death,  but  the  meat  may  become  in- 


^  CentralMatt  f.  Bait.,  Keferate,  Br].  XXXVm. 
'"Festschr.  f.  R.  Koch,"  Jena,  1903. 


MEAT  557 

fected  while  it  is  butchered  or  during  any  stage  in  its  after-care.  The 
joaratyphoid  bacillus  deposited  upon  a  roast,  steak,  or  a  carcass  will 
grow  readily  and  rapidly  throughout  the  mass,  especially  if  kept  warm. 
It  is  easy  to  conceive  how  meat  may  thus  become  infected  through 
the  contamination  of  dirt}^  hands,  butchers'  implements,  soiled  meat 
blocks,  unclean  cloths,  etc.  It  is  not  unknown  that  carcasses  or  cut 
portions  may  fall  upon  the  floor  or  in  other  ways  be  carelessly  handled. 
This  and  other  infections  may  also  be  carried  to  meat  through  flies, 
dust,  and  other  well-known  means  of  bacterial  convection.  Meat  may 
be  infected  in  the  slaughter  house,  in  the  butcher  shop,  during  trans- 
portation, or  in  the  household.  In  fact,  meat  may  become  infected 
in  very  much  the  same  ways  that  milk  becomes  infected,  and  the  same 
care  and  cleanliness  are  called  for  in  each  case. 

Paratyphoid  fever  is  by  no  means  always  contracted  from  meat, 
but  may  be  transmitted  directly  from  man  to  man.^  \\lien  this  takes 
place  the  mode  of  transmission  must,  doubtless,  be  similar  to  that  of 
typhoid  fever. 

The  paratyphoid  bacillus  and  the  Bacillus  enteritidis  of  Gartner 
and  all  the  other  organisms  belonging  to  this  group,  from  the  colon  to 
the  typhoid  bacillus,  grow  well  in  milk.  It  is  strange,  however,  that 
milk  has  never  been  incriminated  as  causing  paratyphoid  infection  in 
man.  The  possibility  is  evident,  but  the  occurrences  have,  perhaps, 
been  overlooked. 

PEEVENTiOisr. — Meat  inspection  affords  but  little  safeguard  against 
the  meat  poisoning  group  of  bacteria,  for  the  reason  that  these  micro- 
organisms may  pervade  the  meat  without  in  the  least  changing  its 
appearance,  color,  flavor,  or  odor.  Their  presence  may  only  be  detected 
by  bacteriological  examination.  In  this  respect  paratyphoid  and  its 
congeners  in  meat  correspond  strikingly  to  typhoid  and  other  infec- 
tions in  milk.  Animals,  however,  suffering  with  septicemic  infections, 
puerperal  fever,  metritis,  diarrhea,  and  serious  inflammations  of  any 
kind  should  be  condemned  by  the  meat  inspector  on  account  of  the 
danger  of  convejang  infections  of  the  kind  in  question.  Scrupulous 
cleanliness  must  be  observed  in  slaughter  houses,  butcher  shops,  and 
the  home.  The  butcher's  hands  and  implements  require  cleanliness  of 
a  surgical  order;  housewives  should  refuse  to  patronize  butcher  shops 
that  are  not  carefully  screened,  that  do  not  have  sufficient  refrigera- 
tion, and  that  are  not  tidy  and  cleanly  throughout.  Greater  care 
should  also  be  exercised  with  meat  in  transportation,  whether  upon  the 
railroad  or  the  delivery  wagon.  ,    . 

Meat  that  is  hashed,  as  in  Hamburg  steak^  or  prepared  in  a  sau- 
sage, is  especially  liable  to  infection  on  account  of  the  additional  hand- 
ling and  because  the  bacteria  pervade  the  minced  articles  more  readily 

^  Gartner,  v.  Ermengen,  Fischer,  Bainbridge. 


558  ANIMAL    FOODS 

than   tliey   do   the   solid   cluinks.      The   paratyphoid   bacillus   has   been 
isolated  from  sausages. 

Thorough  cooking  destroys  the  infection  and  eliminates  the  danger 
of  meat  poisoning  due  to  bacteria  belonging  to  tlie  group  under  con- 
sideration. It  must  not  1)0  forgotten,  however,  that  meat  after  it  is 
cooked  and  allowed  to  stand  may  become  infected,  and,  further,  that 
the  cooking  must  be  thorough. 

Otherwise  the  prevention  of  paratyphoid  fever  corresponds  in  all 
essential  particulars  with   that  discussed  under  typhoid  fever. 

Botulismus  or  Sausage  Poisoning. — Botulismus  is  a  specific  intoxi- 
cation produced  by  a  saprophyte.  The  symptoms  are  caused  by  a  poison 
that  is  generated  by  the  Bacillus  hotulinus  outside  of  the  body.  The 
bacillus  itself  is  harmless  and  does  not  grow  and  multiply  within  the 
body.  In  this  respect  botulismus  is  a  sharp  contrast  to  meat  poison- 
ing produced  by  the  paratyphoid  and  related  bacilli. 

The  Bacillus  hotulinus  may  grow  and  produce  its  toxine  in  sausage, 
meat,  or  fish,  and  occasionally  in  vegetables;  in  fact,  it  may  develop 
upon  protein  media  of  all  kinds.  It  requires  time  for  the  growth  and 
development  of  the  toxine;  fresh  foodstuffs,  therefore,  are  not  danger- 
ous so  far  as  botulismus  is  concerned.  Meat,  sausage,  or  fish  that  con- 
tains the  botulismus  toxine  may  or  may  not  be  altered  in  color,  taste, 
or  odor;  sometimes  the  indications  of  putrefactive  and  fermentative 
changes  are  evident.  But  the  presence  or  absence  of  such  alterations 
are  not  in  themselves  an  index  of  the  presence  or  absence  of  the  botulis- 
mus toxine. 

Botulismus  is  more  common  in  Europe  than  in  this  country.  The 
first  outbreak,  studied  by  v.  Ermengen,  occurred  in  Ellezelles,  Belgium, 
in  1895.  Fifty  persons  were  affected,  of  whom  three  died.  The  par- 
ticular ham  which  was  responsible  in  this  case  was  preserved  in  a  weak 
brine  at  the  bottom  of  a  cask  under  anaerobic  conditions.  Another  ham 
in  the  same  cask  above  the  brine  had  a  different  bacterial  flora  and  was 
not  poisonous. 

Sausages  are  the  most  frequent  source  of  botulismus.  The  sausages 
readily  become  infected  and  present  ideal  anaerobic  conditions  for  the 
growth  of  the  organism,  especially  as  they  are  rarely  refrigerated  and 
frequently  contain  old  and  contaminated  scraps.  The  disease  is,  there- 
fore, frequently  called  sausage  poisoning  from  hotulus,  a  sausage. 
Certain  sausages,  as,  for  example,  the  blood  sausage  and  the  liver  sau- 
sage prepared  in  Wiirttemberg  and  Baden,  are  especially  apt  to  be  in- 
fected. Salt  fish,  smoked  ham,  preserved  meat,  venison,  old  roasts 
have  produced  the  intoxication.  The  bacillus  may  even  grow  in  ni- 
trogenous vegetables;  thus,  spoiled  beans  were  responsible  for  an  out- 
break in  Hessen. 

Symptoms. — After  a  period  of  incubation  of  about  20  to  24  hours 


MEAT  559 

there  are  nausea,  gastric  pains,  vomiting,  visual  disturbances,  such  as 
fogging  of  the  eyes,  sometimes  amounting  almost  to  blindness,  dilatation 
of  the  pupils,  and  loss  of  reaction  to  light,  ptosis  of  both  lids,  and  a 
peculiar  stony  stare.  There  are  burning  thirst  and  difficulty  in  swal- 
lowing, the  mucous  membrane  of  the  respiratory  tract  is  strongly  red- 
dened and  covered  with  a  thick  viscid  secretion,  which  causes  severe 
attacks  of  coughing  and  even  suffocation.  There  is  extreme  muscular 
weakness;  the  respiration  and  circulation  remain  normal;  there  is  no 
fever;  death  may  ensue;  recovery  is  slow. 

The  Bacillus  hotulinus  discovered  by  v.  Ermengen  in  1899  is  a 
large,  slightly  motile  rod,  4  to  6/i  long,  9  to  12/i  thick.  It  has  slightly 
rounded  ends;  4  to  8  flagellse,  generally  single;  rarely  occurs  in  fila- 
ments; has  a  large  polar  spore;  stains  readily,  and  is  Gram-positive. 

The  bacillus  grows  best  between  20°  and  30°  C,  but  does  not  thrive 
above  35°  C,  hence  does  not  multiply  in  the  body.  It  is  a  strict 
anaerobe,  and  requires  a  distinctly  alkaline  medium.  Its  growth  is  fa- 
vored by  the  addition  of  2  per  cent,  grape  sugar;  gelatin  is  not  liquefied, 
but  active  gas  formation  takes  place  similar  to  cultures  of  malignant 
edema  and  other  anaerobes.  It  does  not  alter  milk.  All  the  cultures 
emit  the  odor  of  butyric  acid.  The  spores  are  killed  at  85°  C.  for  15 
minutes  or  80°  C.  in  one  hour. 

The  Bacillus  hotulinus  has  been  isolated  from  various  foodstuffs. 
Kempner  obtained  it  from  the  feces  and  Landtman  isolated  it  from 
poisonous  canned  beans.  In  habitat  and  biology  it  resembles  tetanus 
sj)ores,  and  it  is,  therefore,  supposed  to  exist  in  the  soil,  but  attempts 
to  find  it  in  the  soil  have  resulted  negatively.  It  is  perhaps  not  widely 
distributed  in  nature. 

BoTULisMUs  ToxixE. — The  bacillus  produces  a  soluble,  true  toxine 
comparable  in  all  respects  to  the  poisons  produced  in  cultures  of  diph- 
theria or  tetanus.  The  poison,  however,  is  produced  outside  of  the 
body,  not  in  it.  There  is  no  toxine  production  and  little  growth  at  body 
temperature.  The  bacillus  is  a  true  saproph3^te;  thus,  the  Bacillus 
hotulinus  occupies  a  position  of  its  own,  being  pathogenic  only  by 
virtue  of  the  poison  formed  on  dead  nitrogenous  substances.  It,  there- 
fore, is  the  type  of  a  toxicogenic  organism,  a  term  proposed  by  v. 
Ermengen.  The  Bacillus  hotulinus,  however,  is  the  only  definitely 
known  example  of  this  category. 

There  are  doubtless  other  microorganisms  that  produce  substances 
in  dead  organic  matter  which  are  poisonous  when  partaken  of  by  man. 
Of  these  the  Bacillus  proteus  vulgaris  and  the  Bacillus  coli  communis 
(Bacterium  coli)  are  believed  to  play  such  a  role.  Instances  of  poison- 
ing with  these  organisms  have  been  studied  by  numerous  investigators, 
but  their  toxines  and  their  action  are  less  well  understood  th^n  in  the 
case  of  botulismus, 


560  ANIMAL    FOODS 

The  botiilismus  toxine  is  the  only  one  of  the  true  toxines  that  is 
poisonous  wlien  taken  by  the  mouth.  It  is  thus  pathogenic  for  guinea 
pigs,  mice,  and  monkeys,  as  well  as  for  man.  One  or  two  drops  of  a 
culture  placed  upon  a  piece  of  bread  causes  death  in  a  few  days.  Tox- 
ines of  diphtheria  and  tetanus  are  not  poisonous  when  taken  by  the 
mouth.  Cats  and  rabbits,  however,  withstand  large  doses  of  botulismus 
toxine  by  the  mouth,  but  are  very  su.sceptible  to  subcutaneous  or  intra- 
venous injection.  The  botulismus  toxine  is  readily  killed  by  heat,  and 
is  very  susceptible  to  acids  and  alkalies;  it  also  deteriorates  in  sunlight. 
A  true  antitoxin  may  be  obtained  by  injecting  increasing  amounts 
into  susceptible  animals.  Kempner  first  obtained  the  antitoxin  in  goats. 
Much  work  has  since  been  done  upon  this  toxine  and  antitoxin  by  Mad- 
sen  and  others.  The  botulismus  antitoxin  has  both  protective  and 
curative  virtues  in  man  as  well  as  in  experimental  animals,  even  when 
given  24  hours  after  the  ingestion  of  the  poison.  It  has  recently  been 
prepared  for  distribution  at  the  Institute  for  Infectious  Diseases  at 
Berlin. 

Prevention. — Prevention  of  botulism  consists  in  greater  care 
and  cleanliness  in  the  handling  and  preservation  of  nitrogenous  food- 
stuffs. There  is  no  danger  of  this  poison  in  fresh  foods,  or  in  foods 
preserved  a  long  time,  if  properly  sterilized  in  the  can  or  properly 
refrigerated.  The  chief  danger  is  from  sausages  eaten  without  cook- 
ing. The  heat  destroys  the  toxine,  but  it  must  be  sufficient  and  pene- 
trate throughout  the  mass;  also  the  cooking  must  be  recent,  for  the 
bacillus  grows  well  in  cooked  foods.  When  obtainable  the  antitoxin  may 
be  used  as  a  preventive  in  cases  where  a  number  of  persons  are  show- 
ing symptoms  of  poisoning  from  having  partaken  of  the  same  carcass 
or  sausage  or  other  suspected  food. 

Trichinosis. — TrichineUa   spiralis,   formerly   Trichinn  spiralis,   is   a 

round  worm  which  passes  its  entire 
^"^  life  cycle  in  man,  rat.  or  hog.    Many 

other  animals,  such  as  mice,  foxes, 
guinea  pigs,  rabbits,  cats,  dogs,  etc., 
are  susceptible.  This  parasite  dif- 
fers from  many  other  animal  para- 
sites in  affecting  several  genera  and 
in  passing  its  entire  life  cycle  in 
each  host. 

'*'""  -^  "^^^-^^..^^^--^  The  larvae  are  imbedded  in  the 

^""'"^  muscles.     When  the  trichinous  meat 

Fig.  73.-TRICHINELLA  Spiralis.     Entiee    •      ^^         ^j^^    capsules    are    dissolved 
Life  Cycle  in  Each  Host.  ^ 

in  the  stomach,  the  larvae  set  free, 

the  parasites  enter  the  intestine,  where  they  find  conditions  favorable, 
and  where  in  a  few  days  they  become  large  enough  to  be  seen  with 


MEAT  561 

the  naked  eye  as  fine  threads^  which  grow  into  the  full  mature  worm. 
The  female  parasite  produces  upward  of  five  hundred  young,  and  it 
is  these  embryos  that  pierce  the  bowel  and  penetrate  into  the  tissues. 
They  get  into  the  blood  stream  and  are  thus  distributed  to  the  muscles. 
It  takes  about  7  to  9  days  to  accomplish  these  changes;  that  is,  for  the 
larvae  in  the  muscles  to  develop  from  the  brood  of  embryos  in  the  in- 
testine. 

The  normal  or  common  host  of  Trichinella  spiralis  may  be  regarded 
as  the  rat,  which  gets  infected  about  slaughter  houses  and  butcher  shops. 
Hogs  get  the  disease  by  eating  rats,  through  feces,  or  directly  from  in- 
fected offal.  Man  receives  the  infection  by  eating  trichinous  pork  (occa- 
sionally dog,  cat,  or  bear  meat). 

Not  all  persons  who  eat  trichinous  flesh  have  the  disease.  A 
limited  number  of  the  embryos  do  not  cause  noticeable  symptoms.  In 
man  the  disease  is  well  characterized  in  two  stages:  (1)  gastrointes- 
tinal, (2)  general  infection.  The  symptoms  of  the  second  stage  are 
fever,  intense  pain  in  the  muscles  caused  by  the  migration  of  the  para- 
sites, edema,  and  leukocytosis.  The  count  of  the  white  cells  may  reach 
30,000  with  distinct  eosinophilia. 

The  recognition  of  trichinosis  as  a  distinct  infection  is  recent  (1860). 
The  parasite  was  named  by  Richard  Owen  and  was  long  regarded  as 
harmless  and  as  a  curiosity.  The  infection  was  mistaken  for  typhoid 
fever,  rheumatism,  acute  miliary  tuberculosis,  and  other  diseases  of 
common  occurrence.  The  particular  case  which  finally  revealed  the 
parasite  as  being  capable  of  harm  was  that  of  a  young  woman  admitted 
to  the  hospital  at  Dresden  suffering  from  a  disease  diagnosed  as  typhoid 
fever.  The  patient  had  agonizing  pains  in  the  muscles,  and  the  autopsy 
revealed  the  parasite  imbedded  in  vast  numbers  in  the  muscular  fibers. 
An  investigation  led  to  the  examination  of  some  pork  of  which  she 
had  eaten  four  days  before  the  first  symptoms  appeared,  and  showed 
the  presence  of  the  same  parasite.  Since  then  many  local  out- 
breaks have  been  described,  more  particularly  in  Germany,  where 
the  custom'  prevails  of  eating  raw  or  underdone  pork,  especially  in 
sausage. 

Peeventiox. — The  disease  is  practically  never  recognized  in  swine 
during  life.  The  protection  rendered  by  the  inspection  of  meat  is  quite 
unsatisfactory.  This  inspection  consists  in  compressing  small  fragments 
of  the  muscle  (diaphragm,  tongue,  etc.)  between  two  glass  plates,  which 
are  then  examined  with  a  low  power  of  the  microscope  for  the  en- 
cysted larvae.  That  this  examination  is  not  an  entirely  satisfactory 
safeguard,  even  in  cases  where  it  is  done  with  care  and  precision,  is 
shown  by  the  fact  that  in  Germany,  for  example,  the  disease  is  still 
very  common.  The  microscopic  inspection  of  every  carcass  for  trichina 
is  expensive  and  open  to  several  practical  sources  of  error.     It,  there- 


562  ANIMAL    FOODS 

fore,  gives  a  false  sense  of  security  and  is  impractical  in  country  slaugh- 
ter houses. 

Our  federal  meat  inspection  regulations  no  longer  require  a  micro- 
scopic examination  of  pork  for  tricliina.  Until  recently  all  the  pork 
dressed  for  export  was  examined  by  the  microscopic  method,  but  this 
has  been  discontinued. 

To  show  the  great  prevalence  of  the  disease,  the  microscopists  of 
the  United  States  Department  of  Agriculture  found  the  parasite  in 
41,659  of  the  2,227,740  hogs  examined.  The  disease  in  man  is  prob- 
ably more  prevalent  than  the  figures  of  the  clinicians  indicate.  Care- 
ful search  at  autopsy  showed  that  many  persons  have  been  infected 
but  have  recovered.  Thus,  Williams  of  Cleveland  examined  505  cad- 
avers and  showed  old  encapsulations  and  calcifications  in  27,  or  5.34 
per  cent. 

The  trichinae  are  not  particularly  resistant,  being  killed  at  155°  P. 
if  they  are  not  encapsulated,  otherwise  at  158°  to  160°  F.;  that  is, 
they  have  about  the  same  resistance  as  non-sporulating  1)acteria.  They 
are  not  affected  by  intense  cold,  putrefactive  processes,  nor  by  ordinary 
processes  of  cooking,  but  die  after  thorough  cooking  or  a  prolonged 
period  of  pickling.  As  the  elimination  of  the  disease  in  swine  and 
rats  will  be  a  long  and  difficult  campaign,  the  only  satisfactory  and 
absolute  protection  is  complete  cooking. 

The  rat  should  be  regarded  as  the  common  reservoir  of  trichina, 
and  a  persistent  warfare  should  be  made  against  rats  in  slaughter 
houses,  butcher  shops,  markets,  and  places  where  hogs  are  kept  (see 
page  242.  Human  feces  and  contaminated  ofPal  must  not  be  fed 
to  hogs. 

The  Pork  or  Measly  Tapeworm  (Tcpnia  Solium). — Trrnia  solium 
passes  the  larval  stage  of  its  life  history  in  the  flesh  of  pork.  These 
encysted  larvae  are  known  as  bladder  worms  or  Cysticercus  cellulosce; 
they  are  commonly  called  pork  measles.  Man  eats  these  encysted 
larvae  which  develop  into  adult  tapeworms  in  the  intestinal  tract. 

Infection  with  this  tapeworm  may  be  particularly  dangerous,  be- 
cause the  cysticerci  have  the  peculiarity  that  they  may  occur  in  man 
as  well  as  in  the  hog.  When  the  cvsticerci  develop  in  important  parts, 
such  as  the  eye,  brain,  etc.,  death  or  serious  consequences  may  ensue. 
The  infection  with  this  particular  tapeworm  is  fortunately  rare  in 
the  United  States  and  Canada,  but  is  more  frequently  met  with  in 
the  old  world.  The  adult  tapeworm  occurs  only  in  man;  the  larva  is 
found  especially  in  hogs  and  occasionally  in  sheep  and  dogs.  This 
parasite  is  smaller  than  the  beef  tapeworm.  The  head  is  armed  with  a 
double  row  of  hooks,  with  which  it  maintains  its  hold  to  the  mucous 
membrane.  Each  link  contains  a  uterus  with  lateral  branches,  and  the 
genital  pore   is   marginal  and  irregularly   alternate. 


MEAT 


563 


Man    ( Tania  Solium) 


Man 

.Swine  (Cysticercus  CelluJosce) : 

(Pysticercus  Oellulosas') 
Fig.  74. — T^nia  Solium,  the  Pork  or  Measly  Tape- 
worm.   Note  that  man  may  infect  himself. 


The  source  of  infection  in  man  is  practically  always  undercooked 
or  raw  pork.  Occasionally  the  infection  is  contracted  from  another 
person  through  the  eggs  in  the  feces.  Hogs  become  infected  from 
eating  human  feces  containing  the  eggs,  or  from  food  and  drink  con- 
taminated with  them.  To  Imild  a  privy  over  the  pig  pen,  as  one  some- 
times sees  in  the  country,  means  the  formation  of  an  endless  chain 
in  the  biology  of  this  worm. 

TcBfiia  solium  produces  less  anemia  than  the  fish  tapeworm 
(  D  ih  0  thrio  cephalus 
latus),  but  may  be  dan- 
gerous because  of  cysti- 
cercus formation  in  man. 
This  is  the  only  tape- 
worm in  which  this  oc- 
curs. A  person  infected 
with  Tcenia  solium  may 
reinfect  himself  through 
dirty  finger  nails,  un- 
washed hands,  or  other 
uncleanly  habits,  and  it 
is  also  comparatively  easy 
to  infect  others  through  the  feces. 

In  prevention  one  must  first  consider  the  disposal  of  feces.  Hogs 
heavily  infected  should  be  destroyed;  those  having  a  light  infection 
may  be  thoroughly  cooked  and  the  meat  eaten.  Cold  storage  is  not 
quite  so  effective  in  destroying  the  larvae  of  Tcenia  solium  as  it  is  for 
Tcenia  saginata,  for  the  former  have  been  found  alive  after  29  days, 
whereas  the  latter  die  after  21  days. 

Taenia  Saginata. — Tcenia  saginata,  also 
Manjj^nia  Saginata)  ^^^j^^  Mediocanellata,  occurs  Only  in  cattle 
and  man.  This  tapeworm  is  rather  common 
in  our  country,  but  is  not  dangerous,  like 
Tcenia  solium,  though  at  times  it  produces  a 
certain  degree  of  anemia  and  other  symp- 
toms. It  is  often  difficult  to  expel,  despite 
the  fact  that  it  has  no  hooks.  In  geographi- 
cal distribution  it  is  cosmopolitan.  The 
adult  worm  occurs  in  man ;  the  larva  is  found 
imbedded  in  beef  and  is  known  as  the 
Cysticercus  hovis.  The  uterus  has  15  to  35 
slender  diehotomous  branches  on  each  side. 
The  genital  pore  is  marginal  and  irregularly  alternate. 

Man  becomes  infected  by  eating  raw  or  underdone  beef.  The  tongue 
and   the   muscles   of   mastication   most   frequently   contain   the   larvge. 


Cattle 
(Cysticercus  Bouis) 

FiQ.  75. — Beef  Tapeworm. 


564  ANIMAL    FOODS 

Cattle  become  infected  through  the  embryos  passed  in  human  feces, 
which  contaminate  their  food  or  water. 

Prevention. — The  prevention  depends  first  upon  proper  disposal 
of  human  excrement  and  an  efficient  system  of  meat  inspection.  The 
cysticerci  die  in  three  weeks  after  killing,  hence  meat  that  has  been 
preserved  21  days  may  be  regarded  as  safe.  Proper  cooking  and  thor- 
ough salting  also  kill  the  larvae  of  this  tapeworm. 

FISH 

Fish  poisoning  or  ichthyotoxismus  is  most  frequent  in  Russia,  Japan, 
and  the  West  Indies,  and  other  seacoast  countries  in  which  fish  forms 
a  large  part  of  the  diet.  Some  of  these  poisons  are  now  better  under- 
stood, but  for  the  most  part  are  far  from  being  satisfactorily  explained. 

Physiological  Fish  Poisoning. — ]\[any  fish  are  always  poisonous, 
that  is,  normally  contain  a  substance  toxic  to  man;  some  develop  the 
poison  only  during  spawning  season.  Various  species  of  the  tetrodon 
and  diodon  frequently  cause  serious  and  fatal  poisoning  in  Japan.  In 
Tokio  alone  G80  fatal  cases  out  of  933  were  reported  occurring  in 
1885-1892  from  the  so-called  "fugu."  In  China  and  Japan  such  fish 
are  sometimes  taken  for  suicidal  purposes.  The  active  principle  in 
fugu  poisoning  rCwSembles  curara.  The  poison  is  found  in  the  ovaries 
and  testicles,  and  is  called  "fugin."  Its  exact  chemical  nature  has  not 
been  determined.  The  symptoms  produced  are :  dyspnea,  cyanosis,  dila- 
tation of  the  pupils,  relaxation  of  the  sphincters,  paralysis  of  speech, 
dizziness,  salivation,  and  vomiting.  Death  may  result  in  one  to  two 
hours. 

Few  fish  containing  physiological  poisons  are  found  north  of  the 
tropics.  Some  fish,  such  as  shad  and  smelts,  are  preferred  during 
spawning  season.  However,  during  spawning  season  the  roe  of  differ- 
ent members  of  the  sturgeon  family,  of  the  pike,  and  the  barbel  have 
been  known  to  cause  pronounced  and  even  fatal  intoxication;  the  symp- 
toms resemble  those  of  gastroenteritis.  It  is  interesting  to  note  that 
even  the  codfish  (Gadus  morrhua),  if  eaten  raw,  has  caused  serious 
intoxication. 

Bacterial  Poisons. — Bacterial  poisoning  from  fish  is  fairly  common. 
The  fish  may  be  diseased,  or  when  caught  may  be  healthy,  but  the 
bacteria  gain  access  and  grow  throughout  the  meat  as  the  result  of 
contamination  or  imperfect  preservation.  Bacterial  diseases  among 
fish  are  rather  common  and  often  occur  as  epizootics.  In  almost  all 
the  reported  instances  of  injurious  action  resulting  from  bacteria  the 
fish  has  been  eaten  raw.  Bacteria  may  form  poisonous  substances 
in  fish  closely  resembling  botulismus.  Fish  caught  by  the  gills  in  nets 
die  slowly  and  decompose  rapidly.     They  are  of  inferior  flavor  and 


SHELLFISH  565 

value  and  are  more  liable  to  be  injurious  than  fish  taken  from  the  water 
and  killed  at  once;  under  such  circumstances  they  remain  firm  and  re- 
tain their  flavor  longer  than  those  that  die  slowly.  In  some  parts 
of  the  world  live  fish  in  tanks  are  offered  for  sale  in  the  markets.  This 
procedure  cannot  be  commended  from  a  sanitary  standpoint,  for  the 
tanks  are  apt  to  become  dirty  and  the  fish  liable  to  sicken  and  die 
slowly,  so  that  the  object  of  purveying  only  live,  fresh,  and  wholesome 
fish  is  largely  defeated.  It  is  well  known  that  fish  decompose  readily 
and  should,  therefore,  be  handled  in  a  cleanly  manner  and  used  as 
fresh  as  possible.     When  refrigerated  the  temperature  should  be  low. 

The  Fish.  Tapeworm. — The  principal  animal  parasite  conveyed 
through  fish  is  the  tapeworm,  Dibothriocephaliis  latus,  which  infects 
man  wherever  fresh  fish  forms  a  large  part  of  the  diet.  The  cysticercus 
or  larval  stage  is  found  in  the  muscles  .  and  organs  of  various  fresh 
water  fish,  particularly  pike,  perch,  and  several  members  of  the  salmon 
family,  and  when  partaken  of  by  man  develops  into  the  adult  tapeworm 
in  the  intestines.  The  adult  worm  is  also  found  in  cats  and  dogs  that 
feed  upon  fish. 

The  fish  tapeworm  produces  a  severe  anemia  Man 

resembling  pernicious  anemia.  The  head  of 
the  DihotliriocepJialus  latus  is  armed  with 
hooks  and  attaches  itself  to  the  mucous  mem- 
brane of  the  bowels.  Faust  and  Talquist  have 
shown  that  the  anemia  is  due  to  an  hemolytic 
action  caused  by  oleic  acid  found  in  the  head 
of  the  fish  tapeworm.  Each  link  of  the  fish 
tapeworm  has  a  rosette-shaped  uterus  in  the 
median  line  and  a  special  uterine  pore  from  (oystieereus) 

which  eggs  are  constantly  discharged  and  may   p,^  76.-Dibothriocephaltts 
readily  be  found  in  the  feces.      It   is  through      Latus,  the  Fish  Tapeworm. 
the  pollution  of  the  streams  with  sewage  con-         Produces  serious  anemia, 
taining  the  eggs  that  the  fish  become  infected. 

The  prevention  of  the  fish  tapeworm  consists  in  proper  disposal 
of  feces,  so  as  to  prevent  the  contamination  of  fresh  water  streams,  and 
the  proper  cooking  of  fish. 

SHELLFISH 

Shellfish  include  mollusks,  as  oysters,  clams,  mussels,  and  crustace- 
ans, as  lobsters,  crabs,  and  shrimp.  The  conditions  which  render  such 
food  injurious  are  much  the  same  as  those  discussed  in  connection  with 
fish.  Shellfish  may  be  diseased  when  taken  from  the  water,  but  little 
is  known  of  the  diseases  of  shellfish  that  influence  man.  Shellflsh  may 
be  perfectly  good  and  wholesome  when  fresh,  but  may  become  con- 
taminated and  poisonous  on  keeping,  especially  if  not  kept  cold. 
38 


56G  ANIMAL  FOODS 

With  shellfish,  as  with  other  foods,  the  intermediate  products  of 
putrefaction  are  the  most  dangerous.  For  example,  mussels  that  have 
been  allowed  to  decompose  for  some  days  have  been  shown  to  be  free 
from  toxic  substances  (see  Ptomains),  Perhaps  the  most  important 
condition  bearing  upon  the  injurious  properties  of  shellfish  is  their 
habitat.  It  has  been  shown  repeatedly  that,  wlien  grown  or  kept  in 
polluted  water,  they  acquire  poisonous  or  infectious  properties.  On 
being  transferred  to  fresh,  clean  water  they  may  lose  these  injurious 
characteristics.  It  is  claimed  by  some  observers  that  6  days,  by  others 
that  16  days,  in  clean  water  are  sufficient  for  mollusks  to  purge  them- 
selves of  typhoid  infection. 

It  is  now  well  known  that  03'sters,  and  doubtless  other  mollusks, 
while  in  polluted  water,  may  take  up  large  numbers  of  different  kinds 
of  bacteria,  and  that  these  remain  alive  and  virulent  for  a  long  time. 
Herdman  and  Boyce  found  17,000  colonies  from  an  oyster  obtained 
from  the  neighborhood  of  a  drain  pipe.  Ordinarily  oysters  from  open 
waters  contain  less  than  100  colonies.  Oysters  contain  fewer  bacteria 
during  the  winter  months  (December  to  March),  when  they  probably 
hibernate.  Oysters  placed  in  polluted  waters  may  retain  the  typhoid 
bacillus  as  long  as  14  days  after  infection.  Klein  found  typlioid  to 
persist  in  oysters  from  2  to  3  weeks.  At  times  the  oysters  clean  them- 
selves in  a  week ;  this  is  facilitated  by  clear,  clean,  running  water.  The 
process  by  which  the  oyster  rids  itself  of  bacteria  is  perhaps  both  me- 
chanical and  biological. 

Both  typhoid  and  cholera  have  been  convincingly  traced  to  infected 
oysters.  The  oysters  may  become  infected  where  they  grow  or  during 
the  process  of  "fattening"  or  "floating,''  which  consists  in  soaking  them 
in  fresh  water  for  the  purpose  of  making  them  more  plump  and  in- 
creasing their  size.  In  the  language  of  the  fishermen,  this  is  called 
"floating,"  "drinking,"  or  "laying  out."  On  account  of  the  difference 
in  osmotic  pressure  the  water  enters  the  cells  of  the  oysters  and  cer- 
tain mineral  salts  pass  out.  ^^^lile  the  oyster  increases  in  size  and 
weight  it  is  at  the  expense  of  the  natural  salt,  mostly  sodium  chlorid, 
which  the  oyster  contains. 

It  may  be  stated  as  a  general  rule  that  oysters  and  other  shellfish 
should  not  be  used  when  taken  from  water  which,  upon  bacteriological 
examination,  would  render  it  unfit  if  used  for  drinking  purposes.  It 
should  be  remembered  that  bacteria  found  in  mollusks  represent  the 
flora  of  the  mud  of  the  bed  of  the  stream  rather  than  the  water  itself. 
For  instances  of  tj-phoid  outbreaks  attributable  to  oysters  see  page  91. 

The  prevention  of  typhoid  and  similar  infections  through  oysters 
and  other  shellfish  consists  in  regulating  the  location  of  the  beds  and 
in  transferring  doubtful  ones  to  a  clean  situation  in  clear  sea  water 
until  the  bacteria  have  perished  or  have  been  washed  away.     How  long 


"BOB-VEAL"  567 

this  may  take  is  somewhat  doubtful;  perhaps  a  week,  or,  better,  16 
days,  should  be  allowed.  "Floating"  should  be  prohibited,  especially 
in  water  of  doubtful  character.  Thorough  cooking  will  kill  all  the  non- 
spore-bearing  bacteria. 

Mussel  Poisoning. — My  til  us  edulis,  the  common  mussel,  is  a  rather 
frequent  source  of  poisoning  in  England  and  on  the  Continent. 
Three  types  are  recognized  clinically:  (1)  gastroenteric,  (2)  nervous, 
and  (3)  paralytic.  In  the  first  type  the  symptoms  are  nausea,  vomit- 
ing, diarrhea,  and  sometimes  choleraic  symptoms.  This  form  is  similar 
to  the  common  type  of  meat,  cheese,  and  other  acute  food  poisoning, 
and  when  due  to  mussel  poisoning  is  not,  as  a  rule,  fatal.  In  the 
nervous  type  the  symptoms  are  itching,  erythema,  urticaria,  angina, 
dyspnea.  Eecovery  from  this  form  usually  takes  place  in  a  few  days. 
The  paralytic  type  suggests  curara.  This  is  less  frequent  and  more 
dangerous  than  the  gastroenteric  or  nervous  types.  It  may  be  com- 
pared to  botulismus,  but  differs  in  rapidity  of  onset,  the  nature  of  the 
symptoms,  and  in  the  fact  that  boiling  does  not  destroy  the  poison. 
Death  has  occurred  in  15  minutes  after  eating  boiled  mussels.  A  no- 
table example  of  mussel  poisoning  occurred  at  Wilhelmshaven  in  1885. 
A  large  number  of  dock  laborers  and  their  families  were  poisoned 
shortly  after  eating  cooked  mussels;  three  died.  The  mussels  were 
examined  by  Brieger,  who  isolated  several  basic  substances  or  ptomains, 
one  of  which,  mytilotoxin,  was  poisonous  to  animals,  causing  similar 
symptoms.  Novy  considers  this  a  true  instance  of  a  heat-resisting 
alkaloidal-like  poison  or  ptomain  in  a  sense  analogous  to  mushroom 
poisoning.  Cats  and  dogs  eating  poisonous  mussels  suffer  with  symp- 
toms similar  to  those  seen  in  man,  namely,  paralysis,  coma,  and  death. 
Eabbits  have  been  poisoned  by  giving  them  the  water  in  which  the 
mussels  have  been  cooked.  Under  these  circumstances  they  may  die 
in  a  minute. 

Miscellaneous. — In  addition  to  the  infections  noted,  the  following 
diseases  are  sometimes  transferred  from  the  flesh  or  organs  of  lower 
animals,  or  by  contact  with  the  lower  animals  in  various  ways:  tuber- 
culosis, anthrax,  glanders,  rabies,  actinomycosis,  foot-and-mouth  disease, 
cowpox,  ringworm,  and  various  pyogenic  and  septic  infections. 

Meat  may  occasionally  be  injurious  to  health  from  a  variety  of 
miscellaneous  causes.  Thus,  an  animal  that  has  died  of  arsenic  or  other 
poisonous  substance  may  contain  sufficient  of  the  poison  in  the  tissues 
to  affect  the  person  who  eats  part  of  the  flesh. 

"BOB-VEAL" 

"Bob-veal"  is  the  flesh  of  immature  calves,  that  is,  animals  less  than 
two  or  three  weeks  old.     "Bob-veal"  is  objectionable  from  humanitarian 


568  ANIMAL    FOODS 

and  esthetic  grounds.  The  meat  is  flabby,  edematous,  soft.  The  con- 
nective tissue  is  gelatinous  and  is  present  in  greater  quantity  than  in 
mature  animals.  The  fat  is  reddish-gray  and  soapy,  the  meat  less  nu- 
tritious in  value,  as  it  contains  a  large  proportion  of  water.  On  account 
of  its  moist  and  soft  condition  "bob-veal"  has  a  greater  tendency  to 
spoil  than  the  flesh  of  mature  animals.  Young  calves  are  higlily  sus- 
ceptible to  a  number  of  infections,  particularly  diarrheal  diseases,  which 
enter  through  the  infected  navel.  The  flesh  of  such  animals  may  con- 
vey microorganisms  belonging  to  the  paratyphoid  group. 

Ostertag  states:  "Putrefactive  and  pathogenic  microbes  find  a 
ready  media  for  luxuriant  growth  in  'bob-veal'  carcasses.  In  Switzer- 
land 27  persons  became  ill  from  eating  veal  of  a  calf  five  days  old  which 
had  yellow  water  in  the  joints;  one  patient  died.  In  the  Grand  Duchy 
of  Baden  from  1888  to  1891  5.3  calves  out  of  every  1,000  slaughtered 
furnished  meat  injurious  to  health." 

Bollinger  recites:  "In  the  epidemic  at  Andelfingen  450  people  be- 
came ill  and  10  died.  The  veal  which  was  consumed  was  suspected  and 
it  transmitted  its  poisonous  properties  to  beef  stored  with  it.  At  Ber- 
minstorf  8  people  died  from  eating  veal  from  a  calf  four  days  old.  At 
Morselle,  Belgium,  80  people  became  sick  from  eating  veal  of  two 
calves  with  diarrhea." 

It  is  a  well-known  fact  that  calves  under  three  weeks  old  have 
umbilical  wounds  which  are  liable  to  become  infected.  All  young  ani- 
mals are  subject  to  such  infections,  since  nature  is  left  to  effect  the 
healing  of  the  wound.  The  weight  of  the  calf  is  often  taken  as  an 
indication  of  its  age.  Thus  a  calf  weighing  40  pounds  or  more  is  con- 
sidered mature,  but  the  weight  is  a  poor  index  of  age.  The  condition 
of  the  umbilical  wound  usually  tells  the  tale. 

EGGS 

Perhaps  no  article  of  diet  of  animal  origin  is  more  commonly  eaten 
in  all  countries  and  served  in  a  greater  variety  of  ways  than  eggs. 
Eggs  are  used  in  nearly  every  household  in  some  form  or  another.  It 
has  been  calculated  that  on  an  average  they  furnish  3  per  cent,  of  the 
total  food,  5.9  per  cent,  of  the  total  protein,  and  4.3  per  cent,  of  the 
total  fat  used  per  man  per  day.  When  we  speak  of  eggs  we  ordinarily 
mean  hen's  eggs,  but  the  eggs  of  ducks,  geese,  and  guinea  fowls  are 
used  to  a  greater  or  less  extent;  more  rarely  turkey's  eggs  and  some- 
times those  of  wild  birds.  Plover  eggs  are  prized  in  England  and 
Germany,  while  in  this  country  the  eggs  of  sea  birds,  such  as  gulls, 
terns,  herons,  and  murres.  have  long  been  gathered  for  food.  Other 
eggs  besides  those  of  birds  are  sometim.es  eaten.  Turtle's  eggs  are 
highly  prized  in  most  countries  where  they  are  abundant.     The  eggs  of 


EGGS  569 

the  terrapin  are  usually  served  with  the  flesh  in  some  of  the  ways  of 
preparing  it  for  the  table.  Fish  eggs,  especially  those  of  the  sturgeon, 
are  preserved  in  salt  under  the  name  of  caviare.  Shad  roe  is  also  a 
familiar  example  of  the  use  of  fish  eggs  as  food.  The  eggs  of  alliga- 
tors, lizards,  serpents,  and  some  insects  are  eaten  by  races  who  lack 
the  prejudices  of  western  nations. 

Hen's  eggs  vary  considerably  in  size  and  appearance.  The  shell 
constitutes  about  11  per  cent.,  the  yolk  32  per  cent.,  and  the  white 
57  per  cent,  of  the  total  weight  of  the  egg.  The  egg-shell  consists 
mainly  of  carbonate  of  lime,  and  when  freshly  laid  is  covered  by  a 
mucous  coating.  The  egg-white  consists  of  86.2  per  cent,  of  water, 
12.3  per  cent,  nitrogenous  matter,  0.2  per  cent,  fat,  and  0.06  per  cent. 
ash.  The  yolk  consists  of  49.5  per  cent,  water,  15.7  per  cent,  nitrogenous 
matter,  33.3  per  cent,  fat,  and  1.1  per  cent,  ash.^  These  are  averages; 
different  eggs  vary  somewhat  in  composition  from  each  other.  It  is 
noteworthy  that  eggs  contain  practically  no  carbohydrates. 

In  addition  to  fresh  and  refrigerated,  eggs  are  classified  in  the  trade 
as  "rots,"  "spots,"  "checks,"  "ringers,"  "chickens,"  "dirty  shells," 
"heated,"  or  "incubated,"  etc.  Eggs  are  assorted  by  inspection  and 
candling.  Candling  consists  in  holding  them  before  a  bright  light; 
the  egg  is  translucent  and  the  movable  yolk  may  clearly  be  discerned, 
as  well  as  the  air  space  which  is  always  at  the  larger  end.  A  practiced 
eye  quickly  detects  eggs  that  are  not  first  quality.  Eotten  eggs  are  dis- 
tinguished as  "red  rots"  and  "black  rots,"  depending  upon  the  kind  of 
putrefaction.  By  "spots"  are  understood  eggs  that  contain  opaque  spots 
under  the  light.  These  spots  usually  consist  of  local  growths  of  mold 
that  have  penetrated  a  crack  in  the  shell,  although  they  may  be  due 
to  coccidia,  embryos,  or  foreign  bodies.  "Checked"  eggs  are  those  which 
have  slight  cracks  or  nicks  in  the  shell.  "Eingers"  contain  small  embryos 
of  about  two  days'  growth,  which  are  flat,  disk-like,  and  reddish  in 
appearance.  "Chickens"  contain  embryos  of  larger  growth.  Eggs  with 
dirty  shells  are  undesirable  more  from  esthetic  than  other  reasons.  The 
dirt  usually  consists  of  hen  excrement.  A  "heated"  egg  is  a  shrunken 
egg,  that  is,  an  egg  that  has  been  exposed  to  the  summer  temperature 
for  several  days.  Some  water  is  lost  by  evaporation  through  the  porous 
shell,  the  air  sac  on  the  end  has  increased  considerably  in  volume,  and 
in  many  instances  the  embryo  is  partly  developed;  therefore,  heated 
eggs  are  also  known  as  incubated  eggs.  Many  of  the  eggs  gathered 
during  the  hot  months  of  summer,  especially  in  July  and  August,  belong 
to  this  category.  These  eggs  are  much  less  desirable  than  the  spring 
and  fall  layings.  Eggs  are  also  graded  as  to  size,  the  very  small  eggs 
being  undesirable,  commanding  a  lower  figure  in  the  market.     Further, 

^  Pennington :  "  A  Chemical  and  Bacteriological  Study  of  Fresh  Eggs, ' '  Jour. 
Biol.  Chem.,  Yol.  VII,  No.  2,  .Jan.,  1910,  p.  110. 


570  ANIMAL    FOODS 

eggs  are  classified  as  strong-  or  weak-bodied,  depending  upon  how  they 
"stand  up"  when  broken  out. 

Eggs  as  they  come  from  the  hen  frequently  contain  bacteria,  worms, 
gravel,  blood  clots,  and  foreign  bodies  of  various  kinds.  Practically  all 
eggs  contain  bacteria,  although  numerous  observers  report  occasionally 
that  an  egg  is  sterile.  As  a  rule,  these  observations  are  based  upon 
planting  a  small  part  of  the  egg.  If  the  entire  egg  is  planted  a  growtli 
is  almost  invariably  obtained.  Thus,  in  eighteen  freshly  laid  eggs  which 
I  recently  examined  every  one  of  them  contained  bacteria  in  the  yolk; 
two  of  them  contained  B.  coli.  Curiously  enough,  there  are  practically 
always  more  bacteria  in  the  yolk  than  in  the  white;  the  white  contains 
some  bactericidal  property,  probably  similar  to  that  possessed  by  fresh 
blood.  The  bacteria  doubtless  gain  entrance  to  the  egg  while  in  the 
oviduct.  Pernot  ^  examined  the  eggs  from  over  the  size  of  a  pea  to  the 
perfect  egg  and  found  bacteria  at  every  stage.  It  is  well  known  that 
the  bacteria  may  also  get  into  an  egg  through  the  shell,  as  it  is  porous 
and  permeable.  When  the  shell  is  moist  and  dirty  the  chances  of 
growth  and  mold  piercing  it  are  increased.  Eggs  laid  in  the  summer 
time  (July  and  August)  contain  many  more  bacteria  than  those  laid 
in  the  spring,  fall,  and  colder  months.  It  is  well  known  that  summer 
eggs  do  not  keep  as  well  as  winter  and  spring  eggs. 

Very  large  quantities  of  eggs  are  now  broken  out,  mixed,  frozen, 
or  dried.  These  products  are  largely  used  by  bakers  and  others  who 
use  eggs  in  quantities. 

Of  all  foods,  so  far  as  known,  eggs  are  less  liable  to  convey  disease 
or  contain  harmful  properties  than  any  other  single  food  of  animal 
origin.  The  literature  is  singularly  free  of  instances  of  sickness  at- 
tributable to  eggs.  There  is  no  kno^vn  infection  of  the  hen  transmis- 
sible to  man  through  its  egg.  Eggs  do  not  agree  with  some  people, 
who  have  an  "idiosyncrasy,"  so  that  a  very  small  quantity  will  bring  on 
symptoms  resembling  anaphylaxis.  This  condition  is  doubtless  an  in- 
stance of  specific  hypersusceptibility  to  egg  protein.  There  are  several 
cases  on  record  in  which  this  hypersusceptibility  has  been  cured  by  the 
administration  of  pills  or  candy  containing  at  first  infinitesimal  amounts 
of  egg-white,  gradually  increasing  the  amount.  The  entire  treatment 
should  extend  over  a  period  of  months.  In  this  way  an  immunity  may 
be  established  in  man  precisely  analogous  to  the  immunity  which  may 
be  established  by  repeated  injections  of  an  alien  protein  into  guinea  pigs. 

*  "Investigation  of  the  Mortality  of  Incubator  Chicks,"  Bull.  103,  Oregon 
Agr.  College  Exp.  Station. 


CHAPTER    IV 
PLANT    FOODS 

Vegetable  substances  may  be  injurious  to  health  from  several  causes. 
Many  plants  contain  a  physiological  poison,  such,  for  example,  as  aconite, 
strychnin,  recin,  abrin,  muscarin,  and  a  long  list  of  other  substances 
normally  present.  Certain  plants  develop  poisons,  such  as  rye,  which 
causes  ergotism;  spoiled  corn,  responsible  for  pellagra;  polished  rice, 
associated  with  beri-beri;  the  chickpea,  responsible  for  vetch  poison  or 
lathyrism.  The  plant  may  be  entirely  wholesome  when  fresh,  but  may 
develop  poisons  as  the  result  of  bacterial  action.  Changes  occur  in 
vegetables  entirely  similar  to  those  which  occur  in  nitrogenous  animal 
products,  with  the  production  of  poisons  of  different  kinds.  The  same 
microorganisms  that  produce  "ptomains"  or  other  toxic  substances  in 
meat  when  introduced  into  vegetables  act  in  the  same  manner.  The 
richer  the  vegetable  in  nitrogen  the  more  likely  is  it  to  acquire  such 
poisonous  properties.  Carbohydrates  retard  or  suppress  this  action; 
therefore,  vegetables  containing  large  amounts  of  carbohydrates  are 
less  apt  to  become  dangerous. 

Certain  vegetables,  such  as  lettuce,  celery,  radishes,  and  similar 
plants,  eaten  raw  may  convey  typhoid  fever,  cholera,  dysentery,  both 
amebic  and  bacillary,  the  eggs  and  larvae  of  animal  parasites,  and  other 
infections. 

All  vegetables  which  are  eaten  raw  should  be  washed  thoroughly 
beforehand,  otherwise  they  may  be  contaminated  with  manure  and  other 
impurities  or  the  excrement  of  dom.estic  animals  which  have  been  roam- 
ing in  the  garden.  The  larvae  of  tapeworms  and  roundworms  have 
been  transmitted  to  man  in  this  manner.  Water  from  foul  wells  is 
used  sometimes  for  sprinkling  gardens,  and  it  is  possible  for  typhoid 
and  other  intestinal  infections  to  be  spread  by  this  means  when  the 
vegetables  are  eaten  raw. 

POISONING  FROM  PLANT  FOODS 

Ergotism, — Ergotism  is  a  form  of  food  poisoning  brought  on  by 
prolonged  use  of  meal  made  from  grain  contaminated  with  the  Clavi- 

571 


572  PLANT    FOODS 

ceps  purpurea.  The  fungus  develops  in  the  flowers  of  rye  and  other 
grains.  The  chief  source  of  the  poisoning  in  man  is  from  rye.  in  which 
case  the  fungus  may  entirely  replace  the  grain.  Ergotism  is  practically 
unknown  in  this  country,  but  in  Europe  it  is  still  occasionally  met 
with,  although  not  to  the  same  extent  as  in  former  times.  From  ergot 
Robert  was  able  to  isolate  three  poisonous  substances,  sphacelinic  acid, 
cornutin,  and  ergotin.  Sphacelinic  acid  is  a  non-nitrogenous,  unstable 
body  and  is  believed  to  be  the  active  agent  in  contracting  the  blood 
vessels.  Cornutin  is  also  an  active  alkaloid  and  produces  vasomotor 
contraction.  According  to  Novy,  more  recent  investigations  have  made 
it  probable  that  there  are  other  substances  present  which  constitute  the 
real  toxic  agent.  Thus,  Jacoby  obtained  a  non-nitrogenous  resin 
sphacelotoxin  which  he  regards  as  the  specific  poison.  The  intoxica- 
tion may  have  an  acute  or  chronic  course,  and  in  either  type  the  symp- 
toms may  be  nervous  or  convulsive,  or  else  trophic  or  gangrenous  in 
character. 

The  presence  of  tlic  sclerotium  may  be  suspected  from  the  color  of 
the  meal,  Avhich  is  grayer  than  usual  and  often  shows  violet-colored 
specks.  The  addition  of  potassium  hydroxid  with  heat  produces  an 
odor  of  trimethylamin  resulting  from  the  breaking  up  of  the  grain 
containing  chinolin.  Further,  the  grain  contains  a  dye  which  is  soluble 
in  alcohol  or  ether.  To  10  grams  of  the  meal  add  10  c.  c.  of  ether  and 
20  drops  of  dilute  sulphuric  acid.  Shake  well  and  filter  after  half  an 
hour.  Then  add  several  drops  of  a  saturated  solution  of  sodium  bi- 
carbonate, wliich  dissolves  out  all  the  coloring  matter. 

Lathyrism. — Lathyrism  or  vetch  poisoning  is  a  rather  rare  condi- 
tion met  with  in  some  parts  of  Europe,  notably  Austria  and  Italy,  in 
northern  Africa,  and  in  India.  The  vetch  seed  is  ground  in  the  form 
of  meal  and  used  as  a  partial  substitute  for  that  of  wheat.  The  seed  is 
popularly  known  as  chick-pea.  The  vetch  seeds  are  obtained  chiefly 
from  Lathyrus  sativus  and  Lathyrus  cicera.  Tlie  eating  of  bread 
prepared  from  meal  containing  the  seeds  of  the  lathyrus  is  fol- 
lowed by  sudden  and  severe  pains  in  the  lumbar  region,  girdle  sensa- 
tion, motor  paralysis  of  the  lower  extremities,  tremor,  and  fever.  The 
nature  of  the  poison  is  not  known,  but  it  is  probably  of  the  nature  of 
a  toxalbumose,  of  which  ricin  and  abrin,  the  poisons  of  the  castor  bean 
and  the  jequirity  bean  respectively,  are  well-known  examples. 

Mushroom  Poisoning*. — The  ill  effects  from  eating  mushrooms  are 
due  to  mistaking  the  poisonous  for  the  edible  species.  The  number  of 
species  of  poisonous  mushrooms  which  are  capable  of  causing  death 
is  not  very  great.  The  Amanitas  and  the  Volvarias  are  almost  exclu- 
sively the  poisonous  species.  The  following  is  a  list  of  the  most  poison- 
ous mushrooms  known,  and  all  that  are  likely  at  any  time  to  produce 
death : 


POISONING    FROM    PLANT    FOODS  573 

Amanita  phalloides  Fr. 

Amanita  citrina  Pers. 

Amanita  verna  Bull. 

Amanita  virosa  Fr. 

Volvaria  gloiocephala,  var.  speciosa   (Fr.). 

Amanita  muscaria  (L.)  Pers. 

Amanita  pantherina   DC. 

Lactarius  torminosus   (Schaeff.)  Fr. 

Lactarius  rufiis  Fr. 

Lactarins  zonarius    (Bull.)    Fr. 

Lactarius  pyrogallus  (Bull.)  Fr. 

Eussula  emetica  Fr. 

Eussula  queletii  Fr. 

Eussula  fcetens  (Pers.)   Fr. 

Boletus  felleus  Bull. 

Boletus  satanus  Leiiz. 

Boletus  erythropus  Cke. 

Boletus  luridus  Schaeff. 

Entoloma  lividum  Bull. 

The  Amanita  phalloides,  or  fly  fungus,  is  an  exceedingly  poisonous, 
dangerous,  and  seductive  species,  responsible  for  most  of  the  deaths 
from  toadstool  eating.  Because  of  its  white  color  it  is  mistaken  for 
the  common  mushroom,  Agaricus  campester.  The  Amanita  phalloides 
does  not  grow  in  the  woods,  neither  has  it  white  gills  nor  white  spores 
nor  a  volva  at  the  base  of  the  stem.  The  poisonous  principle  is  a 
syrupy  alkaloid  known  as  muscarin.  The  alkaloid  is  without  taste  or 
color.  It  produces  powerful  intoxicating  effects  somewhat  analogous  to 
pilocarpin  in  its  action  and  antagonized  by  atropin.  The  alkaloid  is 
soluble  in  water,  and  mushroom  poisoning  may  be  prevented  by  soaking 
the  mushrooms  in  water  slightly  acidulated  with  vinegar  before  they 
are  cooked. 

Potato  Poisoning. — It  has  long  been  known  that  potatoes  contain 
normally  a  very  small  amount  (about  0.06  per  cent.)  of  the  poisonous 
principle  solanin,  but  it  is  only  quite  recently  that  it  has  been  discovered 
that,  under  certain  circumstances,  they  may  contain  the  poison  in 
amounts  sufficient  to  cause  grave  disturbance  of  the  system.  The  in- 
crease is  due  to  the  action  of  at  least  two  species  of  bacteria.  Bacterium 
solaniferum  non-colorahile  and  Bacterium  solaniferum  colorahile,  and 
occurs  in  those  tubers  which,  during  growth,  have  lain  partially  exposed 
above  ground,  and  in  those  which,  during  storage,  have  become  well 
sprouted.  The  most  extensive  outbreak  of  potato  poisoning  recorded 
occurred  in  1899  in  a  German  regiment,  fifty-six  members  of  which, 
after  eating  sprouted  potatoes,  were  seized  with  chills,  fever,  headache, 


5T4  PLANT    FOODS 

vomiting,  diarrhea,  colic,  and  great  prostration.  ^lanv  were  jaundiced 
and  several  collapsed,  but  all  recovered.  Samples  of  the  remaining 
potatoes  yielded  0.38  per  cent,  of  solanin,  and  this  would  indicate  that 
a  full  portion  must  have  contained  about  five  grains   (Osier). 

Beri-beri. — Our  knowledge  of  beri-beri  is  now  sufficient  to  place 
this  scourge  of  the  tropics  among  the  preventable  diseases.  Long  as- 
sociated with  rice,  it  is  now  evident  that  beri-beri  is  a  disease  due  to 
an  unbalanced  or  monotonous  diet  made  up  largely  of  polished  rice, 
that  is,  rice  without  the  pericarp.  The  disease  may  be  prevented  or 
cured  by  the  administration  of  rice  bran. 

Beri-beri,  or  kakke,  is  a  specific  form  of  multiple  peripheral  neu- 
ritis occurring  endemically,  or  as  an  epidemic,  in  most  tropical  or  sub- 
tropical climates.  It  is  characterized  clinically  by  disturbances  of  mo- 
tion, sensation,  dropsy,  and  affection  of  the  heart.  The  symptoms 
are  attributable  to  degenerative  changes  in  many  of  the  peripheral 
nerves,  being  a  toxic  neuritis  similar  in  many  respects  to  that  produced 
by  alcohol,  arsenic,  and  other  metals,  or  the  toxone  of  diphtheria.  Three 
types  of  the  disease  are  recognized:  (1)  the  paraplegic,  or  dry;  (2) 
the  dropsical,  or  wet;  and  (3)  the  mixed.  The  course  of  the  disease  is 
uncertain:  sudden  death  owing  to  involvement  of  the  heart  is  a  com- 
mon termination.  Eecovery  is  frequent  and  may  be  complete;  it  is 
promoted  by  change  of  climate,  improvement  in  the  sanitary  surround- 
ings, and  especially  by  change  of  diet.  Two  main  views  as  to  the  na- 
ture of  the  disease  have  long  prevailed:  (1)  that  it  is  an  infection, 
(2)  that  it  is  a  food  poisoning. 

Beri-beri  has  some  of  the  earmarks  of  an  infectious  disease,  resemb- 
ling malaria  somewhat,  so  far  as  telluric  influences  and  seasonal  preva- 
lence are  concerned.  Scheube  insists  that  beri-beri  is  an  infectious  dis- 
ease because:  (1)  young,  strong,  and  well-nourished  persons  are  most 
frequently  attacked,  and  particularly  liable  to  the  severest  form  of 
the  disease;  (2)  beri-beri  has  not  only  its  definite  geographical  region 
of  distribution,  but  even  in  beri-beri  countries  it  does  not  occur  every- 
where, being  confined  to  certain  narrow,  sharply  limited  districts;  (3) 
the  maximum  of  frequency  of  the  disease  is  during  that  season  which 
is,  first  of  all,  distinguished  by  great  moisture,  and,  secondly,  by  a 
high  temperature  liable  to  many  variations;^  (4)  during  recent  decades 
beri-beri  has  obtained  a  considerable  distribution  in  certain  countries, 
as  Java,  Japan,  and  Brazil,  without  any  change  of  food  having  taken 
place  among  the  people.  The  nature  of  the  virus  is  not  Known,  and 
the  various  microorganisms  that  have  been  described  in  the  blood  and 
tissues  are  in  all  likelihood  not  the  specific  excitants. 

Takaki.  the  surgeon-general  of  the  Japanese  navy,  believed  that 
beri-beri  is  due  to  nitrogen  starvation.     He  has  practically  abolished 

^  Hirseh. 


POISOXIXG    FEOM    PLAXT    FOODS  575 

beri-beri  in  that  service  b)^  allowing  a  larger  portion  of  nitrogenous 
food  and  forbidding  the  use  of  fresh  fish  altogether.  It  must  be  re- 
called, however,  that  this  dietetic  change  was  coincident  with  other 
sanitary  reforms.  In  former  years  one-fonrth  of  the  personnel  of  the 
Japanese  navy  suffered  from  beri-beri;  now  it  is  almost  unknown. 

]^Ian5on's  theory  of  beri-beri  is  interesting.  He  believed  that  it 
is  undoubtedly  a  germ  disease,  but  that  it  is  produced  by  a  harmless 
saprophyte  which  develops  a  poison  in  food  outside  of  the  bod\^ 

Many  physicians  who  have  studied  the  subject  in  Japan,  Java,  the 
Philippines,  and  other  countries  have  long  regarded  rice  as  the  impor- 
tant cause  of  the  disease.  In  the  prisons  of  Java  the  proportion  of  cases 
is  1-39  when  rice  is  eaten  completely  shelled,  1-10,000  when  the  grain 
is  eaten  with  its  pericarp.  In  some  places  the  disease  has  disappeared 
when  the  unshelled  rice  has  been  substituted  for  the  shelled. 

Eykman  first  pointed  out  that  beri-beri  is  not  attributable  to  rice 
in  general,  but  that  certain  kinds  of  rice  prepared  in  certain  ways 
are  more  liable  to  produce  the  disease.  It  is  now  known  that  a  disease 
resembling  beri-beri  characterized  by  degeneration  of  the  peripheral 
nerves  may  be  produced  in  fowl  by  feeding  them  on  white  or  polished 
rice.  Furthermore,  the  same  changes  in  diet  which  avoid  or  cure  beri- 
beri in  man  act  in  a  similar  manner  in  respect  to  this  polyneuritis 
in  fowl.  It  has  now  been  established  that  polished  rice  causes  beri- 
beri if  the  diet  is  based  almost  exclusively  on  this  foodstuff,  but  that, 
if  a  sufficient  amount  of  other  things,  such  as  fresh  meat  and  vege- 
tables, are  taken  with  it,  the  disease  is  not  produced.  In  the  polishing 
of  rice  the  pericarp  or  cortical  portion  of  the  grain  is  removed  and  the 
embryo  is  discarded.  It  is  evident  that  these  discarded  portions  con- 
tain some  substance  essential  to  a  well-balanced  ration.  It  has  been 
found  that  most  of  the  phosphorus  is  contained  in  the  pericarp.  The 
amount  of  phosphorus  is  a  good  guide  in  the  selection  of  a  beri-beri- 
preventing  rice.  In  the  East  rice  is  regarded  as  unsafe  if  it  contains 
upon  analysis  a  content  of  less  than  0.35  per  cent,  of  phosphorus  pen- 
toxid.  It  is  not,  however,  the  absence  of  the  phosphorus  which  induces 
beri-beri,  but  the  amount  of  phosphorous,  as  phosphorous  pentoxid 
(P2O5)  may  be  taken  as  an  index  of  the  degree  to  which  the  rice  has 
been  polished.  The  particular  substance  responsible  has  not  as  yet  been 
isolated- 

The  recent  work  of  Eraser  and  Aron,  Breaudat  and  Denier,  Dehaan, 
Heiser,  and  others  leaves  little  doubt  concerning  the  relation  of  polished 
rice  to  beri-beri.  Heiser^  reports  that,  prior  to  February,  1910,  pol- 
ished rice  was  commonly  used  in  the  Cuhon  leper  colony.  The  deaths 
from  aU  eases  between  February,  1909,  to  1910  were  898,  of  which  309 
were  due  to  beri-beri.     From  Februarj^  1910,  to  Febniary.  1911,  un- 

^Jour.  A.  M.  A.,  Vol.  LI,  1911,  p.  1237. 


576  PLANT    FOODS 

jKilished  rice  was  used,  and  there  were  369  deaths,  a  reduction  of  over 
one-half  the  death  rate  for  the  previous  year.  It  is  significant  that 
there  were  no  deaths  from  beri-beri  during  this  interval  following  the 
use  of  unpolished  rice.  Heiser  further  reports  50  cases  of  beri-beri 
treated  by  giving  daily  15  grams  of  rice  polishings.  Improvement  was 
noticed  in  all  except  two  very  advanced  cases.  These  results  have  been 
so  striking  that  the  Philippine  government  has  drafted  a  bill  provid- 
ing for  the  general  use  of  unpolished  rice;  that  is,  rice  containing  at 
least  0.4  per  cent,  of  phosphorus  as  phosphorus  pentoxid,  and  the  levy- 
ing of  a  tax  upon  polislied  rice  which  makes  its  sale  practically  pro- 
hibitive. Breaudat  and  Denier  ^  at  Saigon,  in  Indo  China,  report  good 
results  from  the  prophylactic  use  of  rice  bran.  Forty  grams  are  ad- 
ministered daily  in  the  ordinary  food.  No  case  of  beri-beri  developed 
among  49  native  soldiers  who  took  bran,  while  17.4  per  cent,  of  311 
controls  developed  the  disease. 

The  prevention  of  beri-beri  in  the  Philippine  Islands  based  upon 
the  rice  theory  is  little  short  of  marvelous.  The  disease  has  been  en- 
tirely eliminated  from  the  Philippine  native  scouts  owing  to  the  reduc- 
tion in  the  amount  of  rice  from  20  to  16  ounces,  a  substitution  of 
undermilled  rice  for  the  polished  article,  and  the  addition  of  a  legume 
to  the  dietary.  In  1908  and  1909  there  were  600  cases  of  beri-beri 
annually.  In  the  entire  17  months  since  the  alteration  in  the  ration 
went  into  effect  there  have  been  but  7  cases  of  the  disease;  occasionally 
cases  may  be  expected  owing  to  disobedience  of  instructions. 

Infantile  beri-beri  is  also  common  in  the  Philippines,  and  may  like- 
wise be  prevented  and  even  cured  with  rice  bran. 

Prevention. — The  prevention  of  beri-beri  consists  in  substituting 
the  use  of  whole  rice  for  the  polished  grain;  also  in  improving  the 
quality  of  the  food  and  in  providing  for  better  balanced  dietaries.  The 
prophylactic  value  of  rice  bran  added  to  the  ordinary  diet  must  be  borne 
in  mind. 

It  should  be  borne  in  mind  that  beri-beri  may  be  produced  by  a 
monotonous  diet  of  other  starchy  substances,  such  as  wheat  flour  (Little 
and  Strong).  A  varied  diet  is,  therefore,  one  of  the  prime  essentials 
in  the  prevention  of  beri-beri.  There  are  certain  accessory  factors  favor- 
ing beri-beri  which  must  be  taken  into  account.  The  disease  occurs 
especially  in  overcrowded  places,  such  as  ships,  jails,  and  asylums;  dur- 
ing the  hot  and  moist  seasons;  and  following  exposure  to  wet.  These 
are  to  be  avoided.  Europeans  living  under  good  hygienic  conditions, 
and  enjoying  a  well-balanced  diet,  rarely  contract  the  disease. 

Manson  advises  that  when  beri-beri  breaks  out  in  a  school,  jail,  or 
similar  institution  the  place  should  be  emptied  of  its  inmates  as  soon 
as  possible;  at  all  events,  those  parts  of  the  building  in  which  the  dis- 

'Ann.  de  I'lnst.  Pasteur,  Feb.,  1911,  No.  2. 


POISONING    FROM    PLANT    FOODS  517 

ease  first  appeared  should  be  cleared  out,  and  not  reoccupied  until  they 
have  been  thoroughly  cleansed,  disinfected,  ventilated,  and  dried.  Over- 
crowding must  be  strictly  avoided;  ventilation  must  be  effective.  The 
dietary  should  be  revised  and,  if  necessary,  rice  eliminated  from  it  as 
much  as  possible.  In  the  place  of  rice  fresh  meat,  vegetables,  and 
wheat  flour  should  be  substituted.  All  the  inmates  should  be  obliged 
to  pass  the  largest  part  of  every  day  in  the  open  air.  Their  knee-jerks 
should  be  tested  and  their  legs  examined  for  numbness,  edema,  and 
muscular  hyperesthesia  from  time  to  time.  Any  suspicious  cases  should 
be  removed  and  treated  at  once. 

Pellagra. — For  the  present  pellagra  is  included  among  the  diseases 
due  to  poisonous  food,  for  the  bulk  of  evidence  indicates  that  it  is 
caused  by  spoiled  corn.  This  disease  is  in  all  probability  another  exam- 
ple of  a  food  intoxication  caused  by  some  toxicogenic  saprophyte.  There 
is  also  a  suspicion  that  insects  {Simulium  or  Stomoxys)  may  be  con- 
cerned in  its  transmission.  Pellagra  is  largely  a  preventable  disease  in 
which  the  social  conditions  loom  large;  it  is  especially  prevalent  where 
poverty,  overcrowding,  and  misery  prevail.  It  occurs  both  sporadically 
and  endemically. 

The  history  of  pellagra  in  the  United  States  is  interesting,  es- 
pecially in  view  of  the  fact  that  corn  is  indigenous  to  America  and  is 
extensively  used  by  large  portions  of  the  population,  especially  in  the 
South.  Nevertheless,  compared  to  its  ravages  in  Italy,  Roumania,  and 
other  countries,  we  have  escaped  pellagra  as  a  scourge.  This  is  due 
perhaps  to  the  fact  that,  owing  to  climatic  conditions,  the  corn  here  is 
permitted  to  mature  before  it  is  garnered  and  is,  therefore,  less  apt  to 
spoil.  However,  during  the  past  decade  or  two  the  corn  belt  has  grad- 
ually been  pushed  farther  and  farther  north.  This  means  that  it  is 
often  harvested  before  it  is  mature,  and  the  chances  of  its  spoiling  are 
favored  in  transporting  it  to  our  southland  in  a  moist  condition.  A 
carload  of  corn  starting  from  the  Great  Lakes  may  ferment  and  become 
so  overheated  on  its  journey  south  that  occasionally  it  catches  fire  spon- 
taneously. These  facts  may  account  for  the  notable  increase  in  the 
amount  of  pellagra  in  our  southern  cities.  The  disease  was  first  recog- 
nized in  America  46  years  ago  (1864)  by  Dr.  Gray,  of  Utica,  New 
York,  and  by  Dr.  Tyler,  of  Somerville,  Mass.,  who  each  reported  a  case 
of  probable  pellagra.  It  was  overlooked  until  1906-1907,  when  Searcy 
reported  an  epidemic  in  the  Alabama  Insane  Asylum.  In  the  same 
year  (1907)  Babcock's  article  on  the  cases  in  the  State  Insane  Asylum 
of  Columbia,  South  Carolina,  aroused  our  present  revival  of  interest  in 
the  disease.  In  1908  Wood  and  Lavender  found  four  cases  in  Wilming- 
ton, North  Carolina.  Since  then  a  flood  of  cases  have  come  to  light  all 
over  the  country,  especially  in  the  south;  outbreaks,  however,  occur  as 
far  north  as  Peoria,  Illinois,  where  40  to  50  well-marked  cases  out  of 
2,200  inmates  were  discovered  in  the   State  Hospital  for  the   Insane. 


578  PLANT    FOODS 

Lavender  now  estimates  that  there  are  between  25,000  and  50,000  ])el« 
Lagrins  in  the  United  States. 

The  disease  appeared  in  Italy  about  1750,  but  was  first  described 
there  in  1771  by  Frapolli,  of  Milan,  who  aj)plie(l  the  name  "pel- 
lagra" (Italian  pelle,  skin,  and  agra,  rough).  Marzari  in  1810  first 
called  attention  to  the  relation  between  maize  and  ])ellagra.  In  1844 
Balardini  suggested  the  theory  that  the  disease  might  be  due  to 
spoiled  maize,  that  is,  maize  wliich  had  imdergone  fermentative  change 
by  reason  of  the  growth  of  fungi  on  the  grain.  At  present  pelhigra 
is  most  prevalent  in  nortliern  and  central  Italy  and  in  Eoumania.  Tril- 
ler  states  that  in  190G  there  were  30,000  pellagrins  in  Roumania;  in 
certain  parts  of  Italy  as  much  as  30  to  50  per  cent,  of  the  jjopuhition 
have  the  disease;  in  1899  there  were  nearly  73,000  sick  witli  the  disease 
in  all  Italy,  this  being  upward  of  10  per  thousand  of  the  rural 
population.  The  disease  also  occurs  in  Spain,  Corfu,  Asia  Minor, 
Austria,  Servia,  Bulgaria,  and  occasionally  in  India,  Africa,  Barbadoes, 
Mexico,  South  America,  and  Egypt. 

As  preventive  measures  must  be  based  entirely  upon  our  conception 
of  the  etiology  of  the  disease,  it  is  necessary  to  consider  briefly  some 
of  the  views  upon  this  subject.  It  is  the  accepted  opinion  of  most 
students  of  the  disease  that  pellagra  is  an  intoxication  due  to  using 
Indian  corn  (maize)  as  a  food,  wliich,  under  the  influence  of  some 
parasitic  growth  (bacteria  or  fungus),  has  undergone  certain  changes 
with  a  production  of  one  or  more  toxic  substances.  Lombroso,  who 
studied  this  subject  for  years,  made  alcoholic  and  watery  extracts  from 
spoiled  maize  and  obtained  chemical  substances  of  an  undetermined  na- 
ture, which  were  given  to  men  and  animals  with  the  production  of 
symptoms  analogous  to  pellagra.  The  interpretation  of  all  such  work 
is  as  yet,  however,  in  an  uncertain  state. 

With  regard  to  the  parasites  found  on  maize,  it  may  be  said  that 
the  varieties  are  numerous,  and  no  single  one  seems  to  be  constant 
enough  to  be  rated  as  the  definite  causative  agent.  Seni  incriminates 
the  Aspergillus  fumigatus  as  the  cause  of  the  maniacal  form  of  pel- 
lagra, and  the  Aspergillus  flufvescens  as  the  cause  of  the  depressive 
form.  These  molds  have  resisting  spores  which  withstand  heat,  hence 
ordinary  cooking  is  not  sufficient  to  destroy  them.  The  Bacterium 
mayclis  has  also  been  associated  with  the  disease.  Lombroso,  as  a  re- 
sult of  his  studies,  maintained  that  pellagra  is  due  to  a  poison  (toxine) 
developed  in  maize  by  microorganisms  (molds  or  bacteria),  in  them- 
selves harmless  to  man   (that  is,  saprophytes). 

Other  views  concerning  the  nature  of  pellagra  are :  that  it  is  an  auto- 
intoxication, the  poisonous  substances  being  produced  in  the  bowels  as  a 
result  of  the  constant  and  almost  exclusive  diet  of  com,  which  produces 
certain  changes  in  the  intestinal  flora,  and  the  production  of  poisonous 


POISONING    FROM    PLANT    FOODS  579 

substances.  A  somewhat  similar  view  is  that  the  disease  is  an  in- 
testinal mycosis,  the  offending  microorganisms  being  eaten  with  corn  and 
colonizing  in  the  intestinal  tract.  Others  regard  the  disease  as  of  an 
infectious  nature,  and  several  parasites  have  been  reported  in  the  blood 
and  organs.  In  France  especially  the  idea  has  been  brought  forward 
that  pellagra  is  not  a  definite  morbid  entity  at  all,  but  a  symptom- 
complex  sometimes  observed  in  alcoholics  and  cachectic  states  of  diverse 
origin,  the  erythema  being  regarded  only  as  a  common  solar  erythema. 
Sambon,  as  the  result  of  epidemiological  studies,  brought  forward  (1905 
and  again  recently)  the  view  that  pellagra  is  an  insect-borne  disease, 
and  incriminates  the  Simulium  reptans. 

Eaubitschek  ^  recently  brings  forward  evidence  that  pellagra  de- 
pends upon  some  noxious  substance  (noxe)  activated  by  the  action  of 
sunlight.  This  is  the  photodynamic  theory,  and  corresponds  to  the  ac- 
tion of  light  upon  a  photographic  negative.  It  is  suggestive  that  the 
skin  lesions  in  pellagra  are  mainly  confined  to  the  exposed  surfaces. 
There  is  also  a  substance  in  buckwheat  poisoning  (fugopyrismus)  that 
affects  animals  exposed  to  the  light,  but  not  those  kept  in  the  dark. 

Pellagi'a  usually  runs  a  chronic  course,  with  acute  exacerbations, 
which  usually  occur  in  the  spring  and  fall  of  the  year.  The  disease 
sometimes  runs  an  acute  and  rapidly  fatal  course.  The  development 
seems  to  be  more  rapid  and  grave  in  children.  The  poison,  whatever  its 
nature,  produces  toxic  and  trophic  manifestations.  The  triad  of  symp- 
toms are:  (1)  digestive  disturbances,  (2)  erythema,  and  (3)  nervous 
disturbances.  The  final  scene  usually  includes  profound  cachexia, 
great  muscular  weakness,  and  insanity. 

Corn. — Maize  or  Indian  corn  is  a  native  of  the  Western  Hemisphere 
and  was  cultivated  by  most  of  the  northern  and  western  tribes  of  North 
American  Indians  before  Columbus  reached  these  shores.  The  impor- 
tance of  the  corn  crop  to-day  may  be  gathered  from  the  fact  that, 
according  to  the  census  of  1900,  almost  one-third  of  all  the  land  under 
cultivation  in  the  United  States  was  devoted  to  corn.  It  was  grown 
on  88.6  per  cent,  of  all  the  farms  in  the  country  in  the  crop  for  1889. 
The  value  of  the  annual  crop  now  exceeds  a  billion  dollars.  Corn 
contains  24.7  per  cent,  of  water.  The  water-free  material  consists  of 
12.7  per  cent,  proteins,  4.3  per  cent,  fat,  79.3  per  cent,  starch,  sugar, 
etc.,  2  per  cent,  crude  fiber,  and  1.7  per  cent,  of  mineral  matters.  The 
several  nutrient  substances  in  corn  and  other  common  cereals  are  much 
the  same;  the  individual  compounds,  however,  making  up  these  groups 
differ  considerably. 

The  kernel  or  seed,  it  must  be  remembered,  is  not  inert,  but  a  living 
thing  which,  under  favorable  conditions,  will  develop  into  a  new  plant, 
and  each  part  of  it  is  made  up  of  cells  especially  fitted  for  a  particu- 

"■  Berliner  Uin.   Wochens.,  Vol.  XXIII,  No.  26,  June,   1910. 


580  PLANT    FOODS 

lar  role  in  this  process  of  reproduction.  Roughly  speaking,  a  seed  con- 
sists of  three  divisions:  the  skin,  the  genu,  and  the  endosperm.  It  is 
a  well-known  fact  that  corn,  wlien  allowed  to  rij)en  before  it  is  taken 
from  the  stalk,  keeps  much  better  than  immature  corn.  It  is  certain 
that  protective  substances  (antibodies)  are  developed  in  the  kernel  which 
retard  the  growth  of  bacteria  and  molds.  Moist  corn  kept  warm  spoils 
readily,  whereas  corn  once  thoroughly  dried  is  proof  against  serious 
fermentative  changes. 

The  tests  for  spoiled  corn  are  not  entirely  satisfactory.  They  may  be 
divided  into  physical,  biological,  and  chemical  tests.  The  physical  test 
consists  mainly  in  the  luster,  the  absence  of  molds,  the  odor,  and  taste. 
The  biological  test  consists  in  planting  the  corn;  from  90  to  95  per 
cent,  should  germinate.  The  chemical  test  includes  among  other  de- 
terminations the  pro])ortion  of  ash  after  burning,  and  Gosio's  phenolic 
reaction  with  ferric  clilorid.  A  green  purple  color  with  this  reagent 
indicates  fermentation,  with  the  production  of  phenolic  compounds. 

Spoiled  corn  may  be  renovated  by  polishing  and  then  heating,  to 
prevent  further  growth  of  molds.  It  is  difficult  to  detect  renovated 
corn  by  inspection  alone,  but  the  biological  test  will  disclose  whether 
or  not  it  has  been  heated.  The  practice  of  renovating  corn  should 
either  be  prohibited  or  be  placed  under  strict  official  control. 

There  are  three  hundred  or  more  varieties  of  corn.  It  is  quite 
practicable  to  raise  corn  either  with  a  high  protein  content  or  a  high 
fat  content.  Smith,  at  the  Illinois  Agricultural  Experiment  Station, 
in  ten  generations  raised  the  oil  or  fat  content  from  a  minimum  of 
4.7  per  cent,  to  a  maximum  of  7.337  per  cent.  Such  corn  is  sought 
after  for  the  fattening  of  hogs.  AMiile  of  advantage  to  hogs,  it  may 
be  detrimental  to  man,  for  when  corn  becomes  moldy  it  is  always  the 
embryo  that  is  affected  first,  and  there  the  fungus  flourishes  best.  Ac- 
cording to  Alsberg,  the  greater  part  of  the  toxic  material  is  in  the 
decayed  embryo.  It  happens  that  the  greater  part  of  the  oil  is  also 
located  in  the  embryo.  The  variety  rich  in  oil  is  probably  also  one 
with  a  large  germ.  It  is,  therefore,  possible  that  corn  with  a  large 
embryo  and  high  fat  content  may  spoil  more  readily  and  produce  a 
greater  amount  of  the  poison  responsible  for  pellagra. 

It  should  be  borne  in  mind  that,  while  corn  itself  may  not  be  the 
direct  cause  of  pellagra,  it  may  hold  the  same  relation  to  that  disease 
that  the  swamps  bear  to  malaria. 

Prevention. — The  line  along  which  pellagra  prophylaxis  is  planned 
depends  entirely  upon  our  conception  of  the  disease.  As  pellagra  pre- 
vails aniong  the  poor,  especially  those  who  live  under  uncleanly  and 
squalid  conditions,  it  at  once  becomes  evident  that  economic  and  social 
improvements  are  an  important  part  of  the  program.  Prophylaxis  spells 
prosperity  in  this  disease  as  in  others.     The  Italian  struggle  culminated 


POISONING    FROM    PLANT    FOODS  581 

in  the  law  of  1902  for  "the  prevention  and  cure  of  pellagra/'  which 
was  inspired  by  Lombroso's  views  upon  the  disease.  The  Italian  meas- 
ures may  be  summarized  as  follows :  those  aimed  at  the  cure  of  the 
disease  are  a  free  distribution  of  salt  (a  government  monopoly  in 
Italy),  the  distribution  of  food  either  at  the  homes  of  the  patients  or 
through  sanitary  stations,  and  the  treatment  of  severe  cases  in  hos- 
pitals for  pellagrins  and  in  insane  asylums.  The  prophylactic  meas- 
ures are  mainly  directed  against  the  use  of  spoiled  corn  as  an  article 
of  food.  They  comprise  a  census  of  the  disease  and  a  report  of  all 
cases;  the  testing  of  corn  and  meal  brought  in  at  the  frontiers  or 
offered  for  sale  to  the  mills  and  the  prohibition  of  its  sale  if  found 
spoiled ;  the  exchange  of  good  corn  for  spoiled  corn ;  desiccating  plants ; 
cheap  cooperative  kitchens;  the  improvement  of  agriculture;  and  the 
education  of  the  people.  The  corn  is  inspected  by  experts  and  is  sub- 
mitted to  certain  tests.  If  found  spoiled,  its  sale  for  food  is  prohibited. 
The  tests  are  not  entirely  satisfactory  from  a  scientific  standpoint,  but 
seem  sufficient  for  practical  purposes.  According  to  Mr.  Cutting,'  the 
weak  point  in  the  inspection  of  corn  seems  to  be  in  dealing  with  home- 
grown corn,  especially  the  meal,  either  at  the  mills  or  on  the  markets. 
There  seems  to  be  no  solution  of  this  difficulty  except  governmental 
ownership  of  the  mills.  The  agricultural  improvements  are  directed 
toward  teaching  the  use  of  better  varieties  of  corn  and  proper  methods 
of  culture,  handling,  etc.,  or  how  to  supplant  corn  entirely  with  a  more 
profitable  crop. 

The  desiccating  plants  for  the  artificial  dr}dng  of  corn  are  considered 
a  very  important  prophylactic  measure,  as  they  prevent  the  spoiling  of 
the  grain.  These  desiccators  are  of  two  types,  fixed  and  portable,  and 
there  are  a  large  number  of  public  desiccators  throughout  Italy.  There 
is  also  a  provision  in  the  law  for  public  storehouses  properly  constructed, 
where  the  grain  may  be  stored  under  the  best  conditions  to  prevent  spoil- 
ing. Eural  bakeries  and  economic  kitchens  are  establishments  where 
an  effort  is  made  to  eliminate  from  the  peasant's  diet  bread  made  of 
corn,  by  supplying  good  white  bread  and  other  food  at  a  low  cost. 
Above  all,  however,  stands  the  education  of  the  people  to  the  dangers 
of  spoiled  corn,  and  the  healthfulness  of  a  varied  diet  and  better  liv- 
ing conditions. 

The  results  of  the  campaign  in  Italy  seem  to  be  a  diminution  in 
the  amount  of  the  disease  in  central  Italy.  Strange  as  it  may  seem, 
however,  the  disease  is  increasing  its  area,  and  parts  of  Italy  previously 
free  from  pellagra  are  now  developing  the  disease. 


39 


SECTION   IV 
AIR 

CHAPTEE    I 
COMPOSITION    OF    THE    AIR 

The  air  constitutes  a  gaseous  ocean  in  wliich  we  live;  it  consists 
of  a  vast  volume  of  gases  at  least  one  hundred  miles  high/  Ordinarily 
we  speak  of  this  gaseous  envelope  of  the  earth  as  the  atmosphere,  and 
the  water  resting  upon  the  surface  of  the  earth  as  the  aquasphere,  while 
the  solid  structure  of  the  earth  is  called  the  petrosphere.  Between  the 
atmosphere  on  one  hand  and  the  petrosphere  and  aquasphere  on  the 
otlier  hand  is  the  region  of  most  abundant  life,  and  this  is  spoken 
of  as  the  vivosphere. 

An  abundant  supply  of  fresh  air  is  necessary  at  all  times.  The  im- 
portance of  fresh  air  was  almost  completely  ignored  in  practical  life 
until  recently — thanks  to  the  tuberculosis  propaganda.  While  recent 
studies  have  shown  that  the  air  is  not  to  be  feared  as  a  frequent  medium 
for  conveying  specific  infections,  it  has  been  demonstrated  that  an 
abundant  supply  of  fresh  air  is  necessary  to  perfect  well-being.  Sta- 
tistical studies  seem  to  prove  that,  of  the  predisposing  causes  of  sick- 
ness which  are  usually  in  action,  impurities  of  the  air  are  perhaps  the 
most  important.  Tliis  has  been  demonstrated  over  and  over  again  in 
the  case  of  horses,  cattle,  and  dogs,  as  well  as  in  men  confined  in  badly 
ventilated  barracks,  jails,  and  other  places. 

Many  other  factors  are  now  known  to  be  a  greater  menace  to  health 
than  the  "bad"  air  of  crowded  places;  sanitarians,  however,  have  come 
to  regard  an  abundant  supply  of  pure  fresh  air,  well  conditioned,  as 
one  of  the  real  essentials  for  health  and  maximum  efficiency. 

Further,  it  should  be  remembered  that  the  combustion  of  the  food 
we  eat  depends  upon  the  oxygen  of  the  air  we  breathe,  and  that  diges- 
tion and  metabolism  are  stimulated  and  improved  by  an  abundant  sup- 
ply of  fresh  air  or  rendered  sluggish  and  retarded  by  prolonged  expo- 
sure to  vitiated  air. 

'  Forty-five  or  fifty  miles  is  its  practical  limit,  and  anything  beyond  that 
distance  is  in  an  extremely  tenuous  state. 

582 


GENERAL    CONSIDEEATIONS  583 

The  atmosphere  is  now  known  to  contain  the  following  gases  in  the 
following  approximate  proportions  by  volume,  measured  at  0°  C.  and 
at  760  mm.  pressure : 

Volumes       Weight 
per  Cent,    per  Cent. 

Oxygen    20.94  23.2 

Nitrogen 78.09  76.9 

Carbon   dioxid   0.03 

Argon    0.94 

Helium,  krypton,  neon,  xenon,  hydrogen,  hy- 
drogen peroxid,   ammonia,   ozone traces 

"Pure"  air,  in  addition,  contains  water  vapor  in  varying  amounts, 
dust,  radioactive  substances,  etc. 

The  air  is  a  mixture  of  gases  and  not  a  chemical  compound.  The 
proofs  of  this  are  manifold :  ( 1 )  the  gases  do  not  exist  in  the  air  in 
the  proportion  of  their  combining  weights  or  any  multiple  of  them; 
(2)  on  mixing  the  gases  in  atmospheric  proportions  there  is  no  heat 
evolved;  (3)  the  composition  of  air  within  limits  is  variable;  (4)  when 
water  dissolves  air  it  dissolves  each  gas  according  to  its  partial  pres- 
sure and  its  own  proper  coefficient  of  solubility.  Thus,  air  contains 
more  nitrogen  than  oxygen,  but,  oxygen  being  more  soluble,  water  takes 
up  1.87  parts  of  oxygen  to  1  part  of  nitrogen. 

It  was  Jean  Mayow  in  1669  who  first  proved  that  air  was  not  an 
element,  but  a  mixture  of  gases,  and  later  Lavoisier  discovered  the  two 
gases  which  about  100  years  later  were  separated  by  Priestley  and 
Sheele. 

The  composition  of  the  air  shows  wonderful  uniformity  all  over 
the  earth's  surface  wherever  examined.  This  is  due  to  the  enormous 
amount  of  atmosphere  and  the  mixing  influences  of  air  currents.  How- 
ever, in  confined  spaces  where  the  air  is  not  in  motion,  especially  where 
decomposition  of  organic  matter  is  taking  place  or  where  active  com- 
bustion is  going  on,  or  in  the  presence  of  animal  life,  the  composition 
of  the  air  varies  considerably. 

The  difference  in  composition  between  inspired  and  expired  air  is 
as  follows: 

0 

Inspired   air    20.81 

Expired    air    16.033 

The  expired  air  is  also  warmer,  is  increased  in  volume,  and  contains 
more  moisture,  but  fewer  particles,  such  as  dust  and  bacteria.  Under 
normal  conditions  of  quiet  respiration  the  expired  breath  contains  no 
bacteria. 


N 

CO2 

79.15 

.03 

79.557 

4.38 

584  COMPOSITION    OF    THE    AIR 


OXYGEN 

About  one-fifth  (20.94  per  cent,  bv  volume,  23.2  per  cent,  by  weight) 
of  the  atmosphere  consists  of  oxygen,  which  in  many  respects  is  its 
most  important  element.  Slight  differences  are  noted;  thus,  the  air 
of  towns  contains  somewhat  less  (20.87  per  cent,  by  volume)  than  in 
mid-ocean.  The  slight  differences  that  have  been  noted  in  the  per- 
centage of  oxygen  are  of  no  special  importance.  It  may  drop  to  13 
per  cent,  or  may  rise  to  50  per  cent,  or  even  higher  without  any  very 
apparent  alteration  in  the  vital  functions.  An  atmosphere  containing 
only  11  to  12  per  cent,  of  oxygen  becomes  dangerous,  and  7.2  per 
cent,  results  in  death.  The  constant  percentage  of  oxygen  is  due  in 
part  to  the  enormous  amount  of  it.  Fliigge  estimates  that  at  the 
present  rate  at  which  the  oxygen  is  used  by  respiration  and  combustion 
it  would  take  eighteen  thousand  years  to  reduce  it  by  one  per  cent., 
even  if  not  replaced  by  vegetation.  The  lungs,  of  course,  at  no  time 
after  the  first  breath  contain  air  with  the  full  percentage  of  oxygen. 
This  is  owing  to  the  fact  that  the  lungs  do  not  completely  empty  them- 
selves, and  the  residual  air  remaining  in  the  lungs  accumulates  carbon 
dioxid  and  loses  oxygen. 

Oxygen  is  the  element  in  the  air  that  sustains  all  life.  It  is  ab- 
sorbed by  the  lungs,  passes  into  the  blood,  combines  loosely  with  the 
hemoglobin  of  the  red  blood  corpuscles,  and  is  thus  carried  to  all  the 
tissues  and  cells  of  the  body.  Oxygen  in  combination  with  the  hemo- 
globin forms  an  unstable  compound — oxyhemoglobin — which  gives  the 
bright  red  color  to  arterial  blood.  The  oxygen  bound  with  the  hemo- 
globin in  arterial  blood  consists  of  from  22  to  25  per  cent,  of  the  vol- 
ume of  the  blood.  The  amount  of  oxygen  absorbed  varies  with  the 
age,  condition  of  health,  and  activity.  According  to  Professor  Foster, 
the  average  person  inhales  in  24  hours  about  34  pounds  of  air,  which 
corresponds  to  a  little  over  7  pounds  of  oxygen.  As  the  lungs  absorb 
about  one-fourth  of  the  oxygen  inhaled,  it  appears  that  the  average 
amount  of  oxygen  absorbed  daily  is  nearly  two  pounds.  Oxygen  also 
exists  in  its  gaseous  form  in  blood,  saliva,  bile,  urine,  and  other  fluids 
of  the  body,  but  only  in  minute  amounts. 

The  amount  of  oxygen  in  the  air  may  readily  be  measured  in  the 
Petterson-Palmquist  or  Haldane  apparatus.  The  oxygen  is  absorbed 
by  10  per  cent,  oxalic  acid  in  a  saturated  solution  of  KOH  (sp.  gr. 
1.058)  ;  the  difference  in  volume  before  and  after  absorption  represents 
the  amount  of  oxygen   (pp.  591-593). 

Determinations  of  the  amount  of  oxygen  of  the  atmosphere  have 
no  particular  hygienic  importance. 


OZONE  585 


NITROGEN 


The  nitrogen  in  the  air  may  be  regarded  as  a  diluent,  so  far  as  its 
direct  action  upon  man  is  concerned.  There  is  no  appreciable  differ- 
ence in  the  amount  of  nitrogen  contained  in  inspired  and  expired  air. 
Although  inert^  it  is  very  important,  for  it  serves  to  dilute  the  oxygen 
and  thus  regulate  the  rate  of  combustion  and  its  prototype  respiration. 
The  nitrogen  is  of  more  direct  importance  to  plants,  as  some  are  able 
to  fix  a  certain  amount  of  atmospheric  nitrogen  through  the  action  of 
certain  bacteria,  as  B.  radicicola,  in  the  root  nodules.  While  nitrogen 
in  the  atmosphere  seems  to  be  an  indifferent  element  and  has  no  hy- 
gienic significance,  it  is  a  constant  constituent  of  all  protein  matter. 
The  amount  of  nitrogen  dissolved  as  a  gas  in  the  blood  and  body  juices 
increases  proportionately  with  the  pressure   (P.  Bert). 


ARGON 

Argon,  discovered  in  1894  by  Lord  Eayleigh  and  Professor  Eam- 
sey,  is  quite  inert  chemically ;  that  is,  it  has  not  been  made  to  combine 
with  any  other  element.  It  comprises  from  0.75  to  1  per  cent,  of  the 
atmosphere.  Argon  has  not  been  demonstrated  in  the  body;  it  is  ap- 
parently indifferent,  and,  so  far  as  our  present  knowledge  goes,  has 
no  hygienic  significance. 

OZONE 

Ozone,  described  by  Schonbein  in  1840,  is  rarely  found  in  the  air 
in  greater  proportions  than  mere  traces,  but  it  is  so  potent  chemically 
that  even  small  quantities  may  be  of  importance.  At  Montsouris,  after 
years  of  observation,  the  largest  quantity  of  ozone  found  in  outside  air 
was  1  part  in  700,000.  Ozone  may  be  regarded  as  a  normal  constituent, 
though  by  no  means  constant  in  air.  It  is  generally  absent  in  the  air 
of  large  towns  and  cities,  and  almost  never  present  in  the  air  of  in- 
habited rooms.     It  is  most  abundant  at  sea  and  near  woods. 

Atmospheric  ozone  is  formed  in  nature  during  electric  discharges, 
by  the  oxidation  of  phosphorescent  substances;  and  perhaps  by  the 
respiration  of  plants;  also  by  friction  of  large  masses  of  water,  such  as 
the  sea  against  the  air. 

Ozone  consists  of  three  atoms  of  oxygen  instead  of  two,  compressed 
into  a  molecule,  thus:  SOo^SOg.  It  is  one  of  the  most  powerful 
oxidizing  agents  known,  and  in  small  amounts  is  exceedingly  irritating; 
in  large  amounts  it  is  fatal  to  life.  Ozone  is  one  of  our  most  active 
bleaching  agents,  and  in  proper  concentration  is  one  of  the  most  potent 


586  COMPOSITlOiNT    OF    THE    AIR 

germicides  known,  and  has  been  used  to  sterilize  water,  to  disinfect 
bandages,  and  for  other  purposes. 

The  direct  effect  upon  liealth  of  the  minute  traces  of  ozone  ordi- 
narily found  in  the  atmosphere  must  be  very  small.  From  what  we 
know  of  its  properties,  it  would  at  once  combine  with  the  organic  mat- 
ter in  the  nostrils  and  upper  respiratory  passages.  The  presence  of 
ozone  in  the  air  indicates  the  absence  of  organic  impurities.  That  is 
one  reason  it  is  not  ordinarily  found  in  the  atmosphere  of  an  inhabited 
room. 

It  requires  at  least  13  parts  of  ozone  per  million  in  the  atmosphere 
to  influence  bacteria.  Such  large  proportions  are  never  present  under 
natural  conditions.  Comparatively  small  amounts  are  irritating  to  the 
respiratory  mucous  membrane.  Thus,  Hill  and  Flack  ^  have  studied 
the  action  of  pure  ozone  (free  of  contaminating  oxids  of  nitrogen),  and 
find  it  irritating  in  the  proportion  of  one  part  per  million.  Exposure 
for  two  hours  to  a  concentration  of  15  to  30  parts  per  million  endan- 
gers life.  Hill  and  Flack  conclude  that  there  is  no  harm  in  breath* 
ing  weak  concentrations  of  ozone,  such  as  can  scarcely  be  perceived  by 
a  keen  sense  of  smell. 

Recently  ozonizers  have  been  placed  upon  the  market  for  the  pur- 
pose of  purifying  the  air  of  rooms;  these  are  poor  substitutes  for  ven- 
tilation. Not  only  may  the  ozon«  itself  be  harmful,  but  the  higher 
oxids  of  nitrogen  may  be  formed  when  the  electric  current  acts  upon 
moist  air. 

The  tests  for  ozone  depend  upon  the  fact  that  it  oxidizes  the  color 
of  tincture  of  guaiac,  causing  it  to  turn  blue.  It  also  acts  upon  potas- 
sium iodid,  and  turns  starch  in  presence  of  free  iodin  a  blue  color: 
2KI+H20+0=2KOH+I.. 

HYDROGEN    PEROXID   (H,0,) 

Hydrogen  peroxid  -may  be  found  in  appreciable  traces  in  rain  and 
snow.  One  liter  of  rain  or  snow  water  contains  about  0.182  mg.  of 
hydrogen  peroxid.  This  higher  oxid  gives  many  of  the  reactions  of 
ozone,  being  a  very  active  oxidizing  agent,  and  care  must  be  exercised 
not  to  confuse  them. 

AMMONIA 

The  ammonia  in  the  air  comes  largely  from  the  decomposition  of 
organic  matter.  It  is  produced  in  sufficient  quantities  in  a  manure 
heap  to  be  perceptible  to  the  senses.  Ammonia  may  be  regarded  as  one 
of  the  normal  constituents  of  the  atmosphere,  as  it  is  constantly  pres- 

1  Proceed.  :Royal  Society,  London,  B,  1911,  LXXXIV,  404, 


CAEBON    DIOXID  58? 

ent  in  slight,  traces ;  it  varies  in  distribution,  more  being  found  in  the 
lower  stratum  of  air  near  the  soil.  It  exists  both  in  the  free  state  and 
also  combined  as  nitrate  and  carbonate.  Daily  analysis  of  the  air  at 
the  observatory  at  Montsouris  for  five  years  gave,  as  a  mean  for  am- 
monia, 2.2  mg.  per  100  cu.  m.  There  is  less  after  rain,  because  it  is 
absorbed  by  the  water  during  its  passage  through  the   atmosphere. 

Albuminoid  ammonia,  according  to  Angus  Smith,  is  a  measure  of 
the  sewage  of  the  air;  that  is,  the  amount  of  organic  impurities,  both 
living  and  dead. 

MINERAL   ACIDS 

The  atmosphere  at  times  contains  nitric,  sulphuric,  and  other  acids. 
These  are  derived  from  electric  discharges,  but  mainly  from  the  com- 
bustion of  coal  and  from  industrial  processes.  Sulphuric  acid  or  sul- 
phates in  the  air,  according  to  Angus  Smith,  is  a  measure  of  manu- 
facturing activity  and  also  of  decomposition.  In  other  words,  it  is 
part  of  the  oxidized  and,  therefore,  purified  sewage  of  the  air.  Traces 
of  sulphuric  and  sulphurous  acids  exist  in  the  air.  The  sulphates  and 
sulphites  are  usually  present  as  ammonia  salts.  These  substances  are 
usually  present  in  such  small  amounts  that  they  are  appreciable  only 
when  washed  into  rain  or  snow.  A  liter  of  rain  water  may  contain 
from  0.7  to  2.99  mg.  of  sulphuric  acid.  More  of  this  acid  is  found 
in  the  air  about  industrial  centers  than  in  the  air  over  country  or  sea. 
The  sulphuric  acid  in  the  air  comes  mainly  from  the  sulphur  in  coal. 

CARBON   DIOXID 

Carbon  dioxid  (COo)  is  a  very  important  constituent  of  the  at- 
mosphere. The  amount  of  this  gas  in  the  air  is  relatively  small — 
normally  about  0.03  per  cent.,  usually  expressed  as  3  parts  in  10,000. 
When  we  consider  the  great  bulk  of  the  atmosphere  the  total  amount 
of  carbon  dioxid  is  very  great.  It  is  estimated  that  there  is  more  carbon 
in  the  form  of  carbon  dioxid  in  the  air  than  there  is  in  all  other  forms 
on  the  earth.  Formerly  the  amount  of  carbon  dioxid  in  the  air  was 
stated  as  4  parts  in  10,000,  but  repeated  analyses  with  improved  meth- 
ods have  shown  that  the  correct  amount  is  3  parts  or  slightly  more.^ 
There  is  apt  to  be  more  carbon  dioxid  in  the  air  just  above  the  soil 
than  at  a  height  of  8  or  10  feet.  This  is  not  because  the  carbon  dioxid 
is  heavy  and  settles,  but  because  the  soil  air  usually  contains  more  of 
this  gas.  Air  collected  at  great  heights  by  balloons  has  just  the  same 
percentage  of  COj  as  air  at  sea  level.  The  air  over  the  sea  contains 
somewhat  less  than  air  over  the  land.     Carbon  dioxid  in  the  air  comes 

^Average  of  many  analyses  by  F.  Q,  Benedict  is  0.031.  Carnegie'  Publica- 
tions No.   166,  1912. 


588  COMPOSITION    OF    THE    AIR 

from  the  oxidation  of  organic  matter,  from  respiration,  from  fermenta- 
tion, from  chemical  action  in  the  soil,  and  from  mineral  springs.  The 
exhaled  breath  contains  about  4.4  per  cent,  of  COg. 

Even  a  small  alteration  in  the  percentage  of  carbon  dioxid,  either 
up  or  down,  would  throw  out  of  adjustment  a  long-established  balance, 
and  this  would  alter  the  climate  of  the  earth  and  might  cause  the  death 
of  all  living  beings.  The  carbon  dioxid  in  the  air  is  the  source  from 
which  green  plants  with  the  assistance  of  sunlight  obtain  their  carbon, 
and  is  thus  indirectly  the  source  of  the  carbon  in  the  bodies  of  animals. 
The  normal  variations  in  the  carbon  dioxid  of  air  in  the  open  are 
too  small  to  be  of  sanitary  importance,  and  it  is  only  when  stagnant 
or  inclosed  air  is  polluted  by  combustion  and  respiration  that  we  find 
accumulations  which  may  have  a  bearing  upon  health.  In  narrow 
courts  and  in  smoky  air  the  free  atmosphere  may  contain  0.7  to  0.8 
per  cent.  Workshops  may  contain  from  32  to  53  parts  of  carbon  dioxid 
per  10,000,  and  breweries  as  much  as  10  per  cent.  Its  significance 
varies  with  its  source.  Enormous  volumes  of  carbon  dioxid  are  con- 
stantly being  poured  into  the  atmosphere.  Manchester  adds  8,000,000 
cubic  meters  of  CO,  a  day  from  the  chimneys  of  industrial  establish- 
ments. Even  then  the  air  of  the  city  averages  only  0.385  per  cent.  COo, 
while  the  air  of  the  country  averages  0.318  per  cent. — a  very  slight  dif- 
ference. It  is  estimated  that  from  all  sources  500,000,000  tons  are  dis- 
charged annually  into  the  atmosphere.  The  reason  that  the  carbon 
dioxid  does  not  accumulate  and  increase  is  that  it  is  constantly  re- 
moved, especially  by  growing  vegetation.  Plants  absorb  enormous 
amounts  under  the  influence  of  light  and  chlorophyl  to  build  carbo- 
hydrates. It  has  been  estimated  that  an  acre  of  tree  land  withdraws  in 
one  season  about  41^  tons  of  CO,.  Much  of  the  gas  is  also  absorbed  by 
water,  which  at  ordinary  temperatures  takes  up  its  own  volume. 

The  amount  of  carbon  dioxid  produced  by  respiration  varies  with 
the  vitality,  size,  and  activity  of  the  individual.  During  violent  exer- 
cise almost  ten  times  as  much  carbon  dioxid  may  be  discharged  as  dur- 
ing sleep.  On  the  average  a  man  discharges  about  0.6  of  a  cubic  foot 
of  carbon  dioxid  per  hour  and  a  woman  about  0.4  of  a  cubic  foot.  Dur- 
ing ordinary  activity  a  man  produces,  in  round  numbers,  one  cubic  foot 
per  hour.  An  ordinary  gas  jet  burns  about  6  cubic  feet  of  gas  per  hour 
and  produces  about  3  cubic  feet  of  carbon  dioxid.  Therefore,  so  far  as 
CO,  is  concerned,  a  man  vitiates  the  air  less  than  a  gas  jet. 

CO,  as  an  Index  of  Vitiation. — For  years  the  amount  of  CO,  in  the 
air  has  been  generally  adopted  as  the  most  convenient  index  of  the  total 
conditions  which  are  usually  prejudicial  to  health  and  comfort.  The 
eflBciency  of  ventilation  also  for  years  was  usually  determined  by  an 
estimation  of  CO,. 

CO2  in  itself  is  not  irritating  or  poisonous.     Large  volumes  may 


CAEBOX    DIOXID  589 

be  taken  in  beverages  or  inhaled  without  noticeable  effects.  Effects  are 
first  felt  on  the  human  system  when  the  CO2  reaches  2  or  3  per  cent. 
Eespirations  increase  with  the  percentage,  both  in  frequency  and  depth, 
until  about  5  per  cent.,  when  there  is  distinct  panting,  and  at  7  or  8 
per  cent,  the  dyspnea  becomes  distressing;  at  10  or  11  per  cent,  head- 
ache, nausea,  and  chilliness  may  be  noted.  Observations  made  by  Pro- 
fessor W.  G.  Anderson  in  my  laboratory  show  that  these  symptoms  are 
more  acute  when  the  carbon  dioxid  is  added  to  the  air  rapidly.  Toler- 
ance or  second  wind  may  be  obtained  in  atmospheres  containing  even 
as  much  as  10  per  cent.  Animals  soon  die  when  the  percentage  reaches 
35  or  45  per  cent,  in  an  artificial  atmosphere.  Man  soon  becomes  uncon- 
scious and  suffocates  in  an  atmosphere  containing  30  per  cent,  of  CO,. 

Pettenkoffer  in  1858  proposed  10  volumes  of  COo  in  10,000  volumes 
of  air  as  the  limit  for  inhabited  rooms.  De  Chaumont  (1875)  found 
that  an  unpleasant  odor  becomes  perceptible  in  air  containing  6  volumes 
of  CO^  in  10,000,  and  fixed  this  as  the  limit,  which  for  many  years 
has  been  accepted  by  sanitarians.  It  was  soon  learned,  however,  that 
the  percentage  of  CO,  may  rise  much  higher  before  ill  effects  become 
perceptible.  Carnelley,  Anderson,  and  Haldane  in  1887  concluded  that 
for  the  very  crowded  elementary  schools  a  lower  limit  than  13  volumes 
was  not  practical.  Haldane  and  Osborn  in  1902  recommended  a  limit 
of  12  volumes  for  factories  and  workshops  at  the  breathing  level,  and 
that  when  gas  or  oil  is  used  for  lighting  the  proportion  should  not  ex- 
ceed 20  volumes.  The  general  consensus  of  opinion  to-day  is  that  10 
volumes  in  10,000  is  well  upon  the  safe  side,  although,  so  far  as  CO, 
itself  is  concerned,  more  might  be  permitted  without  fear.  Carbon 
dioxid  is  by  no  means  the  most  mischievous  of  the  constituents  of 
vitiated  air.  It  is  not  merely  a  waste  product.  It  is  one  of  the  impor- 
tant hormones  of  the  body.  It  regulates  the  action  of  the  heart,  in- 
fluences the  tonus  of  blood  vessels,  and  stimulates  the  respiratory  center. 

It  is  certainly  erroneous  and  unscientific  to  rely  upon  determina- 
tions of  CO,  in  the  air  of  a  room  as  the  sole  measure  of  its  condition  for 
respiration.  Carbon  dioxid  never  accumulates  sufficiently  in  any  ordi- 
nary room  to  become  in  itself  serious;  further,  the  amount  of  CO, 
in  the  air  of  a  room  gives  no  indication  whatever  of  the  moisture, 
the  temperature,  or  the  motion  of  the  air  of  that  room.  While  the 
amount  of  CO,,  then,  gives  us  a  rough  index  of  the  degree  of  vitia- 
tion of  the  air,  it  affords  no  information  concerning  its  physical  con- 
ditions, which  are  of  special  importance. 

If  CO,  stratifies  at  all  in  a  room,  more  of  it  will  be  found  nearer 
the  ceiling  than  the  floor,  despite  the  fact  that  it  is  a  comparatively 
heavy  gas.  This  is  owing  to  the  fact  that  the  CO,  rises  with  the  warmed 
expired  breath  and  collects  in  the  stratum  of  hot  air  near  the  ceiling. 
Diffusion  takes  place  but  slowly. 


590  COMrOSlTlOxV    OF    THE    AIR 

The  significance  of  carbon  dioxid  upon  healtli  is  further  discussed 
on  page  643. 

Methods  for  Determining  Carbon  Dioxid.— For  the  ordinary  pur- 
poses of  a  sanitary  analysis  it  is  not  necessary  to  make  an  accurate 
analysis  of  the  carbon  dioxid  in  air,  such  as  the  chemical  analyist  or 
the  student  of  metabolism  would  nuikc  in  scientific  research.  As  the 
carbon  dioxid  in  itself  is  not  poisonous  and  is  only  an  imperfect  in- 
dex of  other  impurities,  and  as  its  significance  varies  with  its  source, 
sufficient  information  may  be  gleaned  for  sanitary  purposes  from 
methods  that  give  results  relatively  comparable. 

The  most  accurate  method  of  determining  CO.  in  the  air  is  that 
described  by  Petterson,  and  used  in  the  Petterson-Palmquist,  the  Sonden 
or  the  Haldane  apparatus.  Both  the  Petterson-Palmquist  and  the  Hal- 
dane  methods  are  convenient,  practical,  and  sufficiently  accurate  for 
all  ordinary  purposes.  The  method  of  Cohen  and  Appleyard  is  rea- 
sonably accurate  and  very  convenient.  The  methods  of  Wolpert  and 
Fitz  give  only  rough  estimates. 

Collection  of  Samples. — The  collection  of  the  samples  of  air 
to  be  analyzed  is  fully  as  important  as  the  actual  test.  The  following 
methods  may  be  used : 

The  ^Vater  Siphon  Method. — Two  bottles  (diameter  one-third  the 
height),  volume  about  one-half  liter,  of  nearly  equal  capacity,  should 
be  fitted  with  rubber  stoppers  carrying  small  glass  tubing  connected 
by  several  feet  of  rubber  tubing  with  clamps.  Fill  one  bottle  com- 
pletely with  water,  nearly  free  from  carbon  dioxid. 

The  pair  of  bottles  is  taken  to  the  place  from  which  the  air  is  to 
be  collected.  The  inlet  or  collecting  tube  may  be  long,  so  as  to  reach 
nearly  to  the  ceiling,  or  short;  if  long,  the  first  siphoning  should  be 
rejected  to  insure  filling  the  inlet  tube  with  the  air  desired.  The  stop- 
pers are  then  exchanged  and  the  sample  taken.  The  air-filled  bottle 
should  be  stoppered  and  taken  to  the  laboratory;  or  the  test  solution 
may  at  once  be  added,  and  the  bottle  stoppered  and  shaken,  noting  min- 
utes and  seconds  in  the  Cohen-Appleyard  method.  One  bottle  of  water 
with  a  small  reserve  will  serve  for  a  number  of  takings  before  absorbing 
a  sufficient  amount  of  COo  to  materially  influence  the  results.  If  the 
water  is  acidulated  it  will  take  up  less  COj. 

The  steam  vacuum  method  may  be  used  as  an  alternative  in  less 
accurate  work.  The  bottles  should  be  of  about  150  c.  c.  capacity,  made 
for  a  ground-glass  stopper,  but  fitted  with  a  rubber  stopper.  These 
are  filled  with  steam  from  water  first  freed  of  CO,  and  air  by  boiling 
for  5  minutes.  The  bottles  are  inverted  and  a  steam  jet  having  suffi- 
cient pressure  to  throw  the  vaporized  steam  at  least  one  foot  is  al- 
lowed to  fill  the  bottle  for  3  minutes.  Meanwhile  a  thin  coating  of 
vaselin  is  applied  half  way  up  the  sides  of  the  stopper.    This  not  only 


CAEBON    DIOXID 


591 


makes  a  tight  joint,  but  facilitates  removing  the  stopper.  As  soon 
as  the  collecting  bottle  is  removed  from  the  steam  jet  the  stopper  is 
instantly  inserted  and  securelv  pushed  in  while  the  bottle  is  still  in  the 
inverted  position.  To  test  the  method  for  completeness  of  vacuum 
hold  the  bottle  in  an  inverted  position  under  water  at  70°  F.  and  re- 
move the  stopper. 

Samplers  consisting  of  special  glass  tubes  provided  with  a  glass 
stopcock  at  both  ends  may  be  used  to  collect  samples  of  air,  particu- 
larly for  the  Sonden,  Petterson-Palmquist,  or  Haldane  apparatus. 
These  samplers  have  a  capacity  of  about  100  c.  c. ;  some  of  them  hold 
about  200  c.  c.  They  must  be  clean  and  absolutely  dry.  The  sampleri^, 
are  filled  by  means  of  a  bulb  from  a  Davidson  syringe.  Care  must  be 
taken  that  enough  of  the  air  to  be  examined  is  drawn  through  the 
sampler  to  force  out  all  of  the  original  air  it  contains.  Samples  may 
be  collected  in  duplicate,  and  duplicate  analyses  are  always  advisable. 

Staxdaed  Lime  Water  for  Testing  COo  (Used  in  the  Cohen- 
Appleyard  and  also  in  the  Fitz  and  Wolpert  methods). — To  a  liter  of 
distilled  water  add  2.5  c.  c.  of  phenolphthalein  (made  by  dissolving  0.7 
gram  of  phenolphthalein  in  50  c.  c.  of  alcohol,  and  adding  an  equal 
volume  of  water).  Stand  the  bottle  of  water  on  a  piece  of  white  paper 
and  add,  drop  by  drop,  saturated  lime  water  till  a  faint  color  persists 
for  a  full  minute.  Now  add  6.3  c.  c.  of  saturated  lime  water  and  quickly 
cork  the  bottle^,  or  connect 
the  pipette. 

The  Haldane  Ap- 
paratus.—This  apparatus, 
shown  in  Fig.  77,  was  in- 
troduced for  the  determina- 
tion of  carbon  dioxid  in 
the  case  of  ordinary  rooms, 
schools,  factories,  etc.  As 
the  apparatus  is  portable, 
the  analysis  can  be  made 
directly  on  the  spot  and  the 
carrying  to  and  fro  of 
samples  is  thus  avoided,  if 
desired.  If  the  burette  is 
allowed  to  fill  while  the 
apparatus  is  carried  across 
the  room,  a  good  average 
sample  is   obtained.     As  it 

takes  some  seconds  for  the  mercury  to  run  do-^m,  this  method  of  taking 
the  sample  can  easily  be  adopted,  or  a  sampler  containing  the  air  to  be 
examined  can  be  connected  directly  by  means  of  rubber  tubing  to  the 


Fig.  77. — Portable  Haldane  Apparatus  for  Smaxl 
Percentages  of  Carbon  Dioxid. 


592  COMruSlTlUX    OF    THE    AIR 

gas  burette.  In  this  ease  it  is  advisable  to  discard  the  first  filling  of 
the  gas  burette  A  in  order  to  get  rid  of  the  air  in  the  rubber  tubing 
and  connections.  About  4  minutes  -are  required  for  an  analysis.  The 
accuracy  is  about  1  part  in  10,000. 

The  air  burette  A,  which  is  enclosed  in  a  water  jacket  0,  consists 
of  a  wide,  ungraduated  and  a  very  narrow  graduated  portion.  This  is 
divided  into  100  divisions,  each  of  which  corresponds  to  1  part  in 
10,000.  The  lowest  division  is  marked  0  and  the  numbering  is  upward 
from  this  point.  Any  difference  between  a  reading  at  or  near  zero  and 
a  second  reading  is  thus  shown  by  the  scale  in  volumes  per  10,000, 
there  being  no  calculations  or  corrections. 

The  absorption  pipette  D  is  filled  to  the  mark  E  with  a  20  per  cent, 
solution  of  caustic  potash  through  reservoir  I.  The  control  tube  G  en- 
closed in  the  water  jacket  is  used  to  correct  for  variations  in  the  tempera- 
ture of  the  sample  during  the  analysis.  It  is  connected  with  the  potasli 
pipette  D  by  the  tube  H,  which  has  a  mark  K.  The  pressures  under 
whicli  the  readings  are  made  are  maintained  constant  by  adjusting  the 
levels  of  the  potash  solution  to  the  marks  E  and  K.  To  compensate  for 
variations  of  temperature  of  the  water  jacket  0,  air  is  blown  through 
the  tube  X,  thus  agitating  the  contained  water. 

The  technique  of  an  analysis  is  summarized  as  follows: 

(1).  Open  the  3-way  cock  B  to  the  air  to  be  examined  and  raise 
the  mercury  bulb  C  to  expel  the  air  in  the  burette  A.  Lower  the  mer- 
cury bulb  and  hang  on  the  adjustable  rack  F  so  that  the  sample  is 
drawn  'in  and  the  level  of  the  mercury  falls  to  near  the  zero  mark. 

(2)  Open  the  cock  M  to  the  air  for  a  moment  and  then  turn  it 
so  as  to  connect  the  control  tube  with  the  potash  solution  in  the  tube  H. 

(3)  Turn  the  cock  B  so  as  to  connect  the  sample  witb  the  potash 
pipette  D. 

(4)  Squeeze  the  rubber  tube  of  the  potash  reservoir  I  so  as  to  raise 
the  potash  level  about  an  inch  above  the  marks  E  and  K,  and  see  that 
the  level  of  the  potash  alters  sharply  and  about  equally  in  the  two  tubes. 

(5)  Blow  air  through  the  water  jacket  0. 

(6)  Eaise  or  lower  the  potash  reservoir  I  till  the  potash  is  exactly 
at  the  mark  K  in  the  tube  H. 

(7)  Eaise  or  lower  the  mercury  bulb  C  by  means  of  the  arrange- 
ment F  till  the  potash  is  exactly  at  the  mark  E. 

(8)  Eead  off  the  mercury  level  on  the  scale  of  the  burette  to  0.2 
of  a  division.     (First  reading.) 

(9)  Eaise  the  mercury  bulb,  so  as  to  drive  the  air  into  the  potash 
pipette  D;  then  lower  it  a  little  and  raise  it  twice  again  so  as  to  wash 
any  carbonic  acid  in  the  connecting  tubing  into  the  pipette. 

(10)  Eeturn  the  air  to  the  burette  A. 

(11)  Again  blow  air  through  the  water  jacket. 


CAEBOX    DIOXID  593 

(12)  Squeeze  the  rubber  tubing  and  adjust  the  two  potash  levels 
at  K  and  E,  as  before,  and  again  read  off  the  mercury  level.  The  first 
reading  subtracted  from  the  second  gives  the  amount  of  COo  in  volumes 
per  10,000. 

(13)  After  the  analysis  open  G  to  the  outside  air  through  cock  M 
and  shut  ofE  A  from  D  by  turning  cock  B.  This  will  prevent  fouling 
of  the  apparatus  by  the  sucking  up  of  the  potash  solution. 

The  Petterson-Palmquist  Method. — This  is  a  simplified  Son- 
den  apparatus  by  which  the  volume  of  CO,  in  the  air  may  be  deter- 
mined directly  in  hundredths  of  a  per  cent,  by  volume.  The  method 
is  accurate  to  one  part  in  20,000  of  air,  provided  care  is  taken  with 
the  tests. 

The  principle  is  essentially  the  same  as  that  found  in  the  Haldane  or 
the  Sonden  apparatus.  A  measured  amount  of  air  is  collected  in  a  gas 
burette.  This  volume  of  air  is  then  transferred  to  an  Orsat  tube  con- 
taining a  strong  solution  (20  per  cent.)  of  potash,  which  absorbs  the 
CO2.  The  air  is  then  returned  to  the  gas  burette  and  remeasured  for 
loss  in  volume.  Great  care  must,  of  course,  be  exercised  that  the  pres- 
sure and  temperature  are  precisely  the  same  before  and  after  absorp- 
tion. The  gas  burette  A,  Fig.  78,  is  first  filled  with  mercury  by  raising 
the  reservoir  E.  The  sample  to  be  analyzed  is  then  drawn  into  A  by  low- 
ering E.  There  must  always  be  a  drop  of  water  on  the  surface  of  the 
mercury  and  also  in  the  compensating  cylinder  C.  In  this  way  the 
air  sample  is  kept  saturated  with  moisture.  In  reading  the  volumes 
the  meniscus  of  the  mercury  is  each  time  so  adjusted  that  the  pressure 
in  A  is  exactly  the  same  as  the  pressure  of  the  air  in  the  compensating 
cylinder  C.  This  is  accomplished  through  a  differential  manometer 
containing  a  drop  of  colored  liquid  (petroleum,  in  which  azobenzol  is 
dissolved).  This  manometer  is  connected  by  capillary  glass  tubes  on 
one  side  with  A  and  on  the  other  side  with  C.  After  the  gas  pipette  A 
is  filled  with  the  sample  of  air  to  be  tested,  close  the  stopcocks  D,  F,  C, 
and  G  and  adjust  the  level  of  the  mercury  in  A,  so  that  the  drop  of  liquid 
in  the  manometer  stands  at  zero  on  the  scale.  This  adjustment  is  accom- 
plished through  the  set  screw  E.  In  this  .way  the  air  in  A  may  always 
be  brought  to  the  same  pressure  as  that  prevailing  in.  the  compensator 
C.  Since  the  air  in  both  compensator  and  pipette  is,  from  the  begin- 
ning of  the  experiment,  separated  from  the  external  atmosphere  by  clos- 
ing the  stopcocks  f,  g,  and  c,  variations  in  -the  external  atmosphere 
have  no  effect.  The  temperature  is  regulated  by  filling  the  jar  with 
water  and  keeping  it  agitated,  preferably  with  bubbles  of  compressed 
air. 

Each  analysis  consists  of  three  operations : 

(1)  The  air  is  drawn  in  from  the  outside  and  is  measured,  the 
level  of  the  mercury  in  the  graduated  tube  being  brought  to  the  zero 


594  COMPOSITION    OF    THE   AIR 

mark.     The  upper  and  narrower  part  of  the  scale,  where  each  division 
denotes  1/10,000  of  the  volume  of  the  pipette,  is  used  in  analyses  of 


Fig.  78. — Pettebson-Palmquist  Appabatus. 


atmospheric  air,  or  the  ordinary  air  of  rooms,  where  the  per  cent,  of 
carbon  dioxid  is  at  the  most  not  higher  than  0.4  per  cent.  In  the  analy- 
sis of  very  impure  air  the  lower  part  of  the  graduated  tube  is  used,  each 


CARBON   DIOXID 


595 


division  here  corresponding  to  1/1,000  of  tiie  whole  volume.     In  meas- 
uring the  volume  the  stopcocks  f,  g,  b,  c,  and  d  must  be  closed. 

(2)  The  stopcocks  d  and  b  are  opened,  a  is  closed,  and  tlie  air 
is  passed  from  A  to  B.  After  one  or  two  minutes  the  carbon  dioxid 
is  absorbed  and  the  air  may  be  brought  back  into  A;  b  is  then  closed 
and  a  is  opened. 

(3)  The.  mercury  level  in  A  is  so  adjusted  that  the  index  again 
takes  its  normal  position.  The  decrease  in  volume  is  then  read  o£E  on 
the  scale. 

Acidulated  water  may  be  used  to  expel  the  air  from  samplers  into 
the  burette  of  the  gas  analysis  apparatus,  if  the  operation  is  quickly 
done.  If  a  refinement  of  accuracy  is  desired  mercury  is  preferable, 
for  even  acidulated  water  will  take  up  some  CO,. 

Method  of  Cohen  and  Appleyabd. — This  method  is  based  upon 
the  fact  that,  if  a  dilute  solution  of  lime  water  slightly  colored  with 
phenolphthalein  is  brought  in  contact  with  a  sample  of  air  containing 
more  than  enough  CO2  to  combine  with  all  the  lime  present,  the  solu- 
tion will  gradually  be  decolorized.  The  time  necessary  to  discharge 
the  color  depends  upon  the  amount  of  CO2  present.  The  amount  of 
lime  water  and  the  volume  of  air  being  constant,  the  rate  of  decolora- 
tion varies  inversely  with  the  amount  of  CO2. 

Collect  samples  of  air  in  clean,  clear  glass-stoppered  bottles  of  half 
liter  capacity.  The  sample  may  be  collected  by  exhausting  the  air  from 
a  bottle  with  a  pair  of  bellows  or  by  completely  filling  the  bottle  with 
water  and  then  emptying  it  at  the  point  where  the  sample  is  to  be  taken. 
Eun  in  quickly  10  c.  c.  of  the  standard  lime  water.  Eeplace  the  stopper ; 
note  time.  Shake  the  bottle  vigorously  until  the  pink  color  disappears; 
again  note  time,  and  ascertain  the  corresponding  amount  of  CO,  from 
the  following  table : 


Time  in  Minutes  to  Decolorize  the 
Solution 


IM 

2.. 

2M 
2% 
3J4 


CO2  per  10,000 


16.0 
13.8 
12.8 
12.0 
11.5 
8.6 
7.7 


Time  in  Minutes  to  De- 
colorize   the    Solution 


3K 
4 

5 

6M 

73^ 


CO2  per  10,000 


7.0 

5.3 
5.1 
4.6 

4.4 
4.2 
3.5 


Methods  of  Wolpert  and  Fitz. — These  are  rough  methods  for 
determining  carbon  dioxid,  and,  while  not  accurate,  are  useful  because 
of  their  simplicity  and  convenience. 

The  volume  of  air  that  must  be  brought  into  contact  with  a  definite 


596 


COMPOSITIOX    OF    THE    AIR 


quantity  of  lime  water  in  order  to  neutralize  all  the 
lime  is  taken  as  a  measure  of  the  COo  in  the  air. 
The  quantity  of  lime  water  and  the  time  of  reaction 
remaining  constant,  the  amount  of  COo  varies  in- 
versely as  the  volume  of  air.  The  apparatus  consists 
of  graduated  shakers,  either 
Wolpert  or  Fitz  (see  illustra- 
tion), and  a  pipette  for  meas- 
uring 10  c.  c.  of  lime  water. 
In  using  these  testers  be  sure 
the  plunger  slides  easily,  then 
remove  it  and  place  10  c.  c. 
of  the  lime  water  solution 
into  the  tube.  Introduce  the 
plunger  and  press  it  to  the  top 
of  the  solution,  then  withdraw 
it  to  the  higher  graduation. 
Close  the  mouth  of  the  small 
tube  in  the  Fitz  apparatus,  or 
the  stem  of  the  plunger  in  the 
Wolpert,  with  the  finger,  and 
shake  vigorously  for  30  sec- 
onds. The  volume  of  air  brought  in  contact  with 
the  lime  water  is  50  e.  c.  in  the  Fitz  apparatus 
and  40  c.  c.  in  the  Wolpert.  Eemove  the  finger 
closing  the  small  end.  press  the  inner  tube  or 
plunger  again  to  the  top  of  the  lime  water  in  the 

Wolpert      ap- 


Fia.  79.— Fitz  Aih 
Tester. 


Dewing  CO:  AppAnATus. 


paratus  or  to 
the  point 
marked  T  in 
the  Fitz  ap- 
paratus, and 
draw  it  up 
again,  thus 
admitting  20 
c.  c.  of  the  air 
to  be  exam- 
ined in  the 
Fitz  and  40 
c.  c.  in  the 
Wolpert. 
Again  shake 
for     30     sec- 


35' 


m^. 


15 


Fig.  80. — Wolpekt's  Aih 
Tester. 


CAEBOJ;r    DIOXID 


597 


onds.  Eepeat  until  the  color  is  discharged.  The  first  test  will  prohahly 
give  an  approximate  result,  and  subsequent  tests  will  serve  to  give  more 
accurate  data.  From  the  volume  of  air  used  the  amount  of  CO2  can  be 
determined  from  the  table : 


Air  in  c.c.  Used 

CO2  per  10,000 

Air  in  c.c.  Used 

CO2  per  10,000 

30 

28 

91 

9 

36 

22 

103 

8 

46 

18 

117 

7 

58 

14 

138 

6 

69 

12 

165 

5 

82 

10 

207 

4 

40 


CHAPTER    II 
PRESSURE,    TEMPERATURE,    AND    HUMIDITY 

PRESSURE 

Normal  Atmospheric  Pressure. — The  pressure  of  the  atmosphere  at 
sea  level  is  15  pounds  to  the  square  inch,  or,  as  indicated  in  the  barom- 
eter, it  will  maintain  a  column  of  mercury  30  inches  or  760  millimeters. 
A  man  of  average  size  living  at  sea  level  is  exposed  to  a  total  pressure 
of  about  3-4,000  pounds — more  than  15  tons.  This  great  pressure  must 
evidently  have  physiological  importance.  All  the  tissues  and  fluids  of 
the  body  are  subjected  to  this  pressure  and  are  in  equilibrium  with  it. 
The  interchange  of  gases  on  which  life  depends  is  largely  a  phenomenon 
of  atmospheric  pressure.  The  pressure  of  the  air  also  keeps  the  heads 
of  the  bones  in  their  sockets  without  muscular  action,  and  doubtless 
performs  other  functions  less  obvious.  The  small  variations  in  pres- 
sure such  as  occur  day  by  day  at  sea  level  have  no  evident  physiological 
effects. 

Diminished  Atmospheric  Pressure. — A  diminution  in  atmospheric 
pressure  is  equivalent  to  breathing  rarefied  or  diluted  air.  The  most 
important  physiological  effects  of  diminished  atmospheric  pressure  are 
due  to  a  diminution  in  the  amount  of  oxygen  absorbed,  hence  the  breath- 
ing is  deeper  and  the  pulse  rate  quickened.  As  the  altitude  increases 
there  is  a  lowered  tension  of  oxygen  in  the  alveolar  air  and  a  diminished 
tension  of  carbon  dioxid.  While  the  rate  of  respiration  may  be  variously 
influenced  in  different  circumstances,  the  depth  of  respiration  is  almost 
invariably  increased.  This  of  itself  not  only  facilitates  the  oxygen 
supply,  but  also  increases  the  elimination  of  carbon  dioxid.  Formerly 
a  great  compensatory  increase  in  the  number  of  red  blood  cells  was  be- 
lieved to  take  place  as  a  result  of  prolonged  residence  in  high  altitudes. 
Thus,  assuming  the  average  number  of  red  blood  cells  per  cubic  milli- 
meter at  sea  level  to  be  about  5,000,000,  at  Davos  (elevation  1,560 
meters)  the  number  of  red  blood  cells  averages  5,500,000  to  6,500,000. 
At  Cordilleras  (altitude  4,392  meters)  the  average  number  of  red  cor- 
puscles is  8,000,000.  A  similar  change  in  the  blood  has  been  produced 
by  keeping  rabbits  and  guinea  pigs  in  rarefied  air  at  sea  level.  Accord- 
ing to  Biirker,  only  a  comparatively  small  increase  takes  place,  amount- 
ing to  4  or  5  per  cent.,  at  altitudes  of  five  or  six  thousand  feet.  The 
same  moderate  results  have  likewise  been  noted  lately  for  much  higher 
598 


PEESSUEE  ■    599 

altitudes.  The  higher  iigures  of  earlier  workers  are  now  accounted  for 
by  the  more  rapid  evaporation  of  blood  samples  at  higher  altitudes,  so 
that  with  improved  technic  the  belief  in  the  great  increase  in  the  oxygen- 
carrying  blood  constituents  disappears. 

At  a  height  of  18,000  feet  the  pressure  of  the  atmosphere  is  only  half 
the  pressure  at  sea  level,  thus : 

Height  of 
Altitude.  Barometer. 

0    foot   30  inches 

910    feet    29       " 

1,850      "       28      " 

2,820      "       27       " 

3,820      "       ". ..     26       " 

4,850      "       25       " 

5,910      "       24       " 

7,010      "       23       " 

8,150      "       22       " 

9,330      "       21       " 

10,550      "       20       " 

13,170      "       18       " 

16,000      "       16       " 

18,000      "       15       " 

"The  highest  dwelling  place  continuously  occupied  is  the  Observa- 
tory El  Mirti,  in  the  Andes,  at  5,880  m.  The  Observatory  at  Arequipa 
is  at  6,100  m.  Thok  djalung  is  a  village  in  the  Himalayas  at  4,980  m. 
In  Peru,  Bolivia,  and  Northern  Chili  a  very  large  part  of  the  population 
live  above  3,000  m.  Potosi,  which  has  numbered  100,000  inhabitants, 
is  at  4,165  m.,  Cerro  de  Pasco  at  4,350  m.,  the  mines  of  Villacota  at 
5,042  m.,  the  railway  from  Callao  to  Oroya  culminates  in  a  tunnel  at 
4,760  m.,  almost  the  height  of  Mont  Blanc.  An  annual  fair  is  held 
at  Gartok,  at  4,598  m.,  in  the  Himalayas,  to  which  thousands  annually 
come."^ 

It  is  evident  that  man  may  become  adapted  to  breathing  a  rarefied 
air  at  great  heights,  which  would  overcome  persons  if  the  change  were 
made  suddenly  from  sea  level. 

The  symptoms  produced  by  a  marked  diminution  in  atmospheric 
pressure  vary  with  circumstances.  The  effects  are  increased  by  cold, 
active  muscular  exertion,  or  improper  clothing.  The  noticeable  symp- 
toms are  increased  rapidity  of  respiration  and  acceleration  of  the  cir- 
culation, noises  in  the  head  and  dizziness,  impairment  of  the  senses  of 
sight,  hearing,  and  touch,  dulness  of  the  intellectual  faculties,  and  a 
strong  desire  to  sleep.  Sudden  changes  to  a  rarefied  atmosphere  cause 
syncope,  weakness,  d5^spnea,  dizziness,  and  nausea.  These  threatening 
symptoms  sometimes  go  by  the  name  of  mountain  sickness.  Bert  and 
Journet  believe  this  condition  is  due  to  lack  of  oxygen  and  the  symp- 

^  Leonard  Hill :   ' '  Eecent  Advances  in  Physiology. ' ' 


600       PRESSURE,    TEMPERATURE,    AND    HUMIDITY 

toms  may,  in  fact,  be  relieved  by  adding  oxygen  to  the  air  inspired. 
Bert  kept  a  bird  alive  in  oxygenated  air,  even  though  tlie  pressure  was 
reduced  to  less  than  0.1  of  an  atmosphere.  Kroneeker  concludes  tliat 
mountain  sickness  is  caused  by  a  congestion  of  the  lungs,  impeding 
the  flow  of  blood  through  them.  Mosso  and  his  followers  attribute  the 
physical  disturbances  of  a  reduced  atmospheric  pressure  to  the  fact  that 
the  blood  loses  carbon  dioxid  more  quickly  than  it  loses  oxygen,  and 
attrilmtes  mountain  sickness  to  this  decrease  of  carbon  dioxid  in  the 
blood  (acapnia).  Cohnheim  believes  there  is  a  concentration  of  the 
blood  at  higli  altitudes;  in  fact,  insignificant  increases  have  been  found 
by  competent  observers.  The  climate  in  high  altitudes  is  always  dry 
and  evaporation  proceeds  rapidly.  As  a  result  individuals  lose  water 
more  readily  than  at  lower  levels.  If  this  explanation  is  tenable,  an  in- 
crease in  corpuscles  and  hemoglobin  content  are  in  no  wise  the  expres- 
sion of  lack  of  oxygen,  but  are  rather  the  outcome  of  the  increased 
evaporation  under  the  altered  conditions  of  climate. 

The  limit  at  which  life  may  be  sustained  is  about  26,000  feet,  at 
which  height  consciousness  is  lost.  At  this  height  the  barometric  pres- 
sure of  the  air  is  251  mm.,  which  represents  a  pressure  of  ox3^gen  of 
52,  which  is  the  equivalent  of  6.8  per  cent,  oxygen.  P.  Bert  remained 
20  minutes  in  a  pneumatic  chamber  with  a  pressure  of  only  248  mm. 
without  serious  inconvenience. 

Increased  Atmospheric  Pressure. — While  man  is  often  exposed  to 
rarefied  air,  he  is  seldom  subjected  to  increased  pressure  except  under 
artificial  conditions,  such  as  in  diving  bells,  diving  suits,  and  caissons. 
The  increase  in  atmospheric  pressure  in  the  deepest  mines  has  little 
physiological  significance.  Divers  and  workers  in  caissons  are  not  sub- 
jected to  more  than  about  4I/2  atmospheres,  and  work  under  such  pres- 
sure for  only  a  few  hours  at  a  time.  When  a  diving  bell  is  lowered  10 
meters  into  the  water  the  air  contained  in  it  is  compressed  to  one-half 
its  original  bulk,  and  the  pressure  of  the  air  is  accordingly  doubled. 
Each  10  meters'  depth  means  an  additional  pressure  of  one  atmosphere. 
At  a  depth  of  30  meters,  about  100  feet,  a  diver  is  exposed  to  a  pres- 
sure of  4  atmospheres  or  about  60  pounds  per  square  inch.  Bert  ex- 
posed dogs  to  a  pressure  of  10  atmospheres,  and  then  slowly  released 
them  without  harm. 

The  physiological  effects  of  an  increased  atmospheric  -pressure  are 
mainly  due  to  an  increase  in  the  amount  of  atmospheric  gases  (espe- 
cially nitrogen)  which  are  taken  up  by  the  blood,  and  also  an  increase 
in  the  chemical  absorption  of  oxygen  by  the  red  blood  cells.  The  se- 
rious consequences  usually  result  from  too  rapid  decompression. 

Caisson  Disease. — The  effects  produced  by  compressed  air  in  cais- 
sons are:  (1)  those  caused  when  the  men  are  undergoing  pressure,  and 
(2)    during  or  after  decompression. 


PEESSUEE  601 

The  symptoms  produced  by  an  increase  of  atmospheric  pressure  are 
a  slowing  of  the  respiration,  which  is  evidently  compensatory,  but  on 
account  of  compression  of  intestinal  gases  the  respirations  are  deeper; 
the  pulse  is  slower,  and  evaporation  of  water-vapor  hindered.  The  voice 
may  be  altered;  pains  in  the  ear  are  common,  due  to  pressure  upon  the 
drum,  and  may  be  obviated  by  swalIo^ving  air  and  thus  passing  it  up 
the  Eustachian  tube  into  the  middle  ear.  Sometimes  the  ear  drum 
ruptures;  headache  and  dizziness  may  also  occur.  During  compression 
the  blood  keeps  absorbing  the  gases  of  the  air  until  the  tension  of  the 
gases  in  the  blood  becomes  equal  to  that  in  the  compressed  air.  As 
soon  as  this  equilibrium  has  been  attained  relief  from  innnediate  troubles 
is  secured. 

It  is  during  and  after  decompression  that  the  greatest  danger  to 
health  and  even  risk  of  life  occur.  The  most  frequent  sjonptom  is 
excruciating  pains  in  the  muscles  and  joints,  called  by  the  workmen 
^T^ends."  These  pains  may  continue  for  a  few  hours  or  for  two  or 
three  days.  Occasionally  there  is  bleeding  at  the  nose ;  also  severe  abdom- 
inal pain,  and  vomiting,  nausea,  vertigo,  dyspnea,  and  unconsciousness. 
Death  may  result  from  internal  hemorrhage,  or  paralysis  may  ensue — 
the  so-called  diver's  palsy. 

The  effects  of  increased  atmospheric  pressure  and  too  rapid  decom- 
pression were  carefully  studied  by  Paul  Bert  in  1878,  who  showed  that 
the  lesions  are  caused  by  the  escape  of  gases  of  the  atmosphere  which 
have  been  taken  up  in  excessive  amounts,  and  are  released  in  the  blood 
and  tissues  when  the  pressure  is  diminished.  The  blood  vessels  may 
contain  air  emboli,  which  may  lodge  in  vital  parts  and  cause  sudden 
death,  or  the  delicate  capillaries  may  break,  leading  to  hemorrhage  with 
resulting  paralysis.  Air  emboli  may  be  distressing  or  dangerous  if 
they  occur  in  the  labyrinth  of  the  ear,  in  the  spinal  cord,  in  the  brain, 
or  in  the  heart  or  other  vital  parts. 

The  prevention  of  caisson  disease  consists  in  gradual  decompres- 
sion. Sometimes  the  sj-mptoms  come  on  several  hours  after  the  work- 
man has  left  the  caisson.  As  soon  as  S}Tnptoms  come  on  the  workman 
should  at  once  be  hurried  back  into  the  compression  chamber  until 
equilibrium  between  the  internal  and  external  pressures  is  restored. 
He  may  then  be  allowed  to  pass  through  the  decompression  chambers, 
but  very  gradually.  A  medical  air-lock  should  be  provided  at  the  works, 
well  heated,  and  furnished  with  bunks  and  emergency  supplies. 

Barometers. — The  pressure  of  the  air  is  measured  by  means  of 
barometers,  the  principles  of  construction  and  use  of  which  are  so  well 
known  that  they  do  not  require  special  description. 


602       PRESSURE,    TEMPERATURE,    AND    HUMIDITY 


MOVEMENTS  OF  THE  ATMOSPHERE 

Moving  air  is  necessary  for  the  maintenance  of  health  and  is  a 
prime  requisite  of  good  ventilation.  The  motion  of  the  air  serves  the 
twofold  purpose  of  bringing  us  a  fresh  supply  and  taking  away  the 
sewage-polluted  air  from  our  immediate  vicinity.  Moving  air  also  favors 
evaporation  and  helps  to  prevent  heat  stagnation  by  keeping  the  surface 
temperature  Avithin  normal  limits.  Paul,  Heymann,  and  Erclentz,  in 
Fliigge's  laboratory,  and  also  Leonard  Hill  in  England,  emphasized  the 
importance  of  moving  air  in  assisting  the  heat  regulation  of  our  body. 
They  believe  that  this  is  a  much  more  important  function  of  moving  air 
than  simply  the  bringing  of  fresh  air  or  the  carrying  away  of  the  prod- 
ucts of  respiration.  In  still  air  the  body  soon  becomes  surrounded  by  a 
warm,  moist  aerial  envelope  which  causes  an  overheating  of  the  surface 
of  the  body  and  results  in  the  familiar  symptoms  of  "crowd  poisoning." 
In  a  still  atmosphere  we  are  soon  surrounded  by  a  blanket  of  stagnant 
and  impure  air,  whether  indoors  or  outdoors. 

Much  of  the  benefit  of  mountain,  seaside,  and  other  health  resorts  is 
attributable  to  the  breezes  that  blow  almost  continuously  at  such  places. 
The  health  of  large  cities  located  upon  the  seacoast  or  the  shores  of 
great  lakes  is  favored  by  the  quantities  of  moving  air  with  which  they 
are  frequently  flushed.  A  healthful  climate  is  always  a  breezy  climate 
— within  reasonable  limits.  Much  of  the  benefit  of  driving,  of  fan- 
ning, and  of  rocking-chairs  is  due  to  the  motion  of  the  air  thus  en- 
gendered. 

If  the  air  in  a  poorly  ventilated  room  can  be  kept  in  motion,  say 
with  an  electric  fain,  many  of  the  ill  effects  of  a  vitiated  atmosphere  are 
avoided,  for  the  products  of  respiration  are  diluted,  and  evaporation  and 
heat  interchange  are  favored.  Thus,  Leonard  Hill  placed  eight  stu- 
dents in  a  small  sealed  chamber  which  held  about  three  cubic  meters. 
He  states  that  "at  the  end  of  half  an  hour  they  had  ceased  laughing 
and  joking  and  their  faces  were  congested.  The  carbon  dioxid  had  gone 
up  to  4  or  5  per  cent.  Three  electric  fans  were  then  turned  on,  which 
merely  whirled  the  air  about  just  as  it  was.  The  effect  was  like  magic; 
the  students  at  once  felt  perfectly  comfortable,  but  immediately  the 
fans  were  stopped  they  again  felt  as  bad  as  before."  The  relation  of 
moving  air  to  temperature  and  moisture,  with  reference  to  ventilation, 
is  further  discussed  on  page  647. 

In  nature  the  atmosphere  is  kept  in  almost  constant  motion  as  a 
result  of  differences  in  temperature.  Thus,  the  hotter  air  in  the  tropics 
rises  and  divides  into  two  currents,  which  flow  toward  the  north  and 
south,  while  heavier,  colder  air  rushes  along  a  lower  level  from  the 
north  and  south  to  take  the  place  of  the  lighter  currents.     The  cold 


TEMPEEATUEE    OF    THE      AIE  603 

currents  from  the  poles  are  known  as  the  trade  winds,  and  the  upper, 
warmer  currents  to  the  poles  as  the  antitrades.  The  upper  currents  to 
the  poles  run  northwest  and  southwest;  while  the  lower  currents  from 
the  poles  run  northeast  and  southeast. 

The  chief  cause  of  periodic  winds,  such  as  daily  sea  breezes  and 
monsoons,  is  the  difference  in  the  heating  of  the  air  above  land  and 
above  sea.  On  a  small  scale  the  same  principle  is  seen  at  play  in 
theaters,  churches,  cathedrals,  and  public  buildings.  The  great  mass  of 
people  crowded  together  heats  the  air  about  them  and  it  ascends;  cool 
air  rushes  in  from  the  aisles  to  take  its  place,  hence  the  almost  unavoid- 
able drafts  in  such  places. 

The  velocity  of  air  currents  is  customarily  measured  by  means  of 
recording  anemometers.  These  instruments  require  a  considerable 
velocity  of  air  and  should  never  be  used  without  a  carefully  prepared 
table  of  corrections  whereby  their  readings  may  be  adjusted. 

It  often  becomes  desirable  in  sanitary  investigations,  particularly 
in  studies  of  ventilation,  to  determine  the  strength  and  direction  of 
currents  of  air  which  are  too  delicate  to  be  measured  by  means  of 
anemometers.  Lighted  candles  will  show  the  direction  of  slight  air 
currents,  the  flame  being  deflected  in  the  direction  in  which  the  cur- 
rent is  moving.  More  delicate  than  this  is  the  method  of  noting  the 
course  taken  by  smoke  from  a  joss-stick,  cigarette,  or  cigar. ^ 

When  a  current  of  air  at  the  temperature  of  55°  to  60°  F.  moves  at 
a  rate  of  one  mile  per  hour,  there  is  no  perceptible  draft.  The  rate  of 
movement  in  relation  to  our  perception  is  as  follows : 

Air  moving  at  1.5  feet  per  second — 1.0  mile     an  hour — imperceptible. 
Air  moving  at  2.5  feet  per  second — 1.7  miles  an  hour — barely  perceptible. 
Air  moving  at  3.0  feet  per  second — 2.0  miles  an  hour — perceptible. 
Air  moving  at  3.5  feet  per  second — 2.3  miles  an  hour — draft. 

The  movement  of  warm  air  is  less  perceptible  than  the  movement 
of  cool  air.^ 

TEMPERATURE    OF    THE    AIR 

The  temperature  of  the  air  depends  mainly  upon  solar  and  ter- 
restrial radiation.  The  air  absorbs  vast  quantities  of  heat  from  the 
sun,  and  as  the  heat  of  the  earth  is  radiated  into  space  a  certain  amount 
is  again  absorbed  by  the  atmosphere.  Accordingly,  the  air  both  keeps 
the  heat  out  and  keeps  it  in.  It  makes  the  days  cooler  and  the  nights 
warmer.  "It  is  a  parasol  at  noon  and  a  blanket  at  night."  Except  for 
it  there  would  be  much  more  violent  changes  in  temperature  (Macfie). 

The  power  of  the  air  to  absorb  heat  and  to  store  heat  depends 
largely  on  its  humidity;  that  is,  on  the  amount  of  water  vapor  it  con- 

^  For  a  further  discussion  of  this  subject  see  "Air  Currents  and  the  Laws 
of  Ventilation,"  by  W.  N.  Shaw. 
^  For  Drafts  see  page  175. 


604        PRESSURE,    TEMPERATURE,    AND    HUMIDITY 

tains,  for  water  vapor  is  opaque  to  heat  rays.  The  water  vapor  is  also 
a  great  reservoir  of  latent  heat.  When  water  evaporates  a  tremendous 
amount  of  latent  heat  is  carried  up  into  the  atmosphere  with  it  and 
again  becomes  actual  heat  when  the  vapor  condenses.  The  quantity 
of  heat  thus  stored  up  in  water  vapor  is  almost  incredibly  great. 

Air  expands  ^^4^:  of  its  volume  for  each  degree  rise  of  temperature ; 
air  at  32°  F.  and  30  inches  barometric  pressure  is  usually  taken  for 
unit  of  volume.  A  cubic  foot  of  dry  air  at  32°  F.  and  30  inches 
barometer  weighs  560.86  grains;  at  any  other  temperature,  therefore, 
its  weight  can  be  ascertained  by  dividing  by  its  increased  volume. 

The  temperature  of  the  air  has  a  very  important  bearing  upon 
health.  Man  has  an  almost  incredible  power  of  adapting  himself  to 
wide  variations  of  temperature.  Workers  in  foundries  have  sometimes 
to  endure  a  heat  of  250°  F.  and  even  higher  for  short  periods  of  time. 
Temperatures  of  — 75°  F.  are  met  with  in  polar  expeditions.  This  is 
a  range  of  at  least  325°  F.  The  reason  that  man,  as  well  as  other 
animals,  is  able  to  maintain  a  constant  body  temperature  when  exposed 
to  such  great  variations  of  atmospheric  temperature  is  due  not  only 
to  the  physiological  mechanism  •  which  regulates  heat  production  and 
elimination,  but  to  the  layers  of  air  immediately  in  contact  with  the 
skin.  We  wear  clothes  to  protect  ourselves  from  external  heat  or  cold, 
but  still  more  do  we  wear  air  for  that  purpose.  That  is  why  very  high 
temperatures  are  better  borne  when  the  air  is  in  motion,  which  facili- 
tates evaporation,  than  when  the  air  is  still,  while  extremes  of  cold 
are  better  borne  when  the  air  is  still,  for  then  we  become  clothed  in  a 
warm  blanket  of  air.  The  effect  of  heat  upon  health,  however,  cannot 
be  considered  alone,  for  it  depends  on  the  humidity  as  well  as  on  the 
movement  of  the  air.  Extremes  of  heat  and  cold  are  much  more  trvdng 
when  the  air  is  humid  than  when  the  air  is  dry. 

It  is  of  first  importance  that  the  arrangements  for  heating  rooms, 
offices,  schools,  etc.,  should  be  so  regulated  that  the  temperature  never 
exceeds  21°  C.  (70°  F.) ;  especially  should  this  control  be  exercised  in 
public  rooms,  such  as  schools,  etc.  As  a  rule,  the  temperature  of  heated 
rooms  should  be  17°  to  19°  C.  (62.6°  to  68.2°  F.).  The  effect  of  tem- 
perature upon  health  is  so  closely  interwoven  with  humidity  that  this 
relationship  is  discussed  on  page  613. 

Methods  of  Recording  Temperature. — Mercurial  or  bimetallic  ther- 
mometers are  best  suited  to  take  the  temperature  of  the  air.  The 
most  accurate  mercurial  thermometers  for  this  purpose  have  an  elon- 
gated bulb  of  mercury  at  one  end  and  a  ring  at  the  other,  through 
which  a  cord  can  be  tied;  the  scale  should  be  etched  upon  the  glass.  A 
good  thermometer  of  this  type  generally  is  accurate  to  about  one-half  to 
one-fifth  of  a  degree.  Thermometers  placed  upon  a  backing  of  metal, 
card,  or  wood,  with  the  scale  painted  upon  the  backing,  are  more  oma- 


•  HUMIDITY  605 

mental  than  accurate.  They  usually  possess  a  decided  lag  and  are, 
therefore,  not  trustworthy.  Thermometers  should  be  suspended  freely 
in  the  atmosphere  or  at  least  placed  in  a  current  of  air  sufficient  to  insure 
good  ventilation  about  the  mercury  column. 

Registering  tliermometers  are  of  two  principal  types:  those  which 
record  maximum  and  minimum  temperatures,  and  those  which  make 
a  continuous  record  of  the  changes  of  temperature  that  occur. 

The  maximum  and  minimum  temperatures  furnish  but  limited  in- 
formation, and,  as  such  self-recording  thermometers  are  almost  invariably 
mounted  upon  a  backing,  they  consequently  have  a  considerable  lag. 
They  are  only  dependable  where  fluctuations  in  temperature  are  not 
rapid.  Under  these  circumstances  they  may  be  used  to  record  the  high- 
est and  lowest  temperatures. 

For  an  intelligent  understanding  of  the  sanitary  condition  of  any 
room  or  inclosed  space  neither  single  determinations  nor  maximum  and 
minimum  records  are  sufficient.  Eecording  thermometers  should  be 
placed  at  various  selected  points  and  records  should  be  obtained  cov- 
ering a  period  of  several  days.  The  best  type  of  recording  thermom- 
eters depend  upon  the  movements  of  bimetallic  bars,  so  arranged  that 
as  they  contract  and  expand  they  cause  a  penpoint  to  bear  upon  a  mov- 
ing paper  scale,  and  so  leave  an  ink  trace.  The  clockwork  is  generally 
wound  up  for  a  week,  for  which  period  the  paper  scale  is  also  adapted. 

HUMIDITY 

Aqueous  Vapor. — "Water  in  its  gaseous  state  is  always  present  in 
the  atmosphere.  Water  vapor  is  the  most  variable  of  the  normal  con- 
stituents of  air,  and  also  one  of  the  most  important,  on  account  of  its 
influence  upon  health.  It  is  usual  to  consider  water  vapor  apart  from 
the  other  gases  of  the  atmosphere,  although  it  is  just  as  much  a  gas  as 
oxygen  or  nitrogen,  and  conforms  to  the  general  laws  that  govern  the 
behavior  of  gases.  As  water  vapor  weighs  only  about  three-fifths  the 
weight  of  air,  dry  air  is  heavier  than  moist  air  under  equal  conditions 
of  temperature,  pressure,  etc.  It  is  customary  to  speak  of  air  ''Tiolding" 
water  vapor.  As  a  matter  of  fact,  the  air  has  nothing  to  do  with  it, 
for  it  should  always  be  clearly  observed  that  the  presence  of  water 
vapor  in  any  given  space  is  independent  of  the  presence  or  absence  of 
air  in  the  same  space.  The  amount  of  aqueous  vapor  which  a  space 
contains  depends  entirely  upon  the  temperature  and  not  upon  the  pres- 
ence or  the  pressure^  of  the  air.  At  32°  F.,  for  instance,  the  air  can 
'"hold"  1/160  of  its  weight  of  water  vapor,  at  59°  F.  1/80  of  its  weight, 
at  86°  F.  1/40  of  its  weight.  Eoughly,  every  27°  F.  increase  of  tem- 
perature doubles  the  amount  of  water  vapor  the  air  can  hold  in  propor- 

^  A   high   barometer   retards   evaporation,   while   a  low   atmospheric   pressure 
accelerates  it.     All  volatile  liquids  evaporate  instantly  in  a  vacuum. 


606        PRESSUEE,    TEMPERATURE,    AND    HUMIDITY 

tion  to  its  weight.  In  tliis  way  the  heat  of  the  atmosphere  is  self-pro- 
tective, for  it  loads  the  air  with  water  vapor,  which  in  turn  absorhs  much 
of  the  heat.  The  latent  heat  is  again  given  off  on  condensation.  The 
actual  amount  of  water  vapor  which  the  air  can  hold  at  different  tem- 
peratures is  shown  in  the  following  table: 

A  cubic  foot  of  air  can  hold  at 

10°  F 1.1  j^rains 

20°   "  L5       " 

30°   "  2.1       " 

40°   "  3.0       " 

50°    "  4.2       " 

60°    "  5.8       " 

70°    "  7.9       " 

80°   "  10.0       " 

90°   "  14.3       " 

100°   "  19.1       " 

As  the  temperature  rises  in  arithmetical  progression  the  power  to 
retain  vapor  increases  with  the  rapidity  of  a  geometric  series  having 
a  ratio  of  two. 

The  amount  of  water  vapor  in  the  air  may  be  expressed  either  by: 
(1)  its  vapor  tension.  The  tension  of  the  water  vapor  in  the  air  is 
expressed  in  inches  or  millimeters  of  mercury.  If  a  drop  of  water  is 
placed  in  a  vacuum,  say  in  a  barometer  tube,  some  of  the  water  vaporizes 
and  the  mercury  is  dejiresscd,  owing  to  the  tension  of  the  water  vapor. 
The  amount  that  evaporates,  as  well  as  the  tension,  depends  upon  the 
temperature.  (2)  Its  w^eight  per  unit  volume  of  air,  i.  e.,  the  absolute 
humidity;  and  (3)  the  ratio  of  the  amount  of  water  vapor  in  the  atmos- 
phere to  the  amount  it  could  hold  at  the  temperature  in  question  if 
saturated;  that  is,  the  relative  humidity.  Complete  saturation  of  the  air 
with  moisture  is  stated  at  100,  and  lesser  amounts  by  percentages. 
(4)  The  amount  of  water  vapor  in  the  air  may  also  be  found  from  its 
dew-point.  The  dew-point  for  an}^  temperature  and  humidity  is  the 
temperature  to  w^hich  the  air  may  be  cooled  when  precipitation  takes 
place. 

The  vapor  tension  or  the  absolute  humidity  indicates  how  much 
water  vapor  the  air  contains,  while  the  relative  humidity  is  an  ex- 
pression of  how  much  vapor  it  might  contain.  The  amount  of  water 
vapor  which  air  can  hold  when  saturated  at  different  temperatures  has 
been  calculated  and  recorded  in  Glaisher's  hygrometric  tables.^  It  is, 
therefore,  very  easy,  by  referring  to  these  or  to  the  tables  in  the  U.  S. 
Weather  Bureau — Bulletin  Xo.  £35 — to  calculate  the  relative  humid- 
ity if  we  know  the  actual  humidity  or  the  dew-point  or  vice  versa. 

^  The  standard  hygrometrieal  tables  in  use  the  world  over  are  those  pre- 
pared by  Mr.  James  Glaisher,  F.  R.  S.,  of  the  Eoyal  Observatory,  Greenwich, 
England. 


HUMIDITY 


607 


The  amount  of  moisture  which  out-of-door  air  ordinarily  contains 
varies  from  about  30  per  cent,  or  less  to  saturation. 

In  meteorological  tables, '  giving  climatic  particulars  of  any  town  or 


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TE/iPEPATURE     DEGREES    FAHRENHEIT. 


Fig.  82. — Diagram  Showing  Absolute  HuMiDrrY  in  Grains  at  Different 

Temperatures. 

locality,  the  relative  humidity  is  usually  stated;  but  it  should  be  no- 
ticed that  the  relative  humidity  bears  no  constant  relationship  to  the 
absolute  humidity.  As  the  relative  humidity  varies  greatly  throughout 
the  day,  and  as  the  readings  are  not  always  taken  at  the  same  time  of 


608 


PEESSUKE,    TEMPEKATUEE,    AND    HUMIDITY 


clay  in  different  localities,  it  at  once  becomes  evident  that  comparisons 
are  not  reliable.  In  fact,  a  moist  or  dry  climate  cannot  be  predicted 
from  the  relative  liumidity.  Thus,  the  mean  relative  humidity  of 
I)avos  is  as  high  as  71)  per  cent.,  whereas  it  is  generally  known  that 
the  climate  of  Davos  is  dry.  On  the  other  hand,  in  Egypt  the  average 
relative  humidity  is  very  low,  although  this  country  is  known  to  have 
a  moist  clinuite.  This  is  for  the  reason  that  the  humidity  readings 
in  Egypt  are  taken  from  10  A.  M.  to  6  P.  M.,  and  vary  from  30.5  per 
cent,  at  Assouan  to  51.7  per  cent,  at  Menahouse.  As  a  matter  of  fact, 
the  relative  humidity  in  Egyi)t  decreases  from  100  j^er  cent,  at  dawn 
to  23  per  cent,  at  noon,  and  may  be  quickly  altered  to  the  extent  of  50 
per  cent,  by  a  warm  wind.  The  humidity,  therefore,  through  tlie  hot, 
sunny  daytime  is  not  a  measure  of  the  climate,  so  far  as  moisture  and 
dryness  are  concerned. 

.  In  England  the  relative  humidity  averages  75  per  cent.  In  Califor- 
nia it  drops  from  100  per  cent,  at  dawn  to  22  per  cent,  at  noon.  A  hot 
wind,  by  increasing  tlic  capacity  of  the  air  for  moisture,  may  also  lower 
the  relative  humidity  very  quickly.  Thus,  the  Fohn  w'ind  wlien  it 
reaches  the  Eiviera  lowers  the  relative  humidity  50  to  60  per  cent,  in 
an  hour  or  two.  The  mean  relative  humidity  of  Denver  for  the  year 
is  only  42  per  cent.,  at  San  Diego,  on  the  coast,  72.9,  at  Los  Angeles, 
a  few  miles  inland,  66.6.  In  the  heart  of  the  Libyan  desert  the  rela- 
tive humidity  may  be  as  low  as  9  per  cent.  At  the  seaside  daily  varia- 
tions in  humidity  are  less  than  inland  (Macfie).  The  air  in  forests  is 
10  or  20  per  cent,  more  humid  than  air  in  the  open.  There  may  be  a 
very  great  difference  in  the  relative  humidity  of  outside  cool  air  and  of 
air  in  a  closed  heated  room,  in  that  the  latter  may  be  very  much  dryer. 
So  far  as  the  effect  of  humidity  upon  health  is  concerned  Dr.  Hug- 
gard  well  states:  "The  really  essential  point  is  not  the  amount  of 
moisture,  relative  or  absolute,  that  is  present,  but  the  amount  that  can 
still  be  taken  up.  This  varies  enormously  with  the  same  degree  of 
relative  humidity  at  different  temperatures,  as  the  followdng  table  from 
Eenk  will  show :" 


AMOUNT    OF  VAPOR   THAT   CAN  STILL  BE  TAKEN   UP  AT   DIFFERENT 
TEMPERATURES  AND  THE  SAME  RELATIVE  HUMIDITY. 


Temperature 

Relative  Humidity 

Absolute     Humidity 
Grams  per  Cubic  Meter 

Grams  of  Vapor  that 
can  still  be  taken  up 

Per  Cent. 

-20°  C. 

60 

0.638 

0.426 

-10°  e. 

60 

1.380 

0.920 

o°c. 

60 

2.924 

1.950 

10°  c. 

60 

5.623 

3.749 

20°  C. 

60 

10.298 

6.866 

30°  C. 

60 

18.083 

12.056 

HIJMIBITY 


609 


We  see  by  this  table  that  the  same  expression,  60  per  cent,  relative 
humidity,  might  be  applied  to  air  capable  of  taking  up  0.426  gram  or 
12.056  grams  of  vapor,  and  thus  the  expression  as  a  measure  of  the 
drying  capacity  of  the  air  is  obviously  misleading. 

Dr.  Huggard  gives  a  second  very  instructive  table,  the  obverse  of 
the  above : 


Relative  Humidity 

Vapor:  Grams  per  Cubic  Meter 

Temperature 

Present 

Capable  of  Still  Being 
Taken  up 

Per  Cent. 

3°C. 

0 

0 

6 

10°  C. 

36 

3.4 

6 

15°  C. 

53 

6.8 

6 

20°  C. 

65 

11.2 

6 

25°  C. 

73 

16.9 

6 

30°  C. 

80 

24.1 

6 

We  see  from  this  second  table  that  air  with  relative  humidities  of 
0,  36,  53,  65,  73,  and  80  per  cent.,  and  containing  quantities  of  water 
vapor  varying  between  0  and  24.1  grams  per  cubic  meter,  are  all  ca- 
pable of  further  taking  up  exactly  the  same  amount  of  vapor.  Again 
the  expression  of  relative  humidity  is  misleading. 

When  the  relative  humidity  reaches  80  to  85  per  cent.,  moisture  con- 
denses and  begins  to  show  upon  objects  in  rooms.  This  influences  natu- 
ral ventilation  through  porous  building  materials. 

There  may  be  a  very  marked  difference  between  the  humidity  of 
indoor  and  outdoor  air,  owing  in  part  to  the  condensation  of  moisture, 
especially  in  winter,  upon  the  cold  walls  and  windows. 

The  difi^erences  between  external  and  internal  humidities  depends 
largely  upon  the  temperature  of  the  surfaces  in  the  room.  These  sur- 
faces, though  apparently  dry,  may,  in  fact,  hold  moisture  in  large 
quantities;  the  walls  and  ceilings  may  contain  more  water  than  all  the 
air  in  the  room.  Ordinarily  there  is  a  continual  exchange  of  moisture 
between  the  air  and  the  room  surfaces.  In  this  way  the  walls  serve 
as  a  compensating  reservoir  to  help  maintain  the  humidity  of  the  air 
approximately  constant.  Cold  walls,  cold  windows,  and  cold  surfaces 
generally  condense  the  moisture  from  the  air  so  rapidly  that  great  diffi- 
culty is  experienced  in  raising  the  relative  humidity  of  the  air  of  a  room 
under  these  circumstances. 

The  humidity  in  the  air  is  influenced  by  altitude.  The  higher  we 
go  the  air  becomes  colder  and  rarer  and,  therefore,  able  to  contain  less 
moisture.  Its  absolute  humidity,  therefore,  decreases.  Half  of  the 
total  water  vapor  of  the  atmosphere  is  below  2,000  meters.     On  the 


610       PKESSURE,    TEMPERATURE,    AND    HUMIDITY 


05 


Fio.  83. — Sling 

PSTCHHOMETER. 


other  hand,  the  relative  humidity  shows  no  regular 
change  with  eliange  of  altitude.  Clouds  do  not  neces- 
sarily iiii])ly  liigh  relative  or  absolute  humidity  of  the 
lower  atmosphere.  Rainfall  also  gives  only  a  very  gen- 
eral indication  of  the  humidity  of  the  atmosphere.  A 
place  with  higli  rainfall  may  have  low  absolute  and  rela- 
tive humidity,  and  vice  versa;  that  is,  a  rainy  district 
is  not  necessarily  a  damp  district,  so  far  as  the  atmos- 
])here  is  concerned.  Dew  also  bears  no  constant  relation- 
sliip  to  the  humidity  of  the  atmosphere,  for  a  clear  sky 
and  a  dry  atmosphere  favor  its  formation.  Air  contain- 
ing mist  is  obviously  moist. 

Methods  of  Determining  Humidity  in  the  Air. — The 
amount  of  water  vapor  in  the  air  may  be  determined 
eitlier  by  (1)  weighing,  (2)  psychrometers  or  hygrom- 
eters, (3)  the  dew-point. 

Weighing. — The  amount  of  moisture  in  the  air  may 
be  determined  by  passing  a  given  volume  of  air  through 
a  tube  or  flask  containing  an  hygroscopic  substance,  such 
as  calcium  chlorid  or  sulphuric  acid.  If  sulphuric  acid 
is  used  small  flasks  are  filled  with  pieces  of  pumice  which 
have  been  heated  to  a  high  temperature  over  a  Bunson 
burner,  and  dropped  while  hot  in  concentrated  sulphuric 
acid,  removed,  and  quickly  drained. 

The  increase  in  weight  represents  tlie  amount  of 
moisture  in  the  volume  of  air  passed  through  the  flasks, 
or  the  al)S()lute  humidity.  Knowing  the  temperature  of 
the  air,  it  is  then  easy  to  determine  the  relative  humidity 
by  reference  to  tables  of  maximum  water  capacity  for 
certain  volumes  of  air  at  varying  degrees  of  temperature. 

PsYCJiEOMETERS. — The  most  convenient  of  all  meth- 
ods for  measuring  atmospheric  moisture  is  to  observe  the 
temperature  of  evaporation,  that  is,  the  difference  between 
the  temperatures  indicated  liy  wet  and  dry  bulb  ther- 
mometers. The  United  States  Weather  Bureau  regards 
the  sling  psychrometer  as  the  most  reliable  instrument 
for  tliis  purpose.  In  special  cases  rotary  fans  or  other 
means  may  be  employed  to  move  the  air  rapidly  over 
stationary  thermometer  bulbs. 

The  sling  psychrometer  consists  of  a  pair  of  ther- 
mometers provided  with  a  handle,  which  permits  them 
to  be  whirled  rapidly  (see  Fig.  83).  The  bulb  of  the 
lower  of  the  two  thermometers  is  covered  with  thin  mus- 
lin,  which   is  wet  at  the  time  an  observation  is  made. 


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611 


613        PEESSURE,    TEMPERATURE,    AND    HUMIDITY 


This  muslin  covering  should  be  kept  in  good  condition  and  should 
be  frequently  renewed.  It  is  also  desirable  to  use  pure  water.  Tlie 
so-called  wet  bidb  is  thoroughly  saturated  by  dipping  it  into  distilled 
water.  The  thermometers  are  then  whirled  rapidly  for  15  or  20 
seconds,- stopped,  and  quickly  read,  the  wet  bulb  first.  This  reading 
is  kept  in  mind,  the  psychrometers  immediately  wliirled  again  and  a 
second  reading  taken.  This  is  repeated  three  or  four  times  or  more,  if 
necessary,  until  at  least  two  successive  readings  of  the  wet  bulb  are  found 
to  agree  very  closely,  thereby  showing  that  it  has  reached  its  lowest  tem- 
peratiire.  A  minute  or  more  is  generally  required  to  secure  a  correct 
reading.  The  psychrometer  should  not  be  whirled  in  the  direct  rays  of 
the  sun,  and  if  used  out  of  doors  the  observer  should  face  the  wind.  It 
is  a  good  plan,  while  whirling  the  instrument,  to  step  back  and  forth  a 
few  steps  to  further  prevent  the  presence  of  the  observer's  body  from 
giving  rise  to  erroneous  observations. 

In  correcting  psychrometric  observations  the  atmospheric  pressure 
at  the  time  must  be  obtained,  and  the  results  deduced  from  the  tables 
based  on  a  pressure  nearest  that  observed.  The  difference  in  the  tem- 
perature between  the  wet  and  the  dry  "bulb  is  computed  to  the  nearest 
tenth  of  a  degree.  Having  the  temperature  and  the  pressure  of  the 
air  and  the  depression  of  the  wet  bulb,  it  is  only  necessary  to  read 
directly  from  the  tables  the  dew-point,  the  vapor  pressure,  and  the  rela- 
tive humidity.     These  tables  will  be  found  in  Bulletin  A^o.  235  of  the 

United  States  Weather  Bureau.  A 
condensed  table  is  given  in  Fig.  84. 
The  Hair  Hygrometer. — This  ap- 
paratus depends  upon  the  expansion 
and  contraction  of  a  suitably  pre- 
pared hair  under  the  influence  of 
moisture.  It  can  be  made  a  reason- 
ably accurate  instrument,  and  some 
types  are  arranged  for  continuous 
record.  One  of  the  principal  difficul- 
ties with  hair  hygrometers  is  that  a 
sufficient  current  of  air  does  not 
always  come  in  contact  with  them. 

The  Dew-poixt. — The  dew-point 
may  be  obtained  by  direct  observation 
from  Regnault's  apparatus,  shown  in 
Fig.  85.  This  instrument  consists 
essentially  of  a  thin  polisbed  silver 
tube  a,  cemented  upon  the  lower  end 
of  a  longer  glass  tube,  as  shown. 
Fig.  85. — Dew-point  Apparatus.         The  stopper  closing  the  upper  end  of 


HUMIDITY  613 

the  glass  tube  is  fitted  with  two  lateral  tubes  of  hard  rubber  h  and  c^ 
and  also  carries  a  delicate  thermometer,  the  bulb  of  which  is  placed  near 
the  center  of  the  silver  tube.  The  tube  b  extends  to  the  bottom  of  the 
silver  tube ;  c  projects  but  a  short  distance  through  the  cork.  A  rubber 
aspirating  apparatus,  as  shown,  is  connected  with  the  tube  h,  and 
a  long  tube  joined  to  c  serves  to  carry  off  the  fumes.  The  ap- 
paratus is  held  in  a  clamp  faced  with  cork  or  other  non-conducting  sub- 
stance. 

Observations  are  made  by  filling  the  silver  cup  with  ether  or  similar 
volatile  liquid,  which  is  caused  to  evaporate  and  cool  the  silver  cup 
by  manipulating  the  aspirating  bulb.  At  the  proper  point  of  cooling 
a  deposit  of  dew  is  seen  to  form  on  the  polished  silver  surface.  The 
object  is  to  ascertain  accurately  the  temperature  at  which  the  dew  will 
just  deposit.  It  is  necessary  that  the  temperature  be  lowered  very 
slowly  at  the  critical  point,  also  that  there  be  plenty  of  liquid  in  the 
cup,  and  that  it  be  agitated  sufficiently  to  have  a  uniform  temperature 
throughout,  and,  finally,  the  surface  of  the  silver  must  be  perfectly 
clean  and  in  a  favorable  light,,  so  that  the  faintest  deposit  of  dew  is 
at  once  visible.  The  temperature  shown  by  the  thermometer  at  this 
moment  may  be  regarded  as  the  temperature  of  the  dew-point.  Know- 
ing the  dew-point,  the  humidity  of  the  air  may  be  found  by  reference 
to  the  above-mentioned  tables. 

Relation  of  Humidity  and  Temperature  to  Health. — The  physiolog- 
ical significance  of  moisture  in  the  air  varies  with  many  factors,  but 
especially  with  temperature.  In  a  general  way  it  may  be  said  that 
moist  air  is  depressing  and  enervating,  while  dry  air  is  tonic  and  stim- 
ulating; also  that  cold  air  is  tonic,  while  warm  air  is  depressing.  The 
human  body  can  adapt  itself  to  wide  variations  in  heat  and  humidity, 
and  by  means  of  suitable  clothing  and  food  the  range  may  be  greatly 
increased.  Various  combinations  of  heat  and  humidity  may  be  trying  or 
even  hurtful;  the  most  mischievous  combinations  are  cold  damp  air  and 
warm  moist  air,  also  an  excessively  dry  air,  especially  when  artificially 
warmed.  Many  climates  in  which  people  are  reasonably  healthy  have  a 
relatively  high  humidity,  and  some  regions  famed  for  their  salubrity  are 
notoriously  dry  and  arid.  The  frequently  changing  temperatures  and 
variable  amounts  of  water  vapor  of  most  climates  may  be  beneficial  in 
stimulating  the  heat-regulating  mechanism. 

The  temperature  and  humidity  of  the  air  affect  health  mainly  by 
influencing  the  heat-regulating  mechanism  of  the  body.  More  heat  is 
produced  within  the  body  than  is  required,  hence  heat  must  be  lost, 
else  heat  stagnation  or  heat  stroke  will  result.  The  temperature  of  the 
air,  but  still  more  its  humidity,  influences  heat  loss.  It  will,  there- 
fore, be  necessary  to  briefly  review  the  mechanism  by  which  the  con- 
stant temperature  of  the  body  is  maintained. 
41 


614       PRESSURE,    TEMPERATURE,    AND    HUMIDITY 

The  cliief  source  of  the  body  heat  comes  from  the  food  we  eat.  Ap- 
proximately 80  per  cent,  of  the  food  we  eat  is  used  to  furnish  lieat 
to  maintain  the  body  temperature,  while  only  about  20  per  cent,  fur- 
nishes energy  in  the  form  of  motion.  Heat  is  lost  from  the  body 
chiefly  in  two  ways:  (1)  by  heat  transfer,  or  loss  by  radiation,  con- 
duction, and  convection;  (2)  by  evaporation,  chiefly  by  the  evaporation 
of  the  water  of  perspiration.  The  loss  by  heat  transfer  diminishes  as 
the  temperature  of  the  surrounding  air  rises.  The  temperature  of 
the  body  would  rise  when  the  atmospheric  temperature  went  above 
70°  F,  were  not  perspiration  then  secreted.  So  long  as  the  perspiration 
can  evaporate  freely  the  heat  production  and  heat  loss  are  balanced. 
With  a  high  humidity  evaporation  is  lessened  and  the  balance  is  main- 
tained by  rushing  blood  to  the  skin,  which  causes  an  elevation  of  the 
temperature  of  the  surface,  and  thus  the  loss  of  heat  by  radiation,  con- 
duction, and  convection  is  facilitated. 

Humidity  influences  the  output  of  heat  from  the  body  in  two  ways: 
(1)  it  increases  the  conductivity  of  atmosphere  for  heat — a  cooling 
influence — hence  cold  moist  air  is  chilling;  (2)  it  interferes  with  evap- 
oration of  perspiration — a  heating  influence — hence  warm  moist  air  is 
enervating.  There  is  a  neutral  zone,  around  GS°  F.,  at  which  humidity 
has  comparatively  little  effect.  Hence,  if  the  temperature  of  a  room 
is  kept  just  right  and  the  occupants  are  sitting  still,  it  makes  little 
difference  whether  the  air  is  humid  or  dry.  However,  a  difference  of 
a  few  degrees  above  or  below  this  temperature  will  have  a  marked 
influence. 

Rubner  and  his  coworkers  showed  that  the  evaporation  of  water 
from  the  body  cannot  be  regarded  as  being  dependent  merely  on  the 
percentage  humidity  of  the  atmosphere.  The  temperature  of  the  layer 
of  air  in  contact  with  the  body  is  the  factor  of  great  importance.  Thin 
clothes  and  still  air,  under  certain  conditions  of  external  temperature, 
may  favor  evaporation,  while  nakedness  and  moving  air  favor  conduc- 
tion and  radiation.  The  heat-losing  mechanisms  of  the  body  are  ad- 
justable to  varying  conditions  within  wide  limitations,  so  that  dimin- 
ished loss  by  evaporation  is  compensated  for  by  increased  loss  by  con- 
duction and  radiation. 

The  amount  of  moisture  in  the  air  conducive  to  health  and  well- 
being  is  often  stated  to  be  somewhere  between  50  and  75  per  cent, 
relative  humidity.  These  figures  may  be  very  misleading.  There  is 
no  such  thing  as  a  normal  humidity,  for  the  amount  of  moisture  in 
relation  to  health  depends  upon  the  temperature,  clothing,  motion  of 
the  air;  also  upon  diet  and  muscular  activity  and  other  factors.  Xeither 
the  relative  humidity  nor  the  absolute  humidity  nor  the  temperature 
of  the  air  alone  is  a  satisfactory  guide  as  to  its  condition  in  relation 
to  health.     One  factor  gives  the  sanitarian  scant  information ;  however, 


HUMIDITY  615 

the  temperature  as  registered  upon  the  wet-bulb  thermometer  is  most 
significant. 

Importance  of  the  Wet-bulb  Temperature. — The  individual  sus- 
ceptibility to  temperatures  depends  entirely  on  the  temperature  recorded 
by  the  wet-bulb  thermometer/  no  matter  what  the  dry  bulb  registers. 
Hill,  Eubner,  Pembrey,  Boycott,  Cadman,  Nagel,  and  practically  all 
authorities  agree  with  Haldane  that  the  air  of  workrooms  should  not 
exceed  70°  F.  by  the  wet-bulb  thermometer. 

Eubner  states  that  an  untrained  man  can  be  in  comfort  in  a  tem- 
perature of  75°  F.  and  80  per  cent,  humidity  (wet  bulb  about  70°  F.) 
only  when  he  is  quiet.  At  73.4°  F.  and  GO  per  cent,  humidity  he  found 
a  resting  man  lost  by  evaporation  75  grams  of  water  per  hour,  and  at 
84  per  cent,  humidity  (wet  bulb  70°  F.)  only  19  grams.  These  figures 
show  that  three-quarters  of  the  heat  loss  may  be  maintained  by  conduc- 
tion and  radiation  when  the  wet  bulb  reaches  70°  F. 

Cadman  concludes  that  at: 

72°  wet  bulb ....  Inconvenience  is  experienced,  unless  heavy  clothing  is  re- 
moved and  light  clothing  worn. 

78°  "  "  ...  .Little  inconvenience  is  felt  if  considerable  bare  body  sur- 
face is  exposed.  Hard  work  is  much  facilitated  if  a 
perceptible  current  is  passing  over  the  body. 

82°  "  "  ....  If  clothes  be  removed,  and  maximum  body  surface  ex- 
posed, work  can  be  done  providing  current  of  air  is 
available. 

85°  "  "  ....  Body  temperature  becomes  affected,  and  only  light  work 
is  possible. 

Boycott  made  the  following  significant  observations  upon  himself : 
"At  rest  and  stripped  I  found  that  my  body  temperature  rose  rap- 
idly if  the  wet  bulb  exceeded  88°  to  90°  F.  with  a  dry  bulb  of  about 
100°,  though  no  rise  occurred  with  a  dry  bulb  of  110°  and  wet  bulb 
of  less  than  85°.  I  have  on  many  occasions  spent  periods  of  about  an 
hour  in  doing  ordinary  laboratory  work  in  air  with  the  dry  bulb  at 
95°  and  the  wet  bulb  at  about  65°  without  any  material  discomfort. 
If,  however,  the  wet  bulb  rises  to  88°  to  90°,  one's  body  temperature 
begins  to  go  up,  even  when  completely  at  rest^  and  one  becomes  ex- 
ceedingly uncomfortable  and  on  occasions  feels  very  ill.  These  sensa- 
tions can  be,  to  some  extent,  remedied  by  local  cooling  of  the  skin 
(e.  g.,  cold  water  on  the  head),  but  the  rise  of  body  temperature  is 
progressive  and  inust  eventually  end  in  heat-stroke." 

A  man  is  much  less  efficient  in  a  warm  moist  atmosphere ;  hence  it  is 
an  advantage  to  both  employer  and  employee  that  work  be  performed 
at  temperatures  below  70°  F.  by  the  wet  bulb.     At  the  lower  tempera- 

^  One  of  the  thermometers  of  a  psychrometer  is  known  as  the  wet  bulb. 
See  page  610. 


616       PEESSTJRE,    TEMPERATURE,    AXD    HUMIDITY 

tures  work  is  done  faster,  more  efficiently,  and  with  less  fatigue,  dis- 
comfort, and  injury  to  health.  To  work  in  a  warm  moist  atmosphere 
increases  the  temperature,  pulse,  and  loss  of  moisture  out  of  propor- 
tion to  the  work  done.  It  is  the  master's  pockets  which  suffer  under 
such  conditions,  for  the  workers  instinctively  avoid  the  discomfort  of 
overheatino-  themselves  through  lessened  exertion. 

Effects  of  Warm  Moist  Air. — When  air  above  88°  F.  becomes  sat- 
urated evaporation  can  no  longer  compensate  for  decrease  in  radiation, 
and  the  body  temperature  accordingly  rises  and  heat-stroke  may  ensue. 
The  injurious  effects  of  the  summer  heat  are  practically  always  the  result 
of  combined  heat  and  humidity. 

According  to  Eubner  and  Lewaschew,  when  the  air  is  very  humid 
tlie  heat  loss  by  evaporation  is  very  much  lessened,  and,  accordingly, 
at  80  per  cent,  humidity  and  temperature  of  24°  C.  (75.2°  F.)  becomes 
after  a  time  insupportable  to  a  man  unaccustomed  to  it,  and  exposure 
to  it  is  only  possible  with  complete  muscular  rest.  If,  however,  the 
air  is  very  dry  a  temperature  of  24°  to  29°  C.  (75.2°  to  84.2°  F.) 
can  be  usually  endured.  These  temperatures  are  often  exceeded  in  the 
summer  time  in  America.  By  practice  a  certain  amount  of  accom- 
modation to  the  effects  of  a  hot  moist  climate  may  be  acquired. 

There  is  no  known  serious  injury  to  health  caused  by  working  in  a 
warm  moist  air,  provided  that  a  considerable  rise  of  body  temperature 
is  avoided.  The  effects  of  heat  and  moisture  may  be  diminished  by  light 
clothing,  bare  legs  and  arms,  whereb}'  the  loss  of  heat  from  the  skin  is 
increased. 

Working  in  moist,  overheated  rooms  has  the  further  disadvantage 
of  wetting  the  clothes  with  perspiration,  which  causes  discomfort,  dirt, 
and  untidiness,  and  liability  to  chilling  the  surface  on  going  outdoors. 

A  poorly  ventilated  room  in  which  the  air  becomes  vitiated  is  usually 
a  warm  moist  atmosphere,  and  the  ill  effects  of  a  vitiated  atmosphere 
are  mainly  caused  by  the  heat  and  moisture. 

Effects  of  Cold  Damp  Air. — Wlien  such  air  is  injurious  the  victim 
is  usually  underclad,  improperly  fed,  or  has  been  living  an  indoor 
life.  In  certain  cases  cold  damp  must  always  be  injurious,  as,  for  in- 
stance, where  the  vital  forces  are  at  a  low  ebb  and  where  there  is  re- 
stricted capacity  for  making  heat,  such  as  infancy  or  old  age;  in  cases 
of  kidney  disease,  where  hindrance  of  evaporation  means  extra  work  for 
the  kidneys;  also  in  cases  where  there  is  a  tendency  to  rheumatism  or 
disorders  of  metabolism.  The  effects  of  cold  damp  air  may  be  neutral- 
ized by  proper  clothing,  by  muscular  activity,  and,  to  a  limited  extent, 
by  diet. 

Just  how  cold  damp  air  influences  health  is  not  well  understood. 
It  throws  an  added  load  upon  the  heat-producing  mechanism  to  main- 
tain the  body  temperature;  the  strain  falls  especially  upon   digestion 


HUMIDITY 


617 


and  metabolism,  and  also  upon  the  circulation  and  the  kidneys,  and 
indirectly  upon  the  nervous  system.  Macfie  suggests  that:  "Dry  air 
quickens  metabolism  both  through  its  cooling  and  drying  capacity, 
while  damp  air  slows  it  by  diminishing  loss  of  water.  It  is  possible 
that  much  of  the  harm  attributed  to  dainp  and  to  cold  is  due  to  a 
depression  of  metabolism  and  accumulation  of  harmful  waste  products 
in  the  body."  Dr.  H.  I.  Bowditch  in  1862  formulated  the  law  of  soil 
moisture,  and  believed  that  tuberculosis  was  more  common  over  moist 
soils  than  dry  ones.  According  to'  our  present  conception,  the  relation 
between  dampness  or  moist  soil  and  tuberculosis  is  quite  indirect;  if 
there  is  any  connection  it  is  due  merely  to  the  fact  that  the  combina- 
tion of  cold  and  dampness  depresses  vitality  and  thereby  lowers  re- 
sistance. 

A  healthy  man  may  daily  move  in  and  breathe  cold  damjD  air  with- 
out suffering  in  health  to  any  appreciable  extent ;  however,  it  is  generally 
believed  that  a  cold  damp  air  predisposes  to  affections  of  the  respiratory 
passages,  to  rheumatism,  and  neuralgias. 

Effects  of  Warm  Dry  Air. — A  relatively  dry  air  feels  better  than 
moist  air  at  most  temperatures.  The  stimulating  and  pleasant  effects 
of  a  dry  climate  can  only  be  appreciated  by  one  who  has  visited  an  arid 
region — such  as  our  southwestern  plateau.  However,  when  air  is  ab- 
normally dry,  especially  if  warm,  the  evaporation  from  the  body  is 
greatly  increased.  Thus,  Eubner  and  Lewaschew  found  that  a  man 
weighing  58  kilograms  gave  off  the  following  amounts  of  carbon  dioxid 
and  moisture  in  one  hour  at  different  temperatures  in  dry  and  moist 
air: 


Dry  Air. 

Moist  Air. 

Relative 

Relative 

Temp. 

Humidity 
of  Air. 

CO. 

H2O 

Humidity 
of  Air. 

CO. 

H,0 

15°  C. 

8% 

32.2  gm. 

36^  gm. 

89% 

34.9  gm. 

9.0  gm. 

20°  C. 

5% 

30.0  g-m. 

54.1  gm. 

82% 

28.3  gm. 

15.3  gm. 

25°  C. 

6% 

31.7  gm. 

75.4  gm. 

81% 

31.4  gm. 

23.9  gm. 

29°  C. 

6% 

32.4  g-m. 

103.3  gm. 

Air  that  is  warm  and  at  the  same  time  abnormally  dry,  such  as  that 
produced  by  furnace  heat,  causes  an  excessive  loss  of  moisture  and  con- 
centration of  the  fluids  in  the  tissues  and  organs  of  the  body.  Man 
consists  of  08.5  per  cent,  of  water.  A  very  small  percentage  of  loss 
may  be  serious;  when  the  percentage  reaches  21  per  cent,  death  results. 
The  warmed  and  dried  atmosphere  of  our  overheated  houses  gives  a  sense 
of  chilliness,  owing  to  excessive  evaporation,  and  favors  irritation  and 
infection  of  the  respiratory  mucous  membranes.     If  a  room  at  68°  F. 


618        PRESSURE,    TEMPERATURE,    AND    HUiMTDITY 

is  not  warm  enough  for  a  healthy  person,  we  may  be  sure  that  it  is  be- 
cause the  humidity  is  too  low. 

The  problem  of  constructing  buildings  in  such  a  way  as  to  keep  the 
interior  up  to  a  fair  degree  of  humidity  is  a  large  one.  So  far  engineers 
have  made  little  practical  progress  toward  its  solution.  Satisfactory 
devices  may  be  had  to  improve  the  moisture  in  large  public  buildings, 
but  these  devices  have  so  far  proved  too  expensive  for  private  dwellings, 
offices,  or  schoolrooms. 

The  humidity  in  living  rooms  may  be  improved  by  setting  about 
growing  plants  and  porous  dishes,  such  as  flower  pots  full  of  water.  If 
such  receptacles  are  set  near  electric  fans  evaporation  is  facilitated.  Pans 
or  pots  of  water  may  also  be  placed  upon  the  radiator. 


CHAPTEB    III 
MISCELLAXEOUS 

Odors, — Odors  in  a  living  room  come  mostly  from  human  sources. 
The  sources  of  these  odors  are:  foul  breath,  decaying  teeth,  unclean 
mouths,  nasal  catarrh,  sudoriferous  glands,  especially  those  of  the  pubes, 
feet,  and  axillse,  also  gases  from  the  stomach  and  bowels.  The  decom- 
position of  matter  on  the  skin  and  also  in  the  clothes  adds  a  ybtj  dis- 
agreeable odor,  accentuated  in  a  warm  moist  atmosphere.  The  pe- 
culiar odor  in  some  rooms,  especially  sick  rooms,  seems  to  be  none  of 
these;  just  what  constitutes  the  somewhat  characteristic  man-smell  is 
not  known. 

While  odors  may  be  very  unpleasant,  they  are  not  known  to  seriously 
influence  health;  contrary  to  common  opinion,  they  are  not  by  any 
means  a  reliable  sign  of  danger.  The  presence  of  bacteria  or  dust  in 
the  atmosphere  has  no  special  relation  to  odors.  Some  poisonous  gases, 
such  as  carbon  monoxid,  are  practically  inodorous. 

The  air  of  inhabited  rooms  ordinarily  must  be  quite  full  of  various 
scents  which  we  do  not  appreciate,  either  because  our  sense  of  smell 
is  not  keen  enough,  or  because  we  have  become  so  accustomed  to  them 
that  they  are  not  noticed.  An  atmosphere  that  does  not  appear  to  be 
unpleasant  while  remaining  in  a  room  may  seem  intolerable  upon  re- 
turning to  it  after  a  period  in  the  fresh  outdoor  air.  Man's  sense  of 
smell  is  not  keen  when  compared  to  that  of  some  of  the  lower  animals ; 
nevertheless  it  is  extremely  sensitive  to  certain  odors.  Thus,  it  can 
determine  0.000,000,03  gram  of  musk.  The  aeuteness  of  the  sense  of 
smell  varies  markedly  in  different  individuals. 

"When  a  room  smells  stuffy  and  close  it  may  be  taken  as  a  fairly 
reliable  index  that  the  air  is  vitiated;  this  is  especially  true  in  a  clean 
room  not  complicated  with  odors  from  clothing  and  sources  other  than 
man.  In  fact,  the  odors  observed  upon  entering  a  room  from  the  out- 
side fresh  air  often  furnish  better  evidence  of  imperfect  ventilation 
than  laboratory  tests. 

De  Chaumont  made  accurate  observations  and  found  that  when  the 
CO2   amounts  to   6   parts   per   10,000  the   atmosphere  begins  to  smell 

619 


620  MISCELLANEOUS 

close  and  stuffy.  Pettenkoffer  found  air  containing  7.5  parts  of  CO, 
per  10,000  from  the  expired  breath  to  have  a  marked  odor,  and  10 
parts  a  very  unpleasant  odor.  With  a  little  practice  various  grades  of 
vitiated  air  can  be  detected  up  to  10  or  12  parts  of  CO,  per  10,000. 

The  odors  from  marshes  and  from  decomposing  organic  matter  are 
not  apparently  hurtful.  One  of  the  most  famous  stenches  that  has 
been  recorded,  if  not  tlie  most  famous,  was  that  which  arose  in  1858 
and  1859  from  the  Thames,  which  at  that  time  was  grossly  polluted 
with  the  sewage  of  London  (Sedgwick).  Dr.  Budd  insisted  that  no 
very  serious  results  followed.  After  giving  his  proof  Budd  ^  states : 
"Before  these  inexorable  figures  the  illusions  of  half  a  century  van- 
ished in  a  moment."  We  now  know  that  odors  in  the  air  bear  no 
reference  to  contagion  or  infection  and,  however  unpleasant,  need  not 
be  feared  as  such.     Sewer  "gas"  is  discussed  on  page  638. 

The  effect  of  odors  upon  health  is  not  at  all  understood.  When  we 
sense  a  pleasant  smell  we  involuntarily  take  deeper  breaths;  on  the 
other  hand,  unpleasant  odors  diminish  the  respiratory  exchange.  The 
latter  are  accordingly  harmful  to  that  extent  and  the  former  stimulat- 
ing. Odors  influence  the  nervous  system  in  various  ways;  some  stim- 
ulate, others  depress  psychic  activity;  some  odors  have  a  well-known 
influence  upon  sexuality.  Occasionally  odors  are  so  disagreeable  that 
they  induce  nausea,  even  vomiting.  It  is  remarkable  how  quickly  we 
may  become  accustomed  to  odors,  but  because  our  sense  of  smell  has 
been  dulled  is  no  guarantee  that  the  cause  of  the  odors  may  not  con- 
tinue to  produce  its  effects.  Leonard  Hill  thinks  that  it  is  very  doubt- 
ful if  the  unpleasant  smelling  exhalations  of  the  bodies  of  men  have 
any  ill  effects  on  men  accustomed  to  them,  and  not  of  esthetic  tem- 
perament. 

Light. — All  the  rays  of  the  sun  pass  tlirough  the  atmosphere  before 
they  reach  the  earth. ^  The  air  acts  as  a  differential  filter,  holding  back 
many  rays,  especially  those  of  shorter  wave-length;  that  is,  the  ultra- 
violet end  of  the  spectrum.  These  rays  have  marked  chemical  power. 
Bunsen  and  Eoscoe  investigated  this  question  of  the  atmospheric  absorp- 
tion of  the  chemical  rays  of  the  sun,  and  came  to  the  conclusion 
that  in  passing  through  the  atmosphere  the  ultraviolet  rays  lost 
about  66  per  cent,  of  their  chemical  power.  We  have  already  seen 
that  many  of  the  heat  rays  are  also  absorbed  by  the  atmosphere. 
"More  heat  and  we  might  be  roasted,  more  light  and  we  might  be 

'Dr.  William  Budd:  "Typhoid  Fever:  Its  Nature,  Mode  of  Spreading,  and 
Prevention,"  pp.  148-151.  London,  1873.  This  is  a  remarkable  contribution 
■which  the  student  is  advised  to  read. 

^  The  waves  of  light  are  not  waves  of  the  atmosphere,  but  of  the  ether;  how- 
ever, they  are  absorbed,  reflected  or  refracted  by  the  dust  and  moisture  contained 
in  the  air.  It  is  convenient  to  consider  light,  as  well  as  electricity  and  radio- 
activity, at  this  point. 


ELECTRICITY  621 

blinded,   more   chemical   energy   and  we  might  be   slain  like  the  mi- 
crobes. 

The  rays  of  shorter  wave-lengths  have  chemical  and  photodynamic 
powers  which  must  have  an  important  relation  to  health.  These  rays 
act  upon  photographic  negatives;  hasten  the  hatching  of  flies'  eggs 
and  frogs'  eggs;  they  sunburn  the  skin;  they  kill  many  bacteria,  in- 
eluding  the  tubercle  bacilli;  they  cause  heliotropism ;  they  combine 
chlorin  and  hydrogen  into  hydrochloric  acid;  they  cause  the  oxidation 
of  oxalic  acid  and  other  chemical  reactions;  they  blacken  silver  salts. 
It  has  been  shown  that  in  buckwheat  poisoning  (fagotoxismus)  these 
actinic  rays  play  an  important  part.  The  skin  eruptions  upon  the 
exposed  surfaces  in  pellagra  are  also  explained  upon  the  photodynamic' 
theory,  that  is,  the  poison  is  believed  to  be  activated  by  certain  light 
rays. 

The  air  as  a  filter  of  the  sun's  rays  bears  a  very  important  but 
little  understood  relation  to  life.  It  is  now  well  known  that  some  of 
the  sun's  rays  have  intense  chemical  and  "vital"  power.  We  know 
something  about  the  chemical  rays,  the  luminous  rays,  and  the  calorific 
rays,  but  there  are  doubtless  many  ether  vibrations  of  which  we  know 
nothing.  Macfie  speculates  that,  "even,  indeed,  as  the  crops  of  the 
northern  zone  outstrip  the  crops  in  the  south  of  France,  so  at  certain 
times  may  the  activity  of  nations  be  stimulated  or  depressed  by  at- 
mospheric variations  affecting  the  composition  of  solar  radiation." 

The  physiological  action  of  light  is  just  beginning  to  receive  the 
serious  attention  it  deserves.  We  are  all  familiar  with  the  calming 
effect  of  the  dim  religious  light  of  churches  and  the  stimulating  effect 
of  the  glare  of  the  theater.  The  intense  light  of  the  tropics  and  of 
high  altitudes  is  believed  in  some  way  to  bring  on  nervous  disorders, 
but  the  relation  is  but  vaguely  understood.  Some  of  the  ill  effects 
of  rooms,  attributed  to  bad  air  and  poor  ventilation,  are  due  in  part 
to  the  over-stimulation  of  excessive  illumination. 

Method  for  Measuring  Illumination. — The  method  which  is 
recommended  as  a  standard  procedure  depends  on  the  use  of  photo- 
sensitive paper,  such  as  can  be  obtained  from  any  dealer  in  photographic 
materials.  By  exposing  the  sensitized  paper  through  a  slot  in  a  card- 
board for  a  sufficient  period  of  time,  and  noting  the  number  of  seconds 
or  minutes  consumed  to  match  in  depth  a  standard  shade  of  color,  the 
intensity  of  light  can  be  determined  with  accuracy.  If  a  fresh  piece 
of  paper  is  exposed  to  the  direct  rays  of  the  sun  for  three  seconds  it 
will  assume  a  shade  which  can  be  used  as  a  standard  for  a  given  series 
of  tests.  The  intensity  of  light  at  other  points  may  be  compared  with 
this  by  noting  the  number  of  seconds  required  to  color  a  fresh  piece  of 
paper  from  the  same  lot  to  the  same  shade. 

Electricity. — The  question  of  electricity  is  also  a  question  of  vibra- 


622 


MISCELLANEOUS 


tions,  not  of  the  air,  but  of  ether,  and  one  shrouded  in  much  obscurit}'. 
The  electric  potential  of  the  air  varies  considerabW.  It  is  highest  in 
winter  and  lowest  in  summer,  and  shows  diurnal  variations.  It  is  in- 
creased by  winds  and  is  especially  increased  by  the  condensation  of  vapor. 
It  also  increases  as  we  ascend. 

It  is  assumed  that  electric  changes  in  the  air  and  in  other  objects 
surrounding  us  exercise  an  influence  on  health  and  vitality,  but  the  in- 
fluence is  obscure  and  mainly  a  matter  of  conjecture. 

Eadioactivity. — Soon  after  the  discovery  of  radium  by  the  Curies 
it  was  proved,  chiefly  through  the  investigations  of  El=ter  and  Geitel, 
that  the  air  and  soil  and  certain  mineral  springs  contained  radioactive 
substances.  Xewly  fallen  rain  and  snow  are  also  radioactive.  Air 
drawn  from  the  soil  by  means  of  a  pipe,  or  air  shut  up  in  underground 
cellars  and  caverns,  is  specially  radioactive,  as  is  also  the  air  on  moun- 
tain tops.  The  air  in  clear  weather  has  greater  radioactivity  than  in 
dull  weather. 

Certainly  radioactive  substances  have  important  physiological,  physi- 
cal, and  chemical  effects.  They  ionize  the  air,  rendering  it  a  conductor 
of  electricity;  they  cause  a  fluorescence  of  certain  chemical  substances; 
they  produce  a  sensation  of  light  if  they  strike  the  eye ;  and  if  too  active 
may  cause  destruction  of  living  tissue.  Substances  so  potent  must  have 
some  physiological  influence. 

Smoke. — Smoke  is  a  product  of  combustion  and  consists  of  a  mix- 
ture of  gases  containing  solid  particles.  Ordinary  smoke  consists  largely 
of  unburned  carbon  particles,  hydrocarbons,  and  other  pyroligneous 
products,  gases,  some  of  them  poisonous,  such  as  carbon  monoxid,  also 
mineral  acids,  etc.  Angus  Smith  gives  the  following  analysis  of  smoke 
from  a  common  house  fire : 

Smoke  from  a  Common  House  Fire 


Carbon 
Dioxid 

Carbon 
Monoxid 

Oxygen 

Nitrogen 

Gas  from  chimney  4  ^eet  above  the  f 
fireplace \ 

0.35 
1.65 

0^38 

16.93 
19.29 

80.02 

78.68 

Gas  from  the  middle  of  a  good  fire. 
A  great  mass  of  coal  over  the  fire,  ^ 
the  gas  taken  from  below  the  glow- 
ing mass 

19.46 
20.90 
17.50 
17.44 

0.09 
0.10 

o^eo 

0.39 

80.45 
79.00 
80.04 
82.17 

A  heap  of  glowing  coal,  gas  taken  close 
to   spot   where   carbonic   oxid   was 
burning 

15.43 

18.17 

3.49 

2.48- 

0.96 

80.12 
79.35 

Gas  from  clear  fire  below f 

16.10 
17.21 
18.20 

0^99 

4.95 
4.25 

78.95 

Gas  from  the  same  fire  at  upper  part, 
1  inch  below  the  surface 

78.54 
78.21 

SMOKE 


623 


Dr.  Cohen  of  the  Manchester  Air  Analysis  Committee  gives  the 
following  analysis  of  soot  collected  from  the  roofs  of  glass  houses  in 
Kew  and  Chelsea : 


Carbon 

Hydrocarbons 

Organic  bases  (pjrridins,  etc.) 

Sulphuric  acid 

Hj'drochloric  acid 

Ammonia 

Metallic  iron  and  magnetic  oxid  of  iron 

Mineral  matter  (chiefly  silica  and  ferric  oxid) 
'^'ater  not  determined  (say  difference) 


Kew 
Per  Cent. 


42.5 

4.8 

'4^6 
0.8 
1.1 

ii'.h 

5.3 


Large  manufacturing  chimneys  are  the  chief  offenders.  There  are 
two  main  causes  of  smoky  chimneys :  ( 1 )  insufficient  boiler  capacity, 
and  (2)  improper  stoking.  The  cure  of  the  smoke  nuisance  consists 
in  the  installation  of  boilers  of  sufficient  power  so  that  they  need  not 
be  forced,  and  the  use  of  mechanical  stokers.  The  electrification  of 
railroads  and  the  more  general  use  of  electric  power  generated  from 
water  pressure  help  materially  to  lessen  the  amount  of  smoke  in  cities. 

The  London  County  Council  permits  black  smoke  for  five  minutes 
after  the  lighting  of  furnaces.  Other  towns  allow  as  much  as  15  minutes. 
Most  laws  distinguish  between  black  smoke  and  white  smoke,  although 
the  one  is  about  as  pernicious  as  the  other. 

In  Boston  the  density  of  the  smoke  is  graded  into  four  classes,  in 
accordance  with  Eingelmann's  chart.  This  is  a  rather  complicated  sys- 
tem, depending  upon  the  character  of  the  stack,  the  density  of  the 
smoke,  and  the  time,  as  shown  in  Fig.  86. 

The  amount  of  smoke  in  some  manufacturing  centers  is  almost  in- 
credible. Dr.  W.  N".  Shaw  estimates  that  London  gives  to  the  atmos- 
phere every  day  about  7,000,000  tons  of  smoky  air  containing  over  400 
tons  of  soot,  and  he  calculates  that  smoke  deprives  London  of  about  one- 
sixth  its  possible  sunlight  and  daylight  in  summer  and  about  one-half 
its  possible  sunlight  and  daylight  in  winter. 

The  injurious  effect  of  smoke  on  health  has  perhaps  been  overesti- 
mated. It  acts  directly  and  indirectly.  Directly  it  irritates  the  mucous 
membranes  of  the  upper  respiratory  passages,  and  Asher  and  also 
Eubner  believe  that  it  increases  the  mortality  from  acute  pulmonary 
diseases.  They  state  that  smoke  and  soot  predispose  to  acute  pulmo- 
nary tuberculosis.  Indirectly  smoke  is  a  source  of  dirt  and  general 
nuisance  and  leads  to  depression  of  the  spirits.  It  shuts  out  the  light, 
soils  with  soot,  and  deters  the  opening  of  windows  in  order  to  let  in 
fresh  air.     The  presence  of  mineral  acids  in  the  air  has  a  corrosive  in- 


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624 


DUST  625 

fluence  upon  inorganic  substances,  and  doubtless  acts  injuriously  upon 
plant  and  animal  life.  The  economic  losses  from  the  soiling  action  of 
soot  are  enormous.  Even  if  it  were  not  injurious  to  health,  smoke  is 
so  evident  a  nuisance  that  communities  are  justified  in  every  effort  to 
check  and  prevent  this  growing  abomination. 

Smoke  polluted  with  poisonous  chemical  vapors  may  be  quite  serious. 
Thus,  hydrogen  sulphid,  found  in  large  quantities  in  the  smoke  generated 
in  sulphate  of  ammonia  and  tar  works  and  from  alkali  wastes,  is  a 
poisonous  gas.  The  arsenical  vapors  given  off  chiefly  from  lead  and 
copper  smelters  kill  vegetation  for  wide  areas  around. 

Fog. — Fogs  are  caused  by  the  condensation  of  water  vapor  on  par- 
ticles of  dust.  Dust  particles  have  a  varying  capacity  for  condensing 
and  attracting  moisture,  depending  upon  their  power  of  radiating  heat 
and  on  their  affinity  for  water.  Carbon  dust  is  hygroscopic  and,  there- 
fore, encourages  fogs.  The  ammonia  and  sulphuric  acid  in  smoky  air 
also  occasion  and  aggravate  fog.  The  air  of  manufacturing  cities, 
therefore,  possesses  all  the  elements  to  form  a  fine  persistent  fog  which 
forms  a  "chemical  pall"  between  the  city  and  the  sky. 

The  more  carbon  a  fog  contains  the  blacker  it  is.  The  general  re- 
sult of  a  fog  is  to  shut  out  sunlight  and  fresh  air  and  to  "partially 
suffocate  unfortunate  citizens  in  clouds  of  noxious  chemicals."  Fog 
contains  all  the  irritating  properties  of  smoke  in  a  concentrated  form, 
and  it  also  in  a  measure  prevents  the  escape  of  the  city-made  carbon 
dioxid.  The  CO2  in  the  city  air  during  a  fog  may  rise  to  10  parts  per 
10,000.  If  smoke  is  bad  fog  is  ten  times  worse.  It  has  been  shown 
that  during  city  fogs  sickness  increases  and  the  death  rate  rises.  From 
the  economic  standpoint  fog  causes  greater  financial  losses  than  smoke. 
Eussell  calculates  the  annual  loss  to  the  people  of  London  from  fog  to 
total  about  $9,000,000  a  year.  The  main  items  in  this  loss  consist  in 
extra  washing,  including  extra  soap,  the  damage  to  dresses,  curtains, 
carpets,  and  textile  fabrics,  the  replacing  of  wall-papers,  and  the  paint- 
ing of  houses,  the  restoring  of  gilt  and  metal  work,  the  slow  destruction 
of  granite,  marble,  and  stonework  of  buildings,  the  extra  cost  of  ar- 
tificial illumination,  etc.  This  estimate  does  not  include  the  losses 
resulting  from  its  action  on  health. 

Dust. — Dust  is  not  only  a  nuisance,  but  under  certain  conditions  is 
known  to  be  prejudicial  to  health.  Dust  is  in  reality  a  normal  and  very 
important  constituent  of  the  air;  it  exists  everywhere  in  the  atmosphere 
and  profoundly  affects  some  of  the  physical  conditions  of  our  environ- 
ment. One  of  the  most  important  functions  of  dust  is  to  limit  the 
humidity  of  the  air  by  causing  the  precipitation  of  moisture  in  the  form 
of  rain,  and  to  help  control  temperature  by  the  formation  of  clouds, 
mists,  and  fogs.  Aitken,  who  has  made  a  special  study  of  this  subject, 
says  that  without  dust  "every  blade  of  grass  and  every  branch  of  tree 


626  MISCELLANEOUS 

would  drip  with  moisture  dej3osited  by  the  passing  air;  our  dresses 
would  become  wet  and  dripping,  and  umbrellas  useless ;  but  our  miseries 
would  not  end  here.  The  insides  of  our  houses  would  become  wet; 
the  walls  and  every  object  in  the  room  would  run  with  moisture." 
Without  dust  there  would  be  no  rain,  no  clouds,  no  mist,  for  the  water 
vapor  which  condenses  upon  each  particle  of  dust  forms  the  nucleus 
of  a  raindrop. 

Dust  disperses  the  light  and  decreases  the  transparency  of  the  at- 
mosphere, especially  if  the  atmosphere  be  also  humid.  What  is  known 
as  haze  is  really  dust  carrying  a  minute  amount  of  moisture. 

Although  dust  particles  are  universally  present  in  the  known  at- 
mosphere, they  are  very  irregularly  distributed.  Organic  dust  exists 
only  in  the  lower  strata,  while  inorganic  particles  are  found  wherever 
the  air  has  been  examined.  Ordinarily  there  is  more  dust  indoors 
than  in  outdoor  air.  The  size  of  the  dust  particles  varies  enormously, 
from  gross  masses  to  microscopic  and  ultramicroscopic  particles.  The 
vast  numbers  and  universal  presence  of  these  particles  may  be  realized 
by  examining  a  sunbeam.  Air  free  of  dust  is  an  artificial  product- 
obtained  only  with  special  care  and  in  small  amounts  in  the  laboratory. 

Most  of  the  dust  is  torn  from  the  earth  by  the  winds;  much  of  it 
comes  from  the  carbon  and  other  particles  in  smoke;  considerable 
amounts  consist  of  minute  grains  of  salt  derived  from  sea  spray;  and 
great  quantities  are  added  by  volcanoes.  Finall}',  the  air  contains  in- 
terplanetary particles  which  fall  through  it  in  a  constant  shower. 

The  spectrum  shows  the  bands  of  sodium  everywhere  in  the  at- 
mosphere. This  is  lifted  into  the  air  by  the  wind  from  the  sea  spray. 
The  water  evaporates,  leaving  the  salt  particles  to  float  about  at  the 
will  of  the  wind. 

Organic  dust  consists  of  the  dry  and  disintegrated  particles  wfiich 
are  blown  into  the  air  from  the  animal  and  plant  kingdoms.  They 
consist  of  epithelial  scales,  seed,  spores,  bacteria,  pollen,  plant  cells, 
fluff  of  various  kinds,  bits  of  insects,  starch,  pus  cells,,  alga?,  rotifers, 
fragments  of  hair,  feathers,  and  bits  of  tissue,  fibers  of  cotton,  etc. 

The  inorganic  dust,  which  is  derived  mostly  from  the  soil,  from 
the  sea,  and  from  interplanetary  space,  consists  chiefly  of  silica,  alumin- 
ium silicate,  calcium  carbonate,  calcium  phosphate,  magnesia,  iron  oxid, 
sodium  chlorid,  etc. 

Dust  particles  may  be  carried  enormous  distances  by  the  winds. 
Ehrenberg  detected  organisms  belonging  to  Africa  in  the  air  of  Ber- 
lin; and  fragments  of  infusoria  belonging  to  the  plains  of  America 
in  the  air  of  Portugal.  The  smoke  of  the  burning  of  Chicago  reached 
to  the  Pacific  coast.  The  volcanic  dust  of  Krakatoa,  consisting  chiefly 
of  glassy  pumice,  was  found  for  years  in  our  atmosphere,  and  it  is 
assumed  that  some  of  it  may  have  traveled  several  times  around  the 


DUST  627 

world.  Macfie  has  seen  in  the  Canary  Islands  clouds  of  dust  sufficient 
to  obscure  the  sun,  though  the  dust  had  come  all  the  way  from  the 
African  mainland.  All  of  us  living  on  the  Atlantic  seaboard  have 
seen  the  yellow  days  caused  by  forest  tires  several  thousands  of  miles 
away. 

Dust  and  Disease. — "Normal"  atmospheric  dust,  free  from  bacteria, 
causes  no  appreciable  irritation  of  the  healthy  respiratory  mucous  mem- 
branes. Dust  becomes  injurious  when  excessive  in  amount  or  when  irri- 
tating in  character,  or  when  it  contains  injurious  microorganisms;  the 
injury  also  depends  upon  the  constancy  of  its  presence  and  somewhat 
upon  the  susceptibility  of  the  individual. 

Dust  may  act  indirectly  as  a  predisposing  cause  of  many  infections, 
as  well  as  directly  irritating  and  inflaming  the  respiratory  passages. 
The  statement  that  dust  opens  the  door  to  tuberculosis  and  other 
infections  of  the  air  passages,  such  as  common  colds,  influenza, 
pneumonia,  etc.,  can  no  longer  be  questioned.  We  must  first  limit 
ourselves  to  a  consideration  of  the  effect  of  dust  free  of  noxious  bac- 
teria; in  the  next  section  we  will  discuss  the  question  of  bacteria  in 
the  air. 

The  general  effect  of  mineral  dust  breathed  for  a  long  period  of  time 
is  to  cause  an  irritation  of  the  mucous  membranes  and  an  inflammatory 
condition  of  the  lung  tissue.  The  term  pneumonohoniosis  is  a  general 
name  for  affections  of  this  kind.  The  term  is  modified  according  to 
the  various  kinds  of  dust.  Thus,  anthracosis  is  caused  by  coal  dust; 
siderosis  by  iron  or  steel  dust;  silicosis  or  chalicosis  by  stone  dust; 
hyssinosis  by  cotton  particles  or  vegetable  fiber  dust. 

In  certain  cases  the  dust  is  retained  as  deposits  in  the  lungs  and 
neighboring  lymph  glands  without  further  damage.  The  lungs  and 
bronchial  glands  of  all  adults  are  more  or  less  discolored  from 
particles,  which  are  constantly  inhaled.  The  particles  are  taken  up  by 
the  phagocytes  and  deposited  in  the  lymphatic  spaces  of  the  lung  or 
carried  to  the  neighboring  lymph  glands,  where  they  are  enmeshed. 
Under  certain  circumstances  the  dust  irritates  the  delicate  structures 
and  leads  to  infections  and  destruction  of  tissue.  Thus,  we  hear  of 
stone  mason's  phthisis,  steel  grinder's  phthisis,  and  potter's  rot.  Among 
the  dusty  trades  may  be  mentioned  pottery  and  earthenware  manufac- 
ture, cutlery  and  file-making,  certain  departments  of  glass-making,  cop- 
per, iron,  lead,  and  steel  manufacturing,  stone-cutting,  chimney-sweep- 
ing, textile  trades,  etc.  Oliver  ("Diseases  of  Occupation")  examined 
the  atmosphere  in  which  the  brushers-off,  the  finishers,  and  the  porce- 
lain-makers generally  work,  and  found  it  to  contain  640  million  par- 
ticles of  dust  per  cubic  meter  of  air,  while  several  of  the  finishers,  i.  e., 
the  persons  whose  work  consists  in  removing  the  excess  of  the  dried 
glaze  on  the  ware,  are  often  breathing  an  atmosphere  containing  680 


628  MISCELLANEOUS 

million  particles  of  dust  to  the  cubic  meter.  It  is  little  wonder  that 
broncliitis  and  plithisis  are  common.^ 

Dust  consisting  of  inorganic  particles  is  more  harmful  than  dust 
consisting  of  organic  particles,  because  the  former  are  sliarper  and 
more  irritating.  House  dust  is  more  harmful  than  outside  dust,  not 
only  because  there  is  more  of  it,  especially  in  badly  ventilated  and  ill- 
kept  rooms,  but  because  it  is  more  apt  to  contain  living  pathogenic 
bacteria.  House  dust  may  be  kept  down  by  cleanliness  and  avoidance 
of  dry  dusting  and  sweeping;  the  use  of  vacuum  cleaning;  and  by  a 
free  system  of  ventilation.  Much  house  dust  is  blown  in  from  the 
outside,  and  some  of  it  comes  in  on  dirty  shoes.  In  buildings  ventilated 
with  a  mechanical  system  the  air  may  be  filtered  through  bags  or  passed 
through  a  water  curtain,  which  will  eliminate  much  dust.  Oiling  floors 
with  a  wax  or  paraffin  mixture  helps  to  keep  down  indoor  dust.  Car- 
pets tacked  down  are  sanitary  abominations  and  should  be  replaced 
with  rugs  that  permit  outdoor  cleaning  and  sunning. 

Street  dust  contains  coal  dust,  metallic  dust  from  the  operation  of 
trolley  cars,  material  swept  from  houses  and  from  shaking  rugs  from 
windows,  the  grinding  up  of  roadbeds  by  vehicles,  ashes,  and  other  ma- 
terials blown  from  barrels  and  teams;  the  bacteria  are  derived  from 
dried  fecal  matter  from  horses  and  other  animals,  dried  sputum,  the 
soil,  and  a  variety  of  other  sources.  Street  dust  may  contain  pathogenic 
organisms,  such  as  the  tubercle  bacillus,  many  varieties  of  cocci,  the 
colon  bacillus.  Bacillus  aerogenes  capsulatus,  and  possibh',  under  spe- 
cial conditions,  tetanus,  malignant  edema,  and  occasionally  otlier  path- 
ogenic microorganisms.  Street  dust,  therefore,  becomes  more  than  a 
nuisance,  for  it  is  not  only  irritating,  but  may  be  a  source  of  infection. 

To  keep  down  street  dust  requires,  first  of  all,  a  well-constructed 
road  with  a  good  surface,  oiled  or  properly  cared  for;  the  control  of 
animals;  the  covering  of  ash  barrels  and  carts  hauling  dusty  loads; 
the  use  of  automobile  vacuum  cleaners  to  replace  the  old  or  the  pres- 
ent-day methods  of  dry  sweeping.  Attention  must  also  be  given  to 
spitting  on  sidewalks  and  streets,  the  enforcement  of  smoke  ordinances, 
the  more  extensive  flushing  of  streets,  and  general  attention  to  clean- 
liness. 

The  pollen  of  certain  plants  flying  in  the  air  as  dust  leads  to  hay 
fever  in  susceptible  individuals   (see  Anaphylaxis,  page  407). 

Methods  for  Examining  Dust. — Petri  Dish  Method. — The  sim- 
plest and  one  of  the  most  useful  methods  of  determining  the  amount 
of  dust  and  its  composition  is  by  means  of  suitable  receptacles,  such 
as  Petri  dishes,  upon  which  the  dust  is  allowed  to  settle  for  a  suffi- 
cient period  of  time  to  enable  a  considerable  quantity  to  accumulate. 

^  For  a  discussion  of  the  dusty  trades,  see  chapter  on  Industrial  Hygiene. 


DUST  629 

Particles  are  then  examined  under  the  microscope^  or,  if  desired,  they 
can  be  gathered  upon  a  watch  glass  and  weighed. 

Weighing. — The  air  may  be  passed  through  cotton  or  filters  of  other 
material,  the  quantity  of  air  being  measured  either  by  means  of  a  gas 
meter  or  other  device  and  the  increase  in  weight  of  the  filter  deter- 
mined. Whatever  the  filtering  medium  the  quantity  of  air  should  be 
large,  in  order  that  the  quantity  of  dust  may  be  appreciable  in  amount 
and  be  fairly  representative.  By  weighing  the  filtering  material  be- 
fore and  after  passing  the  air  through  it,  the  aggregate  weight  of  dust 
in  the  quantity  of  air  taken  for  examination  can  be  determined.  It  is 
necessary  to  guard  against  increase  in  weight  of  the  filtering  material 
through  the  absorption  of  water.  This  can  be  done  by  placing  the 
filtering  material  in  a  desiccator  before  and  after  filtration  and  just 
before  weighing  in  each  case. 

The  Koniscope. — The  koniscope,  invented  by  Professor  John  Ait- 
ken,  consists  of  two  brass  tubes  connected  at  right  angles  and  suitably 
fitted  with  stopcocks  and  a  small  air  pump.  By  exhausting  the  air 
from  one  of  the  tubes,  allowing  the  space  to  become  saturated  with 
water  vapor  by  evaporation  from  wet  blotting  paper  within,  and  then 
allowing  this  moisture  to  condense  upon  the  dusty  atmosphere  under 
examination,  clouds  of  different  degrees  of  density  will  form  inside 
the  tube.  The  approximate  density  of  the  clouds  can  be  measured  by 
looking  through  the  tubes,  windows  being  provided  for  this  purpose. 
A  table  is  supplied  with  the  instrument  to  give  the  approximate  number 
of  dust  particles  corresponding  to  clouds  of  different  degrees  of  density. 


43 


CHAPTER    IV 
BACTERIA    AND    POISONOUS    GASES    IN    THE   AIR 

BACTERIA   IN   THE    AIR 

The  number  of  bacteria  in  the  air  ordinarily  has  a  direct  relation 
to  the  amount  of  dust;  in  fact,  many  of  the  bacteria  in  the  air  are 
attached  to  dust  particles.  Bacteria  in  the  air  are  commonly  consid- 
ered as  one  kind  of  dust,  but  on  account  of  their  significance  they 
are  given  separate  consideration. 

Bacteria  are  not  found  everywhere  in  the  air;  uninhabited  places 
are  quite  free  and  the  number  diminishes  as  we  ascend. 

Bacteria  do  not  multiply  in  the  air;  in  fact,  most  of  them  soon 
die,  especially  when  exposed  in  dry  air  to  sunshine.  For  the  most 
part,  the  bacteria  in  the  air  belong  to  the  harmless  varieties,  although  the 
number  and  kind  vary  greatly  with  circumstances.  They  come  chiefly 
from  the  soil  and  are  carried  into  the  air  by  the  wind  and  traffic 
movements;  that  is,  bacteria  in  the  air  are  derived  from  practically 
the  same  sources  as  dust.  The  dangerous  bacteria  in  the  air,  how- 
ever, come  directly  or  indirectly  from  man  and  some  of  the  lower  ani- 
mals. 

The  number  of  bacteria  differs  greatly  with  the  local  conditions. 
There  are  more  in  the  air  of  towns  than  in  the  open  country;  few 
in  high  moimtains,  desert  places,  or  at  sea;  more  in  windy  weather 
than  calm  air;  more  indoors  than  in  outside  air;  more  in  dry  air 
than  in  moist  air;  more  before  than  after  rain.  The  air  of  badly 
ventilated  rooms,  especially  if  not  kept  clean,  contains  very  many  bac- 
teria, and  more  when  occupied,  as  the  movements  of  the  occupants  stir 
up  the  dust. 

Miquel  of  the  Observatory  of  Montsouris  studied  the  number  of 
bacteria  in  the  air  of  various  localities.  He  found  about  150  per  cubic 
foot  in  the  air  of  Paris,  but  only  6  after  rain;  on  the  top  of  the 
Pantheon  he  found  II/2 ',  in  the  streets  about  12  per  cubic  foot ;  in  a 
neglected  hospital  3,170;  in  a  gram  of  laboratory  dust  75,000,  and  in 
a  gram  of  house  dust  2,100,000. 

Fliigge  considers  that  on  the  average  there  are  about  one  hundred 
630 


BAOTEEIA    in    the    AIE  .        631 

microorganisms  to  a  cubic  meter  of  city  air — an  average  evidently  be- 
low that  of  Paris. 

Dr.  Jean  Binot  did  not  find  a  single  bacterium  in  100  liters  of 
outside  air  taken  at  the  summit  of  Mont  Blanc;  and  he  found  a 
progressive  decrease  in  the  number  as  the  height  increased.  Thus,  he 
found : 

At  Montanvert    49 

At  the  Mer  de   Glace 23 

At  the  Place  de  1' Aiguille 14 

At  the  Grand  Malet    8 

At  the   Grand   Plateau    6 

On   the  summit    0 

Again,  Graham  Smith  found  at  the  top  of  the  Clock  Tower  of  the 
Houses  of  Parliament  in  London  only  one-third  of  the  number  at 
ground  level. 

Pasteur,  in  experiments  that  will  ever  remain  classic,  exposed  or- 
ganic infusions  in  flasks  to  the  air  of  various  places,  and  used  the  re- 
sults thus  obtained  to  prove  the  presence  or  absence  of  bacteria  in  the 
air  and  to  dispel  the  illusion  of  spontaneous  generation.  Of  20  such 
flasks  exposed  to  the  air  of  the  Mer  de  Glace  19  showed  no  contamina- 
tion. About  the  same  time  (1875)  Tyndall  exposed  27  flasks  contain- 
ing an  infusion  to  the  air  of  the  Aletsch  glacier  (8.000  feet) ;  none 
showed  putrefaction,  while  90  per  cent,  of  the  flasks  opened  in  a 
hayloft  were  "smitten." 

It  is  estimated  that  a  person  living  in  London  breathes  about  300,- 
000  microbes  in  the  inspired  air  each  day. 

The  expired  air,  during  normal  respirations,  is  practically  bacteria- 
free,  no  matter  how  many  may  be  contained  in  the  inspired  air.  The 
moist  mucous  membranes  of  the  upper  respiratory  passages  act  as  a 
bacterial  trap.  When  the  expired  air  contains  bacteria  it  is  only  as  a 
result  of  coughing,  sneezing,  talking,  or  other  forced  expiratory  efforts 
(see  Droplet  Infection). 

The  harmful  bacteria  in  the  air  and  the  danger  of  contracting  dis- 
ease through  air-borne  infection  are  considered  in  the  next  section. 

Method  for  Determining  Bacteria  in  the  Air. — A  rough  idea  of 
the  bacterial  population  of  the  air  may  be  obtained  by  exposing  suitable 
culture  media  in  Petri  plates  for  various  periods  of  time,  and  counting 
the  colonies  which  develop  from  the  germs  falling  upon  them. 

A  large  number  of  different  devices  have  been  described  for  a  more 
accurate  determination  of  the  number  of  bacteria  in  the  air.  These 
are  all  adaptations  of  three  general  methods:  (1)  filtration  of  air;  (2) 
bubbling  air  through  some  liquid  medium;  (3)  precipitating  the  bac- 
teria from  a  given  volume  of  air.  Each  of  these  methods  can  be  made 
to  give  fairly  satisfactory  results  in  the  hands  of  competent  workers. 


632     ]?ACTER1A  AND  POISONOUS  GASES  IN  THE  AIR 


but  tlie  Committee  of  tlie  American  Public  Health  Association  recom- 
mend the  following  method  of  Petri  on  account  of  its  simplicity  and 
general  api)licability. 

Filtration  ]\Ietitod  of  Petiu. — The  filter 
tubes  are  glass  tubes  II/2  cm.  in  diameter  and  10 
cm.  long.  In  the  cud  of  each  is  placed  a  per- 
forated cork  stopper,  through  which  a  glass  tube 
(!  mm.  in  diameter  is  passed.  The  filtering  ma- 
terial consists  of  sand  whicli  has  been  passed 
through  a  100-mesh  sieve.  The  sand  in  the  filter 
tube  is  1  cm.  deep  and  supported  by  a  layer  of 
bolting  cloth  covering  the  cork.  Two  filtei-  tubes 
are  connected  in  tandem,  and  a  measured  volume 
of  air,  10  liters  or  more,  is  drawn  througli  at  a 
constant  rate  by  suction.  The  suction  is  ap])lied 
by  means  of  an  aspirator  of  known  volume,  pref- 
erably one  of  the  double  or  continuous  type. 
Fig.  87. — Magnus  As-  ^.,.  ,,        ..^  .,  ,^.       ,^^,  ',, 

piRATOR.  Either   the   Magnus    aspirator    (rig.  <S7)    or   tlie 

double  aspirator  (Fig.  88)  are  suitable  for  this 
purpose.  Before  using  a  pair  of  filter  tubes  a  test  for  possible  leakage 
is  made  by  placing  the  thumb  over  the  cotton  stopper  and  applying  the 
aspirator;  if  the  suction  is  weak  or  absent  the  corks  must  be  tightened 
or  the  tubes  discarded.  All  corks  should  be  tightened 
and  connections  wired  and  the  apparatus  sterilized 
before  using  the  filters.  The  collection  of  the  sample 
should  take  from  1  to  2  minutes  per  liter. 

After  filtering  a  definite  volume  through  the  tubes 
the  sand  is  poured  into  10  c.  c.  of  sterile  water,  thor- 
oughly shaken,  and  aliquot  portions  plated  in  ordinary 
nutrient  agar,  all  plates  being  made  in  duplicate.  The 
plates  are  incubated  at  room  temperature  for  five  days, 
when  final  counts  are  made. 

Rettger's  Method. — A  new  and  improved  method 
of  enumerating  air  bacteria  has  just  been  described  by 
Rettger,^  which  commends  itself  as  the  best  method  yet 
devised.  The  method  consists  of  bubbling  a  given  quan- 
tity of  air  through  salt  solution.  The  bacteria  in  the 
air  are  trapped  in  the  salt  solution,  which  may  then  be 
planted  in  the  usual  way  and  the  number  of  colonies  counted. 

Air  and  Infection. — The  air  was  long  regarded  as  the  vehicle  and 
even  the  source  of  the  communicable  diseases.     Theories,  such  as  nox- 
ious effluvia,  poisonous  emanations,  and  infectious  miasmata,  gave  way 
with  the  advent  of  bacteriology.     When  the  early  classical  researches 
'Jour,  of  Med.  Res.,  June,  1910,  XXII,  3,  pp.  461-468. 


Fig.  88.— Double 
Aspirator. 


BACTEEIA    IN    THE    AIR  633 

of  Pasteur,  Tyndall,  and  others  showed  that  bacteria  exist  in  the  air 
almost  everywhere  in  greater  or  in  lesser  numbers,  the  conclusion  was 
jumped  at  that  the  air  must  be  particularly  dangerous.  Within  recent 
years,  however,  we  have  learned  that  the  air  is  not  very  much  to  be 
feared  on  account  of  the  bacteria  it  may  carry,  except  under  certain 
occasional  circumstances.  This  change  in  our  views  during  recent  times 
is  nowhere  better  illustrated  than  in  the  relation  of  the  air  to  surgery. 
During  the  early  days  of  antiseptic  surgery  so  much  fear  was  enter- 
tained for  the  bacteria  in  the  air  that  Lister  attempted  to  neutralize 
the  danger  with  carbolic  sprays  and  other  means;  now  the  surgeon 
pays  little  heed  to  the  air  of  a  well-kept  operating  room.  Instead 
he  ties  several  layers  of  sterile  gauze  over  his  mouth  and  nostrils  and 
over  his  head  to  guard  against  particles  falling  from  these  sources. 

It  was  one  of  the  great  surprises  when  bacteriologists  demonstrated 
that  the  expired  breath  under  normal  conditions  of  respiration  is  sterile. 

At  one  time  many,  if  not  most,  of  the  contagious  diseases  were 
believed  to  be  air-borne;  many  observations  are  on  record  purporting 
to  prove  that  contagium  may  be  carried  long  distances  through  the 
air.  With  the  increase  of  our  knowledge  concerning  the  modes  of  trans- 
mission of  infection  the  list  of  air-borne  diseases  has  steadily  dwindled. 
The  theory  is  reluctantly  given  up,  for  it  is  the  easiest  method  of  ex- 
plaining the  spread  of  the  readily  communicable  diseases.  There  are 
only  two  diseases  of  man,  viz.,  smallpox  and  measles,  which  may  pos- 
sibly be  air-borne,  in  the  sense  that  this  term  is  generally  used.  Both 
these  diseases,  are  so  readily  communicable  that  the  virus  seems  to  be 
"volatile";  it  is  assumed  that  the  active  principle  is  contained  in  the 
expired  breath;  however,  there  is  no  proof  of  this  assumption,  and  some 
evidence  to  the  contrary.  Further,  it  is  noteworthy  that  we  are  still 
ignorant  of  the  causes  and  the  precise  mode  of  entrance  of  the  con- 
tagium in  both  measles  and  smallpox.  Even  in  these  two  diseases  the 
radius  of  danger  is  much  more  limited  than  was  once  supposed  to  be 
the  case. 

The  more  the  transmission  of  the  communicable  diseases  is  studied 
the  less  the  air  is  implicated.  The  fact  that  malaria  (bad  air), 
yellow  fever,  and  other  diseases  are  conveyed  by  mosquitoes  has  robbed 
the  air  itself  of  false  accusations,  and  given  a  death  blow  to  miasms, 
effluvia,  and  intangible  theories.  Pettenkoffer  insisted  that  the  air 
became  contaminated  with  poisons  that  were  generated  in  a  polluted 
soil,  and  he  believed  that  these  emanations  were  responsible  in  part  for 
typhoid  fever  and  cholera.  Some  association  between  soil,  air,  and 
disease  still  persists  in  both  medical  and  lay  minds,  but  with  a  more 
precise  knowledge  of  the  causes  and  modes  of  transmission  of  infec- 
tions, such  as  typhoid  fever  and  cholera,  the  air  becomes  a  negligible 
factor.     Out-of-door  air  contains  relatively  few  bacteria;  further,  the 


634     BACTEKIA  AM)   I'UlSU.NULS  GASES  l.N    THE  MR 

dilution  is  enormous.  Most  microorganisms  pathogenic  for  man  soon 
die  wlien  dried  or  when  exposed  to  sunlight.  Whatever  danger,  tlien, 
resides  in  the  air,  so  far  as  living  principles  of  disease  are  concerned, 
is  found  rather  in  indoor  air,  and  especially  in  the  air  of  badly  ven- 
tilated, dusty,  and  crowded  places.  Here  the  danger  may  be  either 
from  the  bacteria-laden  dust  or  from  droplet  infection.  In  a  crowded 
and  stuffy  street  car,  in  a  poorly  ventilated  office,  or  in  a  closed, 
close  sickroom  it  would  be  very  easy  for  the  microorganisms  of  diph- 
theria, scarlet  fever,  whooping-cough,  measles,  pneumonia,  influ- 
enza, common  colds,  tuberculosis,  pneumonic  form  of  plague,  and  other 
infections  contained  in  the  secretions  from  the  nose  and  mouth  to 
be  held  in  the  air  in  sufficient  numbers  so  that  exposed  persons  may 
contract  the  disease.  This  probably  occurs  more  frequently  than  we 
are  at  present  inclined  to  admit. 

The  radius  of  danger  through  droplet  infection  is  quite  limited 
It  is  difficult  to  conceive  that  infection  may  be  carried  long  distances 
in  the  air  and  still  be  dangerous.  My  own  experience  indicates  that 
there  is  practically  no  hazard  in  establishing  a  hospital  for  contagious 
diseases  upon  the  high  road  or  even  in  a  thickly  inhabited  part  of  the 
city.  In  fact,  the  communicable  diseases  are  not  conveyed  from  ward 
to  ward  or  even  from  bed  to  bed  in  well-managed  hospitals. 

Chapin  states  that  many  contagious  hospitals  have  been  maintained 
for  years  with  no  increase  of  the  disease  in  the  vicinity,  as,  for  instance, 
at  Boston  and  Providence,  R.  I.  At  the  Kingston  Avenue  Hospital 
in  Brooklyn  various  diseases,  as  smallpox,  measles,  scarlet  fever,  and 
diphtheria,  are  treated  in  wards  only  a  few  feet  apart,  with  no  evidence 
of  aerial  transference.  At  North  Brother's  Island  the  tuberculosis 
ward  is  only  about  25  feet -from  the  diphtheria  ward,  but  the  tuber- 
culous patients  do  not  contract  diphtheria.  A  number  of  hospitals  for 
communicable  diseases  have  recently  been  built  with  entire  disregard 
of  aerial  infection.  At  the  hospital  of  the  Pasteur  Institute,  Paris, 
the  patients  are  each  cared  for  in  a  separate  ward  opening  into  a  com- 
mon hall.  The  same  nurses  go  from  case  to  case.  In  2I/2  years  after 
it  was  opened  in  1900  there  were  treated  2,000  persons,  of  whom  524 
had  smallpox,  443  diphtheria,  126  measles,  163  erysipelas,  92  scarlet 
fever,  and  166  non-diphtheritic  sore  throat.  The  only  evidence  of  the 
transfer  of  infection  was  the  development  of  four  cases  of  smallpox  and 
two  of  erysipelas.  In  the  Hopital  des  Infants  Malades  in  Paris  the 
beds,  instead,  of  being  in  separate  rooms,  are  separated  by  partitions. 
Of  5,017  cases  there  were  only  7  cross  infections,  6  of  measles  and  1 
of  diphtheria.  These  were  attributed  to  lapses  in  aseptic  precautions. 
Dr.  Moizard  thinks  that  this  experience  proves  that  even  measles  is  not 
air-borne.  Dr.  Grancher  in  another  Paris  hospital  has  two  wards  in 
which  there  are  no  partitions,  but  only  wire  screens  around  the  beds. 


POISONOUS    GASES    IN    THE    AIE  635 

simply  as  a  reminder  for  the  nurses.  He  also  insists  that  measles  is 
probably  not  an  air-borne  disease,  and  that  adjacent  patients  do  not 
necessarily  infect  one  another.  At  various  English  hospitals  similar 
methods  have  been  tried  with  success.^ 

While  the  air  plays  a  minor  role  in  the  spread  of  the  infections, 
bad  air  plays  an  important  part  in  reducing  vitality  and  predisposing 
to  disease.     This  will  be  discussed  presently. 

POISONOUS  GASES  IN  THE  AIR 

Some  of  the  poisonous  gases  of  the  air  come  from  natural  sources, 
as  marshes,  mines,  or  decomposing  organic  matter,  but  those  that 
concern  the  sanitarian  particularly  are  the  gases  which  arise  from  the 
works  of  man.  These  gases  are  carbon  monoxid,  ammoniacal  vapors, 
hydrochloric  acid,  carbon  bisulphid,  carburetted  hydrogen,  hydrogen 
sulphid,  etc. 

Carbon  Monoxid. — Carbon  monoxid  (CO)  is  a  frequent  and  serious 
cause  of  chronic  ill  health  or  acute  poisoning.  The  carbon  monoxid 
in  the  air  comes  principally  from  illuminating  gas,  but  it  is  also  found 
about  lime  kilns  and  where  coke  fires  and  brasiers  are  used  in  confined 
spaces;  also  from  iron  and  copper  furnaces,  from  coal  fires,  and  other 
sources.  Air  containing  0.4  per  cent,  of  carbon  monoxid  may,  in  one 
hour,  prove  fatal.  In  higher  concentration  a  person  may  be  overcome 
at  once  and  death  soon  ensues.  Chronic  poisoning  with  smaller  amounts 
may  lead  to  anemia,  depression,  and  other  symptoms. 

Carbon  monoxid  or  carbonic  oxid  is  a  colorless  and  practically  odor- 
less gas;  it  burns  with  a  pale  blue  flame.  Its  poisonous  action  depends 
upon  the  fact  that  it  combines  with  the  hemoglobin  of  the  red  blood 
corpuscles  to  form  carbon  monoxid  hemoglobin.  This  is  a  stable  com- 
pound which,  therefore,  prevents  the  hemoglobin  giving  up  its  oxygen 
to  the  tissues.  When  present  in  only  small  amounts  in  the  atmosphere 
the  effects  of  CO  may  be  compensated  for  by  a  polycythemia — an  in- 
creased number  of  corpuscles  taking  the  place  of  those  disabled. 

Carbon  monoxid  may  be  found  in  the  air  of  inhabited  rooms  as  a 
result  of  leaking  gas  fixtures,  imperfect  combustion  of  illuminating 
gas,  and  defects  in  apparatus  fed  by  coal.  Burning  charcoal  yields 
CO  in  great  abundance,  and  it  is  also  given  off  from  red-hot  cast-iron 
stoves,  and,  finally,  as  a  result  of  incomplete  combustion  of  coal  in 
furnaces  and  ranges. 

One  of  the  most  common  sources  of  carbon  monoxid  in  the  house- 
hold is  from  illuminating  gas.  Illuminating  gas  may  pass  from  a 
broken  gas  main  through  the  soil  into  the  cellar  and  thence  permeate 
a  dwelling;  this  is  aided  by  the  suction  and  pumping  action  of  the 
heating  apparatus  in  the  cellar.     In  passing  through  the  soil  illuminat- 

iChapin:  Jour.  Am.  Med.  Ass'n.,  Dec.  12,  1908,  Vol.  LI,  pp.  2,048-2,051. 


636     BACTEKIA  AND  POISOXOUS  GASES  IN  THE  AIR 

ing  gas  may  be  robbed  of  its  characteristic  odor,  thus  rendering  it  so 
much  more  dangerous  because  not  perceived.  The  danger  from  this 
source  is  further  increased  in  the  winter  time  and  in  cities  with  as- 
phaltum  and  concrete  pavements,  because  under  these  circumstances  the 
escape  of  gas  into  the  air  is  hindered  and  the  chance  of  more  of  it 
reaching  the  house  through  the  cellar  is  favored.  An  occasional  source 
of  CO  in  the  air  of  houses  is  through  hot-water  heaters,  using  illuminat- 
ing gas  as  fuel.  The  soot  gradually  collects  in  these  devices  and  may 
become  incandescent,  thus  furnishing  ideal  conditions  for  the  produc- 
tion of  carbon  monoxid.  In  the  arts  CO  is  formed  by  passing  water 
vapor  over  incandescent  carbon.  I  know  of  one  case  in  Washington 
where  CO  from  a  water  heater  collected  in  a  kitchenette  in  such  con- 
centration that  three  persons  were  overcome  upon  entering  the  room 
and  died.^ 

Illuminating  Gas.' — Illuminating  gas  may  be  harmful  either  from 
the  products  of  its  combustion  or,  more  so,  when  the  unconsumed  gas 
escapes  in  the  household.  The  two  principal  illuminating  gases  used 
are  coal  gas  and  water  gas.  The  poisonous  effects  of  botli  are  due 
mainly  to  the  carbon  monoxid  which  they  contain. 

Coal  gas  is  made  by  the  destructive  distillation  of  coal.  It  contains 
hydrogen,  marsh  gas,  and  carbon  monoxid,  occasionally  also  ethene, 
acetylene,  and  carbon  dioxid.  A  cubic  foot  of  coal  gas  completely 
burned  gives  to  the  atmosphere  about  one-half  a  cubic  foot  of  COg 
and  about  1.34  cubic  feet  of  water  vapor.  An  ordinary  gas  jet  burns 
about  6  cubic  feet  of  gas  per  hour,  and  thus  produces  about  3  cubic 
feet  of  CO,. 

^yater  gas  is  made  by  blowing  a  current  of  steam  tli rough  incan- 
descent coke  or  coal.  The  water  is  decomposed  into  hydrogen  and 
oxygen.  The  hydrogen  passes  on  and  the  oxygen  unites  with  the  carbon 
to  form  carbon  monoxid.  Water  gas  so  produced  burns  only  with  a 
pale  blue  flame.  It  is,  therefore,  enriched  in  a  carburetor  with  vapor- 
ized petroleum;  this  furnishes  the  hydrocarbons  necessary  to  give  a 
luminous  flame.  Water  gas  contains  about  30  per  cent,  of  carbon 
monoxid. 

The  effect  of  these  carbonaceous  illuminants  is  to  elevate  the 
temperature  and  increase  the  moisture  of  a  room.  They  also  add 
carbon  monoxid,  carbon  dioxid,  nitric  and  nitrous  acid,  compounds  of 
ammonia  and  sulphur,  marsh  gas,  carbon  particles  (soot),  acids  of  the 
fatty  group  in  small  but  variable  amounts.  The  following  instructive 
table  gives  the  comparative  candle  power  and  also  the  gases  and  heat 
produced  by  the  usual  forms  of  illuminants : 

^  For  methods  for  determining  carbon  monoxid  and  other  gases  in  the  air, 
see:  Haldane,  J.  S.:  "Methods  of  Air  Analysis,"  J.  P.  Lippincott  and  Co., 
1912. 


POISONOUS    GASES    IN    THE    AIR 


637 


Quantity 

Candle- 

Oxygen 

Carbon 

Dioxid 

Produced 

Moisture 

Heat 

Calories 

Consumed 

power 

Removed 

Produced 

Pro- 
duced 

grains 

cu.  ft. 

cu.  ft. 

cu.  ft. 

2,200 

16 

10.7 

7.3 

8.2 

1,400 

1,740 

16 

9.6 

6.5 

6.5 

1,137 

992 

16 

6.2 

4.5 

3.5 

1,030 

909 

16 

5.9 

4.1 

3.3 

1,030 

cu.  ft. 

5.5 

16 

6.5 

2.8 

7.3 

1,194 

4.8 

16 

5.8 

2.6 

6.4 

1,240 

3.2 

32 

3.6 

1.7 

4.2 

760 

3.5 

50 

4.1 

1.8 

4.7 

763 

lb.  coal 

0.3 

16 

0.0 

0.0 

0.0 

37 

Vitia- 
tion 
Equal  to 
Adults 


Tallow  candles 

Sperm  candles 

Paraffin  oil  lamp 

Kerosene  oil  lamp 

Coal  gas,  No.  5  Bats- 
wing  burner 

Coal  gas,  Argand  burner 

Coal  gas,  regenerative 
burner 

Coal  gas,  Welsbach  in- 
candescent  

Electric  incandescent 
light 


12.0 

11.0 

7.5 

7.0 

5.0 
4.3 

2.8 

3.0 

0.0 


Most  coal  contains  sulphur,  which  appears  in  coal  gas  as  sulphuric 
acid,  which  is  irritating  and  poisonous.  Most  of  the  sulphur  compounds 
in  coal  gas  are  removed  by  processes  of  purification  during  manufac- 
ture, but,  owing  to  the  difficulty  of  complete  removal,  20  grains  of  sul- 
phur in  every  hundred  cubic  feet  are  generally  allowed  by  law.  The 
sulphur  restrictions  have  recently,  but  unwisely,  been  removed  in  Eng- 
land. In  Massachusetts  the  legal  limit  has  been  raised  to  30  grains 
per  hundred  cubic  feet.  These  changes  were  brought  about  by  the 
claims  of  gas  companies  that  it  is  much  more  difficult  than  formerly 
to  procure  coals  low  in  sulphur,  so  that  the  processes  for  the  removal 
of  the  sulphur  have  become  costly  and  burdensome. 

Illuminating  gas  is  required  by  law,  in  Massachusetts  and  in  many 
other  places,  to  be  free  from  ammonia  as  well  as  sulphuretted  hydrogen, 
but  this  is  more  because  of  injury  to  fixtures  than  because  of  danger 
to  health. 

Water  gas  is  cheaper  than  coal  gas,  and  is,  therefore,  preferred  by 
gas  companies.  Usually  a  mixture  of  the  two  gases  is  supplied.  Ex- 
perience shows  that  if  water  gas  is  properly  diluted  with  coal  gas  the 
danger  is  greatly  lessened.  Illuminating  gas  containing  6  per  cent,  of 
carbon  monoxid  is  not  hazardous.  Most  cities  limit  the  amount  to  10 
per  cent.  In  1890  the  10  per  cent,  statute  was  repealed  in  Massachu- 
setts, and  it  is  since  then  that  the  marked  increase  in  illuminating 
gas  poisoning  has  occurred.  There  were  1,231  deaths  caused  by  il- 
luminating gas  in  Massachusetts  during  the  years  1886  to  1909.  About 
one-half  of  these  deaths  were  suicidal.  This  only  represents  the  fatal- 
ities, and  does  not  take  into  account  the  many  cases  of  chronic  poison- 
ing which  occur  in  the  home  and  in  the  industries  where  much  illumi- 
nating gas  is  used. 

Sedgwick  and  Schneider  ^  state  that  the  death  rate  from  poisoning 


"■Jour,  of  Infect,  Dis.,  Vol.  IX,  No.  3,  1911. 


638     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

by  illuminating  gas  in  Massachusetts  and  Rhode  Island  has  become 
nearly  equal  to  that  of  scarlet  fever  or  measles. 

Gas  pipes  in  a  dwelling  should  be  tested  from  time  to  time  with 
a  pressure  gage,  and  minor  leaks  from  faulty  stopcocks,  from  "rubber" 
tubing  used  for  droplights,  etc.,  should  be  carefully  searched  for  and 
corrected.  A  flaring  gas  burner  is  not  only  wasteful,  since  it  im- 
plies the  escape  of  unburned  gas,  but  is  also  harmful  to  health.  A 
gas  jet  should  burn  steadily  without  jumping  and  flaring. 

Other  Gases  in  the  Air. — Ammoniacal  Vapors. — Ammoniacal  va- 
pors irritate  the  conjunctiva,  but  have  no  other  evident  effect  on  health 
in  the  amounts  ordinarily  found  in  the  air. 

Hydrochloric  Acid  Vapors. — Hydrochloric  acid  vapors  in  large 
quantities  are  very  irritating  to  the  conjunctiva  and  respiratory  mucous 
membranes.  In  the  alkali  manufactures  they  are  sometimes  poured 
into  the  air  in  sufficient  quantity  to  destroy  vegetation.  When  in  suffi- 
cient concentration  they  may  induce  bronchitis,  pneumonia,  and  even 
destruction  of  lung  tissue,  as  well  as  inflammation  of  the  eyes. 

Carbon  Bisulphid. — Carbon  bisulphid  is  given  off  in  the  vulcaniz- 
ing of  India  rubber.  It  produces  headache,  vertigo,  pains  in  the  limbs, 
formication,  sleeplessness,  nervous  depression,  and  loss  of  appetite; 
sometimes  deafness,  dyspnea,  cough,  febrile  attacks,  and  even  para- 
plegia. The  effects  seem  due  to  a  direct  anesthetic  action  on  the  nervous 
tissue. 

Carburetted  Hydrogen. — As  much  as  200  to  300  volumes  per 
1,000  of  carburetted  hydrogen  may  be  breathed  for  a  short  time.  Above 
this  amount  it  produces  headache,  vomiting,  convulsions,  stertor,  di- 
lated pupil,  etc.  Breathed  in  small  quantities,  as  it  constantly  is  by 
some  miners,  it  is  not  known  to  produce  any  bad  effects,  although  such 
may  be  the  case. 

Hydrogen  Sulphid. — The  susceptibility  of  man  to  this  gas  varies. 
Its  dangerous  nature  is  fully  recognized  in  all  chemical  laboratories. 
The  effects  of  small  amounts  are  not  well  understood.  Thackrah  could 
find  no  bad  effects.  On  the  other  hand,  Hirt  believed  it  produced  chronic 
poisoning.  The  symptoms  are  chiefly  weakness,  depression,  anorexia, 
slow  pulse,  furred  tongue,  and  marked  pallor. 

Sulphur  Dioxid. — Sulphur  dioxid  is  extremely  irritating  and 
causes  bronchitis.  Those  exposed  to  the  fumes  in  the  bleaching  of 
cotton  and  worsted  goods  are  frequently  sallow  and  anemic. 

SEWER    GAS 

Sewer  gas,  once  a  hygienic  bugaboo,  is  now  not  seriously  regarded 
by  sanitarians.  Sewer  gas  became  the  residual  legatee  of  Murchinson's 
pythogenic  theory,  namely,  that  typhoid  fever  was  "produced  by  emana- 


SEWEE    GAS  639 

tions  from  decaying  organic  matter."  Sewer  "gas"  is  nothing  more 
or  less  than  air  containing  the  volatile  products  of  organic  decay  com- 
ing from  sewers  and  drains.  Sewer  gas  is  a  variable  mixture,  both  as 
to  composition  and  concentration.  Some  of  these  gases  are  more  or 
less  poisonous,  but  not  in  the  great  dilution  ordinarily  found  in  sewer 
air.  As  a  matter  of  fact,  the  air  of  sewers  is  ordinarily  freer  of  dust 
and  bacteria  than  the  corresponding  outside  air,  although  it  may  be  a 
little  higher  in  carbon  dioxid — 10  to  30  volumes  per  10,000.  It  is 
absurd  to  regard  sewer  gas  as  the  cause  of  diphtheria,  typhoid  fever, 
scarlet  fever,  and  other  communicable  diseases.  So  far  as  unpleasant 
odors  are  concerned,  they  are  more  apt  to  come  from  defective  drains 
or  unclean  and  unventilated  house  plumbing  than  from  a  well-con- 
structed sewer.  Workmen  employed  in  sewers  and  about  sewage  ordi- 
narily remain  hale  and  healthy. 

Bacteria  in  Sewer  Air. — When  it  was  found  that  there  are  no  dan- 
gerous volatile  poisons  in  sewer  air  attention  was  focused  upon  the  bac- 
teria; however,  Kageli  as  long  ago  as  1877  showed  that  putrescent  liquids 
Eept  in  the  same  sealed  vessel  for  over  two  years  did  not  infect  each  other. 
Sir  Edward  Frankland  then  showed  that  lithium  carbonate  in  solution 
did  not  contaminate  the  air,  but  that  when  effervescence  was  produced  the 
breaking  of  the  bubbles  on  the  surface  of  the  liquid  carried  the  lithium  a 
distance  of  21  feet  up  a  vertical  tube.  The  inference  was  that  sewage 
through  fermentation  or  splashing  may  send  bacteria  into  the  air. 
Pumpelly  in  1881  and  others  since  have  shown  that  bacteria  are  not 
given  off  from  a  liquid  if  the  surface  remains  unbroken,  even  though 
the  air  may  blow  over  it.  In  1893  Miquel  began  a  monumental  work 
upon  bacteria  of  the  air.  He  made  routine  observations  at  the  Mont- 
souris  Observatory,  and  for  four  years  compared  the  bacteria  in  the 
air  of  a  Paris  street  with  the  air  of  sewers.  He  found  sewer  air  rela- 
tively pure  from  a  bacteriological  standpoint.  Carnelly  and  Haldane 
in  1877  found  fewer  bacteria  in  the  sewers  under  the  House  of  Parlia- 
ment and  other  places  than  in  the  air  of  adjacent  streets.  The  num- 
ber of  bacteria  was  largest  in  the  best-ventilated  sewers,  because  these 
brought  the  street  bacteria  along  with  them.  Abbott  in  1894  showed 
that  cultures  of  B.  prodigiosus  are  not  carried  over  in  bubbles  produced 
by  natural  fermentation  (yeast  in  a  carbohydrate  medium),  but  may 
be  carried  a  short  distance  by  blo^ving  air  at  considerable  velocity 
through  the  culture.  He  concluded  that  the  danger  of  bacteria  being 
transmitted  from  sewage  into  the  air  under  ordinary  circumstances  is 
practically  negligible.  In  1907  Horricks  revived  this  question  by  plac- 
ing B.  prodigiosus  in  the  water-closets  of  a  large  military  hospital  in 
Gibraltar,  and  recovering  them  on  plates  suspended  on  top  of  the  soil 
pipes  and  in  manhole  openings.  His  work  gave  countenance  to  the 
views  of  a  number  of  English  sanitarians,  who  maintain  the  reality 


G40     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

of  the  danger  from  this  soiirce.  Winslow  repeated  Horrick's  experi- 
inoiits  in  li)0*,).  using  the  ordinary  sewage  of  Boston,  and  bv  using 
(piantitative  methods  threw  a  different  light  upon  Horrick's  conclusions. 
He  found  that  a  vigorous  foaming  produced  very  slight  bacterial  in- 
fection of  the  air — only  five  prodigiosus  colonies  in  30  liters  of  air. 
Further,  the  infection  always  remained  localized.  Generally  he  found 
the  air  of  house  drains  singularly  free  from  bacteria.  It,  therefore,  seems 
theoretically  possible,  but  very  imjjrobable,  that  infection  may  take 
place  in  this  way.  Practically  the  question  seems  to  have  little  impor- 
tance. Thus,  out  of  a  series  of  examinations  of  plumbing  systems  in 
actual  use,  Winslow  found  intestinal  bacteria  only  four  times  in  200 
liters  of  air,  and  these  directly  at  the  point  of  local  splashing. 

If  there  is  any  danger  of  sewage  bacteria  coming  into  our  houses, 
it  is  rather  that  they  are  dragged  in  by  rats,  roaches,  water  bugs,  and 
other  vermin  that  use  sewers  and  drains  as  highways. 

Ventilation  of  Sewers. — Sewers  cannot  be  constructed  airtight  on 
account  of  the  numerous  openings  into  them.  The  tension  of  the  air 
in  sewers  is  generally  not  very  different  from  that  of  the  atmosphere 
outside.  The  movement  of  the  air  is  generally  in  the  direction  of  the 
flow  of  the  current.  The  simplest  plan  of  ventilation  is  by  means  of 
a  shaft  from  the  top  of  the  sewer  to  the  surface  of  the  street  or  road 
above,  where  the  opening  of  the  shaft  should  be  covered  by  an  iron 
grating.  These  openings  are  usually  placed  at  intervals  of  100  yards 
or  so.  This  system,  which  is  in  common  use,  has  been  much  criticized, 
mainly  on  account  of  the  fact  that  the  objectionable  gases  are  discharged 
more  or  less  immediately  under  the  noses  of  passers-by.  To  meet  this 
objection  it  has  been  proposed,  and  actually  come  about  in  some  places, 
to  locate  tall  iron  shafts  at  suitable  intervals  to  permit  the  discharge 
of  air  and  gases  at  a  level  well  above  the  roofs  of  houses.  As  a  mat- 
ter of  fact,  if  sewers  are  well  constructed,  have  sufficient  fall  and  flow 
of  water,  there  will  be  no  accumulation  of  foul  gases.  One  of  the  main 
causes  of  decomposition  is  due  to  dead  ends.  These  should  not  be 
tolerated  by  the  engineer  in  charge  of  the  sewage  department.  Recently 
an  agitation  has  been  started  to  solve  this  question  of  sewage  ventila- 
tion by  advocating  the  abolition  of  the  intercepting  traps  on  the  house 
drains  between  the  sewer  and  the  house,  thus  converting  every  house 
drain  and  every  soil  pipe  into  so  many  sewer  ventilators.  There  are 
many  objections  to  this  plan,  as  it  would  destroy  the  drain  isolation 
between  each  house,  which  is  now  possible  from  the  sewer,  and  from 
the  neighboring  houses  of  the  district. 


CHAPTEE   V 
TRESH    AND    VITIATED    AIR 

THE    BENEFITS  OF   FRESH   AIR 

Fresh  air  is  nature's  tonic.  It  stimulates  digestion,  promotes  as- 
similation, improves  metabolism,  strengthens  the  nervous  system,  and 
increases  our  resistance  against  some  diseases.  It  is  a  common  ex- 
perience that  fresh  air  gives  us  a  general  feeling  of  well-being.  Much 
of  the  benefit  of  an  outdoor  life  comes  also  from  the  exercise,  diversion, 
sunshine,  and  other  factors.  The  stimulating  effect  of  outdoor  air 
varies  considerably  with  the  temperature  and  movements  of  the  air. 
Cold  air  is  especially  stimulating,  and  much  of  the  good  of  sleeping 
out  of  doors  is  perhaps  secondarily  due  to  the  tonic  action  of  cold. 
Sleeping  out  of  doors  or  with  open  windows  atones  for  much  bad  air 
during  the  daytime.  However,  the  good  results  of  fresh  air  may  be 
neutralized  by  undue  exposure  to  cold,  especially  in  the  young,  the 
aged,  and  the  feeble — or  even  in  robust  individuals  not  properly  pro- 
tected. 

"We  may  write  and  talk  as  much  as  we  please  about  the  horrors 
of  bad  air  and  the  importance  of  fresh  air,  but  we  should  never  in- 
duce people  to  sit  in  cold  drafts  and  sliiver  for  the  sake  of  pure  air, 
and,  in  fact,  we  would  not  want  to  do  it  ourselves"  (Macfie).  Extremes 
in  this  as  in  all  matters  hygienic  are  to  be  avoided.  It  is  important 
that  those  who  sleep  out  of  doors  or  sit  out  should  be  warmly  clad 
and  sufficiently  fed. 

THE    EFFECTS    OF    VITIATED    AIR 

The  effects  produced  by  an  atmosphere  vitiated  by  the  breath  and 
other  exhalations  from  human  beings  may  be  divided  into  acute  and 
chronic.  The  acute  effects  are  usually  lassitude,  headache,  vertigo, 
nausea,  vomiting,  and  even  collapse.  In  extreme  cases  death  may  en- 
sue. The  chronic  effects,  so  far  as  is  known,  include  anemia,  debility, 
and  disturbances  of  digestion.  Prolonged  exposure  to  vitiated  atmos- 
pheres also  influences  nutrition  and  metabolism,  depresses  vitality, 
and  lowers  the  resistance  to  certain  infections,  especially  to  the  pyogenic 

641 


642  FRESH    AND    VITIATED    AIR 

cocci,  the  tubercle  bacillus,  the  pneumococcus,  and  to  the  microorgan- 
isms causing  common  colds.  It  is  often  dithcult,  especially  in  the 
poorer  classes,  to  know  liow  much  is  due  to  bad  air  and  liow  nuicli  to 
poor  food,  overwork,  loss  of  sleep  and  rest,  worry,  and  other  inflictions 
of  poverty.  There  is  plenty  of  evidence  to  show  that  men  living  in 
insufficiently  ventilated  barracks  and  other  habitations  have  a  high 
death  rate.  The  lower  animals  under  like  conditions  in  crowded  and 
poorly  ventilated  stables  also  have  a  high  mortality.  The  statistical  evi- 
dence of  the  English  Barrack  and  Hospital  Commission,  published  in 
1861,  shows  that  men  living  a  considerable  portion  of  their  time  in 
badly  ventilated  rooms  have  a  higher  death  rate  than  those  having 
well-ventilated  rooms,  other  conditions  being  about  the  same.  The 
high  morbidity  and  mortality  in  crowded  places  are  due,  in  part  at 
least,  to  the  favorable  conditions  for  the  spread  of  the  communicable 
diseases,  and  must  not  be  laid  entirely  to  the  effects  of  vitiated  at- 
mospheres. 

Some  Extreme  Cases. — The  acute  and  fatal  effects  caused  by  breath- 
ing a  seriously  vitiated  atmosphere,  under  unusually  severe  conditions, 
are  well  illustrated  by  the  three  following  instances: 

After  the  battle  of  Austerlitz  300  Austrian  prisoners  were  shut 
into  a  prison  in  a  small  cellar,  and  260  were  killed  by  the  impure  air 
in  a  few  hours. 

In  the  tragedy  known  as  the  Black  Hole  of  Calcutta,  the  military 
prison  of  Fort  William,  January  18,  1756,  146  adults  were  shut  into 
a  room  only  18  feet  square  and  with  but  two  small  windows  on  one 
side  to  ventilate  it.  They  were  shut  in  at  8  P.  M.,  and  within  an 
hour  some  were  dead,  and  when  the  door  was  opened  at  6.20  next 
morning  only  23  were  found  to  be  alive.  One  of  the  survivors  gives 
the  following  description  of  the  horrors  of  the  night:  "At  this  period 
so  strong  a  flavor  came  from  the  prison  that  I  was  not  able  to  turn 
my  head  that  way  for  more  than  a  few  seconds  at  a  time.  Everybody 
except  those  at  the  windows  now  grew  outrageous  and  many  delirious. 
By  eleven  o'clock  greater  numbers  were  dead  or  dying,  and  tliose  living 
.were  in  an  outrageous  delirium  and  others  quite  ungovernable.  A 
steam  now  arose  from  the  living  and  the  dead,  which  most  awfully 
affected  those  who  were  still  alive.  At  six  o'clock  next  morning  it 
came  to  the  ears  of  the  Indian  governor  the  havoc  death  had  made  in 
this  fearful  place,  and  he  ordered  their  release.  At  6.20  there  came  out 
of  this  living  grave  23  half-dead  creatures,  being  all  that  remained  of 
the  146  souls  who  had  entered  the  Black  Hole  prison,  and  these  were 
in  such  a  condition  that  it  seemed  very  doubtful  whether  they  would 
see  the  morning  of  another  day.  Many  of  the  survivors  developed 
putrid  fever  and  boils.  The  remaining  23  were  poisoned  by  exhalations 
from  their  own  lungs  and  bodies." 


THE    EFFECTS    OF   VITIATED    AIR  643 

An  almost  equally  terrible  tragedy  took  place  on  the  steamer  Lon- 
donderry, going  between  Sligo  and  Liverpool.  The  tragedy  is  thus 
described  by  G.  Henry  Lewes  ("Physiology  of  Common  Life")  : 

"On  Friday,  December  2,  1848,  she  left  for  Liverpool  with  two 
hundred  passengers  on  board,  mostly  emigrants.  Stormy  weather  came 
on,  and  the  captain  ordered  every  one  below.  The  cabin  for  the  steer- 
age passengers  was  only  18  feet  long,  11  feet  wide,  and  7  feet  high. 
Into  this  small  space  the  passengers  were  crowded;  they  would  only 
have  suffered  inconvenience  if  the  hatches  had  been  left  open;  but  the 
captain  ordered  these  to  be  closed,  and — for  some  reason  not  explained 
— he  ordered  a  tarpaulin  to  be  thrown  over  the  entrance  to  the  cabin 
and  fastened  down.  The  wretched  passengers  were  now  condemned  to 
breathe  over  and  over  again  the  same  air.  This  soon  became  intolerable. 
Then  occurred  a  horrible  scene  of  frenzy  and  violence,  amid  the  groans 
of  the  expiring  and  the  curses  of  the  more  robust;  this  was  stopped 
only  by  one  of  the  men  contriving  to  force  his  way  on  deck,  and  to 
alarm  the  mate,  who  was  called  to  a  fearful  spectacle :  seventy-two  were 
already  dead,  and  many  were  dying;  their  bodies  were  convulsed,  the 
blood  starting  from  their  eyes,  nostrils,  and  ears." 

The  foregoing  instances  are  exceptional,  and  for  practical  purposes 
may  be  regarded  simply  as  the  results  of  suffocation.  The  usual  con- 
ditions never  approach  such  extremes,  but  are,  nevertheless,  important, 
for  they  may  be  serious.  We  must  first  consider  the  question  why  an 
atmosphere  vitiated  by  the  presence  of  human  beings  produces  ill  effects. 

Three  explanations  have  been  offered:  (1)  increase  of  carbon  dioxid 
and  diminution  of  oxygen;  (2)  poisons  in  the  expired  breath;  (3) 
physical  changes  of  the  air.  Each  of  these  explanations  will  be  con- 
sidered separately. 

The  Effects  of  Increased  Carbon  Dioxid  and  Diminished  Oxygen. 
— According  to  the  older  theories,  the  sensations  of  discomfort,  arising 
in  inclosed  places,  had  their  origin  either  in  an  excess  of  carbon  dioxid 
or  an  insufficiency  of  oxygen.  Thus,  in  the  early  experiments  of  Claude 
Bernard  (1857)  animals  were  confined  in  atmospheric  air  and  in  mix- 
tures both  richer  and  poorer  in  oxygen  than  atmospheric  air.  He  ex- 
plained the  poisonous  effects  of  carbonic -acid  when  respired  to  be  due 
to  the  fact  that  it  deprived  the  animal  of  oxygen.  Similar  results 
were  reported  by  Valentin  and  by  Paul  Bert.  Richardson  in  1860-61 
found  that  a  temperature  much  higher  or  lower  than  20°  C.  had  the 
effect  of  shortening  very  considerably  the  lives  of  animals  confined  in 
an  unventilated  jar.  Pettenkoffer  in  1860-63  cast  the  first  serious  doubt 
on  the  correctness  of  these  theories.  He  believed  that  the  symptoms 
observed  in  crowded,  ill-ventilated  places  were  not  produced  by  the  ex- 
cess of  carbonic  acid  nor  by  a  decrease  in  the  proportion  of  oxygen  in 
the  air.     He  further  did  not  believe  that  the  impure  air  of  dwellings 


644  FRESH    AND    VITIATED    AIR 

was  directl}'  capable  of  originating  specific  diseases,  or  that  it  was 
really  a  poison  in  the  ordinary  sense  of  the  term,  but  that  it  dimin- 
ished the  resistance  on  the  part  of  those  continually  breathing  such  air. 
Hermans^  showed  that  an  atmosphere  containing  only  15  per  cent, 
of  oxygen  and  as  much  as  2  to  4  per  cent,  of  carbon  dioxid  may  not 
be  harmful.  On  removing  the  carbon  dioxid  there  was  no  great  dis- 
comfort, even  when  the  oxygen  was  reduced  to  10  per  cent.  Tlie  air 
of  certain  breweries  examined  by  Lehmann  ^  contained  1.5  to  2.5  per 
cent,  of  carbon  dioxid,  and  men  worked  continuously  in  this  for  years 
without  any  ill  effects.  The  CO,  occasionally  rose  to  6  and  even  10  per 
cent.,  but  then  was  liable  to  produce  temporary  intoxication.  It  is 
now  generally  admitted,  upon  the  testimony  of  numerous  experimenters, 
that  an  atmosphere  containing  as  much  as  3  per  cent,  of  carbon  dioxid 
and  as  little  as  15  per  cent,  of  oxygen  has  no  toxic  effects  and  produces 
no  disturbing  symptoms.  In  the  most  poorly  ventilated  rooms  the 
carbon  dioxid  never  reaches  this  amount,  especially  when  produced  by 
respiration  alone.  It  is  unusual  to  find  0.5  per  cent.  It  is,  therefore, 
plain  tliat  we  must  look  to  otlier  causes  for  the  effects  of  vitiated  air. 
Poisons  in  the  Expired  Breath. — In  1863  Hammond  believed  he 
demonstrated  the  presence  of  organic  matter,  because,  when  vitiated 
air  is  passed  through  potassium  permanganate,  it  decolorizes  that  strong 
oxidizing  agent.  Hammond  confined  a  mouse  under  a  jar  in  which  the 
COo  was  taken  up  by  baryta  water  as  fast  as  it  was  formed  and  the 
moisture  absorbed  by  calcium  chlorid.  Xevertheless,  the  mouse  died 
in  40  minutes.  The  observation  was  repeated  a  number  of  times,  and 
death  ensued  invariably  in  less  than  one  hour.  Brown-Sequard  and 
D'Arsonval  in  1888-9  claimed  to  be  the  first  to  demonstrate  poisonous 
bodies  in  the  expired  breath.  They  condensed  the  moisture  in  the  ex- 
haled breath,  which  was  injected  into  the  veins  of  rabbits.  Death 
usually  took  place  in  a  few  days,  sometimes  in  a  few  weeks.  They 
believed  from  this  that  they  had  discovered  a  volatile  organic  poison 
of  the  nature  of  an  alkaloid,  similar  to  Brieger's  ptomains.  These 
experiments  were  repeated  with  variable  results,  but  in  1889  they  re- 
ported ingenious  experiments  in  which  they  obtained  additional  evi- 
dence in  support  of  their  former  statements.  Rabbits  were  confined 
in  a  series  of  jars  connected  with  rubber  tubing,  permitting  a  con- 
stant current  of  air  to  be  passed.  The  animal  in  the  last  jar  received 
the  air  from  the  lungs  of  the  animals  in  the  other  jars.  This  animal 
died  after  an  interval  of  some  hours,  and  the  animal  in  the  next  jar 
was  the  next  to  die.     The  first  and  second  animals  usually  remained 

^  Hermans :  ' '  Ausschaltung  organischer  Substanzen  durch  den  Menschen, ' ' 
Archil-  f.  Hyg.,  1883.  I.  1. 

=  Lehmann:  "Untersuchung  iiber  die  langdauernde  Wirkung  mittlerer  Kohl- 
ensauredosen  auf  den  Menschen,"  Arch.  f.  Hyg.,  1899,  XXXIV,  335. 


THE    EFFECTS    OF    VITIATED    AIE  645 

alive.  When  absorption  tubes  containing  concentrated  sulphuric  acid 
were  placed  between  the  last  two  jars,  the  animal  in  the  last  jar  re- 
mained alive  while  the  one  in  the  jar  just  before  was  the  first  to  die. 
These  results  confirmed  their  belief  in  the  existence  of  a  volatile  poison 
absorbed  by  the  sulphuric  acid.  Haldane  and  Smith  repeated  the  ex- 
periments of  Brown-Sequard  and  D'Arsonval,  using  five  bottled  mice. 
They  continued  the  exposure  for  53  hours  without  ill  effects  to  the 
mice.  Beu  in  1893  also  repeated  these  experiments,  and  came  to  the 
conclusion  that  acute  poisoning  through  the  organic  matters  contained 
in  the  expired  air  was  not  possible,  and  that  the  death  of  the  animals 
was  due  to  changes  of  temperature  and  accumulation  of  moisture  in 
the  jars.  Eauer  in  1893,  also  Liibberd  and  Peters,  concluded  from 
similar  experiments  that  there  are  no  organic  poisons  in  the  expired 
air.  In  fact,  Merkel  stands  almost  the  only  sponsor  for  the  correctness 
of  the  conclusions  of  Brown-Sequard  and  D'Arsonval,  and  with  some 
slight  changes  of  technique  he  was  unable  to  get  uniform  results. 

Lehmann  and  Jessen  in  1890  collected  from  15  to  20  c.  c.  of  con- 
densed fluid  per  hour  from  the  breath  of  a  person  exhaling  through 
a  glass  spiral  laid  in  ice.  This  fluid  was  always  clear,  odorless,  neutral 
in  reaction,  and  contained  slight  traces  of  ammonia  with  good  teeth; 
more  with  poor  teeth.  Inoculation  of  this  condensed  fluid  into  ani- 
mals gave  negative  results.  Many  other  experimenters,  including  von 
Hoffman-Wellenhof,  Lehmann  and  Jensen,  Haldane  and  Smith,  Bil- 
lings, Weir  Mitchell,  and  Bergey,  have  shown  that  the  fluid  condensed 
from  the  breath  is  no  more  toxic  than  distilled  water  when  injected 
into  animals.  This  has  strengthened  the  general  belief  that  poisonous 
bodies  are  not  present. 

In  1894  Brown-Sequard  and  Davis  reported  further  experiments  in 
which  they  inoculated  over  one  hundred  animals  with  the  condensed 
fluid  of  respiration,  and  not  only  confirmed  their  former  statements, 
but  were  unable  to  understand  the  failure  of  other  experimenters,  and 
emphatically  reaffirmed  that  the  breath  contains  a  volatile  poison  and 
that  the  death  of  animals  under  experimental  conditions  is  not  due  to 
an  excess  of  carbon  dioxid  nor  a  deficiency  of  oxygen.  These  experiments 
were  repeated  by  Billings,  Mitchell,  and  Bergey  ^  in  1895,  who  came  to 
the  conclusion  that  the  ill  effects  of  vitiated  atmosphere  dei^end  almost 
entirely  upon  increased  temperature  and  moisture,  and  not  on  an  ex- 
cess of  carbon  dioxid  or  bacteria  or  dust  of  any  kind.  They  admit 
that  the  cause  of  the  musty  odor  in  unventilated  rooms  is  unknown. 

In  addition  to  reducing  potassium  permanganate,  it  has  been  shown 
that  the  breath  contains  traces  of  ammonia  and  traces  of  hydrochloric 
acid.     These  have  their  origin  in  decaying  teeth  and  decomposing  par- 

1  Published  by  Smithsonian  Institution,   1895.      Contains   a  summary  of   the 
literature  to  date,  with  references  to  authorities. 
43 


<5-i6  FEESH    AND    VITIATED    AIR 

tides  of  food  or  other  putrefactive  or  pathological  changes  occurring 
in  the  upper  respiratory  passages.  The  ammonia  and  hydrochloric 
acid  exist  in  such  small  quantities  that  they  have  no  practical  bearing 
upon  the  question  under  consideration. 

Weichardt '  calls  attention  to  the  fact  that  putrefactive  processes 
go  on  in  the  excretory  products  of  the  respiratory  tract,  especially  in 
older  persons.  He  states  that  the  bronchial  mucus  of  corpses  contains 
a  poison  resembling  kenotoxin  (the  toxin  of  fatigue).  When  injected 
into  laboratory  animals  it  produces  a  lowering  of  temperature,  a  slow- 
ing of  respiration,  and  death.  According  to  Weichardt,  fluids  condensed 
from  the  expired  air  and  then  concentrated,  when  injected  into  mice, 
produce  like  results.  This  investigator  also  evaporated  some  of  the 
condensed  moisture  from  the  expired  breath  and  obtained  a  weighable 
residue  (9  milligrams  from  10  c.  c).  This  he  regards  as  partly  or- 
ganic matter.  As  further  proof  that  the  organic  matter  in  the  expired 
breath  is  active,  he  obtained  from  the  expired  breath  of  a  tired  old  man 
the  condensed  fluid  which  he  then  concentrated.  This  concentrated 
fluid  has  a  distinct  inhibitory  effect  upon  the  oxidizing  power  of  the 
ferments  in  blood,  as  shown  by  the  guaiac  indicator.  Also  by  means 
of  the  epiphanin  reaction  Weichardt  considers  that  he  has  demonstrated 
protein-split  products  in  the  vitiated  air  of  a  room.  He  concludes 
that  substances  having  such  important  biological  power  should  not  be 
longer  overlooked.  These  results  lack  confirmation,  and  the  methods 
are  open  to  criticism. 

Eosenau  and  Amoss  -  demonstrated  the  presence  of  protein  matter 
in  the  expired  breath  through  the  reaction  of  anaphylaxis.  The  first 
injection  into  guinea  pigs  of  the  fluid,  obtained  by  condensing  the 
moisture  of  expiration,  is  harmless,  but  the  animals  become  sensitized, 
so  that  they  react  to  an  injection  of  human  blood  serum  after  an 
interval  of  several  weeks.  Of  99  guinea  pigs  tested  26  responded  defi- 
nitely; in  -i  of  the  animals  the  reaction  was  so  severe  that  death  en- 
sued from  anaphylactic  shock.  This  plainly  indicates  that  protein 
matter,  specific  in  nature,  is  present  in  the  expired  breath.  It  is  in- 
ferred that  the  protein  matter  probably  comes  from  the  blood.  These 
experiments,  however,  do  not  prove  that  these  substances  are  poisonous. 

Further  researches  have  shown  that  guinea  pigs  may  be  sensitized 
by  exposing  them  to  the  expired  breath  of  dogs.  That  is,  the  protein 
matter  thrown  off  in  the  dog's  breath  may  be  inspired  and  absorbed 
by  the  guinea  pigs.  This  indicates  that  organic  matters  in  the  expired 
breath  may  have  a  physiological  significance,  but  we  have  no  proof  that 

^Weichardt:  "Ueber  Eiweifsspaltprodukte  in  der  Ausatemluf  t, "  Arch.  f. 
Hyg.,  1911,  74  Bd.,  Heft  5. 

-"Organic  Matters  in  the  Expired  Breath,"  Jour,  of  Med.  ^Research,  Vol. 
XXV,  No.  1,  Sept.,  1911,  page  35. 


THE    EFFECTS    OF    VITIATED    AIR  647 

they  are  poisonous  in  the  sense  in  which  that  term  is  commonly  em- 
ployed. There  is,  therefore,  no  present  proof  that  the  expired  breath 
contains  a  poisonous  substance. 

Physical  Changes  in  the  Air. — Owing  to  the  failure  of  chemistry 
to  demonstrate  the  cause  of  the  ill  effects  produced  by  a  vitiated  at- 
mosphere, attention  has  recently  been  focused  upon  the  physical  changes, 
such  as  the  increase  in  temperature,  increase  in  humidity,  and  the  still- 
ness of  the  air  in  a  poorly  ventilated  room.  Important  experiments 
were  carried  out  above  five  years  ago  in  the  Institute  of  Hygiene  in 
Breslau  by  Heymann,  Paul,  and  Erclentz.  Fliigge,^  who  was  then  the 
director  of  the  institute,  has  admirably  summarized  and  interpreted 
the  results  as  follows: 

Paul  placed  healthy  individuals  in  a  cabinet  of  3  cubic  meters' 
capacity,  where  they  were  kept  for  a  variable  time  up  to  four  hours, 
and  until  the  carbon  dioxid  had  risen  to  100  or  150  parts  in  10,000 — 
an  accumulation  of  gaseous  excretion  practically  never  developed  un- 
der ordinary  conditions.  In  these  experiments  no  symptoms  of  illness 
or  discomfort  developed  so  long  as  the  temperature  and  moisture  were 
kept  low.  Tests  of  the  psychic  fatigue  of  these  individuals  by  means 
of  the  esthesiometer  and  ergograph,  or  by  means  of  computations,  gave 
negative  results  throughout,  under  similar  conditions  of  temperature 
and  moisture.  Tests  in  a  crowded  schoolroom  were  similarly  negative. 
Erclentz  made  the  same  observations  on  diseased  persons.  Those  suf- 
fering from  emphysema,  heart  diseases,  kidney  diseases,  etc.,  with  the 
exception  of  a  few  peculiarly  susceptible  anemic  and  scrofulous  school 
children,  bore  the  highly  vitiated  air  for  hours  without  any  evidence  of 
bodily  or  mental  depression. 

The  results  were  very  different,  however,  when  the  temperature  and 
moisture  of  the  air  of  the  cabinet  were  allowed  to  increase.  At  80°  F. 
with  moderate  humidity,  or  at  from  70°  to  73.5°  F.  with  high  humid- 
ity, practically  all  persons  began  to  show  depression,  headache,  dizzi- 
ness, or  a  tendency  to  nausea.  The  susceptibility  was  not  alike  for  all. 
School  children  reacted  slightly  and  emphysematics  slightly,  while  those 
with  heart  troubles  were  most  susceptible.  By  means  of  certain  ob- 
jective signs  of  heat  stagnation — the  surface  temperature  of  the  fore- 
head and  the  temperature  and  moisture  of  the  clothed  parts  of  the 
body — it  was  determined  that  subjective  symptoms  appeared  only  when 
the  surface  temperature  reached  a  certain  height.  This  was,  for  healthy 
people,  93°  F.  to  95°  F.  on  the  forehead;  for  the  more  susceptible  and 
diseased,  89.5°  to  91.5°;  and  with  the  moisture  of  the  skin  increased 
by  20  or  30  per  cent.     Under  these  conditions  the  normal  dissipation 

ipiiigge:  Ztschr.  f.  Hyg.,  1905,  XLIX,  363.  Crowder:  Archives  of  In- 
ternal Medicine,  Jan.,  1911,  Vol.  VII,  pp.  85-133.  Contains  an  admirable  sum- 
mary and  references  to  recent  literature  upon  the  subject. 


G48  FRESH    AND   VITIATED   AIR 

of  body  heat  is  interfered  with,  and  it  is  under  these  conditions  that 
symptoms  appear  which  are  in  every  way  similar  to  those  developed 
in  overfilled  and  "stuffy"  rooms. 

Now,  when  these  people  in  the  cabinet  suffering  from  such  symp- 
toms were  allowed  to  breathe  the  fresh  outside  air  through  a  tube, 
such  air  being  raised  to  the  temperature  and  relative  humidity  of  that 
within,  it  gave  them  no  relief  whatever;  nor  did  the  internal  air  pro- 
duce any  symptoms  when  breathed  through  a  tube  by  one  outside  of 
the  cabinet.  But  the  symptoms  of  discomfort  and  illness  experienced 
by  the  person  within  could  be  almost  immediately  relieved  either  by 
drying  the  air  of  the  cabinet  or  by  cooling  it,  or  by  putting  it  in  rapid 
motion  by  means  of  a  fan,  without  any  chemical  change  being  made 
in  the  air.  The  effect  of  these  measures  is  simply  by  purely  mechanical 
means  to  enable  the  body  to  throw  off  its  heat  more  rapidly,  and  thereby 
all  symptoms  disappear;  heat  stagnation  is  the  cause  of  the  discomfort. 

From  the  long  series  of  experiments,  carried  out  with  great  care  as 
to  all  the  details  of  observation  and  control,  it  is  concluded  that  all  of 
the  symptoms  arising  in  the  so-called  vitiated  atmosphere  of  crowded 
rooms  are  dependent  on  heat  stagnation  in  the  body,  and  that  the  ther- 
mic conditions  of  the  atmosphere,  its  moisture,  and  its  stillness  are 
responsible  for  the  effects.  To  change  any  one  of  these  elements  is  to 
change  the  rapidity  of  the  loss  of  heat.  If  the  change  is  such  as  to 
increase  this  loss,  comfort  is  restored.  It  is  also  considered  proved 
beyond  any  reasonable  doubt,  by  their  own  as  well  as  by  previous  re- 
search, that  there  is  no  gaseous  excretion  into  the  surrounding  air, 
either  from  tire  breath  or  from  other  sources,  deserving  of  the  name  of 
poison. 

Angelici,^  working  independently  at  about  the  same  time,  concurs  in 
these  opinions ;  and  Reichenbach  and  Heymann  ^  later  determined  that 
objective  evidence  of  heat  stagnation  in  the  body  always  precedes  the 
development  of  subjective  symptoms  of  discomfort  under  natural  con- 
ditions, in  the  same  way  that  it  does  under  the  artificial  conditions 
of  the  cabinet. 

Leonard  Hill  ^  of  England  also  has  confirmed  these  general  results 
and  conclusions.  It  should  be  noted  that  it  is  exceedingly  difficult  in 
these  cabinet  experiments  to  exclude  the  psychic  factor. 

^AngelJci:  Quoted  by  Reichenbach  and  Hevmann,  Zischr.  f.  Hyg.,  1907, 
LVII,  23. 

^Reichenbach  and  Heymann:  "  Untersuchungen  iiber  die  Wirkungen  klima- 
tischer  Factoren  auf  den  Menschen,"  Ztschr.  f.  Hyg..  1907,  LVII,  23. 

'Hill,  Leonard,  Rowland,  R.  A.,  and  Walker,  H.  R.:  "The  Relative  Influ- 
ence of  the  Heat  and  Chemical  Impurity  of  Close  Air, ' '  London  Hosp.  Med.  Col., 
Journal  of  Physiology,  XLl,  1911. 


SUMMAEY  649 


SUMMARY 


It  is  now  perfectly  plain  that  the  ill  effects  resulting  from  a  vitiated 
atmosphere  are  not  due  to  an  increase  of  carbon  dioxid  nor  to  a  dim- 
inution in  oxygen.  Upon  this  point  all  are  agreed.  The  general  con- 
sensus of  opinion  also  excludes  poisonous  bodies  in  the  expired  breath 
as  a  factor.  On  this  point,  however,  the  last  word  has  not  been  said. 
The  expired  breath  appears  to  contain  protein  bodies  biologically  active, 
which  may  have  an  influence  upon  health. 

Sanitarians  are  satisfied,  with  the  evidence  presented,  that  most  at 
least  of  the  discomfort  is  due  to  physical  changes  only.  If  a  normal 
heat  interchange  can  be  maintained  between  the  body  and  the  air  the 
symptoms  which  are  commonly  attributed  to  poor  ventilation  do  not 
develop.  According  to  this  view  the  vital  element  of  the  ventilation 
problem  becomes  that  of  regulating  the  temperature,  moisture,  and 
motion  of  the  air.  When  the  air  is  still  we  are  surrounded  by  an 
"aerial  envelope"  with  a  temperature  and  moisture  resembling  the 
open  air  on  a  hot  and  humid  day.  The  symptoms  caused  by  crowd 
poisoning,  such  as  oppression,  malaise,  headache,  vertigo,  nausea,  vom- 
iting, and  even  collapse,  indeed  resemble  those  of  heat  exhaustion. 

Even  those  who  look  upon  the  physical  changes  in  the  air  as  the 
sole  cause  of  the  discomfort  rather  than  the  possibility  of  chemical 
changes  admit  that  a  certain  amount  of  fresh  air  must  be  supplied. 
Fliigge  himself  urges  that  life  in  tjie  open  should  be  more  and  more 
resorted  to,  but  he  would  have  the  motive  correctly  understood,  not 
that  the  chemical  condition  of  inside  air  is  harmful,  but  that  it  is  the 
overheating  of  rooms  that  causes  disturbances  of  health.  Fliigge  states 
that  one  should  go  into  the  open  not  because  he  may  breathe  chemically 
purer  air,  but  because  its  almost  constant  motion  carries  away  the  body 
heat  and  causes  a  beneficial  stimulation  of  the  skin  and  reflexly  brings 
about  a  heightened  cell  activity  that  aids  in  the  development  of  sturdy 
health.  The  chemistry  of  air  and  "crowd  poisons"  have  little  or  no 
part  to  play  in  the  explanation  of  outdoor  benefits  or  of  indoor  discom- 
forts. These  are  both  dependent  upon  physical  conditions,  and  their 
explanation  rests  with  the  physics  of  heat  interchange  between  the  body 
and  its  surrounding  medium. 

There  is  some  danger  in  regarding  the  ill  effects  of  poor  ventilation 
as  due  to  thermal  and  other  physical  factors  alone.  According  to  this 
theory  it  is  only  necessary  to  keep  the  temperature  and  moisture  down 
and  keep  the  air  in  motion;  a  closed  office  with  an  electric  fan  would 
take  the  place  of  any  system  of  ventilation.  There  is  already  a  clamor 
against  the  laws  requiring  fresh  air  in  workrooms,  based  upon  Fliigge's 
views.    This  is  a  natural  corollary  of  Fliigge's  views.     If  re-breathing 


650  FRESH    AND    VITIATED    AIR 

the  same  air  is  not  hurtful,  the  ventilation  of  living  rooms  may  be  greatly 
simplified  by  simply  keeping  the  physical  conditions  of  the  air  within 
the  limits  of  comfort.  Furthermore,  a  great  economy  would  be  effected. 
It  is.  however,  not  scientific  to  insist  that  the  chemical  changes  in  a 
vitiated  atmosphere  may  be  disregarded,  because  we  cannot  at  present 
demonstrate  immediate  relationship  between  cause  and  effect;  neither 
is  it  safe  to  deny  dogmatically  the  existence  of  injurious  substances  in  a 
vitiated  atmosphere  simply  because  in  the  present  state  of  our  knowl- 
edge chemistry  has  failed  to  demonstrate  them,  and  because  most  of 
the  symptoms  may  be  explained  upon  disturbances  of  thermic  inter- 
change. 

Furthermore,  most  of  the  observations  have  been  based  upon  short 
exposures;  it  is  very  probable  that  a  decrease  in  mental  and  physical 
efficiency  would  result  from  a  prolonged  exposure  to  a  vitiated  atmos- 
phere, even  though  it  were  kept  dry  and  cool.  The  improvement  in 
appetite,  nerve  vigor,  blood  quality,  and  muscular  tone  which  follows 
open  air  treatment,  even  in  the  rich  and  well-fed,  shows  the  paramount 
importance  of  fresh  air. 


CHAPTER   VI 
VENTILATION    AND    HEATING 

VENTILATION 

The  problem  of  ventilation  is  apparently  a  very  simple  one;  all 
that  is  required  is  to  furnish  a  never-ending  stream  of  fresh  air  from 
the  inexhaustible  supply  without  to  replace  that  which  is  constantly 
being  vitiated.  To  do  this  under  the  artificial  conditions  of  house 
and  factory  life  is  often  extremely  difficult,  and  under  certain  circum- 
stances practically  impossible.  Further,  the  problem  of  ventilation 
must  take  into  account  not  only  the  quantity  of  air,  but  its  physical 
condition,  in  order  that  the  human  machine  may  operate  at  the  highest 
level  of  health  and  efficiency. 

Ventilation  must  serve  a  number  of  purposes  and  comply  with  a 
number  of  conditions  before  it  can  be  considered  satisfactory:  (1)  it 
must  bring  pure  air  from  without  in  order  to  dilute  and  remove  the 
products  of  respiration,  as  well  as  other  sources  of  vitiation;  (2)  it 
must  maintain  the  air  within  the  room  at  a  proper  temperature  and 
humidity,  and,  further,  must  keep  the  air  of  the  room  in  gentle  and 
continuous  motion;  (3)  it  must  remove  the  gases,  odors,  bacteria,  dust, 
and  other  substances  that  contaminate  the  air  of  inclosed  spaces;  (4) 
it  must  dilute  and  remove  the  impurities  produced  by  the  burning  of 
gas,  candles,  lamps,  and  other  sources. 

The  purpose  of  ventilation  is  not  to  bring  outdoor  conditions  in- 
doors; the  art  of  ventilation  consists  in  adapting  indoor  conditions 
to  indoor  life.  Indoor  life  is  necessary  in  order  to  perform  the  deli- 
cate manipulations  which  cannot,  as  a  rule,  be  effectively  conducted 
outdoors.  Indoor  life,  then,  involves  quiet  and  protection  from  sud- 
den changes  or  extremes. 

It  is  a  simple  mechanical  problem  to  condition  the  air  of  an  apart- 
ment. The  ventilating  engineer  finds  no  difficulty  in  regulating  the 
temperature  and  humidity  within  narrow  limits,  and  in  furnishing 
definite  quantities  of  fresh,  moving  air.  To  maintain  these  condi- 
tions, however,  the  doors  and  windows  must  be  kept  shut.  Herein 
?irises  the  first  difficulty  between  the  theory  and  the  practice  of  ven- 

651 


652  VENTILATION    AND    HEATING 

tilation,  for  it  is  plain  that  the  simplest  and  often  the  best  way  to 
ventilate  a  room  is  througji  open  windows.  The  second  difficulty  arises 
from  the  fact  that  tlie  conditions  within  and  without  the  room  to  be 
ventilated  are  not  constant.  The  principal  factors  here  concerned  are 
the  force  and  direction  of  the  wind,  changes  of  outdoor  temperature,  and, 
to  a  less  degree,  movements  witliin  the  room.  It  is,  therefore,  much 
easier  to  maintain  constant  air  conditions  in  a  sub-basement  than  in 
a  room  exposed  to  wind  and  weather. 

The  efficiency  of  any  system  of  ventilation  must  be  measured  by 
the  results  obtained  at  the  breathing  zone.  It  matters  little  what  the 
composition  or  the  condition  of  the  air  is  near  the  ceiling,  provided  the 
heated,  moistened,  and  vitiated  aerial  blanket  which  surrounds  us  is 
constantly  removed  and  replaced  w^ith  a  fresh  supply  properly  condi- 
tioned. 

Ventilation  is  far  from  satisfactory  if  the  air  brought  into  the  room 
is  smoky,  dusty,  or  bacteria-laden,  or  if  it  is  contaminated  with  gases 
or  odors  from  cellars  or  surroundings.  Attention  should,  therefore,  be 
given  to  the  sources  of  the  air,  and  it  is  always  an  advantage  to  filter 
it.  There  is  a  practical  limit  to  the  amount  of  fresh  air  that  may 
profitably  be  forced  into  a  room,  especially  warmed  air  in  the  winter 
time.     Ventilation  and  heating  naturally  go  hand  in  hand. 

The  belief  is  growing  that  it  is  not  dangerous  to  rebreathe  air,  and 
the  view  is  spreading  that  the  hygienic  value  of  ventilation  for  the  pur- 
pose of  maintaining  a  pure  atmosphere  in  dwellings,  schools,  and  hos- 
pitals is  not  so  great  as  is  commonly  supposed.  According  to  this 
view  it  is  more  important  to  ventilate  in  the  interest  of  the  heat  economy 
of  the  body,  by  the  establishment  of  a  suitable  temperature  and  air 
movement,  and  by  the  regulation  of  the  humidity  in  the  atmosphere. 
The  established  facts,  that  the  principal  causes  of  the  ill  effects  of  viti- 
ated air  are  due  more  to  the  heat  and  humidity  and  stillness  of  the  air 
than  to  changes  in  its  chemical  composition,  have  led  some  hygienists  to 
recommend  rebreathing  the  air,  provided  the  physical  conditions  are 
kept  favorable.  This  is  an  extreme  view,  in  which  I  do  not  concur. 
Because  rebreathed  air  has  not  been  demonstrated  to  be  harmful  is 
no  proof  that  it  may  not  be  so.  Satisfactory  ventilation,  therefore, 
must  not  only  take  into  account  the  physical  conditions  of  the  air, 
but  also  demands  a  generous  supply  of  fresh  air  in  order  to  keep  the 
chemical  composition  within  reasonably  normal  limits. 

Dwelling  houses  are  usually  constructed  with  little  regard  for  ven- 
tilation. It  is  desirable  that  adequate  provision  should  be  made  for 
the  ventilation  of  every  house  that  is  built.  This  requires  just  as  much 
care  and  forethought  as  the  system  of  heating  the  house,  or  furnishing 
it  with  w^ater,  gas,  electricity,  plumbing  for  the  disposal  of  wastes,  and 
other  household  conveniences.     WTiatever  system  of  ventilation  may  be 


VENTILATION  653 

adopted,  it  is  wise  to  flush  rooms  frequently  with  fresh  air  and  flood 
them  with  sunshine.  This  helps  to  blow  out  the  accumulated  dust  and 
bacteria,  to  oxidize  organic  matter  that  collects  as  a  film  on  all  surfaces, 
to  diminish  odors,  and  generally  to  purify  the  apartment. 

Vitiation  by  Respiration. — An  adult  individual  at  rest  breathes  at 
the  rate  of  about  seventeen  respirations  a  minute.  At  each  respiration 
about  500  c.  c.  (30.5  cu.  in.)  of  air  pass  in  and  out  of  his  lungs.  The 
air  in  the  lungs  loses  about  4  per  cent,  of  oxygen  and  gains  3.5  to  4 
per  cent.  COj.  The  nitrogen  remains  unchanged.  In  addition  the 
expired  air  is  raised  in  temperature  to  nearly  that  of  the  blood,  98.4°  F. ; 
it  also  contains  much  aqueous  vapor. 

The  amount  of  CO2  which  is  given  off  by  an  adult  male  person  at 
rest  can  be  calculated  from  the  above  figures,  and  will  be  found  to  be 
0.68  cubic  foot  in  one  hour.     Thus: — 

17  X  30  X  60 

^17.2  cubic  feet  breathed  per  hour. 

1728 
4  per  cent,  of  17.2  =  0.68  cubic  foot  per  hour  of  COj. 

From  actual  experiment  it  has  been  determined  that  an  average 
adult  gives  off  0.9  of  a  cubic  foot  of  CO,  during  gentle  exertion,  and 
possibly  as  much  as  1.8  during  hard  work.  The  adult  female  gives  off 
about  one-fifth  less  under  similar  circumstances,  and  an  infant  is  said 
to  give  off  about  0.5  cubic  foot  of  CO2  per  hour.  In  a  mixed  assembly 
at  rest,  including  male  and  female  adults  and  children,  the  CO2  given  off 
per  head  is,  therefore,  taken  as  0.6  of  a  cubic  foot. 

The  volume  of  air  inspired  and  expired  depends  on  the  rate  and 
extent  of  the  respiratory  movement,  but  in  an  adult  man  of  average  size 
and  vigor  about  500  cubic  centimeters  of  air  are  inspired  and  expired 
during  quiet  breathing.  This  volume  of  air  is  known  as  the  tidal  air, 
and,  since  the  total  volume  of  air  in  the  lungs  is  about  3,500  c.  c,  it 
is  evident  that  in  normal  breathing  a  large  amount  of  air — 3,000  c.  c. — 
remains  in  the  lungs  at  the  end  of  expiration.  The  air  which  remains 
behind  is  known  as  stationary  air. 

By  forced  expiration  about  half  of  the  stationary  air,  i.  e.,  1,500 
c.  c,  can  be  expired,  and  this  portion  of  the  stationary  air  is  known 
as  the  supplemental  or  reserve  air,  while  the  final  1,500  c.  c.  which  no 
effort  can  expel  is  known  as  the  residual  air.  The  total  of  3,500  c.  c. 
of  air  in  the  chest,  then,  at  the  end  of  ordinary  inspiration  is  made 
up  as  follows: 

Tidal  air   500  c.  c. 

Supplemental  or  reserve 1,500  c.  c. 


^         '  Residual  air   1,500  e.  c. 

3,500  c.  c. 


654  VENTILATION    AND    HEATING 

When,  however,  inspiration  is  forced,  another  1,500  c.  c.  of  air,  known 
as  complemental  air,  can  be  inspired,  making  altogether  5,000  c.  c. 

The  total  amount  of  air  (com])lemental,  tidal,  supplemental)  which 
can  be  inspired  after  forced  expiration  is  known  as  the  "respiratory 
capacity"  or  "vital  capacity"  or  "extreme  differential  capacity,"  and  the 
amount  varies  eonsideral)ly  according  to  lieight,  weight,  vigor,  age,  etc. 

The  Amount  of  Air  Required. — Omitting  from  consideration  the 
question  of  temperature  and  moisture,  a  certain  amount  of  pure  air 
is  necessary  for  good  ventilation.  This  amount  is  determined  from  the 
amount  of  carbon  dioxid  taken  as  an  index  of  the  impurities  from 
respiration  and  combustion,  and  may  be  ascertained  either  by  direct 
observation  or  from  physiological  data.  The  accepted  amount  of  pure 
air  required  per  person  ])er  hour  is  from  2,000  to  3,000  cubic  feet.  The 
external  air  contains  3  ])arts  of  CO^  per  10,000  (0.03  per  cent.),  and 
the  permissible  limit  for  indoor  air  is  placed  at  from  6  to  10  parts. 

It  has  been  found  from  actual  observation  that  an  adult  in  an  air- 
tight compartment  will  vitiate  the  air  as  follows: 

In  a  room  3,000  cubic  feet  COs^O.GG  per  cent,  in  1  hour 

"    "  "       2,000      "         "       "    =0.07      "      "  "    "  " 

"    "  "       1,500      "         "       "    =0.08      "      "  "    "  " 

"    "  "       2  200      "         "       "    — 0  09      "      "  "    "  " 

"    "  "      1,000      "        "      "    =0.10     "      "  "    "  " 

The  same  results  may  be  obtained  from  physiological  data.  Thus, 
the  average  adult  expires  0.6  cubic  foot  of  COg  per  hour.  The  differ- 
ence between  the  permissible  limit,  0.06  per  cent.,  and  the  amount  of 
carbon  dioxid  in  the  air,  0.03  per  cent.,  is  0.03.  It  follows  that  the 
amount  of  fresh  air  required  per  hour  by  an  adult  to  keep  the  CO, 
down  to  0.06  per  cent,  may  be  determined  from  the  following  equation : 

0.03:0.6::100:x 
x=2,000  cubic  feet. 

If  the  normal  amount  of  carbon  dioxid  in  the  air  is  taken  as  0.04 
instead  of  0.03,  the  result  is  3,000  cubic  feet,  the  amount  generally 
accepted,  which,  however,  is  somewhat  in  excess — as  it  should  be. 
This  does  not  mean  that  there  should  be  3,000  cubic  feet  for  each 
person  in  an  inhabited  room,  for  it  is  sufficient  if  the  air-space  is  1,000 
cubic  feet,  provided,  of  course,  the  air  is  changed  three  times  an  hour. 

The  same  results  may  be  obtained  by  using  the  formula: 

E 

—  =  D 
P 


VENTILATION  655 

E=the  amount  of  carbon  dioxid  exhaled  by  one  person  in  one 
hour;  the  general  average  for  an  adult  being  0.6  cubic  foot. 

P:=the  amount  of  added  CO2  permitted,  stated  in  cubic  feet;  or 
0.06—0.03:^0.03  per  cent.,  or  0.000,3  cubic  foot. 

D=:the  required  delivery  of  fresh  air  in  cubic  feet  per  hour. 

E  0.6 

—  =:  D,  or  —  2,000  cubic  feet. 

P  0.0003 

The  primary  value  of  E  in  this  equation  varies  with  different  con- 
ditions. 

A  male  adult  (160  pounds)  exhales  0.72  cubic  foot  of  CO2  per  hour 
A  female  adult  (120  pounds)  exhales  0.60  cubic  foot  of  CO2  per  hour 
A  child  (  80  pounds)   exhales  0.40  cubic  foot  of  CO2  per  hour 


Average  0.60 

These  values  vary  also  with  rest  or  work.  Thus,  factories  or  work- 
shops where  men  are  actively  employed  need  more  air  proportionately. 
In  light  work  a  man  weighing  160  pounds  exhales  0.95  cubic  foot,  while 
at  hard  work  1.8-4  cubic  feet,  of  CO,  per  hour. 

A 

The  formula  suggested  by  DeChaumont  is  D  = 

B-C 

A=quantity  of  CO,  given  off  per  hour  per  person=:0.6  cu.  ft. 

B:=proposed  permissible  maximum  quantity  of  CO,  per  1,000  cu. 
ft.=0.6  per  1,000. 

C=amount  of  CO2  present  in  1,000  cu.  ft.  of  fresh  air  (0.3  cu.  ft. 
per  1,000  cu.  ft.). 

D=:amount  of  fresh  air  required  per  head  each  hour  to  maintain 
the  standard  B  expressed  in  thousands  of  cu.  ft. 

A  0.6  0.6 

Then  D  = or  =  —  =  2,000   cu.  ft. 

B-C       0.6-0.3      0.3 

of  air  needed  per  head  per  hour. 

In  case  of  individuals  doing  light  work  and  giving  off  0.95  cu.  ft. 
CO2  per  hour,   then 

0.95 

D  = =  3,166  cu.  ft. 

0.6-0.3 

This  is  a  convenient  formula,  for  it  may  be  used  not  only  to  deter- 
mine the  amount  of  fresh  air  required,  but,  knowing  the  other  factors, 
the  amount  of  cubic  feet  of  fresh  air  that  has  been  admitted  to  a  room 


656  VENTILATION    AND    HEATING 

per  liead  may  be  determined.  Further,  probable  conditions  of  the  at- 
mosphere of  a  room  into  wliicli  a  known  amount  of  fresh  air  has  been 
supplied  can  be  determined  bv  findiiii;  the  value  of  B,  thus: 

A 

(B  =  -  +  C). 

D 

Standards  of  Purity — Efficiency  of  Ventilation. — There  is  no  single 
standard  by  which  tlie  purity  of  the  air  or  the  efficiency  of  ventilation 
can  be  determined.  We  must  know  at  least  five  factors :  ( 1 )  the  tem- 
perature; (2)  the  humidity;  (3)  the  movements  of  the  air;  (4)  the 
amount  of  CO2  it  contains;  (5)  dust,  bacteria,  gases,  etc.  In  a  general 
way  it  may  be  stated  that  the  best  results  are  obtained  when  the  tem- 
perature is  between  62°  and  68°  F. ;  the  moisture  between  50  and  75  per 
cent,  relative  humidity  (the  wet  bulb  under  70°  F.)  ;  the  movement 
gentle,  without  draft;  CO2  not  in  excess  of  6  parts  per  10,000;  and, 
finally,  freedom  from  excessive  dust,  bacteria,  gases,  etc.  Even  where 
all  these  factors  are  found  satisfactory  there  is  still  one  test  that  must 
be  made  in  order  to  be  sure  that  our  ventilating  system  is  nowhere  at 
fault — that  is,  the  clinical  test.  Persons  occupying  the  room  should 
suffer  from  none  of  the  well-known  effects  produced  by  air  in  poor  con- 
dition. The  room  should  be  free  from  unpleasant  odors.  If  our  tests 
seem  right,  hut  the  air  is  close,  something  must  be  wrong  with  tlie  tests. 
The  evidence  of  our  senses  and  clinical  experience  cannot  be  disregarded. 

Where  any  ventilating  device  is  installed  it  is  readily  possible  to 
measure,  by  means  of  the  anemometer,  the  amount  of  air  passing 
through  inlets  or  outlets,  but  it  is  often  difficult  to  trace  the  course  of 
the  air  in  the  room.  The  measured  volume  of  air  passing  through  in- 
lets and  outlets  does  not  necessarily  determine  the  efficiency  of  ventila- 
tion in  maintaining  a  continuous  renewal  of  the  air  at  the  breathing 
zone. 

The  volume  of  fresh  air  entering  the  breathing  zone  may  be  esti- 
mated with  considerable  accuracy  by  determining  the  proportion  of 
CO2  which  this  zone  contains.  The  air  supplied  is  inversely  as  the 
respiratory  contamination.  It  may  be  computed  from  the  following 
equation : 

vp 

A  = 

X— N 

v^the  CO,  produced  by  one  person ;  that  is,  0.6  cubic  foot  per  hour. 

p^the  number  of  people  in  the  room. 

x=:the  proportion  of  COg  per  cu.  ft.  in  the  inside  air. 

N=the  proportion  of  CO,  per  cu.  ft.  in  the  outside  air  (0.0003). 

A^the  air  supplied  to  the  room  in  cubic  feet  per  hour. 


VENTILATION  657 

0.6  p 


X— 0.0003 


It  will  be  seen  in  this  equation  that  vp  represents  the  COo  produced 
by  occupants  and  x — N  represents  the  respiratory  contamination. 

In  such  computations,  as  also  in  the  direct  measurement  of  air 
supplies,  it  is  the  averages  which  are  most  important.  From  average 
contamination  we  may  find-  average  air  supplies.  Erroneous  conclu- 
sions are  very  likely  to  be  drawn  from  single  determinations. 

Another  method  of  determining  the  efficiency  of  ventilation  is  in- 
tentionally to  vitiate  the  air  of  a  room,  and  then,  after  a  lapse  of  a 
certain  time,  find  how  far  ventilation  has  removed  the  carbon  dioxid. 
The  amount  of  air  which  has  entered  the  room  may  be  found  by  the 
formula : 

Pi— a 

C=2.303  m    log ■ 

P.— a 

C=amount  of  air  which  has  entered;  2.303  is  a  constant. 

in=capacity  of  the  room. 

P^rrramount  of  carbon  dioxid  originally  present  (found  by  experi- 
ment) . 

P^^ramount  of  carbon  dioxid  present  after  vitiation. 

a^amount  of  carbon  dioxid  in  the  outside  air. 

The  Size  and  Shape  of  the  Room. — These  are  exceedingly  impor- 
tant factors  in  any  system  of  ventilation.  It  at  once  becomes  evident 
that  a  man  in  a  diving  suit  with  a  good  circulation  of  fresh  air  is 
better  off  than  occupants  of  a  spacious  but  poorly  ventilated  apart- 
ment in  which  the  air  has  become  vitiated  through  long  occupancy. 
The  air  in  a  small  cabin  on  a  steamship  may  be  infinitely  better  than 
the  air  in  a  large  room  of  a  country  home.  A  rathskeller  in  the  sub- 
basement  may,  with  a  modern  system  of  ventilation,  have  much  better 
air  than  that  found  in  a  department  store  with  acres  of  floor  space 
and  high  ceilings.  In  other  words,  a  small  space  is  sufficient  if  prop- 
erly ventilated;  a  large  space  inadequate  if  improperly  ventilated. 

The  size  of  rooms  for  dwellings  and  workshops  is  somewhat  of  an 
economic  question,  but  they  should  be  large  enough  to  allow  the  air 
to  be  replaced  two  or  three  times  an  hour  without  causing  perceptible 
drafts.  The  minimal  space,  in  accordance  with  this  standard,  is  about 
one-third  the  quantity  of  air  required  per  hour;  that  is,  from  700  to 
1,000  cu.  ft.  per  person.  The  amount  of  space  naturally  varies  with 
dwellings,  factories,  schools,  theaters,  prisons,  hospitals;  also  with  the 
length  of  time  the  room  is  occupied  and  the  nature  of  the  work  there 
carried  on.     Thus,  in  hospitals  where  ordinary  cases  are  cared  for,  from 


658 


VEXTILATIOX    AXD    HEATIXG 


1,800  to  2,000  cu.  ft.  of  air  is  desirable  for  each  patient,  while  no  less 
than  2.500  cu.  ft.  should  be  allowed  for  each  fever  patient.  Soldiers 
in  barracks  are  allowed  600  cu.  ft.  per  head,  and  the  limit  for  lodging 
houses  is  usually  fixed  at  from  300  to  500  cu.  ft.  The  U.  S.  Emigration 
Law  requires  500  cu.  ft.  per  head  in  the  steerage.  In  figuring  the 
amount  of  air  space  in  a  room  allowance  should  be  made  for  furniture, 
projecting  surfaces,  and  other  objects  which  diminish  the  available 
space.  The  following  table  from  Parkes  and  Kennwood  shows  the 
attempts  made  by  Great  Britain  to  fix  the  minimum  space  allowed  per 
head  bv  legislation : 


Minimum  Space 
per  Head 
in  Cu.  Ft. 


Authority 


Common  lodging  houses  (sleeping 
rooms) 

Registered  lodging  houses — 

Rooms  occupied  by  day  and  night. . 
Rooms  occupied  by  night  only 

Non-textile  wrokrooms 

Non-textile  workrooms  during  over- 
time   

Underground  bakehouses 

Above-ground  bakehouses  where 
night  work  is  carried  on  by  arti- 
ficial light  other  than  electric 
light 

Army  barracks 

Army  hospital  wards 

Public  elementar>'  schools 

London  County  Council  Schools .... 
Canal  boats  (persons  over  12  j^ears).. 
Canal  boats  (persons  under  12  years). 

Seamen's  cabins 

Cows  in  cowsheds 


300 


Local    Government    Board 
(Model  By-laws). 


400 

Ditto. 

300 

Ditto. 

250 

Factory  Act,  1901. 

400 

Ditto. 

500 

Order  under  Factory  Act, 

1901. 

400 

between  9  p.  m. 

and  6  a.  m. 

Ditto. 

600 

British  Army  Regulations. 

1,200 

Ditto. 

80 

Educational  Department. 

130 

London  County  Council. 

60 

Local    Government    Board, 

40 

Regulations     under     the 

Canal  Boat  Act,  1S77. 

72 

Merchant  Shipping  Act. 

800 

Local   Government    Board, 

Model  Regulations  under 

the    Dairies,    Cowsheds, 

and  Milk-shops  Order. 

A  little  consideration,  however,  \vill  show  that  such  regulation  of 
space  is  by  itself  of  little  value.  Unless  there  be  movement  of  air, 
space  alone  is  futile.  However  large  the  space  may  be,  the  air  will 
become  impure  unless  fresh  air  circulates  through  it,  and  however  small 
the  space  the  air  may  be  kept  pure  by  sufficient  circulation. 

As  the  result  of  many  analyses  that  have  been  made  by  Haldane 
and  Osborne,  they  found  that  the  carbon  dioxid  bears  no  relation  to 
the  amount  of  air  space  under  practical  conditions.     In  fact,  the  most 


VENTILATION  659 

highly  vitiated  air  found  was  in  a  room  with  an  air  space  of  about 
10,000  cu.  ft.  per  person. 

It  is  not  alone  the  air  space  but  the  shape  of  the  room  that  influences 
ventilation.  It  is  a  mistake  to  suppose  that  a  lofty  room  is,  there- 
fore, an  airy  room,  for  a  stratum  of  warm  vitiated  air  soon  occupies 
the  upper  portion  of  such  a  space,  and,  so  far  as  good  air  is  concerned, 
has  the  effect  of  lowering  the  effective  height  of  the  ceiling  to  the  top 
of  the  door  or  nearest  outlet.  Anyone  may  convince  himself  of  this 
fact  by  getting  up  on  a  stepladder  in  a  room  with  a  high  ceiling,  im- 
properly ventilated,  and  occupied  for  some  hours.  The  upper  stratum 
of  air  in  such  rooms  is  frequently  stifling.  Ordinarily  12  feet  is  high 
enough  for  the  ceiling  of  school  rooms,  museums,  hospitals,  etc.,  and 
9  feet  for  the  rooms  of  private  dwelling  houses.  Where  there  is  little 
or  no  movement  of  the  air  it  soon  becomes  offensive,  no  matter  what 
the  height  of  the  ceiling. 

Floor  space  is  more  important  than  height.  The  necessity  for  an 
abundant  floor  space  is  shown  by  the  fact  that  a  small  inclosure  with 
four  high  walls  and  without  a  roof,  if  crowded,  speedily  becomes  oppres- 
sive. In  fact,  the  four  walls  are  not  necessary  to  demonstrate  this,  for 
"crowd  poisoning''  in  the  open  air  upon  a  still,  warm  day  is  a  common 
experience.  According  to  Harrington,  when  the  allowance  is  only  500 
cubic  feet  per  inhabitant,  the  floor  space  should  be  42  square  feet 
(81/^x5%).  In  the  English  barracks  the  soldiers  are  allowed  50  square 
feet  of  floor  space.  For  school  rooms  the  British  Educational  Code 
requires  120  cubic  feet  per  child .  in  average  attendance  and  a  floor 
space  of  10  square  feet. 

Inlets  and  Outlets. — Whether  a  room  is  to  be  ventilated  by  natural 
or  mechanical  means,  proper  inlets  for  the  fresh  air  and  outlets  for 
the  vitiated  air  must  be  provided.  No  general  statement  as  to  the  best 
size  and  position  of  these  openings  will  apply  under  all  circumstances. 

Knowing  the  velocity  of  the  incoming  air,  the  area  of  the  inlets 
may  be  proportioned  so  as  to  permit  the  movement  of  the  necessary 
amount  of  air.  The  size  of  the  openings  under  specifled  conditions  is, 
therefore,  a  matter  of  simple  arithmetic.  In  measuring  the  effective  area 
of  inlet  and  outlet  tubes  allowance  must  be  made  for  friction  and  for 
the  guards  or  fretwork  which  protect  the  openings.  These  often  dim- 
inish the  effective  area  about  one-half. 

It  is  usually  better  to  admit  the  incoming  air  into  a  large  apart- 
ment through  a  number  of  openings  rather  than  through  one  large 
one;  the  same  holds  true  of  outlets.  Outlets  should  be  about  the  same 
size  as  inlets  and  should  be  placed  with  reference  to  them. 

All  air  duets  tend  to  become  soiled  with  dust  and  soot  and  should, 
therefore,  be  guarded  with  wire  gratings,  muslin,  porous  flannel,  or 
other  protecting  and  filtering  devices,  and  they  should  also  be  cleaned 


660 


VENTILATION    AND    HEATING 


periodically;  further,  it  should  bo  borne  in  mind  that  ventilating  ducts 
are  favorable  highways  for  mice,  roaches,  and  vermin.  Inlets  opening 
upon  the  floor  are  objectionable,  as  they  collect  unusual  amounts  of 
dirt  and  dust,  which  are  then  blown  into  the  room. 

^\^lcther  the  air  is  to  be  admitted  near  the  floor  and  taken  out  near 
the  ceiling  or  vice  versa  is  a  question  much  discussed  among  ventilat- 
ing engineers.  Various  possibilities  are  shown  in  the  diagram.  Fig. 
89.     The  natural  course  of  the  warmed  vitiated   air   is   upward,   and 


Fig.  89. — The  Position  of  Inlets  and  Outlets,  and  Their  Relation  to  the  Air 

Currents  in  a  Room. 


it  would  seem  that  the  upward  system  has  advantages  over  the  down- 
ward system.  However,  a  little  study  will  soon  convince  one  that  if 
the  incoming  air  is  warm  it  will  rise  at  once,  and  the  maximum  effi- 
ciency will  be  lost  at  the  breathing  line,  which,  after  all,  is  the  essential 
stratum  of  air  in  the  room.  Perhaps  the  best  arrangement  is  to  have 
the  inlet  above  and  the  outlet  below — both  upon  the  same  side  of  an 
inner  wall. 

Outlet  ventilation  may  be  arranged  by  placing  a  bell  cover  or  glass 
globe  over  the  gas  lights  and  conveying  the  heated  air  thence  to  the 
outer  air  by  means  of  ascending  tubes.  This  not  only  removes  the 
products  of  combustion,  but,  if  the  outlet  tubes  have  a  sufficient  area, 


VENTILATION  661 

affords  a  very  good  system  of  ventilation.  An  automatic  system  of 
taking  the  air  out  of  a  room  may  also  be  provided  by  placing  a  shaft 
either  around  the  chimney  flue  or  against  one  side  of  it.  The  column 
of  heated  air  in  the  ventilating  duct  will  rise  and  draw  the  vitiated 
air  out  of  the  room  with  which  it  is  connected.  The  same  "may  be 
accomplished  by  placing  a  steam  jet  or  a  gas  burner  within  the  ven- 
tilating duct  to  create  a  draft. 

Ventilating  ducts  usually  extend  up  the  walls  of  the  building 
through  the  roof,  and  should  be  in  as  direct  a  line  as  practicable.  The 
openings  upon  the  roof  may  be  protected  by  an  umbrella-like  covering 
against  rain,  or  they  may  be  cowled  to  prevent  down  drafts.  It  ap- 
pears that  none  of  the  exhaust  cowls  cause  a  more  rapid  current  of 
air  than  prevails  in  an  open  pipe  under  similar  circumstances. 

External  Ventilation. — Model  city  planning  should  provide  streets 
of  sufficient  width,  and  should  regulate  the  height  of  buildings  and 
also  limit  the  extent  upon  which  the  land  may  be  built,  so  as  to  allow 
a  free  circulation  of  air  about  all  structures  and  admit  a  flood  of  sun- 
shine for  at  least  a  few  hours  during  the  day.  Some  of  our  metropoli- 
tan streets  resemble  canyons  rather  than  city  thoroughfares.  Crowded 
tenements  facing  upon  narrow  streets  with  shafts  for  courts  and  back- 
ing almost  directly  upon  the  houses  in  the  rear,  and  further  surrounded 
by  tall  buildings  which  prevent  the  free  movements  of  the  outer  air, 
and  shut  out  the  sunshine,  should  be  prohibited,  whether  used  as  dwell- 
ings or  workshops.  In  such  places  the  ground  stays  moist,  the  air 
becomes  stagnant,  natural  ventilation  is  greatly  retarded,  and  the  con- 
ditions upon  a  hot,  still,  moist  day  in  summer  become  almost  intoler- 
able. 

Generous  parks,  which  are  the  lungs  of  a  great  city,  should  be 
scattered  throughout  the  residential  and  business  sections;  playgrounds, 
boulevards,  and  small  open  areas  treated  as  parkings  not  only  beautify 
but  help  to  ventilate  a  city  and  add  to  the  comfort,  happiness,  and  health 
of  its  inhabitants. 

Natural  Ventilation. — Natural  ventilation  depends  upon  openings, 
such  as  doors  and  windows,  also  upon  the  air  that  comes  through  the 
pores  of  plaster,  brick,  and  stone  and  through  floors  and  ceilings  and 
through  the  cracks  and  crevices  about  window  frames,  etc. 

Natural  ventilation  depends  mainly  upon  three  principal  factors : 
(1)  perflation  and  aspiration;  (2)  gravity  or  thermal  circulation;  (3) 
diffusion  of  gases.  These  factors  constantly  operate,  whether  in  the 
presence  or  absence  of  any  mechanical  system.  In  fact,  most  schemes 
for  mechanical  ventilation  are  simply  an  application  of  these  natural 
forces. 

Perflation  is  simply  the  blowing  of  the  air  into  the  room  as  a  result 
of  the  movement  of  natural  air  currents.     Aspiration  is  the  sucking 
44 


662  VENTILATION    AND    HEATING 

action  of  the  wind  wliich  draws  air  out  of  a  space  that  it  is  blowing 
across.  Thus,  a  wind  blowing  across  an  open  tube  carries  along  with 
it  some  of  the  air  in  the  upper  part  of  that  tube.  This  causes  an  up- 
ward movement  of  the  air  in  the  tube.  The  same  phenomenon  takes 
place  when  wind  blows  by  a  window.  The  aspirating  action  of  air 
is  well   demonstrated  in  the  construction   of   an  ordinary  atomizer. 

The  air  is  kept  in  almost  constant  motion  through  changes  in  tem- 
perature. Warm  air  expands,  is  therefore  lighter,  and  rises.  This 
is  a  familiar  phenomenon  in  the  hot-air  balloon.  Thermal  circulation, 
though  often  imperceptible,  is  constantly  in  operation,  especially  in  oc- 
cupied rooms.  Even  in  calm  w^eather  there  is  considerable  ventilation 
owing  to  differences  in  temperature,  and  hence  differences  in  pressure 
between  the  air  of  the  room  and  the  outside. 

More  air  than  is  commonly  supposed  enters  or  leaves  a  room  through 
the  cracks  about  doors  and  windows  and  other  crevices.  From  the 
standpoint  of  natural  ventilation  it  is,  therefore,  not  advisable  to  have 
windows  fit  too  snugly.  The  use  of  weather-strips,  tongue  and  grooved 
metal  strips,  and  similar  devices  to  keep  out  the  cold  air  saves  coal 
bills,  but  is  a  considerable  hindrance  to  natural  ventilation. 

Under  certain  conditions  very  considerable  amounts  of  air  pass 
through  the  building  materials  used  in  the  construction  of  walls,  floors, 
and  ceilings.  Ordinary  mortar  is  most  permeable,  then  comes  brick, 
then  sandstone,  next  plaster  of  paris,  while  enamel  and  tile  are  im- 
pervious. Under  a  pressure  of  108  millimeters  of  water  the  following 
amounts  of  air  pass  in  one  hour  through  one  square  meter  of: 

Mortar    3,264            liters 

Plaster    of  paris 146                 " 

Bricks    312-1,396     " 

Sandstone    426-   496      " 

A  pressure  of  108  millimeters  of  w^ater  is  equivalent  to  the  pressure 
of  a  strong  wind.  The  amount  of  air  that  will  pass  through  porous 
materials  varies,  of  course,  with  the  temperature,  moisture,  and  other 
factors. 

Marker  and  Schultze,  in  their  researches  on  the  spontaneous  ven- 
tilation of  stables,  found  that  the  following  interchange  of  air  occurred 
per  hour  over  one  square  yard  of  free  wall  at  9.5°  F.  difference  of 
temperature : 

With   walls   of  sandstone 4.7  cu.  ft. 

Quarried    limestone    6.5    "      " 

Brick     7.9    "      " 

Tufaeeous   limestone    10.1    "      " 

Mud    14.4    "      " 

It  is  possible  to  force  sufficient  air  through  an  ordinary  brick  to 
deflect  the  flame  of  a  candle  on   the  other  side.     This  demonstration 


VENTILATION 


663 


fflllffT 


is  usually  accomplished  by  coating  the  edges  and  exposed  portions  of 
the  brick  with  sealing-wax  and  arranging  glass  funnels  on  eitlier  side. 
Air  forced  with  a  bellows  through  one  funnel  may  be  measured 
either  as  to  its  amount  or  velocity  as  it  comes  out  of  the  opposed 
funnel. 

Natural  ventilation  is  better  in  winter  than  in  summer,  owing  to 
greater  differences  in  temperature.  It  may  be  almost  nil  on  a  hot 
calm  day.  Too  much  moisture  in  the  air  of  a  room  settles  upon 
the  surfaces  and  thus  stops  the  pores  of  building  materials,  and  also 
prevents  the  escape  of  carbon  dioxid.  Eain  has  a  similar  effect  on  the 
outside.  An  ordinary  brick  will  soak  up  a  pint  of  water.  Ventilation 
through  the  walls  is  also  hindered  by  oil  and  enamel  paints  and  by 
wall-paper.  Outside  obstacles,  such  as  excessive  foliage  and  narrow 
streets,  are  also  considerable  factors. 

Natural  ventilation  may  be  greatly  favored  by  simple  devices.  This 
may  be  demonstrated  by  placing  a  lighted  candle  in  a  bottle  with  a 
narrow  neck.  The  flame  soon  dies  out,  but  by  placing  a  partition  in 
the  neck  of  the  bottle,  so  that  the  products  of  combustion  will  escape 
on  one  side  and  the  fresh  air  enter  upon  the  other,  natural  ventilation 
proceeds  so  that  the  candle  remains  lighted.  There  are  numerous 
simple  devices  that  may 
be  placed  at  the  top 
or  bottom  of  windows 
which  favor  the  en- 
trance of  fresh  air  or 
the  exit  of  vitiated  air. 
An  arrangement  shown 
in  Fig.  90  gives  very 
satisfactory  results.  One 
of  the  upper  window 
panes  may  be  valved  or 
fitted  with  a  fan  to  per- 
mit the  entrance  of 
fresh  air  or  the  exit  of 
vitiated  air.  Openings  in  ceilings,  ridged  ventilators,  Sheringham's 
valves,  Ellison's  bricks,  Tobin's  tubes,  and  Stevens'  drawer-ventilator  are 
all  useful  accessory  devices  to  aid  natural  ventilation. 

Ellison's  bricks  are  bricks  with  conical  perforations,  the  widened 
end  of  the  conical  opening  debouching  on  the  interior  of  the  wall.  The 
holes  through  the  bricks  are  about  2/10  inch  in  diameter  externally 
and  11/4  inches  internally. 

Tobin's  tube  consists  of  a  large  upright  tube,  about  5  or  6  feet 
high,  which  conducts  outside  air  into  the  room  through  the  wall. 

The  Sheringham  valve  is  a  small  vertical  flap  door  in  the  wall  near 


Fig.  90. — Window  Ventilator. 


664 


VENTILATION    AND   HEATING 


the  ceiling,  balanced  by  a  counterpoise,  and  hinged  so  as  to  fall  forward 
toward  the  room;  it  is  cased  in  at  the  sides  and  front,  so  that  the 
current  can  only  pass  upward. 

Stevens'  drawer  ventilator  is  like  a  drawer  lacking  its  back.  It  is 
made  to  fit  into  a  hole  in  the  wall  in  such  a  way  that  when  the  drawer 
is  shut  the  hole  is  airtight,  and  when  the  drawer  is  open  air  can  enter. 

Hinckes-Bird  ventilator  is  made  of  the  opening  between  two  ordi- 
nary window  sashes  when  the  lower  is  raised,  and  the  lower  opening 


Fio.  91. — Diagrammatic  Sketch  of  Various  Provisions  for  Ventilation. — A,  Sash 
window  with  Hinckes-Bird's  arrangement.  B,  Hopper  sash-light  falling  inwards.  C, 
Louvred  outlets.  D,  McKinnell's  ventilator.  E,  Sheringham's  valve.  F,  Tobin'a 
tube  (showing  valve  open).  G,  Ellison's  conical  bricks.  H  and  I,  Grid  ventilators 
below  floor  joists.  (From  "  Hygiene  and  Public  Health,"  by  Drs.  L.  C.  Parkes  and 
H.  R.  Kenwood,  London,  H.  K.  Lewis,  Philadelphia,  Blakiston,  1911.) 

closed  by  means  of  a  specially  high  sill  or  by  an  accurately  fitting 
block  of  wood. 

These  various  devices  should  be  protected  with  valves  so  that  they 
may  be  regulated.  Sometimes  it  is  advisable  to  provide  gauze  or  cot- 
ton filters  to  keep  out  the  dust. 

Natural  ventilation  is  greatly  aided  by  means  of  warming  the  air 
in  the  outlet  duct.  The  best  example  of  this  is  the  open  fireplace,  or 
other  devices  for  warming  the  air  in  outlet  tubes  already  referred  to. 

Wherever  possible,  open  windows  are  the  best  and  simplest  means 
of  ventilating  a  room.  Any  system  of  mechanical  ventilation  at  best 
is  costly  and  frequently  unsatisfactory.  Open  windows  are  cheap  and 
adequate,  but  the  limitations  and  disadvantages  of  natural  ventilation 


HEATIXG  665 

are  obvious,  and,  therefore,  we  are  frequently  required  to  resort  to 
mechanical  means. 

Mechanical  Ventilation. — All  "artificial"  systems  of  ventilation  de- 
pend upon  one  of  three  methods:  (1)  plenum  system,  which  consists 
in  the  mechanical  propulsion  of  air  into  the  room;  (2)  the  vacuum 
system,  which  consists  of  the  mechanical  extraction  of  the  air  out  of 
the  room;   (3)  a  combination  of  the  plenum  and  vacuum  systems. 

Air  may  be  propelled  into  a  room  either  by  means  of  a  warming 
apparatus  or  by  mechanically  propelling  the  air  by  means  of  rotary 
fans.  Every  heating  apparatus  is  secondarily  a  ventilating  device,  es- 
pecially hot-air  furnaces,  and  the  direct-indirect  systems  in  use  with 
hot-water  or  steam  pipes.  Stoves,  open  fireplaces,  and  similar  heating 
arrangements  are  also  good  ventilating  devices  in  that,  if  well  con- 
structed, they  take  out  large  quantities  of  air  from  the  room. 

For  the  mechanical  propulsion  of  air  either  fans  or  "blowers"  are 
used.  These  may  be  run  by  electricity,  gas,  or  steam  power.  The  air 
is  forcibly  driven  through  ducts  to  where  it  is  wanted.  Without  this 
system  of  mechanical  ventilation  the  great  office  buildings,  basement 
restaurants,  large  passenger  steamships,  and  other  modern  structures 
would  not  be  habitable. 

If  dependence  is  placed  solely  upon  drawing  the  vitiated  air  out  of 
a  room  we  are  leaving  to  chance  where  the  fresh  air  is  coming  from 
to  replace  it.  In  other  words,  it  is  impossible  when  the  so-called  vacuum 
system  alone  is  used  to  control  the  source  of  the  fresh  air  and  insure 
its  purity.  As  a  rule,  all  well-ventilated  structures  depend  neither 
upon  the  plenum  nor  the  vacuum  systems  alone,  but  combine  the  two. 

The  disadvantages  of  the  mechanical  systems  of  ventilation  are  that 
they  are  expensive  as  to  first  installation  and  as  to  maintenance ;  further- 
more, they  are  designed  to  work  only  when  all  the  doors  and  windows 
are  kept  closed.  The  advantages  are  that  they  are  effective  in  all  kinds 
of  weather,  and  require  less  space  for  tbe  air  ducts  than  natural  ven- 
tilation. 

HEATING 

Heating  and  ventilation  go  hand  in  hand.  A  large  share  of  the 
cost  of  heating  is  chargeable  to  ventilation,  hence,  if  ventilation  is 
overdone,  it  is  an  unnecessary  expense.  The  artificial  warming  of 
houses  has  a  similar  action  to  clothing.  "Burning  fuel  in  the  furnace 
saves  fuel  in  the  human  machine."  It  especially  saves  the  strain  upon 
the  metabolism  of  the  young,  the  old,  and  the  feeble.  The  tendency 
in  winter  is  to  wear  too  much  clothing  indoors  in  order  to  compensate 
for  our  imperfect  systems  of  heating.  This  results  in  coddling — that 
is,  loss  of  vasomotor  tone  of  our  peripheral  capillary  circulation,  from 
the  constant  bathing  of  the  skin  in  a  close  moist  layer  of  air.     This  in 


666  VENTILATION    AND    HEATING 

turn  results  in  susceptibility  to  drafts  and  liability  to  colds.  It  is  quite 
unnecessary  to  wear  heavy  winter  clothing  in  rooms  and  offices  properly 
heated  and  ventilated. 

Most  of  our  American  houses  are  overheated  with  abnormally  dry 
air  in  the  winter  time.  This  is  a  mischievous  combination.  It  causes 
excessive  evaporation  from  the  skin  and  mucous  membranes,  which  gives 
rise  to  a  feeling  of  chilliness.  It  also  causes  dryness  of  the  skin  and 
mucous  membranes,  irritation  of  the  throat,  and  thus  predisposes  to 
colds  and  respiratory  infections.  ^Yarm  dry  air  does  not  give  the  same 
sense  of  warmth  and  comfort  afforded  by  a  cooler  moist  air.  Thus,  air 
at  62°  to  65°  F.  and  a  relative  humidity  of  70  per  cent,  feels  warmer 
than  air  at  70°  to  72°  F.  and  a  relative  humidity  of  50  per  cent,  or 
less.  Furnace  heat,  hot-water,  and  steam  pipes  tend  to  dry  the  air, 
and  thus  it  becomes  necessary  to  overheat  our  offices  and  houses  be- 
fore they  become  comfortable. 

Heat  is  measured  by  the  British  thermal  unit  (B.  T.  U.),  which  is 
the  quantity  of  heat  required  to  raise  the  temperature  of  a  pound  of  pure 
water  one  degree  at  its  point  of  maximum  density,  39°  F.  The  French 
thermal  unit  is  the  calorie  and  is  the  amount  of  heat  required  to  raise 
one  kilogram  of  water  one  degree  centigrade  at  corresponding  tempera- 
ture (4°  C).    One  calorie  equals  3.968  B.  T.  U. 

Heat  travels  by  radiation,  conduction,  and  convection.  All  three 
routes  are  constantly  in  operation  in  any  system  of  heating.  Thus,  with 
an  open  fireplace  the  heat  waves  radiate  in  straight  lines  to  the  near- 
est objects,  where  they  are  absorbed  or  reflected,  just  as  light  passes 
through  space  independent  of  the  atmosphere.  That  is  why  our  face 
toasts  and  our  back  freezes  before  an  open  fireplace.  The  heat  ab- 
sorbed by  any  object  passes  through  that  object  from  particle  to  par- 
ticle by  conduction.  Most  metals  are  good  conductors;  air  is  a  very 
poor  conductor  of  heat.  Convection  is  the  process  by  which  heat  is 
communicated  through  gases  and  liquids  as  a  result  of  their  mobility. 
Thus,  the  air  is  warmed  by  our  bodies,  by  hot-water  pipes,  and  by  all 
heated  objects,  and  therefore  rises  and  establishes  convection  currents. 

There  are  five  main  methods  of  heating:  (1)  open  fires;  (2)  stoves; 
(3)  hot  air;    (4)   hot-water  or  steam  pipes;   (5)   electricity. 

Open  Fires. — The  open  fireplace  heats  mainly  through  direct  radia- 
tion. It  has  the  advantage  of  being  cheerful  and  a  good  ventilator. 
It  has  the  disadvantage  of  being  wasteful  and  very  unequal  if  depended 
upon  as  the  chief  source  of  heat. 

Parkes  and  Kenwood  estimate  that,  in  an  ordinary  medium-sized 
sitting  room  with  an  ordinary  fire,  from  10,000  to  15,000  cu.  ft.  of 
air  are  drawn  up  the  chimney  in  an  hour,  the  current  being  generally 
from  3  to  6  ft.  a  second.  "As  ventilating  agents,"  say  Notter  and 
Firth,  "the  best  types  of  open  fireplace  cause  some  2,600  cu.  ft.  of  air 


HEATING  667 

to  pass  up  the  flue  per  pound  of  coal  consumed,  or  the  passage  of  about 
18,000  cu.  ft.  up  the  chimney  per  hour." 

Franklin  Stoves. — Franklin  stoves  consist  of  coal  fires  in  a  cast- 
iron  stove,  the  products  of  combustion  being  carried  off  through  a  stove- 
pipe. Such  stoves,  standing  free  in  the  room,  are  very  efficient,  so  far 
as  heating  is  concerned,  and  also  favor  ventilation  through  the  circu- 
lation of  air,  which  is  drawn  into  the  stove  to  support  the  burning  of 
the  fuel.  The  heating  of  the  room  is  unequal,  as  it  depends  largely 
upon  radiation  and  somewhat  upon  convection.  Such  stoves  are  apt 
to  become  red-hot,  in  which  case  it  is  believed  they  allow  carbon 
monoxid  to  pass  through  the  feast  iron.  The  organic  dust  in  the  air 
falling  upon  the  hot  stove  is  burned  and  produces  an  unpleasant  smell. 

Open  Gas  Heaters. — Open  gas  heaters  without  flues  to  carry  off  the 
products  of  combustion  are  bad,  from  a  sanitary  standpoint.  These 
heaters  consist  of  a  series  of  metal  tubes  containing  air  or  water,  which 
are  heated  with  naked  flames.  The  heat  is  thus  imparted  to  the  room 
by  convection  and  also  by  radiation.  Such  devices  may  contaminate  the 
air  with  carbon  monoxid  from  leakage  or  from  unconsumed  gas,  or  from 
the  formation  of  soot,  which  becomes  incandescent.  Such  heaters  also 
contaminate  the  room  with  CO,  and  other  products  of  combustion. 
The  "rubber"  tube  feeding  these  gas  heaters  often  leaks,  and  there  is 
frequently  a  perceptible  odor  of  gas  in  rooms  where  these  devices  are 
used.  Open  heaters  burning  oil  are  less  objectionable  than  those  using 
gas. 

Hot-air  Furnaces. — A  hot-air  furnace  consists  of  a  coal  flre  which 
heats  a  series  of  tubes  or  plates  in  the  dome  of  the  furnace.  The  air, 
which  is  usually  taken  from  the  outside  through  a  duct,  flows  into  this 
dome,  where  it  comes  in  contact  with  very  hot  surfaces,  and  is  thus 
conducted  by  thermal  circulation  through  a  series  of  ducts  into  the 
rooms  of  the  house.  A  hot-air  furnace  of  this  kind  constantly  pumps 
fresh  air  into  the  house  and  is,  therefore,  a  very  efficient  system  of 
ventilation.  The  objection  to  the  hot-air  furnace  is  that  the  air  is  ex- 
cessively dry  and  frequently  partly  "burned"  in  passing  over  the  heated 
surfaces  in  the  dome.  The  odor  caused  by  the  burning  of  the  organic 
particles  in  the  air  may  frequently  be  noticed  in  houses  heated  with  a 
hot-air  furnace.  The  heated  air  entering  the  rooms  is  usually  allowed 
to  escape  as  it  will.  In  order  to  overcome  the  disadvantage  of  the  dry- 
ness of  the  air  furnished  by  the  hot-air  furnace,  water  pans  are  always 
provided,  from  which  the  water  is  supposed  to  evaporate.  These  pans 
are  ridiculously  small  and  cannot  possibly  furnish  sufficient  moisture 
for  the  great  volume  of  air  constantly  passing  through  one  of  these 
furnaces.  For  instance,  according  to  Harrington,  air  at  25°  F.  satu- 
rated with  moisture  and  then  heated  to  70°  F.  would  need  half  a  pint 
in  every  thousand  cubic  feet  to  give  it  a  humidity  of  65  per  cent.     The 


668  VENTILATION    AM)    HEATING 

air  from  a  hot-air  furnace  is  perhaps  drier  than  that  furnished  by  any 
other  system  of  heating  or  ventilation.  Thus,  an  out-of-door  air  in 
winter  at  a  temi)erature  of  0°  F.,  with  a  relative  humidity  of  50  per 
cent.,  when  heated  to  70'^  F.,  will  have  a  relative  humidity  of  only 
3  per  cent.  This  is  drier  than  the  air  of  the  driest  climate  known, 
which  is  seldom  less  than  30  per  cent.  It  is  not  unusual  for  the  ex- 
cessively dry  air  of  a  furnace-heated  house  to  cause  the  woodwork  to 
shrink  and  fall  apart,  the  bindings  of  books  to  crack,  etc.  Living  in 
such  an  atmosphere  is  not  normal  and  must  be  harmful. 

Hot-water  and  Steam  Pipes. — This  is  a  very  simple  and  effective 
system  of  heating  buildings.  The  hot-water  system  is  especially  ap- 
plicable to  small  buildings  and  steam  pipes  to  large  buildings.  The 
hot  water  is  more  readily  controllable  than  steam,  which  has  a  ten- 
dency to  overheat.  Special  furnaces  are  found  on  the  market  to  heat 
the  water  or  to  generate  the  steam,  which  then  circulates  through  pipes 
to  the  rooms  where  wanted.  If  the  hot-water  radiators  or  steam  coils 
are  exposed  directly  in  the  room,  the  system  is  known  as  the  "direct." 
In  the  direct-indirect  system  the  hot-water  pipes  or  steam  coils  are 
placed  in  a  special  box  where  the  air  from  the  outside  is  heated,  and 
this  heated  air  flows  by  thermal  circulation  through  ducts  into  the 
rooms  where  wanted.  In  the  direct  system  the  air  of  the  room  is 
simply  heated  and  reheated  over  again,  while  in  the  direct-indirect  sys- 
tem the  fresh  warmed  air  is  constantly  pumped  into  the  building  and  it 
is,  therefore,  an  efficient  method  of  ventilation.  In  both  these  systems 
the  air  is  abnormally  dried,  just  as  it  is  in  the  hot-air  furnace,  though 
not  to  the  same  degree. 

Electric  Heating. — Electric  heating  is  clean,  easily  regulated,  but 
expensive.  It  has  the  disadvantage  of  being  insufficient  as  a  ventilat- 
ing device,  unless  special  inlets  and  outlets  are  provided.  Electric 
heaters  consist  simply  of  resistance  coils  which  heat  the  room  mainly 
through  radiation  and  convection. 

The  Cooling  of  Rooms. — Much  attention  has  been  given,  through 
necessity,  to  the  heating  of  rooms  in  winter  time,  but  heretofore  little 
attention  has  been  given  to  the  cooling  of  rooms  in  the  hot  season. 
It  is  quite  as  practicable  to  cool  rooms  as  it  is  to  heat  them,  and  some- 
times quite  as  important  to  health. 

The  principle  of  practically  all  cooling  devices  depends  upon  the 
fact  that  when  a  fluid  evaporates  to  its  gaseous  state  it  absorbs  a  con- 
siderable amount  of  heat — latent  heat.  This  heat  is  taken  from  the 
surrounding  objects  "which,  therefore,  become  correspondingly  cold. 
Cold  may  also  be  produced  by  the  expansion  of  air.  This  was  pointed 
out  in  1845  by  Joule.  Thus,  if  a  jet  of  air  at  60°  F.  were  blown  into 
a  room  under  a  pressure  of  10  inches  of  mercury  above  the  ordinary 
barometric  pressure,  the  sudden  expansion  of  this  compressed  air  would 


HEATING  669 

reduce  it  to  a  theoretical  temperature  of  13.3°  F.  below  freezing.  This 
principle  of  dynamic  cooling  has  been  applied  to  refrigerators. 

Ammonia  gas  is  now  almost  universally  employed  in  freezing  ma- 
chines. This  gas  is  readily  condensed  into  a  liquid.  The  compressed 
gas  is  allowed  to  expand  into  tubes,  and  the  cold  thus  produced  utilized 
directly;  more  frequently  an  indirect  method  is  used  by  which  the  ex- 
panding gas  first  cools  a  freezing  mixture  consisting  of  a  saturated  solu- 
tion of  calcium  chlorid;  this  chilled  brine  is  then  pumped  through  a 
series  of  pipes  to  the  refrigerator  or  apartment  where  it  is  desired. 

A  simple  method  of  cooling  a  room  is  by  the  rapid  evaporation  of 
water.  Dr.  Manning  was  able  satisfactorily  to  cool  a  large  room  in  the 
Government  Printing  Office  at  Washington  by  blowing  air  by  means 
of  an  electric  fan  over  a  moist  sheet.  This  sheet,  about  a  yard  wide, 
was  hung  near  the  ceiling,  and  constantly  wetted  by  a  stream  of  water 
flowing  over  it.^ 

^  Many  of  the  facts  in  this  chapter  upon  "Ventilation  and  Heating"  are 
taken  from  Donald  C.  Macfie's  book  on  "Air  and  Health,"  1909,  published  by 
E.  P.  Dutton  &  Co. 


SECTION     V 
SOIL 

CHAPTEK    I 
GENERAL    CONSIDERATIONS 

The  upper  layer  of  the  eartli's  crust,  known  as  the  soil,  is  derived 
from  the  disintegration  of  rocks  and  the  decay  of  animal  and  vege- 
table matter  of  all  kinds.  It  varies  from  a  few  inches  in  depth  to 
several  feet.  The  sub-soil  also  varies  from  a  few  feet  to  hundreds  of 
feet  in  depth,  to  hard  pan  or  an  impermeable  stratum. 

From  a  sanitary  standpoint  the  soil  must  be  regarded  as  our  friend 
rather  than  our  enemy.  Enormous  quantities  of  organic  matter  and 
infections  of  all  kinds  find  their  final  resting  place  in  the  soil  and 
are  there  disposed  of  and  rendered  harmless  by  nature's  beneficent 
processes.  In  fact,  a  closer  study  of  the  functions  of  the  superficial 
layer  of  the  soil  shows  that  it  is  not  only  the  organ  of  digestion  and 
respiration  of  the  earth,  but,  like  the  liver,  it  is  the  great  organ  in 
which  toxic  substances  of  all  kinds  are  neutralized  or  destroyed. 

The  sanitarian  does  not  look  upon  the  soil  as  dead  and  inert,  but 
rather  as  a  living  being,  for  it  presents  many  of  the  vital  phenomena 
that  characterize  life:  digestion,  metabolism,  assimilation,  growth,  res- 
piration, motion,  and  even  reproduction.  The  soil  breathes,  it  absorbs 
oxygen  and  exhales  carbon  dioxid ;  it  is  capable  of  digesting  and  as- 
similating vast  amounts  of  organic  matter  by  a  complex  process  of 
metabolism ;  the  waste  products  are  excreted.  If  these  wastes  are  re- 
tained the  soil  may  be  choked  or  killed  by  an  accumulation  of  its  own 
poison — a  sort  of  autointoxication.  The  soil,  like  all  living  things,  de- 
mands water,  but  it  may  be  drowned  by  an  excess.  A  water-logged  soil 
dies  in  very  much  the  same  sense  that  an  individual  dies  who  has  sup- 
pression of  urine.  Sedgwick  speaks  of  the  "living  earth"  in  the  sense 
that  it  is  teeming  with  life;  bacteria,  molds,  amebge,  and  many  of  the 
primitive  forms  of  the  animal  kingdom,  as  well  as  worms,  insects,  snakes, 
birds,  rodents,  and  many  other  animals,  make  their  temporary  or  per- 
manent homes  in  the  upper  layers  of  the  earth.  Earth  worms  by  their 
670 


SUEFACE    CONFIGURATION  671 

plowing  action,  so  beautifully  shown  by  Darwin  in  1881,  constantly  turn 
over  the  upper  layers  of  the  earth.  The  soil,  therefore,  is  in  constant 
peristalsis,  which  helps  its  digestive  functions.  The  rise  and  fall  of  the 
ground  water  is  analogous  to  the  movements  of  the  diaphragm  and 
assists  the  respiratory  functions  of  the  soil. 

Classification  of  Soils. — Soils  are  variously  classified,  depending  upon 
the  amount  of  sand,  gravel,  clay,  loam,  humus,  peat,  muck,  rock,  alkali, 
etc.,  which  they  contain.  The  difference  between  a  sandy  and  gravelly 
soil  depends  mainly  upon  the  size  of  the  particles.  These  soils  in- 
terest the  sanitarians  because  hookworms  live  and  flourish  in  them  bet- 
ter than  they  do  upon  clay  or  rock  formations.  "Clay  exists  in  par- 
ticles of  the  smallest  possible  size.  It  is  very  cohesive,  possesses  a  high 
degree  of  plasticity,  and  plays  a  very  important  part  in  determining 
the  fertilit}^  of  soils,  their  texture,  and  their  capacity  for  holding  water. 
Its  plasticity  is  due  to  the  presence  of  a  small  proportion  of  hydrated 
silicate,  and  is  modified  very  greatly  by  the  addition  of  less  than  a 
hundredth  part  of  caustic  lime.  It  is  exceedingly  impermeable  to 
water,  and  when  wet  dries  with  great  slowness"  (Harrington).  Loam 
consists  of  a  mixture  of  sand,  clay,  and  humus.  If  the  sand  predomi- 
nates the  soil  is  said  to  be  light;  if  the  clay  predominates,  heavy.  A 
rich  soil  contains  an  abundance  of  humus. 

By  humus  is  meant  the  products  of  vegetable  decomposition  in  their 
various  intermediate  stages  of  decay.  It  is  the  essential  element  of 
vegetable  mold,  and  is  necessarily  of  most  complex  composition.  It  is 
coniposed  of  a  great  nmnber  of  closely  related  definite  chemical  com- 
pounds, chief  among  which  are  ulmin  and  ulmic  acid,  which  are  sup- 
posed to  characterize  brown  humus;  humin  and  humic  acid,  which 
dominate  dark  or  black  humus ;  and  crenic  and  apocrenic  acids.  Humus 
contains  a  high  percentage  of  nitrogen,  especially  marked  in  some  of 
our  prairie  soils  and  in  the  '"iDlack  soil"  found  in  the  provinces  of  the 
Ural  Mountains,  which,  according  to  von  Hensen,  contains  as  much  as 
from  5  to  12  per  cent,  of  organic  matter. 

Surface  Configuration. — Geodesy,  or  surface  configuration,  has  an 
important  relation  to  health.  Low  and  swampy  ground  is  a  breeding 
place  for  the  malarial  mosquito.  Highlands  are  apt  to  be  drier  and 
more  healthful  than  lowlands.  A  slope  affords  better  drainage  than 
flat  lands,  and  thus  diminishes  the  dangers  from  soil  pollution,  but  in- 
creases the  risk  of  infection  being  washed  down  from  those  living  above. 
In  narrow  valleys  the  air  stagnates,  the  moisture  is  excessive  in  both 
the  soil  and  the  air,  and  there  is  an  unpleasant  blanket  of  cold  layers 
of  air  at  night.  ]\Iountain  sides  are  notoriously  windy.  High  plateaux 
suffer  from  extremes  of  temperature.  Thus,  at  ]\Iexico  Cit}'  (about 
8,000  feet  above  sea  level)  there  is  a  sharp  contrast  between  the  tem- 
perature during  the  day  and  night,  and  even  during  the  daytime  be- 


(373  GENERAL    CONSIDERATIONS 

tween  the  sunsliine  and  the  shade.  At  Quito,  which  is  9,350  feet  above 
the  sea  level,  the  daily  variation  of  temperature  at  some  periods  of  the 
year  is  no  less  than  34°  F.  Northern  exposures  do  not  get  enough 
sunshine,  and  southern  exposures  sometimes  too  much. 

The  relation  of  tlie  surface  configuration  of  the  land  to  health  is 
intimately  interwoven  with  the  whole  question  of  climate,  and  must 
take  into  consideration  temperature,  air  movements,  humidity,  sun- 
shine, barometric  pressure,  precipitation,  and  the  seasons  with  their 
endless  varieties  from  tropical  to  arctic. 

Composition  of  the  Soil. — ]\Iueh  attention  was  formerly  given  to  the 
hygienic  importance  of  the  chemical  constituents  of  the  soil.  The  pres- 
ence of  organic  substances  was  regarded  not  only  with  suspicion,  but 
as  a  serious  menace  to  health.  It  was  claimed  that  organic  pollution 
of  the  soil  made  a  good  culture  medium  for  the  germs  of  infectious 
diseases.  The  gaseous  products  of  decomposing  organic  matter  in  the 
soil  have  long  been  looked  u])on  as  particularly  injurious.  These  gases, 
with  other  ill-defined  but  unknown  volatile  substances,  are  spoken  of 
as  miasma  or  effluvia. 

We  now  know  that  ver}'^  few,  if  any,  of  the  bacteria  pathogenic  for 
man  grow  and  multiply  in  the  soil  under  natural  conditions.  The  spores 
of  tetanus,  malignant  edema,  and  anthrax  may  live  in  garden  earth 
for  many  years,  but  it  is  doubtful  whether  these  microorganisms,  es- 
pecially the  anaerobes,  ever  find  conditions  favorable  for  growth  and 
multiplication  in  the  soil.  Ordinarily  typhoid,  dysentery,  and  cholera 
bacilli  do  not  flourish  in  the  soil ;  on  the  contrary,  they  soon  die  there. 
It  has  been  shown  that  cities  built  upon  polluted  soils  have  sometimes 
suffered  relatively  less  from  typhoid  and  cholera  than  cities  built  upon 
rocky  or  virgin  soil.  In  some  cities  (as  Budapest)  it  has  been  pointed 
out  that  the  greatest  morbidity  and  mortality  rate  was  in  that  part  of 
the  city  built  upon  made  ground  filled  in  with  trash  and  much  organic 
waste.  These  instances  have  been  largely  coincidences,  for,  as  a  rule, 
the  low-lying,  polluted  soil  happened  to  be  the  poor,  crowded  tenement 
district.  A  sanitarian  does  not  recommend  polluted  soils  for  building 
sites,  but  it  seems  that  their  influence  upon  health  has  been  overstated, 
especially  where  cellars  are  properly  constructed.  While  a  polluted  soil 
may  not  be  hazardous  in  the  vrays  just  indicated,  it  may  be  dangerous 
so  far  as  hookworms  and  other  parasites  are  concerned,  or  indirectly  it 
may  lead  to  contamination  of  drinking  water,  food,  etc.  See  '"Pollution 
of  the  Soil,"  page  682. 

MiXERAL  Matters  ix  the  Soil. — By  far  the  most  abundant  ele- 
ment in  the  soil  is  oxygen.  According  to  various  estimates,  from  33  to 
50  per  cent,  of  the  solid  crust  of  the  earth  consists  of  oxygen.  The  other 
elements  found  in  abundance  in  the  soil  are :  silicon,  carbon,  sulphur, 
hydrogen,  chlorin,  phosphorus,  fluorin,  aluminium,  calcium,  magnesium, 


PHYSICAL   PEOPERTIES  673 

potassium,  sodium,  iron,  manganese,  and  barium.  Aluminium  silicate 
or  clay  makes  up  perhaps  two-thirds  of  the  inorganic  components  of 
soils.  Other  compounds  are  lime  and  magnesia  carbonates  (limestone) 
and  numerous  chlorids,  sulphates,  phosphates,  oxids,  etc.,  of  the  various 
bases. 

Iron  is  universally  present  and  gives  the  red  color  to  soils.  Kitrogen 
exists  in  soils  in  three  distinct  forms:  (1)  protein  and  its  split  products, 
(2)  ammonia  and  its  salts,  and  (3)  nitric  acid  and  nitrates  or  nitrous 
acids  and  nitrites. 

Vegetable  Matter  in"  the  Soil. — The  vegetable  matter  exists  in 
the  soil  in  various  stages  of  decomposition.  One  result  of  the  decay 
of  vegetable  substances  is  the  formation  of  well-defined  compounds,  such 
as  ulmic,  humic,  and  apocrenic  acids.  These  organic  acids  have  con- 
siderable power  to  dissolve  mineral  substances,  which  accounts  in  part 
for  the  plumbosolvent  action  of  acid-reacting  surface  waters  from  swampy 
lands. 

Peat  or  muck  results  from  the  incomplete  decay  of  vegetable  matter 
under  water. 

Animal  Matter  in  the  Soil. — Organic  matter  of  animal  origin  in 
soils  results  chiefly  from  the  decomposition  of  carcasses  or  from  con- 
tamination wifli  the  excreta  of  animals.  As  a  rule,  animal  matter  is 
neither  so  abundant  nor  so  widely  distributed  in  the  soil  as  vegetable 
matter.  From  a  sanitary  standpoint  soils  polluted  with  organic  mat- 
ter of  animal  origin  present  a  greater  danger  than  soils  polluted  with 
vegetable  matter. 

Physical  Properties. — In  general  it  may  be  said  that  the  physical 
properties  of  a  soil  are  more  important,  from  the  standpoint  of  health, 
than  its  chemical  composition. 

Porosity. — By  the  porosity,  or  pore  volume,  of  a  soil  is  meant  the 
volume  of  the  interstices  between  the  particles,  which  may  be  filled  with 
water  or  air,  or  both.  Ordinarily  the  pore  volume  in  soil  amounts  to 
about  40  per  cent.;  some  apparently  compact  masses,  such  as  sand- 
stone, have  as  much  as  30  per  cent.  The  pore  volume  of  the  soil  is 
independent  of  the  size  of  the  individual  grains. 

Permeability. — The  permeability  of  a  soil  to  air  does  not  depend 
upon  the  pore  volume,  but  upon  the  size  of  the  individual  pores. 

Water  Capacity. — The  water  capacity  of  the  soil  is  the  amount 
of  water  held  in  the  interstices  of  the  soil  when  saturated,  while  the 
water-retaining  capacity  is  the  amount  of  water  held  back  after  a  satu- 
rated soil  is  drained. 

Soil  Temperature. — The  sun  is  the  principal  source  of  the  soil 
temperature.  Some  heat  is  produced  from  chemical  changes,  but  not 
in  considerable  amounts.  The  original  heat  of  the  earth's  interior  fur- 
nishes a  constant  source  of  heat  that  is  of  much  importance. 


674  GENERAL    CONSIDERATIONS 

The  heat  absorbed  and  given  off  by  the  soil  has  a  notable  influence 
upon  the  atmospheric  temperature.  Some  soils  and  moist  surfaces  ab- 
sorb heat  from  the  sun  and  give  it  off  again  when  the  sun  has  set. 
The  most  heat-absorbent  soils  are  sandy  soils.  The  sand  of  the  desert 
may  be  heated  to  200°  F.,  and  when  this  hot  sand  is  raised  by  simoons 
the  temperature  of  the  air  in  the  shade  may  reach  125°  F.  or  more. 
The  power  of  absorbing  or  reflecting  solar  heat  also  depends  upon  tlie 
color  of  the  soil. 

Adsorption. — The  soil  has,  to  a  remarkable  extent,  the  property  of 
absorbing  odors  and  gases,  and  ordinarily  it  is  very  hygroscopic.  The 
soil  is  also  capable  of  holding  toxins,  colors,  and  other  substances 
through  the  physico-chemical  property  of  absorption.  In  this  respect 
it  acts  like  charx-oal.  Illuminating  gas  from  leaky  mains  may  be  di- 
vested of  its  odorous  constituents  in  its  passage  through  the  soil,  so 
that  its  presence  in  houses  may  be  undetected,  thereby  greatly  increas- 
ing the  danger.  In  the  experiments  made  by  Abba,  Orlandi,  and 
Rondelli  about  the  filtering  galleries  of  the  Turin  water  supply  the 
property  of  the  soil  to  hold  back  substances  in  solution  was  shown. 
Cultures  of  Bacillus  yrodigiosus  in  large  volumes  of  water  poured  into 
the  ground  at  various  points  made  their  appearance  200  meters  away  in 
42  hours,  whereas  dyes,  such  as  methyleosin  and  uranin,  could  not  be 
detected  until  after  75  hours. 

Soil  Air. — Air  is  present  in  all  soils,  even  in  the  hardest  rocks. 
Sandstone  may  contain  from  20  to  40  per  cent.,  sand  from  40  to  50 
per  cent.,  and  humus  as  much  as  2  to  10  times  its  own  bulk.  The 
soil  air  differs  markedly  in  composition  from  that  of  the  atmosphere. 
It  is  usually  very  moist  and  contains  various  gases,  especially  carbon 
dioxid,  resulting  from  the  decomposition  of  organic  matter.  For  the 
same  reason  soil  air  contains  less  oxygen  than  the  free  atmosphere.  The 
soil  air  varies  greatly,  according  to  the  character  of  the  soil,  the  cli- 
mate, the  season,  and  rainfall.  There  is  a  continual  interchange  be- 
tween the  air  of  the  soil  and  the  air  of  the  atmosphere.  This  inter- 
change is  influenced  by  differences  in  temperature,  by  rainfall,  and  by 
the  movements  of  the  ground  water  and  by  barometric  pressure.  Rain 
chokes  the  pores  and  checks  soil  ventilation.  The  soil  air  is  in  con- 
stant motion. 

Following  the  teachings  of  Pettenkofer,  the  amount  of  carbon  dioxid 
in  tlie  soil  air  was  for  years  taken  as  an  index  of  the  amount  of 
soil  pollution.  It  is  now  well  known,  however,  that  this  is  not  a  re- 
liable index,  for  the  reason  that  many  conditions  influence  the  amount 
of  CO2  in  soil  air.  A  soil  recently  manured  may  contain  from  2  to  5 
or  even  10  parts  of  CO,  per  thousand.  In  a  gravelly  soil  the  propor- 
tion may  be  as  high  as  80  parts  per  thousand. 

Soil  air   may   influence  health  when  contaminated   with   poisonous 


SOIL   WATEE  675 

gases,  such  as  carbon  monoxid.  This  occasionally  happens.  In  the  open 
these  gases  would  be  so  greatly  diluted  that  they  could  scarcely  exert 
a  deleterious  influence,  but  when  concentrated,  as  they  sometimes  are 
in  dwellings,  and  breathed  for  a  long  period  of  time  they  may  be  re- 
sponsible for  anemia,  headache,  and  other  symptoms.  Soil  air  contain- 
ing carbon  monoxid  may  be  sucked  into  a  dwelling  from  long  distances 
in  a  lateral  direction.  Leaky  gas  pipes  may  thus  render  the  air  of  a 
dwelling  impure  if  the  cellar  is  permeable.  This  is  favored  by  the 
pumping  action  of  the  furnace,  especially  when  the  surface  of  the  ground 
is  frozen. 

Soil  air  is  practically  sterile;  that  is,  under  ordinary  conditions  it 
contains  few  bacteria.  Odors  sometimes  contained  in  the  air  from  a 
polluted  soil  have  no  known  injurious  effect. 

Soil  Water. — The  passage  of  water  through  the  soil  is  essential  to 
soil  activity.  The  moisture  favors  the  bacterial  growth  by  which  soils 
purify  themselves  and  favors  vegetation.  Nitrates,  chlorids,  and  other 
soluble  substances  are  dissolved  in  the  water  and  pass  into  the  sub- 
soil, or  furnish  food  to  the  roots  of  plants.  A  soil  absolutely  dry,  as 
a  desert  soil,  is  lifeless.  A  soil  with  an  excess  of  moisture,  that  is, 
one  in  which  the  ground  water  level  is  at  or  near  the  surface,  delays  and 
alters  the  natural  decomposition  of  organic  matter.  In  the  deeper  layers 
of  the  soil,  where  no  bacterial  action  takes  place,  vegetable  matter  may 
remain  almost  permanently  without  change.  Thus,  wooden  piles  are 
not  attacked  after  centuries. 

Water  exists  in  the  soil  in  two  principal  forms:  (1)  soil  moisture, 
which  comprises  the  water  present  in  the  interstices  of  the  upper 
partly  saturated  layer,  as  well  as  the  watery  vapor  contained  in  the 
soil  air,  and  (2)  ground  water,  or  sub-soil  water,  in  which  case  the  in- 
terstices of  the  soil  are  completely  filled. 

The  soil  moisture  is  estimated  by  determining  the  loss  of  weight  by 
drying  10  grams  of  soil  at  100°  C.  to  constant  weight.  The  dry  sample 
may  then  be  exposed  to  air  saturated  with  moisture  under  a  bell  jar 
and  again  weighed.  The  increase  in  weight  indicates  the  absorptive 
power  of  the  soil. 

Water  may  also  be  regarded  as  existing  in  the  soil  under  three 
conditions,  viz.,  hygroscopic,  capillary,  and  gravitation.  The  hygro- 
scopic water  is  that  which  adheres  to  the  surface  of  the  soil  particles 
in  the  presence  of  air.  The  capillary  moisture  is  that  which  is  held 
within  the  spaces  that  are  capillary  in  their  nature.  The  gravitation 
water  is  that  which  drains  through  the  soil  and  accumulates  in  the  sub- 
soil over  an  impermeable  stratum.  For  a  discussion  of  ground  water 
see  chapter  on  water. 

It  is  generally  stated  that  a  persistently  low  ground  water  level, 
viz.,  15  to  20  feet,  is  healthful,  and  that  a  persistently  high  ground 


676  GENERAL    CONSIDERATIONS 

water  level,  viz.,  3  to  5  feet,  is  unhealthful,  and  that  a  ground  water 
level  that  fluctuates  suddenly  is  still  more  unhealthful.  Pettenkofer 
found  that  typhoid  fever  was  more  likely  to  occur  at  Munich,  Berlin, 
and  Leipzig  when  the  ground  water  level  was  at  its  lowest.  His  ex- 
planations to  account  for  this  were  ingenious,  but  we  now  know  that 
the  relation  was  only  a  coincidence,  for  the  same  does  not  hold  in  other 
places. 

Sub-soil  drainage  is  usually  considered  more  of  an  agricultural 
necessity  than  a  public  health  question.  Large  tracts  of  our  land  in 
the  middle  West  and  in  other  parts  of  the  world  have  normally  a  high 
ground  water  level,  and  it  is  necessary  to  bring  this  down  in  order  to 
increase  the  fertility  of  the  soil.  This  is  done  by  draining  the  sub- 
soil, which  also  abolishes  marshy  and  swampy  lands,  and  thus  puts  a 
check  upon  malaria. 

•  One  of  the  principal  influences  of  the  soil  upon  general  health  is 
through  soil  moisture.  Dampness  in  or  near  the  surface  of  the  soil 
may  affect  the  health  of  those  dwelling  nearby.  Such  a  soil  is  cold, 
and  the  atmosphere  immediately  above  it  is  liable  to  be  damp,  and  this 
appears  to  conduce  to  rheumatism,  neuralgia,  and  diseases  of  the  res- 
piratory tract.  Investigations  seem  to  indicate  that  the  general  health 
of  those  dwelling  on  damp  soils  is  inferior  to  that  of  those  more  favor- 
ably circumstanced  in  that  regard. 

The  Nitrogen  Cycle. — The  most  interesting  of  the  vital  phenomena 
taking  place  in  tlie  soil  is  the  disposal  and  utilization  of  organic  matter. 
This  may  best  be  illustrated  by  the  nitrogen  cycle,  which  must  be  under- 
stood in  order  to  have  a  clear  conception  of  soil  pollution,  water  purifica- 
tion, and  sewage  disposal. 

The  nitrogen  cycle  is  a  complex  series  of  events  which  protein 
matter  undergoes,  in  which  it  is  reduced  to  simple  and  stable  inorganic 
compounds,  and  then  returns  through  plant  life  to  the  animal  kingdom. 
One  phase  of  the  cycle,  namely,  the  breaking  down  of  animal  and 
vegetable  matter,  is  due  almost  entirely  to  bacterial  action.  The  other 
phase,  namely,  the  building  up  of  complex  living  organic  matter  from 
simpler  compounds  and  elements,  is  mainly  a  function  of  living  plants. 

The  nitrogen  cycle  is  a  process  in  which  the  anabolism  or  synthesis 
occurs  in  plants,  while  the  catabolism  or  analysis  is  brought  about 
chiefly  through  bacterial  action.  Hence  the  series  of  events  constituting 
the  nitrogen  cycle  largely  depends  upon  the  plant  kingdom.  The  im- 
portant phases  of  the  cycle  occur  upon  the  soil  and  in  its  superficial 
layer.  It  will  presently  be  seen  that  this  cycle  is  of  fundamental  im- 
portance in  sanitary  science,  and  has  a  special  significance  in  prevent- 
ing soil  pollution,  in  the  purification  of  water,  and  in  the  disposal  of 
sewage.  It  is  evident  that  any  permanent  break  in  this  cycle  would 
result  in  the  cessation  of  life  upon  the  earth. 


THE    NITEOGE^sT    CYCLE 


QTI 


As  soon  as  an  animal  or  plant  dies  its  protein  constituents  are  at 
once  attacked  by  putrefactive  bacteria.  The  proteolytic  microorganisms 
growing  in  and  upon  the  nitrogenous  matter  break  it  up  into  secondary 
and  simpler  products,  which  have  a  striking  resemblance  to  the  cleav- 
age products  of  gastric  and  pancreatic  digestion.  Some  of  the  putre- 
factive bacteria,  of  which  the  Bacillus  suhtilis  and  the  Bacillus  proteus 
are  important  t}^es,  liquefy  protein  matter  during  the  process  of  putre- 
faction. Other  bacteria,  of  which  the  colon  bacillus  is  a  t^-pe,  break 
down  organic  matter  without  evident  liquefaction.  Very  many  other' 
species  of  bacteria  take  part  in  this  stage  of  the  cycle.     For  the  most 


r 


v 


[.Kinetic  Energy] 
Fig.  92. — The  Nitrogen  Cycle. 


part  the  microorganisms  pathogenic  for  man  are  killed  during  the 
process  of  putrefaction;  they  die  in  the  struggle  for  existence.  The 
processes  of  decomposition  are  essentially  the  same,  whether  the  organic 
matter  is  the  carcass  of  an  elephant,  a  beetle,  a  tree,  or  a  leaf,  pro- 
vided that  the  necessary  moisture,  warmth,  and  other  conditions  for 
bacterial  growth  are  present.  The  breaking  down  of  vegetable  matter 
is  slower  and  more  difficult  than  the  breakdown  of  animal  matter.  This 
is  due  in  part  to  the  fact  that  the  latter  contains  larger  percentages  of 
putrescible  protein  and  also  usually  contains  more  moisture,  which  favors 
bacterial  activit}\ 

The  breaking   down   of  the   complex  protein   molecules   to   simpler 

and   stabler   compounds    is   usually   spoken   of    as   mineralization,    and 

may  be  regarded  as  a  series  of  oxidations.     According  to  our  present 

chemical  conception,  it  is  really  a  series  of  hydrolyses.     The  complicated 

■45 


678 


GENERAL   CONSIDERATIONS 


molecular  structure  of  protein  matter  is  analyzed  into  amino  compounds 
of  simpler  and  simpler  composition,  until  nitrogen  finally  appears  in 
the  form  of  ammonia.  We  know  little  of  the  chemistry  of  the  early 
stages  of  protein  decomposition.  The  process  seems  hopelessly  compli- 
cated from  the  intricate  structure  of  the  molecule.  Eventually  from 
the  seething  caldron  of  molecular  disintegration  there  appear  simpler 
substances,  such  as  proteoses,  peptone,  ptomains,  amins,  leucin,  and 
tyrosin,  and  other  amino  substances,  as  well  as  organic  acids,  indol, 
skatol,  phenol,  and  finally  sulphuretted  hydrogen,  mercaptan,  carbonic 
acid,  and  ammonia.  One  of  the  final  products  of  the  process  is  carbon 
dioxid,  part  of  which  passes  into  the  atmosphere  and  part  of  which 
is  retained  in  the  soil  as  carbonates  of  alkalies  or  alkaline  bases.     The 


^-  Impermeable  Strain 

Fio.  93. — The  Nitrogen  Cycle  in  Diagrammatic  Vertical  Section. 

ammonia,  as  such,  cannot  be  used  by  plants.  Some  of  it  may  escape 
into  the  atmosphere,  but  for  the  most  part  it  is  retained  in  the  soil 
as  ammonium  chlorid  or  ammonium  carbonate.  In  the  soil  the  am- 
monia is  oxidized  by  the  action  of  nitrifying  bacteria  into  nitrates.  This 
nitrifying  action  of  bacteria,  elucidated  by  Winogradski  in  1888,  was 
one  of  the  brilliant  discoveries  in  bacteriology.  Through  his  work  and 
that  of  later  workers,  it  is  now  known  that  this  process  is  usually  accom- 
plished in  two  distinct  steps.  In  the  first  stage  the  ammonia  is  oxidized 
to  nitrous  acid.  This  is  done  by  the  nitrosobacteria.  These  nitrous  or 
nitrite  bacteria  were  called  by  Winogradski  nitrosomonas  and  nitrosococ- 
cus.  It  is  now  known  that  a  large  number  of  microorganisms  belong 
to  this  group.  The  nitrites  exist  in  the  soil  probably  as  salts  of  potas- 
sium and  sodium.  They  remain  as  the  lower  oxid  a  very  short  time 
and,  therefore,  never  accumulate,  and  are  never  found   in  any   large 


THE    NITROGEN    CYCLE  679 

amount  for  they  are  unstable  and  readily  oxidized  to  nitrates. 
The  special  nitric  or  nitrate  bacteria  (nitrobacter)  were  first  accurately 
described  by  Winogradski.  The  nitrates  are  stable  and  represent  the 
final  stage  of  the  mineralization  of  nitrogenous  matter.  In  certain  arid 
parts  of  the  world  large  deposits  of  nitrates  (KNO3,  saltpeter)  are  found 
as  the  result  of  the  nitrification  of  bird  excrement  (guano),  which  is 
rich  in  available  nitrogen.  These  collections  do  not  occur  in  places 
where  there  is  enough  rain  to  carry  away  the  readily  soluble  nitrates. 

Ordinarily  the  nitrates  go  into  solution  in  the  soil  moisture  and  are 
either  taken  up  by  the  roots  of  plants  or  are  washed  away  in  the  ground 
water.  In  a  sanitary  analysis  of  water  taken  from  the  soil  the  presence 
of  nitrates  and  nitrites,  therefore,  has  a  special  significance.  If  nitrites 
are  found  in  soil  water  it  indicates  pollution  and  signifies  active  bacterial 
action  and  the  presence  of  organic  matter.  Nitrates  in  soil  water,  with- 
out nitrites,  are  an  index  of  past  pollution   (see  Water  Analysis). 

In  1886  Gayon  and  Dupetit  described  two  organisms,  B.  denitrificans 
a- and  /?,  capable  of  completely  reducing  nitrates.  Many  bacteria  have 
this  power  of  denitrification,  a  sort  of  reversible  process  by  which  nitrates 
are  reduced  to  ammonia.  This  is  characteristic  of  very  many  of  the 
well-known  microorganisms,  such  as  the  colon  group,  pyocyaneus,  sub- 
tilis,  and  other  soil  bacteria.  '  Denitrification,  however,  does  not  occur 
to  any  notable  extent  in  a  well-ventilated  soil. 

In  plant  metabolism  the  nitrates  are  used  to  build  up  new  protein. 
Certain  plants  get  some  of  their  nitrogen  through  the  bacterial  tubercles 
on  their  roots,  which  have  the  power  of  fixing  the  free  nitrogen  of  the 
air.  These  small  nodules  are  abundant  on  the  roots  of  various  legumin- 
ous plants  (peas,  clover,  etc.).  Pure  cultures  of  the  legume  or  nitrogen 
fixing  bacteria,  such  as  Bacillus  radicicola  of  Beyerinck,  may  be  obtained 
from  these  root  tubercles. 

It  should  be  noted  also  that  certain  bacteria  (azobacter)  have  the 
ability  to  fix  the  free  nitrogen  of  the  air  independently  of  plant  life  and 
may  grow  under  either  aerobic  or  anaerobic  conditions.  One  of  the 
first  known  of  tliis  group  was  an  anaerobe  described  by  Winogradski  in 
1895  and  named  by  him  Clostridium  pasteurianus. 

It  will  be  noted  that  in  the  nitrogen  cycle  all  the  essential  steps 
from  proteolysis  to  mineralization  of  the  organic  matter,  nitrification, 
oxidation,  and  reduction,  as  well  as  the  fixation  of  free  nitrogen  from 
the  atmosphere,  are  all  the  result  of  bacterial  action.  Each  stage  of 
the  complex  process  is  specific,  in  the  sense  that  it  requires  a  particular 
species  or  group  of  bacteria  to  affect  the  result,  and  also  specific  in  the 
sense  that  special  conditions  of  environment  are  necessary  for  its  action 
to  take  place. 

It  is  important  to  remember  that  practically  the  entire  cycle  takes 
place  upon  the  surface  and  in  the  upper  layers  of  the  soil.     A  few 


680  GENERAL   CONSIDERATIONS 

feet  below  the  surface  of  an  undisturbed  area  the  soil  contains  few 
or  no  bacteria.  Carcasses  buried  deep,  or  sewage  placed  too  far  below 
the  surface,  do  not  profit  by  the  nitrogen  cycle  in  its  entirety,  and 
under  such  circumstances  incomplete  nitrification  takes  place.  Na- 
ture's method  of  disposing  of  dead  wastes  is  thereby  defeated,  and  pol- 
lution of  the  soil  and  infection  of  the  ground  water  may  result. 

The  Carbon  Cycle. — Carbohydrates,  such  as  cellulose,  starch,  sugars, 
and  similar  constituents  of  vegetable  and  animal  matter,  are  fermented, 
with  the  formation  of  carbon  dioxid,  alcohol,  and  various  organic  acids. 
The  carbon  in  carbohydrates  passes  through  a  series  of  clianges,  which 
may  be  regarded  as  the  carbon  cycle.  The  carbon  dioxid  resulting  from 
fermentation  unites  with  water  in  the  plant  life,  and  under  the  action 
of  chlorophyll  and  sunlight  is  again  synthetized  to  starch  and  sugars. 

The  fermentation  of  the  carbohydrates  is  also  due  to  the  action 
of  microorganisms.  In  a  mixture  containing  both  carbohydrates  and 
protein,  as  a  rule,  the  bacteria  act  upon  the  carbohydrates  first.  In 
other  words,  the  putrefaction  of  protein  is  delayed  or  hindered  by  the 
presence  of  fermentable  carbohydrates.  For  this  reason  the  disposal 
of  sewage  containing  wastes  from  breweries  is  difficult. 

Fats  are  also  attacked  by  bacteria,  with  the  consequent  production 
of  acids.  The  hydrocarbons  are  broken  down  with  more  difficulty  than 
either  the  carbohydrates  or  protein.  An  excessive  amount  of  fat  in 
sewage  always  gives  trouble  on  a  filter.  For  instance,  the  drainage 
from  a  wool-scouring  mill  containing  lanolin  and. the  discharges  from 
slaughter  houses  and  the  wastes  from  creameries  and  cheese  factories 
containing  animal  fat  present  special  problems  in  sewage  disposal. 


CHAPTEE    II 
THE    SOIL    AND    ITS    RELATION    TO    DISEASE 

Bacteria  in  SoiL — Countless  millions  of  bacteria  occur  in  the  upper 
few  inches  of  the  soil.  The  enormous  overgrowth  of  bacteria  in  the 
upper  layers  of  the  soil  gives  it  the  sticky,  moist  feeling  which  rich 
soils  possess.  The  odor  of  the  soil,  such  as  that  which  is  particularly 
noticed  after  a  rainstorm,  is  due  in  large  part  to  Cladothrix  odorifera 
and  other  organisms  which  are  commonly  found  in  the  soil.  Few  bac- 
teria are  found  in  an  undisturbed  soil  below  a  depth  of  4  to  6  feet.  A 
sand  bed  used  for  filtering  sewage  shows  a  similar  vertical  distribution 
of  bacteria.  Below  six  feet  the  statement  is  made  that  the  soil  is  usually 
sterile.  This  is  not  strictly  true,  but  the  numbers  are  much  diminished 
and  bacterial  activity  has  practically  ceased.  As  a  rule,  living  bacteria 
are  not  obtained  from  samples  of  soil  obtained  10  to  12  feet  below  the 
surface,  except  in  soils  with  large  pores  or  crevices,  or  in  cases  where 
the  bacteria  have  been  carried  by  burrowing  animals.  It  is  exceedingly 
difficult  to  determine  the  number  of  bacteria  in  the  soil,  as  so  many  of 
them  are  anaerobes  and  vast  hordes  belong  to  the  nitrifying  groups,  which 
grow  only  upon  selective  media.  The  soil  is  also  the  home  of  other 
species,  requiring  special  conditions  for  growth  in  artificial  culture  media. 

Of  the  ordinary  bacteria  that  grow  upon  the  usual  laboratory  media 
Houston  found  an  average  of  100,000  per  gram  in  an  uncultivated 
sandy  soil,  1,500,000  per  gram  in  a  garden  soil,  and  115,000,000  per 
gram  in  a  sewage  soil.  Peaty  soils  have  smaller  numbers.  The  actual 
numbers  must  be  vastly  greater,  for  many  microorganisms  in  the  soil 
do  not  grow  upon  the  common  media.  In  fact^  the  soil  is  the  home 
of  the  greatest  number  and  variety  of  bacteria  found  anywhere.  It  is 
the  bacteria  in  the  upper  layers  of  the  soil  that  make  it  resemble  a  living 
gland.  Each  particle  of  earth  is  coated  with  a  zoogleal  envelope.  The 
sand  and  mineral  particles  form  the  supporting  structures,  the  coat- 
ing of  bacteria  corresponds  to  the  glandular  epithelium,  and  the  in- 
terspaces between  the  particles  are  the  capillary  and  lymph  channels. 

Most  of  the  bacteria  in  the  soil  are  saprophytes.  The  microorgan- 
isms pathogenic  for  man  do  not  find  conditions  favorable  for  growth 
and    development    in    the    soil.      For    the    most    part    the    tempera- 

681 


r,82       THE    SOIL    AND    ITS    K ELATION    TO    DISEASE 

ture  is  too  low ;  further,  they  are  crowded  out  by  the  overgrowth  of 
the  saprophytes.  Koch  has  demonstrated  that  anthrax  and  other  path- 
ogenic bacteria  may  be  grown  in  sterile  soil,  but  cannot  be  grown  in 
unsterilized  soil,  that  is,  in  living  soil.  They  die  in  the  struggle  for 
existence.  Experiments  have  shown  that  the  soil  of  graveyards  con- 
tains no  more  bacteria  than  the  corresponding  soil  in  the  same  locality, 
and  is  noticeable  by  the  absence  of  pathogenic  microorganisms.  The 
soil  often  contains  the  bacteria  (or  their  spores)  of  certain  wound 
infections,  such  as  malignant  edema,  anthrax,  B.  aerogenes  capsulatus, 
and  tetanus.  The  relation  of  the  soil  to  typhoid,  cholera,  dysentery, 
hookworm  disease,  Cochin-China  diarrhea,  and  other  infections  will  be 
discussed  presently. 

The  function  of  the  bacteria  in  the  soil  may  best  be  understood  by 
studying  the  fate  of  organic  matter  polluting  the  soil  and  the  processes 
which  accomplish  its  purification  (see  Xitrogen  Cycle,  page  676). 

Pollution  of  the  Soil. — The  soil  is  capable  of  disposing  of  great 
quantities  of  organic  matter.  However,  if  it  is  overburdened  it  remains 
polluted  and  may  endanger  health  through  contamination  of  the  drink- 
ing water  and  in  other  ways.  It  is  not  only  the  amount  but  the  kind 
of  pollution,  and  also  the  manner  of  its  disposal,  that  plays  a  very 
important  part.  It  must  first  of  all  be  remembered  that  the  purify- 
ing action  of  the  soil  is  largely  dependent  upon  bacteria,  and  that  this 
action  takes  place  almost  solely  in  the  upper  layers.  If  carcasses  are 
buried  deeply,  or  if  sewage  is  allowed  to  enter  the  soil  at  several  or 
more  feet  below  the  surface,  the  process  of  purification  is  long  delayed 
or  checked.  A  leaky  cesspool  or  broken  drain  which  discharges  its 
contents  into  the  soil  at  a  depth  of  5  feet  or  more  may  seriously  pol- 
lute the  ground  water,  whereas  the  same  material  placed  upon  or  just 
beneath  the  surface  may  be  entirely  mineralized  and  all  infection  de- 
stroyed before  it  reaches  the  depth  of  5  feet.  Vegetable  matter  in  a 
water-logged  soil  undergoes  a  partial  and  unusual  decomposition  into 
muck  or  peat.  Trees  buried  deeply,  where  bacterial  action  is  practically 
absent,  remain  for  many  hundreds  of  years  practically  unchanged.  Many 
factors  retard  the  purifying  action  of  the  soil.  Among  these  the  tem- 
perature and  moisture  and  absence  of  oxygen  predominate. 

"VNTien  organic  matter  falls  upon  the  soil  it  is  consumed  and  di- 
gested by  the  hungry  earth.  Without  this  property  the  surface  of  the 
earth  would  long  ago  have  become  clogged  with  vegetable  and  animal 
matter.  Albuminous  substances  are  dissolved  by  the  action  of  the 
proteolytic  bacteria,  and  converted  into  simpler  chemical  compounds. 
The  intermediate  products  of  protein  putrefaction  are  exceedingly  com- 
plex. For  our  present  purposes  it  is  sufficient  to  know  that  ultimately 
the  nitrogen  is  largely  converted  into  ammonia  and  the  carbon  into  car- 
bon dioxid.     The  amnipnia  is  then  oxidized  by  the  action  of  nitrifying 


DIET  683 

bacteria  to  nitrites,  and  the  nitrites  again  oxidized  to  nitrates.  The 
nitrates  are  the  final  products  of  the  mineralization  of  organic  matter. 
Most  of  the  nitrates  pass  into  solution  and  are  carried  down  into  the 
deeper  layers  of  the  soil  or  sub-soil;  some  of  it  is  taken  up  through  the 
roots  of  plants.  The  carbon  dioxid  passes  off  into  the  air  as  a  gas, 
remains  in  the  soil  moisture  in  solution,  or  is  converted  into  carbonates. 

Pathogenic  bacteria  that  may  be  thrown  upon  the  soil  in  feces  or 
otherwise  are  usually  detained  in  the  upper  layers  and  finally  destroyed 
there.  Under  ordinary  conditions  pathogenic  microorganisms  are 
caught  in  the  upper  layers  of  the  soil,  just  as  they  are  caught  upon 
the  "schmiitzdecke"  of  a  slow  sand  filter.  The  soil  does  not  act  simply 
as  a  mechanical  trap.  The  bacteria  are  detained  and  destroyed  by 
a  combination  of  physical,  chemical,  and  vital  processes  taking  place 
in  the  upper  layers  of  the  soil. 

All  polluted  soils  are  not  equally  dangerous.  Soils  polluted  with 
human  feces  and  urine  present  the  greatest  hazard  to  man.  The  special 
menace  of  soils  polluted  with  human  excreta  is  from  typhoid  bacilli, 
hookworms,  and  other  infections  discharged  in  the  feces  or  urine.  Hook- 
worm infection  is  usually  contracted  directly  from  soils  polluted  with 
human  feces,  and  the  eradication  of  hookworm  disease  depends  pri- 
marily upon  preventing  pollution  of  the  soil.  The  danger  in  the  case 
of  typhoid,  dysentery,  cholera,  and  other  bacterial  infections  is  usually 
indirect  through  infection  of  drinking  water  or  occasionally  through 
flies  or  other  mechanical  means  of  transference.  A  soil  polluted  with 
typhoid  may  endanger  either  the  surface  water  or  the  ground  water, 
particularly  in  limestone  formations.  Pathogenic  microorganisms  in  a 
polluted  soil  may  also  find  their  way  back  to  man  upon  vegetables.  Tape- 
worms and  other  intestinal  parasites  pass  part  of  their  life  cycle  on  or 
in  the  soil,  and  may  infect  man  directly  or  indirectly  in  various  ways. 
The  question  of  soil  pollution  and  the  particular  ways  in  which  it  is 
related  to  health  have  been  discussed  separately  under  each  disease  con- 
cerned. 

Dirt. — The  soil  is  often  spoken  of  as  dirt.  The  soil  in  the  field 
is  "earth,"  but  in  the  parlor  or  on  our  hands  it  becomes  dirt;  that  is, 
matter  out  of  place.  The  word  "dirt"  is  from  the  old  Saxon  "drit," 
meaning  excrement.  Dirt  in  the  ordinary  sense  becomes  a  potential 
danger,  especially  when  containing  human  excretions  or  soil  bacteria 
associated  with  wound  infections. 

To  the  sanitarian  dirt  includes  rubbish,  manure,  and  organic  wastes 
of  all  kinds.  It  may  be  the  vehicle,  but  not  the  source,  of  infection. 
It  breeds  and  harbors  flies,  fleas,  lice,  rats,  mice,  and  vermin  of  all 
sorts  that  act  as  intermediate  hosts  or  carriers  of  infection.  While  dirt 
cannot  originate  typhoid  fever  or  other  infections,  it  favors  conditions 
which  encourage  the  spread  of  such  diseases.     Rubbish  in  vacant  lots, 


684:       THE    SOIL    AND    ITS    EELATION    TO    DISEASE 

in  backyards,  in  alleys,  in  cellars,  garrets,  and  other  places  may  be 
taken  as  an  index  of  the  failure  to  appreciate  the  modern  teachings  of 
hygiene  and  sanitation.  It  was  once  the  chief  duty,  and  still  an  im- 
portant one,  of  the  health  officer  to  insist  upon  cleanliness  of  premises 
and  surroundings,  both  in  country  and  city. 

Cleanliness. — Cleanliness  is  the  heart  and  soul  of  sanitation.  We 
are  inclined  to  place  it  even  before  godliness,  for  cleanliness  of  body, 
cleanliness  of  mind  and  soul,  and  cleanliness  of  our  surroundings  are 
essential  to  a  full  appreciation  of  the  spiritual  virtues.  Our  concep- 
tion of  cleanliness  has  greatly  changed  with  our  advance  in  knowledge 
of  the  kinds  of  dirt,  the  degrees  of  dirtiness,  and  the  nature  of  these 
dangers.  ^Ye  can  no  longer  be  satisfied  with  physical  or  esthetic  clean- 
liness, but  must  insist  upon  biological  cleanliness.  A  tetanus  spore 
upon  the  shining  blade  of  a  surgeon's  knife  makes  that  instrument 
filthy,  whereas  many  such  spores  on  the  skin  of  a  chicken  may  be 
harmless.  We  cannot  see  the  infection  upon  the  common  drinking 
cup,  upon  the  roller  towel,  upon  the  point  of  a  pencil  that  has  just 
been  moistened  with  saliva,  or  in  water,  milk,  or  food,  although  we 
well  know  the  danger  of  such  invisible  "dirt"  that  these  objects  may 
harbor. 

It  requires  a  bacteriologist  to  tell  the  difference  between  clean  dirt 
and  dirty  dirt.  We  lack  a  sixth  sense,  or  microscopic  eye,  to  see  and 
distinguish  the  harmful  germs.  We,  therefore,  must  practice  scrupu- 
lous cleanliness  and  educate  the  people  to  the  biological  meaning  of 
this  term.  Long  experience  has  taught  the  lesson  that  cleanliness  offers 
a  protection  against  disease;  that  clean  surroundings  are  apt  to  be  free 
of  infection;  and  that  clean  food  is  apt  to  be  safe  food. 

At  one  time  the  theory  of  the  filth  diseases  reached  the  dignity  of 
a  special  name — the  pythogenic  theory,  first  propounded  by  Murchin- 
son  in  1858.  Typhoid  fever  was  long  regarded  as  the  type  of  a  filth 
disease,  and,  while  we  are  now  dropping  that  term,  we  should  not 
forget  that  typhoid  fever  is  really  a  filth  disease,  for  each  case  means 
that  a  short  circuit  has  been  established  between  the  discharges  from 
one  person  and  the  mouth  of  another. 

The  Influence  of  the  Soil  upon  Health. — The  soil  was  formerly  ac- 
cused of  being  one  of  the  largest  and  most  important  factors  in  the 
spread  of  the  communicable  diseases.  It  was  once  regarded  as  the 
cause,  if  not  the  nesting  place,  of  infections  of  all  kinds;  tuberculo- 
sis, malaria,  typhoid  fever,  plague,  yellow  fever,  cholera,  dysentery,  and 
many  other  diseases  were  directly  associated  with  the  soil.  We  now 
know  that  comparatively  few  of  the  microorganisms  pathogenic  for 
man  live  in  the  soil,  and  practically  none  of  them  grow  and  multiply 
there. 

The  soil  contains  a  number  of  bacteria  that  may  be  serious  when 


DISEASES    ASSOCIATED    WITH    THE    SOIL  685 

introduced  into  wounds,  as  tetanus,  malignant  edema,  anthrax,  B.  aero- 
genes  capsulatus;  ofttimes  organisms  belonging  to  the  hemorrhagic  sep- 
ticemic group;  sometimes  staphylococci  and  streptococci. 

A  soil  polluted  with  human  excrement  presents  the  possibility  of 
danger  of  intestinal  infections  of  all  kinds.  Thus,  bacterial  infections, 
such  as  typhoid,  cholera,  and  dysentery,  or  protozoal  infections,  such 
as  amebic  dysentery,  or  the  higher  worms,  such  as  hookworms,  may  all 
more  or  less  be  associated  with  polluted  soils. 

Soils  containing  much  organic  matter  and  presenting  other  favor- 
able conditions  afford  resting  and  nesting  places  for  a  number  of  in- 
sects, such  as  flies,  ticks,  etc.,  which  may  carry  infections. 

Vegetables  grown  in  polluted  soils  may  transfer  bacteria,  protozoa, 
or  the  eggs  of  worms  in  a  mechanical  way  from  the  ground  to  the 
mouth.  This  applies  particularly  to  vegetables  eaten  raw,  such  as 
radishes,  lettuce,  etc. 

Practically  all  the  water  used  for  drinking  and  other  purposes  has 
either  rested  upon  the  soil  or  has  percolated  through  it  into  the  ground. 
.The  soil  materially  affects  the  character  of  the  water.  In  this  way  the 
soil  indirectly  influences  health  variously  and  sometimes  seriously.  The 
relation  of  water  to  health  is  a  subject  in  itself,  and  is  discussed  in 
a  separate  chapter. 

The  physical  conditions  of  the  soil  which  have  special  reference  to 
■  health  are  those  which  influence  the  tem.perature  and  moisture  of  hu- 
man habitations.  Persons  working  about  cold  and  damp  soils  are  sub- 
ject to  rheumatic,  neuralgic,  and  respiratory  affections. 

Diseases  Associated  with  the  Soil. — Tetanus. — Spores  of  the  tet- 
anus bacillus  commonly  occur  in  the  soil  of  inhabited  regions.  They  have 
been  found  not  only  in  the  superficial  layers,  but  sometimes  at  a  depth 
of  several  feet.  The  normal  habitat  and  the  great  reservoir  of  tetanus 
are  the  intestines  of  the  herbivora.  It  may  also  be  found  in  the  intes- 
tinal contents  of  man  and  other  animals.  Certain  savages  in  the  New 
Hebrides  used  to  smear  their  arrow  heads  with  dirt  from  crab  holes 
in  the  swamp,  which  they  knew  by  experience  to  be  poisonous.  We 
now  know  that  this  material  contained  tetanus  spores. 

Tetanus  increases  as  we  approach  the  tropics,  where  puerperal  tet- 
anus and  tetanus  of  the  newborn  are  relatively  frequent.  Tetanus  spores 
are  much  more  abundant  in  certain  localities  than  others.  For  ex- 
ample, certain  parts  of  Long  Island  and  New  Jersey  have  become 
notable  for  the  number  of  cases  of  tetanus  caused  by  small  wounds. 

The  tetanus  bacillus  probably  does  not  grow  and  multiply  in  the 
soil.  It  cannot  there  find  the  necessary  anaerobic  conditions,  tempera- 
ture, and  other  factors  necessary  for  multiplication.  The  resistance 
of  the  spores  accounts  for  the  persistence  of  the  infection. 

The  prevention  of  tetanus  has  been  discussed  on  page  66. 


686       THE    SOIL    AND    ITS    KELATION    TO    DISEASE 

Anthrax. — Like  tetanus,  anthrax  does  not  grow  in  the  soil  under 
natural  conditions.  Its  persistence  is  accounted  for  by  its  resistant 
endosjjore.  Anthrax  spores  have  been  found  in  pastures  where  infected 
animals  have  been  confined. 

The  anthrax  bacillus  requires  oxygen  in  order  to  sporulate;  the 
spores,  therefore,  do  not  form  in  the  blood,  and  it  is  veiy  important 
not  to  open  the  carcass  of  a  sheep  or  cow  dead  of  this  disease  before 
it  is  buried.  Tlie  classic  researches  of  Pasteur  on  anthrax  should  be 
studied  in  this  connection.  Pasteur  examined  the  field  where  animals 
dead  of  anthrax  liad  been  buried  twelve  years  previously.  He  found 
the  specific  bacillus  in  the  soil  and  demonstrated  its  virulence  by 
inoculations  into  guinea  pigs.  Pasteur  thought  that  the  spores  were 
brought  to  the  surface  of  the  soil  by  earthworms,  and  proved  the  pos- 
sibility of  this  by  sowing  virulent  cultures  in  soil  and  recovering  the 
bacillus  from  worm  casts.  It  seems,  however,  in  the  light  of  subse- 
(|uent  investigations  that  the  danger  from  this  source  is  negligible,  so 
that  anthrax,  with  a  few  exceptions,  can  hardly  be  called  a  soil  in- 
fection. This  is  the  case  at  least  with  man,  for  there  is  no  instance 
on  record  in  which  human  anthrax  has  been  contracted  from  contact 
with  the  soil. 

MalignAxVt  Edema. — The  bacillus  of  malignant  edema  is  found  in 
the  superficial  layers  of  the  soil.  It  is  very  widely  distributed.  This 
organism  is  also  found  in  putrefying  substances,  in  foul  water,  and  in 
the  intestinal  tract  of  various  animals.  In  1877  Pasteur  first  recog- 
nized an  organism  belonging  to  this  group  by  injecting  animals  with 
putrefying  liquids.  He  called  the  organism  the  vibrione  septique, 
recognized  its  anaerobic  nature,  but  did  not  obtain  it  in  pure  cul- 
ture. Koch  and  Gaffky  in  1881  studied  it  carefully  and  renamed  it 
the  bacillus  of  malignant  edema.  The  bacillus  has  lateral  flagella,  an 
oval  spore,  and  is  a  strict  anaerobe.  It  is  very  pathogenic  for  almost 
all  animals,  causing  extensive  hemorrhagic  edema  without  the  produc- 
tion of  gas,  which  distinguishes  it  from  the  gas  bacillus  of  Welch. 
Wound  infections  with  malignant  edema  occur,  especially  with  deep 
punctured  or  lacerated  wounds,  which  favor  anaerobic  growth.  Before 
the  days  of  antisepsis  this  complication  was  frequent,  especially  during 
wars. 

Welch's  gas  bacillus  (B.  aerogenes  capsulatus)  has  a  similar  rela- 
tion to  the  soil  to  that  just  described.  Many  other  microorganisms, 
especially  those  belonging  to  the  hemorrhagic  septicemic  group,  occur 
in  the  soil  and  occasionally  complicate  wounds. 

Typhoid  Fever. — There  is  a  widespread  belief,  even  among  sani- 
tarians, that  this  disease  is  fre(piently  connected  with  soil  pollution. 
This  belief  was  given  scientific  confirmation  by  Pettenkofer,  who  pro- 
pounded the  theory  that  the  poison,  whatever  it  may  be,  is  introduced 


DISEASES    ASSOCIATED    WITH    THE    SOIL  687 

into  the  soil  where,  under  proper  conditions  of  organic  filth,  tempera- 
ture, moisture,  etc.,  a  special  fermentation  takes  place.  Pettenkofer 
believed  that  the  gases  or  effluvia  thus  produced  rise,  and  in  some  way 
were  capable  of  provoking  disease.  Pettenkofer's  views  of  typhoid  in 
relation  to  the  height  of  the  ground  water  have  already  been  men- 
tioned. 

Typhoid  bacilli  frequently  find  their  way  upon  and  into  the  soil 
along  with  human  excreta.  Multiplication,  however,  rarely  takes  place 
there.  As  a  rule,  the  typhoid  bacillus  scarcely  lives  a  month,  possibly 
two  or  three  months,  in  the  soil.  When  frozen  they  may  live  and  re- 
main virulent  for  several  months,  as  in  the  case  of  the  Plymouth  epi- 
sode and  the  New  Haven  epidemic.  While  typhoid  fever  in  cities 
and  towns  has  no  evident  direct  relation  to  soil  pollution,  it  is  pos- 
sible to  conceive  an  indirect  relation  in  many  cases,  especially  in  camps 
and  in  rural  districts. 

There  are  numerous  ways  by  which  typhoid  bacilli  may  be  returned 
from  the  stDil  to  the  mouth  of  a  susceptible  person.  It  is  possible,  though 
not  likely,  for  this  to  occur  directly.  So  far  as  typhoid  is  concerned, 
perhaps  the  greatest  danger  from  a  polluted  soil  consists  in  infection 
of  the  drinking  water.  The  ways  in  which  this  may  occur  are  dis- 
cussed in  the  chapter  on  water.  The  transfer  of  typhoid  bacilli  from 
the  soil  to  the  mouth  may  also  occur  mechanically  by  means  of  flies, 
dust,  and  dirt.  Vegetables  grown  in  a  polluted  soil  may  carry  typhoid 
bacilli  to  the  very  tips  of  their  leaves. 

The  pollution  of  soil  with  human  feces  is  always  a  danger  and  should 
be  prevented.  The  worst  offense  in  this  particular  occurs  in  country 
districts,  where  the  potential  danger  is  greater  than  in  the  city. 

Cholera. — There  is  every  reason  to  believe  that  the  cholera  vibrio 
dies  quickly  when  deposited  upon  or  in  the  soil  under  natural  condi- 
tions. The  cholera  vibrio  may  be  transferred  from  the  soil  to  the  mouth 
in  the  ways  mentioned  above  in  the  case  of  typhoid.  Formerly  cholera 
was  believed  to  be  associated  with  polluted  soils,  but  it  now  appears  that 
the  disease  is  rarely  contracted  from  the  soil,  and  that  the  physical  and 
chemical  conditions  of  the  ground  play  little,  if  any,  role  in  the  epi- 
demiology of  this  disease. 

Tuberculosis  and  Other  Diseases. — In  1863  Dr.  H.  I.  Bowditch 
formulated  the  law  of  soil  moisture  from  studies  which  seemed  to  indi- 
cate that  tuberculosis  was  more  common  in  Massachusetts  over  moist 
soils  than  dry  ones.  If  there  is  any  connection  between  tuberculosis 
and  the  soil,  the  relation  must  be  indirect.  Exposure  to  cold  and  damp 
depresses  vitality  and  lowers  resistance  to  tuberculosis.  It  does  not 
necessarily  follow  that  habitations  or  workshops  are  cold  and  damp 
because  the  ground  on  which  these  houses  are  built  is  wet  and  cold. 

The   soil  was   formerly   accused   of   being   responsible   for  plagugj. 


688       THE    SOIL    AND    ITS    RELATION    TO    DISEASE 

malaria,  yellow  fever,  and  a  long  list  of  other  diseases.  The  impor- 
tance of  the  soil  with  reference  to  the  communicable  diseases  diminishes 
with  our  increase  in  knowledge.  The  number  of  infections  directly, 
associated  with  the  ground  are  very  few,  and  the  indirect  influences 
are  less  tlian  formerly  supposed.  Apart  from  tlie  one  real  danger,  viz., 
soil  pollution  with  human  excrement,  the  sanitarian  is  now  inclined  to 
belittle  the  influence  of  the  soil  upon  health. 

Dampness  and  cold  may  favor  rheumatic  and  neuralgic  conditions, 
and  also  predispose  to  respiratory  infections.  In  this  way  association 
with  a  cold,  damp  soil  may  be  prejudicial  to  health.  Clay  soils  are 
apt  to  be  damp ;  sand  and  gravel  soils  are  readily  drained  and  may 
be  kept  dry  by  means  of  sim})le  devices.  Such  soils,  therefore,  make 
the  best  building  sites  for  habitations.  As  a  rule,  the  foundation  of  a 
house  should  be  at  least  two  or  three  feet  above  the  level  of  the  ground 
water. 

The  soil  greatly  influences  the  character  of  the  water  which  rests 
upon  it  and  which  passes  through  it.  This  will  be  discussed  in  the 
section  on  water. 

Hookworm  Disease. — Hookworm  disease  is  closely  associated  with 
the  soil.  It  may  fairly  be  considered  an  infection  the  result  of  soil 
pollution.  It  occurs  especially  in  moist  sandy  soils  rather  than  on 
clay  or  rocky  soils.  This  is  due  to  the  fact  that  hookworm  eggs,  when 
deposited  in  fecal  matter,  soon  dry  up  and  die  upon  hard  rocky  or 
clay  surfaces,  whereas  they  find  favorable  conditions  for  development 
upon  moist  sand  or  loam.  Under  these  conditions  the  larvae  develop 
as  far  as  the  second  ecdysis,  which  have  the  power  of  penetrating  the 
skin  (see  page  114). 

Other  Animal  Parasites. — In  a  somewhat  similar  sense  many 
of  the  animal  parasites  of  man  are  deposited  on  the  soil  and  reinfect 
man  during  one  of  the  stages  of  their  cycle  of  development.  Most  of 
the  intestinal  parasites  of  man  are  deposited  on  the  soil,  and,  after  a 
varying  journey,  sometimes  through  an  intermediate  host,  again  find 
lodgment  in  man.  In  the  case  of  trichina,  for  instance,  man  pollutes 
the  soil  with  feces  containing  the  eggs.  Hogs  devour  this  infection 
and  return  the  disease  to  man.  In  a  somewhat  similar  way  the  tape- 
worms of  cattle  and  also  some  ameba  and  flagellates  pass  part  of  their 
life  history  upon  the  soil. 

The  Ascaris  lumbricoides  and  the  Trichiuris  iricliiura,  two  very  com- 
mon worms  inhabiting  the  intestinal  tract  of  man,  have  thick-shelled 
eggs  and  must  rest  in  the  soil  about  a  month  before  they  are  infective. 
It  requires  about  a  month  for  the  embryo  to  develop.  If  fresh  eggs 
of  these  two  worms  are  ingested,  they  pass  through  the  intestinal  tract 
without  hatching. 

Dr.  Stiles  has  prepared  the  following  list  of  animal  parasites  which 


DISEASES    ASSOCIATED    WITH    THE    SOIL  689 

have  some  relation  to  the  soil  during  some  part  of  their  life  history, 
and  may,  therefore,  be  more  or  less  associated  with  soil  pollution: 


List  of  Animal  Parasites  of   Man   Which  May  Be  Spread  By    Soil,    Pol- 
lution 


I 

II 

III 

Direct  (i.  e. ,  without 

Indirect  (i.  e.,  with 

Further  Study  on  Life  Cycle 

Intermediate  Host) 

Intermediate  Host) 

Desired,  Probably  Belongs 

in  I  or  II  as  Marlced 

Protozoa : 

Protozoa: 

Protozoa: 

EntamcEba  coli 

Entamoeba      gingivalis     sp. 
inq.'                                       I 

Entamoeba  histolytica 

Entamoeba    den  talis    sp. 
inq.                                      I 

Entamoeba  buccalis 

Entamoeba     pulmonala    sp. 
inq.                                      I 

Entamoeba  tetragena 

Entamoeba    urogenitalis  sp. 
inq.                                        I 

Paramoeba  hominis 

Entamoeba    kartulisi    sp. 
inq.                                      I 

Leydenia    gemmipara    (  = 

Chlamydophrys  stercorea  or 

C.  enchelys) 

Entamoeba  miurai  sp.  inq.    I 

Trichomonas  vaginalis 

Trichomonas  intestinalis  ( =  ? 

vaginalis) 

Trichomonas  pulmonalis  sp. 

inq.                                        I 
Cercomonas    hominis    sp . 

inq.                                        I 
Monas  pyophila  sp.  inq.       I 

Eimeria  cuniculi 

Monas  lens  sp.  inq.                I 

Eimeria  hominis 

Bodo  urinarius  sp.  inq.          I 

Isospora  bigemina 

Balantidium  coli 

Balantidium  minutum          I 
Nyctotherus  faba                   I 
Nyctotherus  africanus           I 
Nyctotherus  giganteus          I 

Rhinosporideum  kinealyi      I 

Trematoda  (Flukes) : 

Trematoda: 

Trematoda  : 

Fasciola  hepatica 

Gastrodiscus  hominis           II 

Schistosoma  japonicum 

Opisthorchis  felineus 

Watsonius  watsoni               II 
Fasciola  gigantica                 II 
Fasciolopsis  buskii                ii 
Fasciolopsis  rathouisi           II 
Paragonimus  westermanii    II 
Opisthorchis  noverca           II 
Metorchis  truncatus             II 
Cladorchis  sinensis               II 
Cladorchis  endemicus          II 
Fascioletta  ilocana               ii 
Schistosoma  haematobium     I 
Schistosoma      mansoni      sp. 
inq.                                        I 
Heterophyes  heterophyes     I 
Dicrocoelium  lanceolatum     I 

^ ' '  Sp.  inq. ' '  =  require  further  study. 


690       THE    SOIL    AND    ITS    RELATION    TO    DISEASE 
List  of  Animal  Parasites  of  Man. — Continued. 


Direct  (i.  e.,  without 
Intermediate  Host) 


Indirect  (i.  e.,  with 
Intermediate  Host) 


III 

Further  Study  on  Life  C>'cle 

Desired,  Probably  Belongs 

in  I  or  II  as  ^Iarked 


Cestoda  (Tapeworms): 


Nematoda  (Roundworms) : 
Ascaris  lumbricoides 


Toxocara  canis 
Oxjuris  vermicularis 
Necator  americanus 


Agchylostoma      (or     Ancylo- 

etoma)  duodenale 
HsemoDcbus  contortus 


Trichiuris  trichiura 
Strongj-loides  stercoralis 
Aca^tthocephaxi  : 


Cestoda  : 
Taenia  solium 
Taenia  saginata 

Dipylidium  caninum 

HjTnenolepis     dimi- 

nuta 
Hymenolepis  lanceo- 

lata 

Dibothriocephalus 

latus 
Nematoda  : 


Acanthocephali  : 
GigantorhjTichus  gi- 

gas    (or_  hirudina- 

ceus) 
G.  moniliformis 


Cestoda : 

Hymenolepis  nana  I 

Taenia  africana  II 

Taenia  confusa  II 

Davainea    madagascariensis 
II 


Davainea  asiatica 


II 


Dibothriocephalus    cordatus 
II 

Diplogonoporus  grand  is  ll 
Nematoda  : 

Ascaris  texana  sp.  inq.  I 

Ascaris  maritima  II? 


Trichostrongylus  instabihs    I 

Trichostrong>'lu3      brobolu- 

rus  I 

Trichostrongj'lus  \atrinu3    II 

Metastrongj'lus  apri  I 

DioctophjTne  renalis  II 

CEsophagostomum    brumpti 
I 
Temidens  diminutus  I 

Physaloptera  caucasica         I 

AC.AXTHOCEPHALI : 


SECTION    VI 
WATER 

CHAPTEE    I 

GENERAL    CONSIDERATIONS 

"The  greatest  influence  on  health  is  exerted  by  those  things  which  we 
most  freely  and  frequently  require  for  our  existence,  and  this  is  especially 
true  of  water  and  air"   (Aristotle). 

While  water  is  not  teclinically  classed  as  a  food^  it  is  an  essential 
article  of  diet.  In  nature  water  conies  in  contact  with  many  surfaces 
and  substances  and,  therefore;,  is  particularly  liable  to  contain  impuri- 
ties, especially  as  it  is  the  most  universal  solvent  known.  Water  is 
also  a  frequent  medium  for  the  transmission  of  infection. 

From  the  remotest  antiquity  the  highest  value  has  been  placed 
upon  an  abundant  and  pure  water  supply.  Centers  of  population  sprang 
up  in  ancient  times  around  those  points  where  it  was  most  readily 
available,  and  great  expenditures  of  labor  and  treasure  were  made  to 
carry  it  to  places  where  it  was  not  naturally  plentiful.^ 

Water  is  a  prime  necessity  of  life — not  only  as  an  article  of  diet, 
but  also  for  the  proper  cleanliness  of  person,  clothing,  and  things. 

It  is  interesting  to  note  that  the  number  of  towns  in  this  country 
before  1800  having  a  public  water  supply  was  only  16,  supplying  about 
2.8  per  cent,  of  the  existing  population  at  that  time.  In  1850  there 
were  only  83  public  water  works,  supplying  about  10.6  per  cent,  of  the 
census  population.  In  1897  the  total  number  was  3,196,  supplying 
about  41.6  per  cent,  of  the  population.  Since  then  the  number  has 
greatly  increased,  but  exact  information  is  not  available." 

^  The  date  of  construction  of  the  Appian  aqueduct  carrying  water  to  Eome 
is  placed  at  312  B.  C.  Eighteen  other  aqueducts  were  constructed  at  various  times 
until  226  A.  D.  The  one  commenced  by  Emperor  Caius  and  completed  by 
Claudius,  according  to  Pliny,  cost  350,000,000  sesterces,  or  about  $12,700,000. 

2  Baker,  M.  N.:   "Manual  of  American  Water  Works,"  1891  and  1897. 

691 


692  GENERAL   CONSIDERATIONS 


COMPOSITION 

At  the  close  of  the  eighteenth  century  water  was  regarded  as  an 
elementary  substance.  In  1781  Cavendish  discovered  that,  when  an 
electric  spark  is  passed  through  a  mixture  of  2  parts  of  hydrogen  to 
1  part  of  oxygen,  these  gases  combine  to  form  water.  Since  then 
water  has  been  made  synthetically,  and  separated  analytically  into  its 
component  constituents  by  various  methods. 

The  composition  of  pure  water   (HoO)   is: 

By  Volume.    By  Weight. 

Oxygen    1  part  8  parts 

Hydrogen   2  parts         1  part 

Pure  water  is  a  chemical  curiosity;  it  does  not  exist  in  nature. 
All  water  in  nature  contains  impurities,  in  solution  and  in  suspension. 
Some  of  these  impurities  are  organic  and  some  are  inorganic.  They 
consist  of  various  gases,  fluids,  and  solid  substances.  The  more  im- 
portant impurities  and  their  sanitary  significance  will  be  considered 
in  detail  under  the  chemical  analysis  of  water. 


CLASSIFICATION    OF    WATER 

From  a  sanitary  standpoint  water  is  either  good  or  bad.  Commonly 
waters  are  classified  as  pure  or  impure.  It  is  not  possible,  however, 
in  the  present  state  of  our  knowledge,  to  draw  a  sharp  line  of  distinc- 
tion. In  the  classical  reports  of  the  Massachusetts  State  Board  of 
Health  waters  are  spoken  of  as  normal  or  polluted.  A  normal  water 
is  free  from  direct  or  indirect  pollution  by  waste  products  from  human 
life  or  industries.  The  difficulty  with  this  classification  is  that  normal 
waters  may  differ  widely  in  color,  taste,  odor,  and  composition,  and  may, 
therefore,  be  unfit  for  household  or  manufacturing  purposes. 

A  practical  classification  of  waters  is  as  follows:  (1)  good,  (2) 
polluted,  (3)  infected.  A  good  water  may  be  defined  as  one  of  good 
sanitary  quality,  as  determined  by  physical  inspection,  bacteriological 
and  chemical  analyses,  a  sanitary  survey  of  the  watershed,  and,  finally, 
by  clinical  experience.  A  polluted  water  is  one  containing  organic 
waste  of  either  animal  or  vegetable  origin.  A  polluted  ^  water  is  a 
suspicious  water.  An  infected  water  contains  the  specific  microorgan- 
isms of  human  diseases.^ 

In  Europe  waters  are  frequently  classified  as  potable  or  non-potable. 

*  Sometimes  spoken  of  as  contaminated  water. 

^  Chemical  poisons  such  as  lead  are  not  included  in  this  classification. 


THE    USES    OF    WATEE    IX    THE    BODY  693 

Many  cities  on  the  Continent  have  a  double  water  supply  with  faucets 
plainly  labeled  "potable"  or  "non-potable,"  the  first  being  suitable  for 
drinking  and  cooking  purposes  and  personal  use,  while  the  second  is 
intended  for  miscellaneous  household  and  industrial  uses. 

According  to  location,  waters  are  considered  under  three  classes, 
viz.,  rain  water,  surface  water,  or  ground  water. 

PROPERTIES    OF    WATER 

Water  is  a  clear,  transparent,  tasteless,  and  odorless  fluid;  colorless 
in  small  quantities;  pale  blue  through  a  deep  column.  It  freezes  at 
0°  C.  and  boils  at  100°  C.  under  a  barometric  pressure  of  760  mm.  It 
is  practically  incompressible ;  has  its  greatest  density  at  4°  C. ;  is  a 
remarkable  solvent.  The  latent  heat  of  water  and  other  properties 
that  have  a  sanitary  bearing  will  be  considered  in  the  succeeding  pages. 

Practically  all  substances  yield  to  water;  it  is  the  most  universal 
solvent  known.  It  dissolves  gases;  in  fact,  one  of  the  most  important 
constituents  of  all  natural  waters  is  carbonic  acid.  Carbon  dioxid  is 
always  present  in  the  air,  and  all  rain  waters  contain  some  of  it.  Still 
more  is  taken  up  by  the  water  as  it  percolates  through  ground  covered 
with  vegetation.  The  presence  of  this  gas  increases  the  solvent  powers 
of  the  water,  enabling  it  especially  to  dissolve  limestone  and  many 
other  inorganic  substances. 

THE   USES    OF    WATER    IN   THE    BODY 

As  a  rule,  water  is  not  considered  a  food,  for  it  may  be  said  to 
have  little  or  no  value  when  estimated  as  a  force  producer  within  the 
body.  Much  of  the  water  which  is  either  drunk  or  ingested  as  a  part 
of  other  foods  passes  through  the  body  unchanged,  but  some  of  it  is 
undoubtedly  altered  or  split  up  into  elements  which  unite  with  other 
compounds.  The  nature  of  these  processes  is  obscure,  and  as  yet  very 
little  understood.  Water  is  entitled  to  rank  as  a  food  because  it  enters 
into  the  structural  composition  of  all  foods  as  well  as  all  the  tissues  of 
the  body;  it  is  an  essential  element  of  diet,  even  though  it  cannot  of 
itself  build  tissue,  repair  waste,  or  produce  heat  or  energy. 

Water  composes  about  70  per  cent,  of  the  entire  body  weight,  and 
its  importance  to  the  system,  therefore,  cannot  be  overrated.  The 
elasticity  or  pliability  of  muscles,  cartilages,  tendons,  and  even  bones 
is  in  a  great  part  due  to  the  water  which  these  tissues  contain.  "The 
cells  of  the  body  are  aquatic  in  their  habits."  The  amount  of  water 
required  by  a  healthy  man  in  24  hours  is,  on  the  average,  between 
1,800  and  2,100  c.  c,  beside  about  600  c.  c.  taken  in  as  an  ingredient 
of  solid  foods,  thus  making  a  total  of  2,400-2,700  c.  c.  Twenty-eight 
46 


694  GENERAL    CONSIDERATIONS 

per  cent,  of  the  loss  of  water  from  tlie  body  takes  place  through  the 
skin,  20  per  cent,  through  the  lungs,  50  per  cent,  through  the  kidneys, 
and  2  per  cent,  through  other  secretions  and  the  feces. 

The  use  of  water  in  the  body  may  be  summarized  as  follows :  It 
enters  into  chemical  composition  of  the  tissues;  it  forms  the  chief  in- 
gredient of  all  the  fluids  of  the  body  and  maintains  their  proper  de- 
gree of  dilution,  and  thus  favors  metabolism ;  by  moistening  various 
surfaces  of  the  body,  such  as  mucous  and  serous  membranes,  it  prevents 
friction;  it  furnishes  in  the  blood  and  lymph  a  fluid  medium  by  which 
food  may  be  taken  to  remote  parts  of  the  body  and  the  waste  material 
removed,  thus  promoting  rapid  tissue  changes;  it  serves  as  a  distributor 
of  body  heat;  it  regulates  the  body  temperature  by  the  physical  process 
of  absorption  and  evaporation. 

One  of  the  most  universal  dietetic  faults  is  neglect  to  take  enough 
water  into  the  system. 

THE   AMOUNT   OF    WATER   USED   AND   WASTED 

From  a  sanitary  standpoint  our  aim  should  be  to  encourage  a  gen- 
erous use  of  water,  but  to  discourage  waste.  The  conservation  of  pure 
water  and  the  economic  value  of  a  purified  water  are  pressing  prob- 
lems that  a  growing  and  expanding  country  must  meet  and  solve  as  a 
matter  of  self-interest  if  not  of  self-preservation. 

It  is  possible  to  get  along  with  a  surprisingly  small  amount  of 
water.  Thresh  found  that  in  a  number  of  country  places  the  amount 
used  in  cottages  could  not  have  greatly  exceeded  one  gallon  per  person 
per  day.  This  is  not  sufficient  for  modern  requirements  of  cleanli- 
ness and  health.  On  the  other  hand,  where  the  supply  is  abundant  and 
easy  of  access  large  quantities  of  water  are  heedlessly  wasted. 

The  average  amount  of  water  per  capita  required  for  domestic  pur- 
poses is  usually  stated  at  about  17  gallons  a  day.-  Rankine  considers 
10  gallons  sufficient.  Parkes  found  that  the  average  amount  used  by 
'a  man  in  the  middle  class,  who  may  be  taken  as  a  fair  type  of  a  cleanly 
man  belonging  to  a  fairly  clean  household,  is  12  gallons  per  day.  This 
includes  the  amount  used  in  cooking,  drinking,  ablution,  utensil  and 
house  washing,  and  laundry.  Davies'  estimate  of  17  gallons  a  day 
is  divided  as  follows: 

Drinking,  3  pints;  eookinof,  5  pints 1  eral. 

Ablution    (including  sponge   bath,    2'V2    gals.) 5     " 

Washing    (laundry,   3 ;    house,   etc.,   3) 6     " 

.     Water  closets 5     " 

17     " 

The  actual  per  capita  daily  consumption  of  water  in  some  cities  is, 
in  fact,  not  much  above  this  figure.     Thus,  Manchester  uses  20  gallons 


THE  AMOUNT  OF  WATEK  USED  AND  WASTED       695 

and  Berlin  22  gallons  a  day  for  each  individual.  Some  small  English 
towns,  as  Saffron  Walden  (population  6,108),  use  11  gallons  per  cap- 
ita per  day,  and  Melrose  (population  1,300)  uses  13  gallons.  As  a 
contrast  to  these  low  figures  most  cities  in  America  are  furnished  with 
an  extravagant  qiiantity — Pittsburgh,  250  gallons  per  capita  daily,  Buf- 
falo, 223,  Philadelphia,  227,  Washington,  218.  The  small  amount  of 
water  used  by  some  European  cities  is  not  an  ideal  to  strive  for  under 
American  conditions.  The  European  figures  are  steadily  increasing, 
even  where  all  water  is  sold  by  meter.  In  towns  having  a  metered  sup- 
ply the  per  capita  consumption  varies  from  6.6  gallons  daily  for  the 
lowest  class  of  dwellings  to  59  gallons  for  the  highest  class  of  dwellings. 
The  following  tables  from  Hazen's  "Clean  Water  and  How  to  Get  It" 
give  the  per  capita  consumption  in  some  American  cities,  contrasted 
with  similar  figures  abroad. 


THE  QUANTITIES  OF  WATER  SUPPLIED  IN  A  NUMBER  OF  AMERICAN  CITIES 


Place 

Year 

Gallons 

per  capita 

Daily 

Percentage 

of  Services 

Metered 

Pittsburgh                  

1905 
1900 
1905 
1906 
1900 
1905 
1905 
1905 
1902 
1900 
1905 
1904 
1900 
1905 
1900 
1906 
1905 
1905 

250 

233 

227 

218 

190 

190 

151 

137 

129 

94 

91 

82 

70 

68 

67 

63 

52 

37 

1 

Buffalo                    

2 

Philadelphia           

Washington.               

3 

Chicago               

3 

Detroit.                   

29 

Boston                 .        

6 

Cleveland                

68 

New  York                  

35 

Newark                       

21 

Milwaukee.                

94 

Minneapolis                ■ 

42 

Worcester                   

94 

Providence                    

86 

St.  Paul                         

28 

Hartford 

100 

Lowell                           

69 

FaU  River 

97 

THE   QUANTITIES  OF  WATER  SUPPLIED  IN  A  FEW  FOREIGN  CITIES 


Place 

Year 

U.  S.  Gallons    , 
per  Capita 
Daily 

Place 

Year 

U.   S.  Gallons 

per  Capita 

Daily 

1906 
1902 
1901 
1905 
1905 
1905 

39 
38 
65 
37 
63 
39 

Berlin 

1905 
1905 
1905 
1905 
1906 

22 

Liverpool 

Paris 

Amsterdam 

Melbourne 

Sydney 

Hamburg 

Dresden 

Copenhagen .... 
Brisbane 

44 
26 
27 
58 

696  GENERAL    COXSIDERATIONS 

The  amount  of  water  ^  expressed  by  the  per  capita  consumption 
of  a  community  is  very  misleading  for  purposes  of  comparison.  The 
figures  are  usually  obtained  by  dividing  the  total  theoretical  amount 
of  water  pumped,  by  the  population.  The  result,  therefore,  does  not 
take  into  account  many  factors,  for  the  actual  amount  of  water  pumped 
does  not  equal  the  theoretical  possibilities;  corrections  for  slip  and 
other  factors  should  be  made.  The  figures  also  do  not  take  into  account 
the  amount  of  water  lost  through  broken  pipes,  leaky  joints,  etc.  It  is 
estimated  that  in  some  places  almost  half  the  water  pumped  is  wasted 
in  this  way.  Further,  there  are  great  discrepancies  when  contrasting 
different  cities  in  the  amount  of  water  used  for  business  purposes.  The 
amount  of  water  used  in  trades  and  manufactures  varies  enormously. 
Certain  industries,  such  as  mining,  tanneries,  coal  washing,  paper  mills, 
breweries,  wool  scouring,  etc.,  require  great  quantities.  It  is  estimated 
that  in  the  iron,  coal,  and  steel  regions  of  Pennsylvania  a  quantity  of 
water  representing  the  entire  flow  of  the  Allegany  River  passes  through 
the  large  steel,  iron,  and  other  mills  along  its  banks  several  times  before 
it  reaches  the  city  of  Pittsburgh.  Therefore,  unless  the  per  capita 
consumption  is  based  upon  the  amount  of  water  actually  measured  by 
meter  for  domestic  purposes,  the  figures  of  one  city  cannot  be  properly 
compared  with  those  of  another. 

Few  persons  realize  the  immense  amount  of  water  that  is  wasted 
in  almost  every  town.  Taking  it  right  through,  probably  one-half  of 
the  water  supply  of  American  cities  is  wasted.  While  some  of  this  is 
unavoidable,  the  greater  part  of  it  could  be  stopped.  There  are  three 
principal  causes  of  this  waste:  (1)  leakage  from  faulty  mains  and  serv- 
ice pipes;  (2)  waste  from  defective  house  fittings;  (3)  waste  resulting 
from  an  unmetered  or  unmeasured  service.  The  first  cause  includes 
leaks  from  faulty  mains  and  service  pipes  and  all  other  hidden  defects 
where  the  water  escapes  unperceived  into  drains  and  sewers  or  into  the 
sub-soil.  It  is  possible  to  check  a  large  part  of  this  waste  by  the  use  of 
instruments  known  as  detectors.  With  these  instruments  leaks  may  be 
located.  The  detectors  are  of  two  sorts:  (1)  aquaphones,  instruments 
resembling  a  large  stethoscope,  by  which  a  trained  ear  may  locate  mur- 
murs; (2)  pitometers,  instruments  which  measure  the  rate  of  flow  in 
branch  lines  during  the  small  hours  of  the  night,  when  practically  no 
water  is  used.  In  this  way  leaks,  defective  taps,  and  open  stopcocks  may 
be  discovered.  It"  requires  but  a  moment's  calculation  to  figure  out  the 
great  number  of  gallons  wasted  by  forgetting  to  close  a  stopcock.     In 

*  It  has  been  calculated  that  altogether  the  supply  of  Rome  was  332,306,624 
gallons  daily,  which  would  have  been  over  332  gallons  per  capita  upon  a  basis 
of  a  population  of  one  million.  This  calculation,  however,  has  been  based  upon 
data  furnished  by  Prony  in  1817.  Mr.  Clemens  Herschel  has  lately  shown  a 
much  more  probable  figure  for  the  daily  water  consumption  of  Rome,  namely: 
32,000,000  U.  S.  gallons. 


DOUBLE  WATER  SUPPLIES  697 

some  cities,  such  as  Washington,  in  the  winter  time  the  water  in  many 
houses  is  allowed  to  run  continuously  from  the  cold  water  faucet,  in 
order  to  prevent  freezing.^  The  waste  from  this  cause  is  enormous,  and 
may  be  corrected  by  properly  placing  the  service  pipes  so  as  to  avoid  all 
danger  from  bursting  through  freezing.  It  has  been  the  universal 
experience  that  much  water  is  thoughtlessly  wasted  where  the  service 
is  not  metered.  The  only  objection  to  a  metered  service  is  the  preju- 
dice common  to  all  innovations,  but  the  advantages  are  soon  realized 
and  the  saving  is  very  considerable.  The  introduction  of  meters  in 
the  city  of  Washington  during  the  past  few  years  has  resulted  in  check- 
ing the  waste  by  reducing  the  total  amount  of  water  consumed  one- 
third,  making  a  saving  of  from  20  to  30  million  gallons  of  water  a  day 
without  annoyance  or  inconvenience  to  any  one.  This  great  saving  did 
not  all  result  from  the  metering  alone,  but  was  aided  by  the  use  of 
detectors  and  an  efficient  system  of  inspection,  which  checked  waste 
from  other  causes.  In  Milwaukee,  before  meters  were  generally  adopted, 
the  water  used  per  tap  was  1,781  gallons  per  day.  After  the  ma- 
jority of  houses  were  furnished  with  meters,  the  amount  used  per  tap 
was  only  644  gallons.  Another  notable  instance  of  checking  waste  was 
furnished  by  Liverpool,  where  the  average  amount  supplied  daily  per 
head  was  33.5  gallons.  Deacons'  water  waste  detectors  were  introduced, 
and  these,  together  with  efficient  inspection,  reduced  the  supply  to  23 
gallons  without  any  restrictions  being  placed  upon  the  consumers.  At 
Shoreditch,  in  England  (population  87,000),  the  introduction  of  waste 
detectors  effected  in  the  course  of  three  years  a  diminution  of  waste 
and  undue  consumption  amounting  to  720,000,000  gallons  per  annum. 
At  Exeter  the  introduction  of  waste  detectors  reduced  the  waste  from 
75  to  12  gallons  per  head  per  day. 

It  is  estimated  by  engineers  that  45  per  cent,  of  the  water  supplied 
to  Manhattan  and  the  Bronx  is  wasted,  and  that  if  this  waste  were 
checked  the  new  aqueduct  from  the  Catskills,  which  is  costing  $140,000,- 
000,  would  not  be  needed.  Wliile  it  is  necessary  to  allow  a  liberal  supph^, 
there  is  no  sanitary  advantage  in  an  excess.  Good  clean  water  in  large 
quantities  is  difficult  to  obtain  and  expensive.  Economy  and  avoidance 
of  waste  are,  therefore,  essential. 

DOUBLE    WATER    SUPPLIES 

The  question  of  a  double  supply  of  water,  one  cheap  for  general 
purposes  and  the  other  high  class  for  personal  use,  has  often  engaged 
the  attention  of  engineers  and  sanitarians.  Ancient  Eome  had  a  sort 
of  double  supply,  and  Paris  and  other  European  cities  have  it  at  pres- 

^  In  cities  where  this  practice  prevails,  more  water  is  used  in  the  winter  time 
than  in  the  summer  months. 


698  GENERAL    CONSIDERATIONS 

ent.  Tlie  advantages  and  disadvantages  of  the  double  system  are  evi- 
dent. Even  where  the  community  served  is  intelligent  and  careful, 
the  danger  of  a  double  system  is  very  great,  and  it  will  probably  never 
be  resorted  to  except  through  stress  of  circumstances. 

Sedgwick  has  recently  suggested  that  cities  may  be  given  a  double 
water  supply  provided  the  one  for  general  use  is  disinfected  or  de- 
natured in  such  a  way  as  to  discourage  its  use  for  drinking  purposes. 
Thus,  if  the  second  supply  had  added  to  it  a  large  amount  of  bleaching 
powder,  perhaps  sufficient  to  make  it  distasteful,  it  would  at  least  be 
harmless  so  far  as  infections  are  concerned.  The  proposition  is  attrac- 
tive, and  would  serve  well  for  street  washing,  fire,  and  other  purposes. 

SOURCES    OF    WATER 

We  may  begin  the  circle  by  considering  that  all  water  comes  to  us 
from  the  aqueous  vapor  condensed  in  the  form  of  rain  or  snow.  Of 
this  a  certain  amount  returns  to  the  atmosphere  by  evaporation;  the 
rest  collects  upon  the  surface  of  the  earth  or  soaks  into  the  ground. 
Some  of  it  flows  off  in  the  direction  of  surface  slope  to  join  the  ponds, 
lakes,  rivers,  or  seas,  or  some  of  it  may  penetrate  the  earth  to  variable 
depths.  The  sources  of  our  water  supply  may,  therefore,  be  classified 
as:  (1)  rain  or  snow  water,  (2)  surface  water,  including  ponds,  lakes, 
streams,  and  rivers,  and  (3)  ground  water,  including  springs  and  wells. 
This  classification  is  evidently  an  arbitrary  one,  used  for  convenience. 
There  is  no  sharp  line  of  demarcation  between  rain,  surface,  and  ground 
water.  Rain  water  soon  becomes  surface  water,  and  surface  water 
quickly  passes  into  the  ground;  the  ground  water  frequently  reappears 
as  springs  to  form  streams  and  lakes  and  other  surface  supplies. 

Rain  water  is  nominally  the  purest  and  may  be  free  from  all  traces 
of  organic  matter,  but  is  liable  to  irregularity  of  composition,  and  in 
built-up  sections  it  is  very  difficult  to  collect  it  so  as  to  be  free  from 
contamination  and  fit  for  drinking.  Surface  water  from  inhabited 
watersheds  is,  in  its  raw  condition,  never  entirely  safe  for  drinking 
purposes.  Ground  water  obtained  from  the  sub-soil  of  a  catchment 
area,  free  from  sources  of  pollution,  is  usually  of  a  satisfactory  char- 
acter. Artesian  water,  which  is  ground  water  obtained  from  the  deeper 
underlying  strata,  is  often  so  rich  in  mineral  matters  that  it  is  unsatis- 
factory for  most  uses.  The  various  sources  of  pollution,  its  character, 
and  dangers  will  be  considered  in  subsequent  pages. 

RAIN    WATER 

Rain  water  is  really  "distilled  water,"  that  is,  it  is  water  that 
has  been  vaporized  and  then  condensed.  The  process  of  distilla- 
tion is  one  of  the  best  known  methods   for  purifying  liquids  of  all 


SOUECES    OF    WATEE  699 

kinds.  All  the  non- volatile  substances  are  left  behind;  theoretically, 
therefore,  rain  water  should  approach  nearer  to  absolute  purity  than 
any  other  kind  of  natural  water.  However,  it  receives  impurities  from 
the  moment  it  condenses,  for  each  droplet  of  mist  is  formed  about  a 
particle  of  dust  in  the  air.  The  rain  drop  further  absorbs  gases,  and 
as  it  drops  through  the  air  collects  a  large  amount  of  the  "dirt"  floating 
in  the  lower  portions  of  the  atmosphere.  It  is  a  common  observation 
how  a  shower  will  wash  the  air  so  that  it  becomes  beautifully  clear  and 
clean.  The  impurities  collected  by  the  rain  before  it  reaches  the  sur- 
face of  the  earth,  while  considerable  in  amount,  are  practically  negli- 
gible from  a  sanitary  standpoint.  After  rain  touches  the  earth's  sur- 
face it  becomes,  to  all  intents  and  purposes,  a  surface  water,  unless 
collected  with  special  precautions  to  avoid  contamination.  If  collected 
from  a  clean,  impervious  surface  in  the  open  country,  it  is  the  purest 
of  natural  waters.  The  use  of  rain  water  for  drinking  purposes  has 
met  with  little  favor  by  sanitarians,  despite  its  exceptional  purity, 
because  it  is  so  frequently  collected  and  stored  in  such  a  careless 
manner  that  it  is  subject  to  impurities.  It  is  true  that  rain  water  is 
not  likely  to  be  infected  with  sewage,  nevertheless  some  of  the  filthiest 
waters  used  for  domestic  purposes  come  from  rain-water  tanks.  Even 
casual  inspection  will  often  show  that  rain  water  collected  and  stored 
in  the  usual  way  is  very  far  from  being  pure,  though  rarely  infected. 

Because  rain  water  is  soft  it  recommends  itself  for  use  in  the  laun- 
dry, and  the  absence  of  lime  salts  renders  it  desirable  for  cooking.  On 
the  whole,  however,  it  is  not  considered  as  practicable  as  a  good  ground 
or  surface  water  for  general  domestic  supply. 

The  use  of  rain  water  stored  in  cisterns  is  the  principal  factor 
in  keeping  yellow  fever  alive  in  endemic  foci.  The  yellow  fever  mos- 
quito {Stegomyia  calopus)  breeds  by  preference  in  artificial  containers 
holding  rain  water.  It  was  the  abolition  of  such  breeding  places  that 
has  protected  Philadelphia,  Boston,  and  many  other  seaports  that  for- 
merly fostered  the  stegomyia  and  suffered  from  yellow  fever  epidemics 
(see  page  212). 

Usually  it  is  advisable  to  filter  rain  water  collected  from  the  roofs 
of  buildings,  especially  if  situated  in  towns,  near  dusty  roads,  etc. 

Underground  filters  for  rain  water,  in  order  to  purify  it  before  it 
enters  the  storage  tanks,  are  frequently  provided.  ■  These  filters  are 
for  the  most  part  unsatisfactory.  Either  the  material  is  so  coarse  that 
little  purification  is  effected,  or  so  fine  that  it  speedily  becomes  clogged 
and  useless.  They  rarely  receive  proper  attention  and,  therefore,  are 
apt  to  become  filthy. 

Amount.— The  average  annual  rainfall  on  the  globe  is  computed  to 
be  33  inches.  The  mean  annual  rainfall  for  different  portions  of  the 
United  States  has  been  tabulated  by  the  United  States  Weather  Bureau 


700  GENERAL    CONSIDERATIONS 

to  average  some  30  inches.  In  New  England  and  the  middle  states  it 
amounts  to  40  inches.  In  Assam  from  GOO  to  805  inches  have  been 
recorded,  while  in  the  Sahara  desert,  part  of  Arabia,  the  desert  of 
Gobi,  and  portions  of  Mexico,  Chili,  and  Peru  it  has  seldom  been  known 
to  rain.  Coles-Finch  states  that  it  seems  to  be  a  fact  that  the  atmos- 
phere of  the  earth  is  growing  drier.  The  glaciers  are  retreating,  the 
Caspian  Sea  and  many  other  lakes  are  growing  smaller,  and  the  great 
deserts  seem  to  be  extending.  Some  of  the  richest  countries  on  earth 
have  seen  their  fertility  decreasing,  mainly  owing  to  lessened  rainfall, 
and  this  caused,  at  least  in  part,  by  the  ruthless  destruction  of  tlie 
forests.  Ruined  forests  mean  flooded  rivers,  periodic  droughts,  eroded 
soil,  and  dried-up  springs. 

The  amount  of  water  given  by  rain  can  easily  be  calculated  if  two 
points  are  known — the  mass  of  rainfall  and  the  area  of  the  receiving 
surface.  The  amount  is  determined  by  a  rain  gage  and  the  area 
of  the  receiving  surface  must  be  measured.  Roughly,  the  amount  may 
be  calculated  by  multiplying  the  area  of  the  receiving  surface  in  square 
feet  by  half  the  rainfall  in  inches,  the  result  being  in  gallons.  Here 
the  error  is  about  4  per  cent.  Thus,  according  to  Church,  one  inch  of 
rain  on  a  house  roof  20x20  feet  area  would  be  about  250  gallons.  With 
a  rainfall  of  40  inches  per  annum  this  would  amount  to  10,000  gallons, 
or  27  gallons  per  day. 

The  total  theoretical  amount,  however,  is  never  available,  for  the 
reason  that  some  is  lost  by  evaporation  and  the  first  flow  should  be 
wasted.  Only  a  very  small  proportion  of  water  may  be  collected  from 
a  light  shower  spread  over  a  considerable  interval,  especially  in  hot 
weather,  as  nearly  all  is  lost  by  evaporation. 

The  stations  of  Prussia  allow  the  following  average  for  evaporation, 
the  amount  evaporated  in  the  open  fallow  field  being  called  100 : 


Evaporated 

Retained  More 
than  in  Open 
Fallow  Field 

Under  beech  growth 

Per  Cent. 
40.4 
45.3 
41.8 
90.3 

Per  Cent. 
59  6 

Under  spruce  growt  h 

54  7 

Under  pine  growth 

58  2 

From  cultivated  field 

9  7 

It  is  this  protection  against  evaporation  which  gives  to  the  forest 
its  chief  value  as  a  guardian  of  water  supply.  The  forest  floor,  with 
its  irregularities  and  its  sponge-like  qualities,  moreover  stops  the  rapid 
and  ruinous  draining  of  the  surface,  with  attendant  denuding  of  the 
land,  and  favors  slow  percolation  through  the  soil  and  reinforcement  of 
the  springs. 


SOUECES    OF    WATER  701 

The  amount  of  water  that  can  be  utilized  from  the  rainfall,  drain- 
ing a  catchment  area,  may  be  stated  as  follows:  Taking,  for  example, 
an  average  of  46  inches  of  rainfall  each  year  upon  the  catchment  area, 
one-half  of  this  is  lost  by  evaporation  from  the  water  surfaces,  from 
the  surface  of  the  ground,  and  especially  from  the  leaves  of  all  the  plants 
and  trees  that  grow  upon  it.  Tlie  other  half,  equal  to  a  rainfall  of  23 
inches,  flows  off  into  streams,  and  sooner  or  later  reaches  the  lake  or 
impounding  reservoir.  In  wet  years  the  amount  that  flows  off  is 
greater;  in  dry  years  it  is  less  than  the  average;  in  the  winter  and 
spring  months  the  flow  is  very  much  greater  than  at  other  times. 

Collection  and  Storage. — The  points  of  prime  importance  in 
the  collection  and  storage  of  rain  water  for  domestic  purposes  are :  ( 1 ) 
the  material  and  care  of  the  surface  from  which  it  is  caught;  (2)  the 
separation  of  the  first  flow,  which  contains  most  of  the  grossest  im- 
purities;  (3)  the  location  and  construction  of  the  storage  cistern. 

Storage  cisterns  for  collecting  rain  water  are  frequently  placed 
underground.  In  some  places,  such  as  New  Orleans,  rain  water  cis- 
terns are  built  of  cypress  wood  and  always  above  ground.  Tanks  of 
wood  serve  their  purpose  well,  provided  they  be  kept  full.  If  there 
is  great  fluctuation  in  the  water  line  the  tank  itself  falls  out  of  repair. 
Eain  water  attacks  iron,  lead,  zinc,  and  other  metals,  and  when  metal 
cisterns  are  used  the  metal  should  be  coated  with  a  good  asphaltum 
paint.  This  applies  also  to  the  delivery  pipe.  Under  no  circumstances 
should  lead  cisterns  or  lead  service  pipes  carry  rain  water  used  for 
drinking  purposes.  It  should  not  be  forgotten  that  cisterns  are  liable 
to  the  grossest  kinds  of  pollution,  and  they  require  frequent  inspection 
and  cleansing. 

Where  overflow  pipes  from  rain  water  tanks  are  connected  with 
drains  precautions  must  be  taken  to  prevent  sewage  backing  up  and 
entering  the  tank. 

Composition. — Eain  water  varies  in  composition  with  the  purity 
of  the  atmosphere  through  which  it  has  passed.  It  always  contains 
dissolved  gases,  an  average  of  25  c.  c.  per  liter.  These  gases  are 
mainly  nitrogen,  oxygen,  and  carbon  dioxid,  taken  up  in  proportion  to 
their  absorption  coefficients,  and  not  in  proportion  to  the  amount  con- 
tained in  the  atmosphere.  The  gases  contained  in  rain  water  consist 
of  about  64  per  cent,  nitrogen,  34  per  cent,  oxygen,  and  2  per  cent, 
carbon  dioxid.  In  addition  ammonia  is  very  commonly  present.  The 
amount  of  total  solids  varies;  throughout  England  it  averages  0.39 
part  per  million.  The  principal  inorganic  constituent  of  rain  water 
is  sodium  chlorid;  nitric  acid  and  nitrates,  sulphuric  acid  and  sul- 
phate; a  small  quantity  of  nitrogenous  organic  matter  is  also  pres- 
ent. The  sodium  chlorid  comes  mostly  from  the  sea  spray  lifted 
into  the  atmosphere  through  wind  action.     The  sulphuric  acid  comes 


702  GENERAL    CONSIDERATIONS 

largely  from  the  waste  products  of  burning  coal.  Rain  water  is  soft 
on  account  of  the  absence  of  the  alkaline  earths,  and  is  almost  always 
acid   in  reaction.     It  has  a  mawkish  taste. 

Bacteria. — Rain  water  contains  a  varial)le  number  of  l)acteria  and 
other  microorganisms,  the  number  and  kind  depending  upon  tlie  germ 
population  of  the  atmosphere  through  which  tlie  rain  passes.  Fortu- 
nately the  various  microorganisms  floating  in  the  air  and  carried  down 
mostly  by  the  first  shower  are  not  of  serious  moment,  as  far  as  health 
is  couceraed.  Pathogenic  microorganisms  in  the  air  are  few  in  num- 
ber, and  these  are  soon  killed  by  desiccation  or  the  germicidal  action 
of  the  direct  sunlight,  to  which  they  are  so  thoroughly  exposed. 

Miquel,  at  the  Montsouris  Observatory  in  Paris,  found  rain  water 
to  contain  bacteria,  pollen,  spores  of  fungi,  protococci,  etc.,  especially 
numerous  in  the  warmer  months.  In  the  first  showers  after  a  long  spell 
of  dry  weather  over  100,000  such  organisms  may  occur  in  a  pint. 

SURFACE    WATERS 

Surface  waters  include  rivers,  creeks,  and  smaller  streams,  large  and 
small' lakes,  ponds,  and  impounding  reservoirs,  all  resting  upon  the  bosom 
of  the  earth  in  contact  with  the  atmosphere.  Surface  waters  vary 
greatly  in  composition,  depending  largely  upon  the  character  of  the 
catchment  basin.  A  water  flowing  over  a  rocky  soil  or  through  deep 
layers  of  sand  and  gravel  is  more  likely  to  be  free  of  organic  impurities 
than  one  that  is  drained  over  loam  or  has  stood  in  swamps. 

From  the  way  in  which  surface  waters  are  exposed  they  are  subject 
to  impurities,  and  from  a  sanitary  standpoint  are  frequently  dangerous 
and  almost  always  open  to  suspicion.  Most  cities,  especially  in  America, 
depend  upon  surface  waters  for  their  supply.  This  is  usually  taken  from 
rivers,  lakes,  or  impounding  reservoirs.  It  is  scarcely  possible,  in  a  pop- 
ulous country,  to  obtain  a  large  quantity  of  surface  water  free  from 
pollution  with  human  wastes.  Sanitarians  have,  therefore,  more  and 
more  come  to  the  conclusion  that,  while  surface  waters  used  for  drink- 
ing purposes  should  be  guarded  against  contamination,  as  far  as  prac- 
licaljle,  they  should  always  be  purified  before  they  are  used. 

Rivers. — Streams  are  the  natural  sewers  of  the  regions  they  drain, 
and,  when  used  as  a  source  of  water  supply,  we  have  established  a 
direct  connection  between  the  alimentary  canals  of  the  people  living 
upstream  with  the  mouths  of  those  below.  Most  of  our  large  rivers 
flow  through  more  than  one  state;  therefore,  the  interstate  pollution 
of  streams  becomes  a  national  problem.  In  the  older  countries  of  Eu- 
rope, with  more  centralized  power,  laws  to  prevent  the  pollution  of 
streams  arc  enforced.  In  our  country  the  federal  authorities  are  not 
authorized  to  enforce  this  pressing  sanitary  problem  of  growing  im- 
portance.    This  is  discussed  more  in  detail  under  Sewage. 


SOUECES    OF    WATEE  703 

In  our  country  the  rivers  furnish  the  chief  source  of  water  supply 
for  most  of  our  large  cities.  The  succession  of  cities  and  the  combined 
use  of  the  river  as  a  sewer  and  source  of  water  supply  on  such  rivers 
as  the  Merrimac,  Hudson,  Delaware,  Ohio,  Missouri,  and  Mississippi 
are  particularly  impressive,  and  when  the  water  has  been  used  in  its 
raw  or  unpurified  state  much  unnecessary  sickness  has  resulted  and 
thousands  of  lives  have  been  lost  in  this  way. 

jSTo  stream  draining  an  inhabited  region  can  be  considered  safe 
without  some  method  of  purification.  There  are  a  thousand  minor 
sources  of  pollution  that  practically  cannot  be  stopped,  even  though 
the  sewage  flowing  into  the  stream  is  treated  and  all  reasonable  pre- 
cautions taken  in  connection  with  it.  It  is  well  known  that  very  few 
sewage  purification  works  treat  all  the  sewage  from  the  districts  which 
they  serve.  Thus,  there  are  storm  overflows  and  the  street  wash  that 
cannot  pass  through  sewers,  and  other  sources  of  pollution. 

Looking  at  the  whole  matter  of  streams  pollution  solely  as  an 
economic  engineering  problem,  it  is  cheaper  to  purify  the  water  sup- 
plies taken  from  the  rivers  than  to  purify  the  sewage  before  it  is  dis- 
charged into  them.  The  volume  to  be  handled  is  less  and  the  cost  of 
purifj'ing  water  per ,  million  gallons  is  much  less  than  the  cost  of 
purifying  sewage.  Further,  in  the  present  state  of  our  knowledge 
water  may  be  purified  more  effectively  and  with  greater  certainty  than 
sewage.  On  the  other  hand,  it  is  perfectly  clear  to  the  sanitarian  that 
the  future  will  require  both  methods,  that  is,  a  reasonable  protection  of 
our  streams  against  pollution  and  the  purification  of  the  water  served  to 
cities. 

Composition. — The  composition  of  river  water  varies  very  much, 
according  to  the  part  of  the  river  whence  it  is  taken.  ISTear  its  source 
the  water  may  be  comparatively  pure,  but  it  soon  becomes  polluted. 
The  composition  is  complex,  as  the  water  of  rivers  consists  of  a  mixture 
of  rain  water  and  ground  water,  to  which  are  added  surface  impurities. 
As  a  rule,  river  water  is  softer  than  ground  water,  but  contains  a  greater 
amount  of  organic  matter. 

Sudden  and  great  changes  in  the  character  of  river  water  are  to 
be  expected.  Other  changes,  slow  in  operation  but  serious  in  result, 
come  from  the  increasing  pollution  with  sewage  from  a  growing  popu- 
lation upon  the  upper  regions  of  the  watershed. 

Eivers  are  generally  purer  near  their  source.  The  amount  of  impuri- 
ties increases  as  we  descend  the  stream,  since  the  water  courses  are 
the  natural  drainage  channels  of  the  country,  and  the  wastes  of  human 
life  and  occupation  as  well  as  the  scourings  of  the  land  find  their  .way 
into  the  streams.  It  is  for  this  reason  that  rivers,  after  passing  through 
cultivated  valleys  with  cities,  towns,  or  settlements  along  their  banks, 
often  contain  a  verv  great   amount  of  mineral   and  organic  matter. 


704  GENERAL    CONSIDERATIONS 

Thus,  the  ]\Iississipi)i  at  Minnesota  contains  only  18.6  total  solids  per 
100,000,  while  the  same  river  at  St.  Louis  contains  244.3  per  100,000. 

The  amount  of  mineral  matter  picked  up  by  a  stream  depends 
largely  on  the  geological  I'ormatiou  of  the  country  and  the  erosive 
power  of  the  stream. 

Frequent  attempts  have  been  made  to  correlate  the  flow  of  streams 
and  the  stages  of  the  river  with  the  outbreaks  of  disease,  especially 
typhoid  fever.  It  is  to  be  remembered  tliat  the  flow  of  streams  is 
dependent  in  most  cases  not  only  on  the  rainfall,  but  on  springs  of  local 
origin.  Typhoid  may  be,  and  usually  is,  independent  of  the  stage 
of  the  river.  Outbreaks  are  often  connected  with  sudden  freshets  fol- 
lowing a  long  dry  spell,  and  the  explanation  seems  to  be  that  the 
accumulated  fdth  is  thereby  washed  down  from  the  slopes  and  banks 
of  the  stream.  When  streams  are  very  low  the  flow  becomes  slug- 
gish, sedimentation  and  other  factors  influencing  self-purification  take 
place  in  comparatively  short  distances;  when  the  river  is  high  the 
rapid  flow  is  more  apt  to  bring  fresh  and  virulent  infection. .  The 
decline  of  typhoid  fever  in  Alleghany  in  1908  and  1909  was  coinci- 
dent Avith  an  exceptionally  low  stage  of  the  river.  During  the  spring 
and  fall  freshets,  when  the  water  is  cold  and  the  current  swift,  the 
danger  is  the  greatest.  In  other  words,  it  is  the  rapidity  of  flow  or  the 
time  consumed  rather  than  the  stage  of  the  river  or  the  dilution,  that  is 
most  often  responsilile  for  typhoid  and  other  infections  in  river  waters. 

If  typhoid  bacilli  are  discharged  into  a  stream  which  flows  at  a 
rate  of  5  miles  an  hour,  which  is  a  comparatively  quiet  stream,  and 
accepting  the  usual  figures  that  the  bacteria  may  die  in  5  days,  these" 
organisms  could  be  carried  600  miles,  surely  far  enough  to  reach  some 
domestic  supply.  Hence,  it  may  be  concluded  that  any  pollution,  how- 
ever remote,  is  apt  to  reach  some  consumer  unless  it  occurs  near  the 
sea.  Nevertheless,  the  Potomac  River  at  Washington  seems  to  be  re- 
sponsible for  little  or  none  of  the  typhoid  fever  in  that  city,  although 
it  drains  an  area  of  about  11,400  square  miles,  having  a  population  in 
1900  of  about  half  a  million  and  receiving  directly  the  sewage  of  some 
45,000  persons.  The  question  of  the  self-purification  of  streams  is 
considered  on  page  777. 

Lakes  and  Ponds. — Fresh  water  lakes  and  ponds  make  admirable 
sources  of  water  supply  when  kept  free  from  pollution  with  the  wastes 
of  human  life  and  industry.  This  is  much  more  practical  than  in  the 
case  of  rivers,  on  account  of  the  limited  area  of  the  catchment  basin 
directly  draining  into  a  small  lake  or  pond.  Lake  water  is  apt  to  be 
soft  and  free  from  serious  organic  impurities.  In  large  lakes  the  dilu- 
tion of  accidental  contamination  is  enormous,  and  the  effects  of  time, 
storage,  sedimentation,  and  other  purifying  factors  have  a  good  chance 
of  exerting  their  maximum  influence.     The  problem  from  a   sanitary 


SOtJECES    OP    WATER  705 

standpoint  is  quite  different  when  we  consider  large  bodies  of  fresli 
water,  such  as  our  Great  Lakes,  or  smaller  lakes  and  ponds. 

The  Great  Lakes. — The  lake  cities  suffer  most  from  the  mingling 
of  their  own  sewage  with  their  own  water  supplies.  This  is  avoided 
in  part  hj  building  the  intakes  farther  out  into  the  lake  or  by  placing 
the  intakes  in  deep  water  at  points  where  there  seem  to  be  fairly  defi- 
nite currents,  bringing  fresh,  clear  water  from  the  body  of  the  lake  to 
the  intake.  The  currents  are  never  constant,  being  controlled  by  the 
wind,  hence  safety  cannot  be  secured  in  this  way.  Almost  every  lake 
city  has  at  one  time  or  another  suffered  from  outbreaks  of  typhoid 
fever.  Chicago  has  cut  a  drainage  canal  to  keep  her  sewage  from 
entering  the  lake,  so  that  it  now  flows  through  tributaries  to  the  Missis- 
sippi Eiver.  This  sanitary  reform  cost  the  city  of  Chicago  upward 
of  $40,000,000,  and  it  eliminates  the  sewage  of  a  large  part  of  the  city, 
but  not  including  certain  areas  of  Evanston  and  the  north  side.  Despite 
this  commendable  piece  of  sanitary  engineering  designed  to  keep  the 
water  clean,  it  is  probable  that  in  time  Chicago  will  resort  to  some 
method  of  jDurifying  ifs  water  supply.  This  applies  with  equal  force 
to  all  lake  cities  similarly  situated. 

Hazen  points  out  that  in  the  smaller  cities  upon  the  lakes  the 
mingling  of  the  sewage  and  water  may  be  relatively  just  as  important 
as  in  the  larger  ones.  They  have  less  money  to  spend,  their  intakes 
do  not  go  out  so  far,  their  sewers  are  apt  to  discharge  at  the  nearest 
point,  sometimes  directly  in  front  of  the  waterworks  intake.  The  water 
may  be  shallow  and  stirred  by  the  Avind  to  the  bottom,  and,  in  short, 
"Menominee's  sewage  in  Menominee's  water  may  be  just  as  bad  as 
Chicago  sewage  in  Chicago  water." 

The  Great  Lakes  are  so  large  and  the  dilution  and  time  intervals 
and  exposure  to  sun  and  air  are  so  great  that  there  is  practically  no 
chance  of  infection  being  carried  from  one  of  the  great  cities  to  another. 
Thus,  Chicago  sewage  would  scarcely  endanger  the  purity  of  Detroit's 
water  supply,  even  with  no  drainage  canal.  The  little  city  of  St.  Clair, 
with  2,543  inhabitants,  only  45  miles  away,  is  far  more  dangerous  to 
Detroit.  In  the  same  way  Detroit's  sewage  is  probably  harmless  at 
Cleveland,  and  Cleveland  sewage  is  harmless  at  Buffalo.  The  sewage 
of  Buffalo,  however,  is  a  great  menace  to  those  drinking  the  water 
at  Niagara. 

Impounding  Reservoirs. — Impounding  reservoirs  are  artificial  ponds 
or  lakes,  usually  made  by  throwing  a  dam  across  a  narrow  valley. 
Most  impounding  reservoirs  are  made  along  the  course  of  a  small 
stream. 

The  principal  use  of  impounding  reservoirs  is  to  hold  the  excess 
of  water  of  the  winter  and  spring  flows  and  make  it  available  during 
the  summer  and  fall. 


706  GENERAL    CONSIDERATIONS 

The  impounding  reservoir  designed  to  furnish  New  York  City  with 
a  new  supply  of  water  to  supplement  the  Croton  system  will  be  the 
largest  artificial  reservoir  for  water  supply  in  America,  if  not  in  the 
world.  It  is  situated  in  the  Catskill  mountains,  and  is  made  by  dam- 
ming Esopus  Creek,  and  will  ultimately  hold  one  hundred  and  twenty 
billion  gallons  of  water.  Boston  is  supplied  from  impounding  reser- 
voirs on  small  streams;  the  Cochituate  (1848),  the  Sudbury  (1878), 
and  the  Nashua  (1898).  The  Wachusett  reservoir  stores  the  combined 
water  from  the  smaller  sources  of  supply,  and  has  a  capacity  of  63,000,- 
000,000  gallons  of  water.  Baltimore  has  an  impounding  reservoir  upon 
the  Gunpowder  River;  other  cities  similarly  supplied  are  Newark  and 
Jersey  City  in  New  Jersey;  Worcester,  Cambridge,  and  Springfield  in 
Massachusetts;  New  Haven  and  Hartford  in  Connecticut;  Altoona  in 
Pennsylvania,  and  Denver  in  Colorado;  San  Francisco  and  Oakland  in 
California;  and  numerous  other  smaller  cities.  From  a  sanitary  stand- 
point the  great  advantage  of  an  impounding  reservoir  is  that  it  drains 
a  comparatively  small  area  that  is  amenable  to  control;  often  the  catch- 
ment area  is  in  uninhabited  hilly  or  mountainous  districts.  The  other 
sanitary  advantage  lies  in  the  fact  that  benefit  is  taken  of  the  great 
sanitary  safeguard  of  storage.  Most  pathogenic  microorganisms  die  a 
natural  death  during  the  time  that  the  water  is  stored  in  a  large  im- 
pounding reservoir.  In  Boston  it  is  estimated  that  the  water  is  stored 
an  average  of  30  days  before  it  reaches  the  consumer.  Few  non-sporu- 
lating  bacteria  dangerous  to  man  can  live  so  long  in  water  under  natural 
conditions. 

The  chief  disadvantage  of  impounding  reservoirs  as  storage  basins 
is  that  they  are  open  to  the  air  and  light,  and  thus  favor  the  growth 
of  algae  and  other  microscopic  organisms  responsible  for  objectionable 
tastes  and  odors.  Further,  the  stagnation  of  the  water  favors  the  ac- 
cumulation of  the  products  of  decomposition,  which  is  another  source 
of  evil  smells  and  vile  tastes.  The  stagnation  of  water  in  impounding 
reservoirs  and  small  lakes  and  ponds  deserves  special  mention. 

Stagnation  of  Water  in  Impounding  Beservoirs  and  Small  Lakes. — 
Hazen  points  out  that  in  our  climate,  when  a  reservoir  or  lake  is  more 
than  20  to  40  feet  deep,  the  upper  part  of  the  water  is  usually  in  cir- 
culation under  the  influence  of  the  wind,  and  the  lower  part  remains 
stagnant.  There  is  little  or  no  mixing  between  the  surface  water  and 
the  bottom  water,  except  for  two  short  periods  each  year,  one  in  the 
spring  and  one  in  the  fall.  These  periods  of  circulation  to  the  bottom 
are  known  to  waterworks  men  as  the  spring  turnover  and  the  fall 
turnover. 

During  the  summer  weather  a  blanket  of  warm  and,  hence,  light 
water  remains  at  the  surface.  This  layer  may  be  20  feet  in  small 
reservoirs,  and  40  feet  in  great  lakes.     The  temperature  of  thi?  surface 


SOUECES    OF    WATER  707 

layer  may  reach  75°  or  80°  F.  or  more  in  midsummer.  The  wind 
stirs  it  up  to  a  certain  depth  (about  20  to  40  feet),  depending  upon 
the  depth  of  the  reservoir  and  the  force,  direction,  etc.,  of  the  winds. 

The  bottom  layer  is  cool  and  quiet.  As  the  air  temperature  falls 
with  the  approach  of  winter  the  surface  water  cools,  until  it  approaches 
that  of  the  bottom  water.  When  the  difference  in  temperature  between 
the  surface  and  bottom  layers  is  less,  the  wind  action  extends  deeper, 
until,  all  at  once,  often  when  the  wind  is  blowing,  vertical  currents 
arise,  so  that  all  the  water  in  the  reservoir  turns  over  and  mixes  from 
top  to  bottom.  The  mixing  continues  for  a  few  weeks,  until  the  tem- 
perature of  the  surface  water  falls  below  the  point  of  maximum  density, 
namely,  4°  C.  Then  the  colder  water  commences  to  accumulate  at  the 
top.  The  top  often  freezes  and  entirely  shuts  out  wind  action,  so  that 
the  period  of  winter  stagnation  is  even  more  quiet  than  the  summer 
period.  The  spring  turnover  is  caused  by  a  reversal  of  the  conditions 
causing  the  fall  turnover;  surface  water  is  warmed  until  it  reaches  the 
temperature  of  the  bottom  water,  when  the  upward  and  downward 
currents  take  place. 

It  can  readily  be  seen  that  this  phenomenon  has  much  to  do  with 
the  quality  of  the  water.  Thus,  the  organic  matter  upon  the  bottom 
of  almost  all  reservoirs  decomposes,  and  in  the  absence  of  oxygen  pro- 
duces the  vile  odors  and  nasty  tastes  of  putrefaction.  These  odors  and 
tastes  accumulate  in  the  bottom  water  until  the  fall  turnover;  then 
they  become  mixed  with  all  the  water  in  the  reservoir.  If  the  water  is 
drawn  from  the  reservoir  near  the  top,  as  it  usually  is,  there  will  be 
a  great  change  in  the  quality  of  the  water  on  the  day  of  the  fall  turn- 
over. The  surface  water  is  well  charged  with  oxygen,  and,  as  this  falls 
to  the  bottom,  it  oxidizes  and  neutralizes  some  of  these  products  of  de- 
composition. Tastes  and  odors  due  to  this  cause  may  be  removed  by 
aerating  the  water  by  means  of  fountains,  cascades,  falling  over  a  dam, 
or  any  other  similar  means.  For  a  further  discussion  of  this  interesting 
subject  see  Hazen's  "Clean  Water  and  How  to  Get  It." 

, Stripping. — Stripping  consists  in  removing  the  organic  matter  of 
the  surface  soil,  which  is  to  become  the  bed  of  a  reservoir.  The  ob- 
ject of  stripping  is  to  diminish  the  amount  of  putrefaction  taking  place 
in  the  bottom  stagnant  water,  and  also  to  furnish  less  food  for  bac- 
teria and  algae.  A  number  of  the  reservoirs  in  Massachusetts  were 
first  stripped  at  considerable  expense.  It  has  been  found  that  in  the 
older  reservoirs  prepared  in  this  way  putrefaction  has  not  taken  place 
for  some  years,  although  in  some  cases  putrefaction  seems  not  to  have 
been  entirely  prevented,  even  at  the  outset.  Stripping  does  not  prevent 
objectionable  growths;  it  only  reduces  them  somewhat,  because  many 
of  the  organisms  do  not  need  or  make  use  of  the  organic  matter  of  the 
soil  as  their  food  supply.     The  algae  live  rather  on  the  mineral  mat- 


708  GENERAL    CONSIDERATIONS 

ters  of  the  water  and  the  air,  and,  with  the  aid  of  the  sunshine,  they 
build  up  their  own  organic  matter,  precisely  as  the  higher  plants  do 
growing  in  soil. 

GROUND    WATER 

Water  which  is  taken  from  the  ground  by  means  of  wells  or  flow- 
ing naturally  from  the  ground,  as  in  springs,  is  usually  satisfac- 
tory, as  far  as  injurious  impurities  are  concerned.  The  surface  water 
is  greatly  purified  as  it  percolates  through  soil.  This  is  nature's  process 
of  filtration;  the  organic  matter  is  oxidized,  the  bacteria  are  largely 
strained  out.  The  soil  can  take  care  of  a  large  amount  of  pollution, 
and,  if  not  overburdened,  or  if  it  has  no  cracks  or  crevices,  the  ground 
water  may  be  entirely  free  of  objectionable  organic  subsiances  and  bac- 
teria. In  passing  through  the  soil  the  water  takes  up  a  rather  large 
amount  of  carbon  dioxid,  which  is  set  free  from  organic  decomposition. 
The  water,  thus  acidulated,  has  a  greater  solvent  action  for  lime  and 
other  mineral  constituents,  so  that  ground  water  is  apt  to  be  harder  than 
surface  waters,  and  to  contain  a  larger  amount  of  dissolved  inorganic 
substances.  In  deeper  waters  the  solvent  action  is  favored  by  increased 
heat  and  pressure,  so  that  deep  wells  and  artesian  waters  are  frequently 
unfit  for  domestic  use  on  account  of  the  large  amount  of  inorganic 
impurities  which  they  contain,  such  as  lime,  iron,   common   salt.   etc. 

The  water  that  soaks  into  the  soil  finally  rests  upon  an  impervious 
stratum.  Such  water,  as  a  rule,  does  not  exist  in  the  ground  as  a 
river  or  lake,  but  occupies  rather  the  spaces  between  the  sandy  particles, 
except  in  limestone  formations.  Ground  water,  therefore,  in  any  quan- 
tity is  found,  as  a  rule,  in  sand}',  gravelly,  or  sandstone  formations. 

It  is  only  in  limestone  regions  that  the  ground  water  exists  as  flow- 
ing rivers  or  in  large  bodies.  In  such  instances,  as,  for  example,  the 
mammoth  cave  in  Kentucky,  the  underground  river  may  appear  and 
disappear  suddenly.  The  sanitary  significance  of  water  from  limestone 
crevices  is  entirely  different  from  that  obtained  from  a  sandy  soil. 


Fig.  94. — Ground  Water.     A.  High  level.     B.  Low  level.     C.  Intermittent  spring. 

The  surface  of  the  ground  water  does  not  follow  the  surface  of  the 
land,  but  more  approximately  the  contour  of  the  impervious  stratum  on 
which  it  rests.  It  crops  out  at  the  surface  here  and  there,  to  form 
rivers,  ponds,  lakes,  and  springs.  The  irregularity  of  the  surface  of  the 
ground  water  table  is  due  to  a  certain  extent  to  the  rainfall.     During 


SOURCES    OF   WATER  709 

drought  the  level  becomes  more  and  more  uniform^  until  it  may  become 
quite  horizontal.  In  most  cases,  except  where  water  lies  in  deep  de- 
pressions and  pockets,  the  ground  water  is  in  constant  lateral  motion. 
This  motion  is  usually  in  the  direction  of  outfall,  that  is,  toward  the 
nearest  large  body  of  water — lake,  river,  or  sea.  That  is  why  fresh 
water  may  frequently  be  obtained  by  sinking  a  well  at  the  seacoast.  In. 
some  places  the  rate  of  lateral  flow  is  so  slow  as  to  be  almost  impercep- 
tible; at  other  places  it  is  comparatively  rapid.  Thus,  at  Munich,  Pet- 
tenkofer  estimated  15  feet  per  day;  at  Budapest,  Fedor  found  the 
ground  water  to  flow  at  an  averag.e  of  167.6  feet  per  day.  The  rate  of  flow 
of  ground  water  may  be  determined  approximately  by  several  methods. 

The  method  of  determining  the  velocity  of  ground  water  which  has 
been  used  with  satisfactory  results  by  Thiem  is  as  follows: 

Three  or  four  borings  are  sunk  to  ground  water  in  a  line  in  the 
direction  of  flow.  A  large  dose  of  salt  is  then  put  into  the  upper  hole, 
and  at  frequent  intervals  analyses  are  made  of  water  drawn  from  each 
hole  below,  until  the  salt  content  has  reached  its  maximum  in  each  case, 
and  the  rate  of  movement  is  computed  from  these  results. 

Amount. — The  amount  of  water  that  may  be  obtained  from  the 
ground  can  only  be  determined  by  means  of  actual  pumping  tests  car- 
ried on  for  a  sufficient  length  of  time  to  bring  about  an  approximate 
state  of  equilibrium  between  the  supply  and  the  demand,  as  determined 
by  the  level  of  the  ground  water.  It  is  rarely  practical  to  continue  such 
tests  until  perfect  equilibrium  is  reached,  for  in  many  cases  several 
years  of  operation  would  be  required  to  determine  the  ultimate  capacity 
of  a  source.  Pumping  tests  of  short  duration  are  apt  to  be  very  decep- 
tive, as  ground  water  may  exist  in  the  form  of  a  large  basin  or  reservoir 
with  very  little  movement,  corresponding  to  a  surface  pond  with  small 
watershed,  and  brief  tests  would  give  little  more  information  than  sim- 
ilar tests  on  a  pond. 

It  is  easier  in  proportion  to  get  a  little  ground  water  than  to  get 
a  large  amount,  and  for  this  reason  ground  water  supplies  are  more 
generally  available  for,  and  better  adapted  to,  the  needs  of  small  places 
than  of  large  cities. 

In  Europe,  ground  water  supplies  have  been  secured  for  many  large 
cities;  there  has  been  no  corresponding  development  in  America.  The 
reasons  for  the  greater  use  of  this  method  of  supply  in  Europe  are: 
smaller  quantity  of  water  required  per  capita,  more  favorable  geologi- 
cal conditions,  and  more  study  given  to  the  subject  and  greater  efforts 
to  secure  them,  especially  in  Germany. 

Ground  water  may  be  obtained  from:  (1)  sand  and  gravel  deposits, 
(2)  sandstone  rock,  (3)  limestone  formations. 

Ground    Water    from    Sand    and    Gravel    Deposits. — Water    flows 
through  sand  with  some  difficulty.     From  a  given  pumping  station  it 
47 


710  GENERAL    CONSIDERATIONS 

is  only  possible  to  draw  the  water  for  a  limited  distance.  This  distance 
depends  upon  the  depth  and  coarseness  of  the  sand.  Therefore,  the 
only  way  to  secure  a  large  quantity  of  water  from  such  formations  is 
by  the  use  of  a  number  of  comparatively  small  pumping  stations,  sepa- 
rated so  as  not  to  draw  from  the  same  territory. 

Only  a  given  amount  of  water  can  be  secured  from  a  square  mile 
of  ground.  The  amount  depends  upon  the  rainfall,  upon  the  evapora- 
tion from  the  surface  of  the  ground  from  transpiration  of  vegetation, 
and  upon  the  amount  of  storage  in  the  pores  of  the  soil. 

Most  of  the  sand  deposits  of  our  country  are  not  practically  avail- 
able for  water  supply  purposes,  because  the  grains  of  sand  are  too  small 
and  the  flow  of  water  through  them  is  too  slow.  It  is  only  the  coarse- 
grained sands  that  are  practically  available. 

A  few  cities  in  America  obtain  their  drinking  water  supplies  from 
ground  water  obtained  from  sand  and  gravel  deposits.  At  Brooklyn  the 
conditions  are  particularly  favorable,  and  it  is  estimated  that  78  mil- 
lion gallons  of  ground  water  are  obtained  each  day  for  that  city.  For 
this  purpose  24  separate  pumping  stations  are  used.  The  water  sup- 
plied to  Camden,  N.  J.,  is  obtained  .from  the  ground  through  wells 
close  to  the  Delaware  River,  and  the  amount  is  increased  by  taking 
river  water  from  the  surface  of  some  of  the  ground  about  the  wells. 
This  water  filters  through  the  sand  slowly  and  is  well  purified.  This 
method  of  adding  to  the  yield  of  wells  is  used  in  some  places  in  Ger- 
many and  France.  Memphis,  Tenn.,  is  probably  the  largest  city  in  the 
United  States  supplied  entirely  with  water  drawn  from  sand  and  grave! 
deposits.  In  this  case  the  water-bearing  area  is  several  hundred  feet 
below  the  surface,  and  is  below  a  clay  layer.  Lowell,  Mass.,  obtains 
ground  water  from  three  stations,  draining  different  areas  of  glacial 
drift. 

Filter  galleries  or  excavations  in  sandy  materials  near  river  l)anks 
have  been  used  in  the  past.  Such  water  corresponds  in  all  practical 
respects  to  the  ground  water  obtained  from  sand  and  gravel  deposits 
by  means  of  wells.  The  wells  are  preferable,  as  they  allow  water  to 
be  drawn  at  a  lower  level,  and  this  tends  to  a  drainage  of  a  greater 
area,   thereby   securing  a   larger   quantity   of  water. 

Filter  galleries  are  apt  to  furnish  a  diminishing  supply,  because  the 
pores  of  the  filtering  material  become  filled  with  the  sediment  of  the 
river  water.  When  this  happens  there  is  no  way  of  renewing  the  source. 
In  some  torrential  streams  the  filtering  surface  is  renewed  from  time 
to  time,  but  this  usually  does  not  occur. 

Ground  water  obtained  from  sand  and  gravel  deposits  is  usually 
clean  and  free  from  unwholesome  impurities.  Nevertheless,  many  towns 
and  cities  which  were  formerly  supplied  with  such  water  were  com- 
pelled to  seek  other  sources,  because  sufficient  water  was  not  obtainable 


SOUECES    OF    WATER  711 

from  the  ground  to  supply  the  increasing  quantities  required  by  rapidly 
growing  population. 

Ground  Water  from  Sandstone  Rock. — The  method  of  driving 
wells  in  sandstone  rock  differs  from  that  in  driving  wells  in  sand  or 
gravel,  but  the  collection,  storage,  and  flow  of  water  are  precisely  the 
same. 

The  cementing  material,  which  binds  what  otherwise  would  be  loose 
sand  into  a  solid  rock,  often  seems  to  offer  but  little  resistance  to  the 
flow  of  water,  and  the  sandstone  for  water  supply  purposes  acts  as  so 
much  sand  would  act. 

"Water  drawn  from  sandstone  is  always  well  filtered.  It,  however, 
is  usually  limited  in  amount,  and,  while  of  the  greatest  value  for  small 
supplies,  is  not  available  for  large  communities. 

The  Marshall  and  Potsdam  sandstone  underlying  parts  of  Michigan, 
Illinois,  Wisconsin,  and  Minnesota  are  used  extensively  for  supplying 
towns  and  small  cities.  Thus,  Jackson,  Mich.,  with  a  population  of 
over  25,000,  is  one  of  the  largest  cities  so  supplied. 

Ground  Water  from  Limestone  Formations. — In  limestone  for- 
mations the  underground  flow  of  the  water  is  not  through  sandy  or 
porous  rock,  for  limestone  is  not  porous.  The  water  travels  through 
fissures  or  passages.  When  these  are  large  they  are  called  caverns  or 
caves,  as,  for  example,  the  mammoth  cave  in  Kentucky.  These  cav- 
erns or  caves  are  natural  seams  or  cracks  enlarged  by  the  gradual  solu- 
tion and  removal  of  the  limestone  by  the  passing  water.  Limestone 
is  the  only  common  rock  that  is  soluble  in  this  way,  and,  for  water 
supply  purposes,  limestone  formations  must  be  distinguished  from  all 
others. 

The  crevices  may  be,  and  often  are,  continuous  for  many  miles. 
They  are  remarkably  tortuous  and  anastomose  freely,  and  the  direction 
and  flow  of  the  water  bear  no  relation  whatever  to  the  surface  topog- 
raphy. Pollution  at  one  point  may,  therefore,  endanger  those  using 
the  water  at  a  far  distant  place. 

Limestone  formation  has  little  ability  to  hold  the  abundant  winter 
flows  to  maintain  a  supply  through  droughts.  The  difference  between 
limestone  and  sand  in  this  respect  is  striking,  and,  from  a  sanitary 
standpoint,  the  fact  that  water  flowing  through  sand  is  filtered  and 
purified,  whereas  no  such  action  takes  place  through  limestone  fis- 
sures, is  significant.  Wliile  much  water  is  frequently  available  at  one 
point  in  limestone  formations,  the  amount  is  subject  to  greater  fluctua- 
tions, and  the  supply  may  fall  short  when  most  needed. 

That  contamination  at  one  point  may  soon  reappear  at  a  far  .dis- 
tant point  may  be  demonstrated  by  the  use  of  fluorescent  dyes,  or  by 
the  use  of  massive  cultures  of  some  harmless  microorganism,  such  as 
3''east  or  Bacillus  prodigiosus. 


712 


GENERAL    CONSIDERATIONS 


In  our  country  San  Antonio,  Texas,  is  supplied  with  water  from 
limestone  springs  flowing  in  greater  volume.  Indianapolis  was  at  one 
time  and  Winnipeg  in  Canada  is  still  supplied  largely  from  this  source. 
Paris  in  France  is  partially  supplied  with  limestone  water.  Vienna 
obtains  its  supply  from  the  wonderful  Kaiserbrunnen  and  other  lime- 
stone sources,  which  are  all  in  the  high  mountains,  where  there  is  scarcely 
any  population  or  pollution.  This  supply  is  mainly  from  the  melting 
ice  and  snow  of  the  high  mountains  which  replenishes  the  springs,  so 


^^teiT 


Fio.  95. — Usual  Method  of  Pollution  and  even  Infection  of  Wells. 

that  the  amount  of  water  obtainable  is  greater  in  summer  than  winter. 

Typhoid  fever  has  been  caused  rather  frequently  by  the  use  of  ground 
water  from  limestone  formations.  This  has  been  demonstrated  in  Paris, 
Switzerland,  France,  and  England.  Water  supplies  from  limestone  for- 
mations must,  therefore,  be  regarded  with  suspicion. 

Wells. — A  well  is  nothing  more  or  less  than  a  hole  sunk  into  the 
earth  to  reach  a  supply  of  water.  Wells  may  be  either  shallow  or  deep, 
dug  or  bored.  By  a  shallow  well  is  usually  understood  one  which  is 
dug  and  lined  with  stone  or  brickwork.  The  cylinder  is  usually  5  or  6 
feet  in  diameter  and  rarely  over  30  feet  deep.  By  deep  wells  are  meant 
drilled  or  the  so-called  artesian  wells.     They  consist  of  an  iron  pipe  or 


SOUECES    OF    WATER 


713 


tube  6  to  8  inches  in  diameter,  and  may  extend  many  hundred  feet  into 
the  earth.  If  the  water  is  drawn  from  a  depth  of  100  feet  or  more 
without  passing  an  impervious  stratum,  the  well  is  usually  spoken  of 
as  a  deep  well.  If  the  well  passes  through  an  impervious  stratum  into 
a  pervious  one  beneath,  in  which  the  water  rests  upon  another  im- 
pervious stratum,  it  is  spoken  of  as  an  artesian  well.  Water  is  usually 
pumped  from  the  wells  either  by  means  of  the  ordinary  suction  pump 
or  by  means  of  compressed  air. 

Contrary  to  the  generally  accepted  opinion  wells  are  usually  pol- 
luted from  the  surface  and  not  from  the  sub-soil  drainage.  The  fil- 
tering power  of  the  soil  is  usually  sufficient  to  protect  the  water  drawn 
from  a  well,  unless  (1)  the  soil  is  overburdened  with  organic  matter,  or 
(2)  a  cesspool,  broken  sewer,  or  other  gross  source  of  pollution  is  very 
close,  or  (3)  channels,  fissures,  or  crevices  exist  in  the  soil  and  sub- 
soil so  that  impurities  reach  the  well  without  undergoing  the  process 
of  biologic  filtration. 

In  locating  a  well,  therefore,  much  depends  upon  the  surface  config- 
uration of  the  ground,  the  character  of  the  soil,  and  the  proximity  of 
possible  sources  of  pollution.  The  casing  of  the  well  should  be  sound 
and  tight,  preferably  of  brick  laid  in  cement  mortar,  pointed  on  the 
inside.  This  impervious  casing  should  extend  as  deeply  into  the  well 
as  practicable,  and  after  it  is  laid  the  outer  space  between  the  casing 
and  the  earth  should  be  filled  in  with  well-tamped  clay  soil.  One  of 
the  most  important  points  in  the 

construction  of  a  shallow  well  is  ^m  l-BV        concrete 

to  extend  the  casing  at  least  18 
inches  above  the  surface  of' the 
ground  and  to  build  around  it  a 
shield  of  concrete  or  brick  laid  in 
cement  extending  in  a  circle  from 
the  top  of  the  well  3  or  4  feet 
wide.  This  shield  should  join  the 
well  casing  so  as  to  make  a  tight 
joint  with  the  casing.  The  floor 
of  the  well  should  rest  upon  the 
top  of  the  casing,  so  that  no  space 
is  left  for  frogs,  mice,  or  bugs  to 
crawl  in.  The  floor  should  like- 
wise be  water-tight,  and  is  best 

made  of  reinforced  concrete  with  a  cement  surface.  If  this  is  not  prac- 
ticable, it  should  be  made  of-  sound,  hard,  tongue-and-grooved  boards 
well  driven  up,  and  the  edges  painted  with  white  lead.  Upon  this  should 
be  laid  another  floor  of  similar  material  at  right  angles  to  the  first. 
The  piimp  should  be  let  into  the  floor  and  firmly  fastened  to  it,  and 


Fig.  96. — Proper  Conbtrtjction  of  a  Well,. 


714 


GENERAL    CONSIDERATIONS 


protected  with   a  flashing  of  tin  to  prevent  water  washing  back  into 
the  well. 

The  widely  prevalent  idea  that  some  form  of  ventilation  must  be 
provided  for  a  well  is  entirely  unnecessary.  Well  water  keeps  better  in 
the  dark  and  protected  from  the  outer  air. 


'  '  ^   "'  '       ■  /  '   '•  ■'■'"  -.5^, :  ^^ ■ 


\^^J"./  ■■   .  ■...-''■■■■  :'.--■ 


mmmmMmh 


Fig.  97. — Popular  Idea  of  How  Wells  Become  Infected  from  Surface  Pollu- 
tion. This  probably  rarely  takes  place  in  rural  districts,  as  the  soil  can  usually  hold 
back  most  of  the  impurities.  The  danger  is  great,  however,  where  fissures,  cracks, 
or  crevices  exist,  or  where  sewage  enters  beneath  the  surface  of  the  soil  from  broken 
drains  or  leaky  privies. 


The  top  of  driven  wells  should  be  as  carefully  protected  as  those 
just  described  for  a  dug  well,  as  otherwise  the  polluted  surface  water 
may  work  down  the  sides  of  the  pipe.  Care  should  be  taken  that  the 
pipes  of  a  driven  well  near  the  surface  of  the  ground  do  not  rust  and 
become  leaky.  Such  wells  should  be  provided  with  a  heavy  top,  to 
which  the  pump  frame  should  be  tightly  bolted,  in  order  to  prevent 
the  loosening  of  the  joints  in  the  pipe  by  the  vibration  of  pumping. 
The  ground  about  all  wells  should  be  kept  clean,  and,  where  possible, 
should  be  turfed.  The  waste  water  should  be  carried  by  pipes  to  a 
considerable  distance  from  the  well. 

Artesian  water  and  water  from  deep  wells  furnish  the  safest  and 
most  satisfactory  sources  of  supply  we  have.  Such  water  is  usually 
clear  and  of  high  sanitary  quality.  Sometimes  such  waters  contain  a 
large  amount  of  inorganic  impurities,  which  render  them  unfit  for  do- 
mestic purposes.  Frequently  they  contain  iron  in  the  ferrous  state, 
which  soon  oxidizes  upon  contact  with  the  air  and  is  thrown  out  as  an 
insoluble  ferric  salt,  which  renders  the  water  vellowish  or  brownish. 


SOUECES    OF    WATEE 


715 


Imperuiaus  Stratum 

Fig.  98. — Depression  of  the  Ground  Water  Level  by  Pumping  and  Tendency  to 
Draw  Nearby  Pollution  from  the  Soil  or  Cesspool. 


Deep  well  waters  may  also  contain  an  excess  of  lime  salts  or  common 
salt. 

Water  from  shallow  wells  obtained  from  sandy  or  gravelly  forma- 
tions are  entirely  satisfactory,  provided  there  are  no  nearby  sources  of 
pollution.  The  proximity  of  well  and  privy  may  be  especially  hazard- 
ous. Shallow  wells  in  limestone  regions  must  be  carefully  guarded  and 
always  looked  upon  with  suspicion. 


^          /■ 
i£^       X 


Fig.  99. — In  a  Limestone  Formation  It  Is  Difficult  to  Tell  Anything  about  the 
Source  of  Water  Obtained  from  a  Well. 


716  GENERAL    COXSIDEEATIONS 

It  is  evident  tliat  in  a  densely  inhabited  area  with  miles  of  sewers, 
some  of  them  doubtless  broken  or  leaky,  and  with  the  thousands  of  privy 
vaults  which  still  survive  in  most  of  our  American  cities,  we  have 
a  more  or  less  sewage-polluted  condition  of  the  soil  favorable  for  the 
contamination  of  shallow  wells.  Shallow  wells,  on  general  principles, 
have  been  gradually  eliminated  from  all  large  cities  having  an  abundant 
water  supply.  Tliis  danger  was  well  shown  in  the  studies  upon  typhoid 
fever  in  the  District  of  Columbia,  in  which  many  of  the  shallow  wells 
situated  within  the  city  limits  were  shown  to  be  polluted  by  chemical  and 
bacteriological  analyses. 

Wells  may  be  disinfected  with  lime,  which  has  been  found  to  be 
fairly  effective.  A  mixture  of  carbolic  acid  and  sulphuric  acid  in  suffi- 
cient quantity  will  sterilize  a  well,  but  these  substances  have  evident 
objections.  The  method  of  injecting  steam  under  a  pressure  of  two 
atmospheres  has  been  used.  The  steam  is  forced  into  the  water  until 
the  temperature  is  brought  to  near  the  boiling  point.  Bleaching  powder, 
however,  is  the  cheapest  and  most  practical  method  of  disinfecting 
wells  that  need  such  purification. 

Springs. — Spring  water  does  not  differ  in  any  essential  particular 
from  the  ground  water  obtained  from  shallow  wells.  Springs  may  be 
regarded  as  natural  wells,  outcropping  where  the  geological  formation 
is  favorable.  Spring  water,  as  a  rule,  is  of  a  high  degree  of  purity,  and 
as  the  water  flows  spontaneously  it  can  easily  be  utilized;  and,  as  no 
form  of  machiner}'  is  necessary  to  pump  it,  it  is  less  subject  to  contami- 
nation than  well  water.  Spring  waters  differ  greatly  in  character,  de- 
pending upon  the  temperature  of  the  water  and  the  inorganic  constitu- 
ents which  it  contains.  Springs  may  be  perennial,  the  flow  being  con- 
stant or  intermittent. 

Springs  may  be  polluted  from  various  sources.  The  overlying 
porous  layer  of  soil  may  be  too  thin  to  remove  the  contamination  of 
surface  washings  from  privies,  stables,  hog  pens,  and  other  sources  of 
contamination.  This  is  probably  not  a  frequent  source  of  danger  in 
such  waters.  Springs  may  be  contaminated  from  surface  washings; 
that  is,  the  infective  material  may  be  washed  down  and  into  the  spring 
by  heavy  rains,  and,  unless  the  spring  has  a  bold  flow,  the  polluting 
material  may  remain  in  it  for  some  time.  Leaky  cesspools  above  a  spring 
may  carry  dangerous  material  almost  directly  into  the  water,  just  as 
they  endanger  wells  in  precisely  the  same  way. 

The  protection  of  a  spring  against  contamination  requires  a  careful 
study  of  each  location.  Stables,  hog  pens,  and  privies  should  be  dis- 
tant, and,  if  possible,  on  another  slope.  Soil  pollution  must  be  prevented 
in  the  neighborhood  of  the  spring,  and  animals  kept  away,  and  special 
regard  must  be  had  for  the  location  and  character  of  the  privy.  The 
spring  should  be  protected  above  with  a  masonry  or  concrete  wall.    This 


SOUECES  AND  NATURE  OF  WATEE  POLLUTIOX  717 

should  extend  well  into  the  ground,  so  as  to  guard  against  surface 
washings.  A  ditch  should  be  dug  to  carry  off  the  surface  water  around 
both  sides  of  the  spring,  and  the  neighborhood  kept  clear  of  weeds  and 
growth.  It  is  well  to  plant  grass  about  the  spring  so  as  to  keep  out  dust 
and  prevent  erosion  of  the  soil. 


Fig.  100. — Spring  (ox  the  Left)  Exposed  to  Contamination  from  Surface  Wash- 
ings FROM  THE  Hill  Above.  Spring  (on  the  Right)  Protected  from  Surface 
Washings;  the  Bucket  Can  Be  Filled  without  Contaminating  the  Flow. 
(Virginia  Health  BuUetin.) 

In  limestone  regions  springs  are  subject  to  the  danger  already 
spoken  of  in  the  case  of  wells.  A  spring  in  such  a  region  may  be  the 
same  underground  stream  that  runs  through  the  neighbor's  back  yard 
and  disappears  in  his  meadow.  A  limestone  spring  that  becomes  muddy 
soon  after  a  rain  should  be  regarded  as  particularly  suspicious. 


THE  SOURCES  AND  NATURE  OF  WATER  POLLUTION  AND 

INFECTION 


A  distinction  is  drawn  between  a  polluted  and  an  infected  water. 
A  polluted  water  is  one  that  contains  organic  matter  and  the  products 
of  deca}',  either  of  vegetable  or  animal  origin.  An  infected  water  is 
one  that  contains  the  specific  parasites  causing  disease.  A  polluted 
water  may  not  be  particularly  harmful  to  health ;  it  is  always  susiDicious. 
That  is,  a  polluted  water  is  not  necessarily  infective;  an  infected  water 
is  practically  always  polluted.     Practically  all  surface  waters  are  pol- 


718  GEXERAL    COXSIDERATIONS 

luted;  ground  waters  usually  show  evidence  of  past  pollution;  that  is, 
they  contain  inorganic  salts  in  solution  resulting  from  the  mineralization 
of  organic  matter. 

The  greatest  hazard  to  man  is  found  in  a  water  polluted  with  the 
discharges  from  the  human  body — feces,  urine,  and  sputum.  There 
is  comparatively  little  danger  from  water  containing  the  wastes  of  other 
animal  life,  for  the  reason  that  few  of  the  infections  of  the  lower  ani- 
mals are  thus  transmissible  to  man.  There  is  still  less  danger  in  water 
contaminated  with  organic  matter  of  plant  origin.  Water  containing 
inorganic  substances  in  solution  plays  a  relatively  minor  role,  as  far  as 
health  is  concerned. 

From  a  sanitary  standpoint,  then,  it  is  the  wastes  of  human  life 
that  concern  us  especially.  These  may  enter  a  surface  water  directly 
from  overhanging  privies,  or  from  sewers,  or  from  washings  of  the  land. 
Ground  water  becomes  polluted  in  ways  already  discussed. 

The  prevention  of  the  pollution  of  our  streams,  lakes,  ponds,  and 
other  surface  supplies  is  an  important  sanitary  problem  with  a  large 
economic  side.  As  far  as  streams  and  large  lakes  are  concerned,  the 
most  dangerous  infection  is  that  which  is  nearby — that  is,  that  which 
is  quickly  transferred  in  a  fresh  and  virulent  form.  Distant  infection 
is  much  less  dangerous.  Cities  taking  water  from  an  average  stream 
should  prevent  the  access  of  direct  pollution  for  at  least  50  miles,  or 
better  100  miles,  above  the  intake.  Partial  protection  may  also  be  accom- 
plished by  requiring  sewage  disposal  works  for  all  towns  and  settlements, 
and  abolishing  all  overhanging  privies  upon  the  river  and  its  tributaries. 
A  sanitary  inspection  could  cover  a  large  shed  for  this  purpose.  When 
these  measures  are  not  feasible,  intercepting  sewers  may  be  built,  as 
on  the  Schuylkill  at  Philadelphia.  Canals  that  parallel  a  river,  as  the 
one  upon  the  bank  of  the  Potomac,  may  receive  the  sewage  and  surface 
drainage  and  thus  protect  the  stream.  It  is  comparatively  easier  to 
guard  smaller  lakes  and  ponds  and  impounding  reservoirs. 

Simple  Tests  to  Determine  Sources  of  Pollution. — Sources  of  pol- 
lution and  possibly  of  infection  may  often  be  determined  by  simple 
tests  which  may  be  carried  out  by  a  layman.  These  tests  afford  valu- 
able information  and  consist  in  the  addition  of  some  chemical  substance 
to  the  source  from  which  pollution  is  possible  and  then  determining 
whether  the  same  reappears  in  the  water  supply.  For  this  purpose  a 
large  number  of  substances  that  may  be  readily  recognized  by  their 
taste,  odor,  or  appearance  may  be  used,  such  as  coal  oil,  carbolic  acid, 
fluorescin,  and  common  salt.  Coal  oil  poured  near  the  ground  of  an 
artesian  well  is  an  easy  and  convincing  method  of  establishing  the 
presence  of  defective  piping  and  surface  or  sub-soil  contamination. 
Xordlinger  recommends  for  this  purpose  saprol,  which  tastes  like 
naphtha  and   is   so  penetrating  that   its   odor  may   be   readily   recog- 


SOUECES  AND  NATUEE  OF  WATEE  POLLUTION  719 

nized  in  proportions  of  1-1,000^000  or  by  taste  in  solutions  of  1-2,000,- 
000.  Trillat  experimented  witli  a  large  number  of  dj-es  and  finds  that 
fluorescin  dissolved  in  alcohol  and  diluted  with  5  per  cent,  ammonia 
solution  can  be  detected  by  a  fluoroscope  in  proportions  of  1-2,000,- 
000,000.  The  fluoroscope  is  a  tube  of  clear  glass  three  or  four  feet 
long  and  one-half  inch  in  diameter,  closed  at  one  end  with  a  rubber 
cork.  In  such  a  tube  natural  waters  have  a  soml^er  blue  color  which 
changes  to  a  clear  green  if  fluorescin  is  present.  This  dye  possesses  the 
evident  advantage  of  not  being  precipitated  by  the  soil  ingredients,  a 
reaction  that  readily  occurs  with  most  aniline  dyes  brought  in  contact 
with  calcareous  solutions.  Salts  of  lithium  are  sometimes  used,  for 
they  may  be  detected  in  the  minutest  traces  if  the  water  is  examined 
by  the  aid  of  a  spectroscope. 

The  conclusion  must  not  be  drawn  that  because  these  soluble  salts 
reappear  in  the  water  microorganisms  and  dangerous  pollution  would 
likewise  flnd  its  way  through  the  soil  for  an  equal  distance,  for- 
the  soil  has  well-known  filtering  power  when  free  from  fissures  or 
actual  channels  and  is  capable  of  removing  bacteria  and  oxidizing  large 
quantities  of  organic  matter.  However,  these  methods  are  of  service 
in  indicating  the  possibility  of  danger  under  certain  circumstances  and 
are  particularly  useful  in  discovering  sources  of  pollution  near  wells  or 
in  limestone  formations. 

Massive  cultures  of  prodigiosus,  yeasts,  and  other  microorganisms 
if  not  normally  present  in  the  water  under  examination  may  be  used  to 
detect  the  possibility  of  pollution.  The  cultures  are  poured  upon  the 
ground  or  into  suspicious  places  and  the  water  tested  at  varying  inter- 
vals to  determine  whether  they  reach  the  supply.  Careful  controls 
must  be  made  beforehand  to  assure  the  absence  of  the  particular  or- 
ganism used. 

The  Interstate  Pollution  of  Streams.' — Sanitarians  have  maintained 
for  years  that  no  community  or  individual  has  a  right  to  pollute  streams 
used  for  public  water  supplies,  any  more  than  a  man  has  a  right  to 
poison  his  neighbor's  well.  The  legal  aspects  of  water  pollution  have 
been  carefully  considered  by  Dr.  J.  L.  Leal.  England  enjoyed  the  ben- 
efit of  a  Eivers  Pollution  Commission  as  early  as  1855,  in  order  to 
prevent,  remedy,  and  remove  the  danger  of  polluted  water  supplies. 
This  commission  adopted  a  comprehensive  system  for  the  disposal  of 
sewage  and  for  water  purification,  the  fruits  of  which  England  is  en- 
Joying  to-day.  This  country  has  no  law  regarding  the  interstate  pol- 
lution of  streams,  and  with  our  growing  population  and  increasing 
amount  of  pollution  this  is  becoming  a  live  and  pressing  sanitary  ques- 
tion. After  the  Chicago  drainage  canal  was  opened  the  city  of  St. 
Louis  (state  of  Missouri)  sued  the  city  of  Chicago  (state  of  Illinois) 
through  the  federal  courts,  asking  an  injunction  against  the  pollution 


720  GENERAL    CONSIDERATIONS 

of  the  Mississippi  River,  from  which  St.  Louis  draws  its  drinking  sup- 
ply. The  testimony  occupied  many  weeks,  and  in  published  form  takes 
up  many  volumes.  The  verdict  was  "no  cause  for  action,"  or  "not 
guilt}',"  that  is,  it  was  not  proven  that  typhoid  bacilli  or  other  organisms 
dangerous  to  health  reached  St.  Louis  from  Chicago. 

The  principles  of  common  law  as  to  interstate  waters  have  been  ap- 
preciated by  some  of  the  nations  of  Europe.  Thus,  the  inhabitants 
of  a  town  in  Belgium  suffered  from  the  effects  of  a  river  polluted  by 
the  French,  and  the  French  government  not  only  compelled  the  offend- 
ing city  to  dispose  of  its  sewage  by  irrigation,  but  granted  a  subsidy 
for  this  purpose.  In  some  of  our  more  progressive  states,  as,  for  ex- 
ample, Massachusetts,  Pennsylvania,  Connecticut,  Minnesota,  New 
Hampshire,  New  Jersey,  New  York,  Vermont,  and  others,  the  State 
Board  of  Health  is  given  control  over  the  pollution  of  streams  within 
the  borders  of  the  state. 

Speaking  generally,  jurisdiction  over  the  pollution  of  waters  in  the 
United  States  is  confined  to  the  several  states.  There  is  no  provision 
in  the  Constitution  which  gives  to  Congress  authority  in  the  premises. 
Hence,  by  the  familiar  principle  in  our  Constitution  that  the  several 
states  retain  full  sovereign  power,  except  so  far  as  such  powers  are 
restricted  by  the  national  constitution  or  expressly  delegated  there- 
by to  the  national  government,  the  individual  states  have  full  con- 
trol of  this  subject — a  subject  with  which  they  are  individually 
impotent  to  deal  and  which  logically  belongs  to  the  federal  govern- 
ment. 

The  Care  of  Catchment  Areas. — The  ideal  catchment  area  is  free 
from  human  habitation  and  is  covered  with  forests.  The  catchment 
areas  supplying  impounding  reservoirs  and  the  natural  ponds  and  lakes 
used  as  reservoirs  are  limited  in  area  when  compared,  for  example, 
with  the  catchment  areas  of  the  great  rivers,  from  which  many  public 
water  supplies  are  drawn.  It  is,  therefore,  possible  to  inspect  and 
control  the  former  more  readily  than  the  latter. 

It  is  often  impossible  to  remove  population  from  a  catchment  area, 
and,  in  fact,  it  is  usually  unnecessary  to  do  so.  Very  good  water  may 
be  drawn  from  areas  upon  which  there  is  a  large  population,  when  proper 
and  well-known  precautions  are  taken.  Thus,  there  are  776  people  per 
square  mile  upon  the  Cochituate  catchment  area,  282  upon  the  Sud- 
bury, 49  upon  the  Wachusett,  furnishing  Boston's  water  supplv,  and 
59  upon  the  Croton,  furnishing  New  York's  water  supply.  The  pro- 
longed storage  of  the  water  in  large  reservoirs  is  a  sanitary  safeguard, 
and  makes  the  Boston  water  and  the  New  York  water  safer  than  it 
otherwise  would  be. 

The  greatest  danger  is  that  some  polluted  water  will  sometimes  get 
by  the  reservoir  or  flow  through  it  by  some  short  circuit,  and  so  reach 


SOURCES  AND  XATUEE  OF  WATER  POLLUTIOX  721 

the  consumer,  before  it  is  subjected  to  full  storage  conditions  for  a 
sufficient  length  of  time. 

The  proper  sanitary  care  of  a  catchment  area  requires,  first  of  all, 
sufficient  laws  granting  suitable  authority,  especially  concerning  the 
disposal  of  human  wastes. 

Care  must  also  be  exercised  to  keep  out  manufacturing  wastes  and 
the  surface  washings  that  may  carry  pollution  from  human  sources  or 
undesirable  contamination  from  other  sources.  This  object  may  be  ac- 
complished in  various  ways.  The  city  should  own  the  shores  of  the 
reservoirs  and  also,  as  much  of  the  land  along  the  important  streams 
as  is  necessary  to  carry  out  these  objects.  Old  sources  of  pollution 
must  be  removed,  and  new  sources  not  permitted.  Wliere  the  danger 
from  human  pollution  is  especially  great,  as  around  the  imj^ounding 
reservoir  itself  or  at  nearby  suburban  settlements,  engineering  projects, 
sometimes  of  considerable  magnitude,  are  necessary  to  carrv  away  the 
sewage  and  the  surface  drainage.  A  strict  patrol  of  the  catchment 
area,  in  order  to  supervise  picnic  and  camping  parties,  the  camps  of 
construction  gangs,  and  other  sources  of  danger,  must  be  exercised. 
A  good  man  on  the  alert  can  patrol  a  large  district,  getting  his  in- 
formation through  various  ways,  and  personally  inspecting  all  sus- 
picious localities  frequently. 

In  the  investigation  of  a  stream  and  its  watershed  the  chief  points 
requiring  attention  are  the  relative  proportions  of  the  polluting  inat- 
ter  and  the  flow  of  the  river  when  at  its  minimum;  the  general  char- 
acter of  the  stream,  the  rate  of  flow,  and  the  distance  between  the 
source  of  pollution  and  the  intake  of  the  water. 

Many  water  boards,  having  control  of  large  tracts  of  land,  are  plant- 
ing their  catchment  areas  with  trees  with  advantage  and  profit,  for  it  is 
found  that  the  presence  of  trees  adds  to  the  retention  of  water  falling 
as  rain  as  well  as  by  radiation,  and  cooling  the  adjacent  atmosphere, 
perhaps  aiding  condensation  and  rain.  It  prevents  floods,  regulates  and 
helps  to  purify  the  supply,  for  water  draining  through  the  soil  of  wooded 
areas  is  naturally  cleaner  than  that  scouring  the  surface  of  barren  land. 


CHAPTEK    II 
SANITARY    ANALYSIS    OF    WATER 

A  complete  sanitary  anal^'sis  of  water  includes:  (1)  a,  physical 
examination  to  determine  color,  turbidity,  odor,  and  taste;  (2)  a  micro- 
scopic examination  to  determine  the  number  and  character  of  particles 
in  suspension,  especially  algae;  (3)  a  chemical  analysis  to  determine  the 
nature  and  amount  of  chemical  impurities;  (4)  a  bacteriological  exam- 
ination to  estimate  tlie  number  and  kind  of  bacteria;  (5)  a  sanitary 
survey  of  the  Avatershed,  including  the  methods  of  collecting,  storing, 
handling,  and  distributing  the  Avater;  and  (G)  clinical  experience,  which, 
after  all,  is  the  final  tetst,  for  Avafer  may  contain  impurities  that  are 
not  recognizable  by  any  other  method. 

Water  is  particularly  liable  to  contamination  under  prevailing  con- 
ditions and  must,  of  necessity,  demand  increasing  Avatchfulness  and  a 
continual  readjustment  of  restrictions  governing  its  use.  Water  may 
contain  impurities  beyond  the  power  of  science  to  disclose.  Thus,  the 
water  supply  of  Vienna  from  the  famous  Ivaiserbrunnen  is  particularly 
pure,  as  determined  by  laboratory  analysis.  Nevertheless,  this  water 
supply  is  said  to  be  responsible  for  a  great  increase  in  the  amount  of 
goiter  which  has  occurred  in  Vienna  since  its  introduction. 

The  fact  that  Avater  is  the  most  universal  solvent  known  is  not  to 
be  neglected.  The  Avater  we  drink  has  come  in  contact  with  the  earth 
and  many  other  substances.  It  dissolves  many  organic  and  many  in- 
organic impurities,  few  of  AA'hich  can  be  detected  in  the  laboratory  by 
the  routine  methods  used.  The  influence  of  many  of  these  substances 
upon  healtli  is  unknown.  Exceedingly  small  amounts  of  poisonous 
substances  in  Avater  may  act  injuriously  Avhen  Ave  recall  hoAv  much  water 
is  daily  taken.  All  these  facts  should  make  us  cautious  before  we  giA'e 
a  water  supply  a  clean  bill  of  health,  and  communities  will  find  it  paA'S 
in  the  end  to  go  to  great  expense  to  improve  this  important  article 
of  daily  use. 

Standard  Methods. — The  advantages  of  using  a  standard  method  are 

self-evident ;  it  at  least  gives  results  that  are  fairly  comparable  with  tho 

work  of  others.     The  standard  methods  for  water  analysis  have  been 

carefully  considered  by  a  competent  committee  of  the  American  Public 

722 


ODOES    AXD    TASTES  723 

Health  Association.  The  first  report  was  published  in  the  Journal  of 
Infectious  Diseases,  Supplement  Xo.  1,  May^  1905.^  Amendments  and 
improvements  to  the  method  are  published  from  time  to  time.  For  any- 
one not  having  special  skill  in  chemical  analysis  or  bacteriological  tech- 
nique it  is  advisable  to  adhere  closely  to  the  standard  procedures.  Any 
deviation  from  these  methods  should  always  be  noted  in  published  re- 
ports. Because  a  method  is  "standard''  does  not  mean  that  it  has  a 
iixed  and  permanent  value  as  a  model  to  be  blindly  followed  under  all 
circumstances.  Standard  methods  are  established  by  common  consent 
as  the  rule  to  be  followed  under  ordinary  circumstances,  especially  for 
routine  work  and  by  those  who  are  not  especially  skilled  in  laboratory 
technique.  For  reasons  that  seem  self-evident,  it  is  of  special  impor- 
tance to  follow  the  standard  methods  for  bacterial  counts. - 

Our  standards  by  which  the  purity  of  water  is  judged  are  constantly 
rising.  There  is  no  doubt  that  many  waters  now  considered  pure  and 
wholesome  will  not  be  acceptable  in  the  future. 


ODORS   AND   TASTES 

The  purest  water  is  absolutely  devoid  of  taste  and  odor,  but  it  is 
also  insipid.  If  such  water  is  aerated  by  agitation  or  by  filtration 
through  a  porous  air-containing  substance,  it  becomes  sparkling  and 
agreeable. 

Odors  in  waters  are  objectionable,  rather  than  detrimental  to  health. 
As  a  rule,  the  most  objectionable  odors  develop  in  surface  waters  and 
are  caused  by  the  growth  of  algs,  diatoms,  protozoa,  and  other  microscopic 
beings.  The  earthy  odor  of  some  ground  waters  is  due  to  substances 
taken  up  during  the  passage  of  the  water  through  the  soil.  When  a 
well-water  becomes  offensive  it  is  evidence  of  stagnation  at  the  bottom 
of  the  well  or  the  presence  of  dead  animals.  In  the  case  of  deep  wells 
hydrogen  sulphid  and  other  inorganic  compounds  may  impart  odors  to 
the  water.  The  odors  and  tastes  which  develop  in  impounding  reser- 
voirs from  stagnation  and  putrefaction  of  the  organic  matter  have  been 
discussed  on  page  706. 

On  the  whole,  the  waters  of  natural  lakes  and  ponds  are  less  subject 
to  objectionable  odors  and  tastes  than  are  the  waters  of  artificial  reser- 
voirs, and  putrefaction  is  less  troublesome,  but  the  difference  is  one  of 
degree,  not  of  kind. 

The  power  of  water  to  dissolve  or  absorb  gases  and  odors  is  an  im- 

^  The  second  edition  can  be  obtained  from  the  secretary  of  the  association, 
289  Fourth  Avenue,  New  York  City. 

-  In  the  methods  for  water  analysis  described  in  this  book  the  standard 
methods  have  been  closely  followed,  and  due  acknowledgment  is  here  given  to 
the  splendid  and  self-effacing  work  of  the  committee  that  de%'ised  them. 


■S'?^* 


r 


■'**«?53(Bi»' 


m 


ALGAE:    I,  UR0GLENA-X300       2,  SPIR03YRA-X  500.,    3  .  RtSTING  SPORES  Of  SPIROGYRA-X  500 
4.  ChLAMYDOMONAS    showing  resting  condition  and  reproductive;   bodies  -y    !000 


Fig.  101. — Alg^  Commonly  Found  IN  Water.     [Year  Book,  U.  S.  Dep't.  of  Agr.,   1902.] 

724 


/iJ> 


ALGAE:  I,  Clathrocystis- X500;      2.  Anabaena-x  50O; 

3    OSClLLATORIA-X    500;  4  ,  ASTERiONELLA-X  500  : 

r    \'av!cula  showing  structure  or  diatom  -x  500. 


Fig.   102. — Alg^  Commonly  Fouxd  in  Water.    [Year  Book,  U.  S.  Dep't.  of  Agr  ,   1902.] 
48  '"25 


726  SANITARY    ANALYSIS    OF    WATER 

portant  one,  and  explains  how  water  may  become  "contaminated"  by 
mere  exposure  to  an  impure  atmosphere,  as  when  an  uncovered  cistern 
is  placed  in  a  water-closet  or  when  an  overflow  pipe  is  directly  connected 
with  a  drain. 

Method  of  Determining  Odor. — The  odor  of  the  water  should  be 
observed  both  at  room  temperature  and  just  below  the  boiling  point. 
Odors  may  be  detected  at  room  temperature  (20°  C.)  by  shaking  a 
sample  violently  in  a  gallon  collecting  bottle  when  it  is  half  or  two- 
thirds  full;  or  by  heating  aljout  150  c.  c.  in  a  tall  beaker  without  a  lip 
and  covered  with  a  well-fitting  watch  glass.  In  either  case  care  should 
be  taken  to  observe  the  character  of  the  odor  the  instant  the  receptacle 
is  uncovered.  The  kind  of  odor  observed  may  be  described  as  vegetable, 
aromatic,  grassy,  fishy,  earthy,  moldy,  musty,  disagreeable,  peaty,  sweet- 
ish, etc.,  and  the  intensity  by  such  terms  as  very  faint,  distinct,  decided, 
or  very  strong. 

The  odors  and  tastes  in  water  caused  by  microscopic  organisms  de- 
serve special  consideration,  because  they  are  common  faults  in  water 
stored  in  open  artificial  reservoirs  of  all  kinds.  Certain  organisms  can 
be  distinguished  by  their  odor,  as,  for  example,  the  "fishy"  odor  of 
Uroglena,  which  is  a  protozoon  and  classed  with  the  Infusoria;  the 
"aromatic"  or  "rose  geranium"  odor  of  Asterionella,  which  belongs  to 
the  Diatomacece;  and  the  "pig-pen"  odor  of  Anahcena,  which  is  one  of 
the  blue-green  algae.  These  microscopic  organisms  mostly  grow  near 
the  surface  and  require  sunlight  for  their  development ;  hence,  odors 
produced  by  them  never  occur  in  covered  reservoirs  or  in  waters  kept 
in  the  dark. 

Calkins  has  shown  that  the  odors  caused  by  the  undecomposed 
microscopic  organisms  are  due  to  compounds  of  the  nature  of  essential 
oils,  and  Whipple  points  out  that  the  amount  of  such  oil  produced  by 
an  abundant  growth  of  the  organisms  is  quite  sufficient  to  account  for 
the  effect  observed.  He  notes  for  comparison  that  oil  of  peppermint  can 
be  recognized  when  diluted  with  water  in  the  proportion  of  one  part 
of  oil  to  fifty  million  parts  of  water,  and  that  when  Asterionella  is 

present  to  the  extent  of  50,000  organ- 
isms per  c.  c.  the  dilution  of  its  oil  is 
in  the  proportion  of  about  one 
part  to  two  million  parts  of  water. 
Whipple  further  suggests  that  the 
FiQ.  103.— The  Oil  Droplets  in  a  flo^  of  water  through  pipes  may 
Diatom.  _, .    .  .  .  •  ■  i 

cause  disintegration  ot  organisms  with 

liberation  of  the  odor-producing  oil,  hence  the  odor  at  the  tap  may  be 
greater  than  at  the  intake. 

The  AlgoB  responsible  for  the  vile  tastes  and  odors  in  water  do  not 
depend  upon  organic  matter  or  the  bodies  of  other  organisms  for  their 


ODOKS    AND    TASTES  727 

food  supply.  They  require  only  carbonic  acid  and  the  nitrogen  and 
mineral  matters  always  present  in  the  water  and  in  the  air,  and  the 
sunshine  for  their  growth.  In  other  words,  they  have  properties  com- 
parable in  many  respects  to  the  higher  orders  of  chlorophyll-containing 
vegetation. 

There  are  very  many  kinds  of  algce,  and  they  differ  greatly  in  their 
odor-producing  powers.  Practically  all  American  impounding  reservoir 
waters  suffer  from  them,  but  some  far  more  than  others.  English 
reservoirs  seem  to  be  comparatively  free  from  this  nuisance,  probably 
because  of  the  lower  temperatures  of  the  surface  waters.  There  is  an 
average  difference  of  at  least  10°  F.  between  the  surface  temperatures 
of  English  and  American  reservoirs. 

A  certain  degree  of  quiet  and  repose  is  necessary  for  the  develop- 
ment of  a  large  growth  of  algae;  that  is  why  they  never  develop  to 
any  extent  in  rivers  and  flowing  water.  Wave  action  from  wind  also 
prevents  growth,  and  this  seems  to  be  the  only  reason  why  large  lakes 
and  reservoirs  are  less  troubled  by  them  than  smaller  ones. 

In  most  American  impounding  reservoirs  the  water  is  drawn  from 
near  the  surface  layer,  so  as  to  avoid  the  odors  and  tastes  of  putrefaction 
in  the  bottom  water,  but  it  sometimes  happens  that  the  surface  water 
is  the  more  objectionable. 

Prevention  and  Removal  of  Tastes  and  Odors. — The  natural  flow  of 
water  in  the  bed  of  a  mountain  stream  over  stones  and  ledges  aerates 
it  very  well.  This  is  nature's  method  of  removing  undesirable  tastes 
and  odors.  Aeration  may  also  be  accomplished  by  bringing  the  water 
in  contact  with  the  air  by  devices  such  as  fountains,  waterfalls,  etc. 
Such  aeration  always  reduces,  and  sometimes  removes,  tastes  and  odors 
from  the  waters  of  reservoirs  and  small  lakes,  whether  resulting  from 
putrefaction  in  the  stagnant  bottom  water  or  from  growths  of  organ- 
isms in  the  surface  water. 

In  general  it  may  be  stated  that  filtration  alone  is  not  efficient 
in  removing  tastes  and  odors;  however,  slow  sand  filtration  has  consid- 
erable power  of  reducing,  and  in  some  cases  of  removing,  tastes  and 
odors,  but  cannot  be  relied  upon  when  the  raw  water  is  very  bad. 

Intermittent  filtration  is  particularly  successful  in  removing  tastes 
and  odors.  It  is  successful  because  it  brings  the  organic  matter  in  con- 
tact with  more  air  and  in  more  intimate  contact  with  air,  and  for  a 
longer  time  in  the  pores  of  the  sand,  than  can  be  secured  in  any  other 
way. 

It  is  practically  impossible  to  prevent  the  seeding  of  reservoirs  and 
ponds  with  algse  and  other  organisms  responsible  for  the  objectionable 
odors.  The  growth  may  be  checked  and  the  odors  temporarily  con- 
trolled by  the  use  of  copper  sulphate  (see  page  800). 

If  a  well  becomes  stagnant  at  the  bottom,  and  thus  develops  vile 


728  SANITARY    ANALYSIS    OF    WATER 

odors  from  putrefying  organic  matter,  the  trouble  may  be  corrected  by 
lowering  the  pump  to  near  the  bottom  so  as  to  prevent  stagnation, 
or  by  filling  up  all  unnecessary  space  with  clean  gravel  and  sand. 

COLOR 

Pure  water,  when  viewed  in  small  quantities,  appears  to  be  perfectly 
colorless,  but,  when  viewed  in  bulk,  as  in  the  white-tiled  baths  at  Bux- 
ton, and  in  certain  Swiss  lakes,  it  is  seen  to  possess  a  beautiful  greenish- 
blue  tint.  A  very  small  amount  of  suspended  or  dissolved  impurity 
is  sufficient  to  obscure  this  color. 

Impure  waters  almost  invariably  exhibit  a  color  varying  from  green 
to  yellow  and  brown,  when  examined  through  a  depth  of  two  feet  in 
suitable  tubes.  It  does  not,  however,  follow  that  a  colored  water  is, 
therefore,  polluted  or  infected. 

Color  in  surface  water  is  usually  of  vegetable  origin;  animal  matter 
contributes  but  little  color.  The  coloring  matter  is  extracted  largely 
from  dead  leaves,  bark,  and  roots,  from  soil,  and  from  peat.  It  seems 
to  be  the  same  material  as  the  coloring  matter  of  tea,  and  it  is  cer- 
tainly harmless,  but  it  makes  the  water  less  pleasing  in  appearance,  and 
great  efforts  have  rightly  been  made  to  prevent  it  and  to  remove  it. 
Water  from  swamps  is  usually  highly  colored,  the  degree  of  color  de- 
pending upon  the  length  of  exposure. 

Ground  waters  are  usually  colorless.  If  the  water  contains  iron 
it  will  be  perfectly  clear  on  coming  from  the  ground,  but  will  soon 
turn  a  rusty  yellow  color.  This  is  caused  by  the  oxidation  of  the  soluble 
ferrous  salts  to  insoluble  ferric  salts. 

Color  in  water  should  be  distinguished  from  turbidity.  True  color 
is  due  to  dissolved  impurities,  turbidity  to  substances  in  suspension.  The 
"apparent  color"  is  the  color  of  the  original  sample,  due  to  both  dis- 
solved and  suspended  matter. 

The  prevention  of  color  in  surface  waters  consists  in  draining 
swamps.  Thus,  in  the  catchment  areas  of  the  various  reservoirs  sup- 
plying Boston  thousands  of  acres  of  swampy  land  have  been  drained 
for  the  purpose  of  reducing  the  color  of  the  supplies,  and  with  good 
results. 

A  colored  water  may  be  bleached  by  exposure  to  sunlight  and  air, 
but  the  bleaching  of  the  water  in  reservoirs  requires  great  storage 
capacity,  and  the  drainage  of  swamps  is  likewise  very  expensive.  Ozone 
applied  in  large  amounts  also  destroys  color,  and  the  only  objection  to 
its  use  is  the  cost.  Color  may  be  removed  to  a  considerable  extent  by 
simple  filtration  through  sand.  If  the  coloring  matter  is  first  rendered 
insoluble  by  the  use  of  coagulants  (sulphate  of  alumina),  it  is  readily 
removed  by  filtration.     Color  is  thus  successfully  removed  from  the 


TUEBIDITY  729 

waters  used  by  JSTorfolk,  Va. ;  Charleston,  S.  C,  and  Watertown,  N.  Y. 
Sulphate  of  iron  is  less  satisfactory  as  a  coagulant  than  sulphate  of 
alumina  for  the  removal  of  color. 

Method  for  Estimating  Color. — Turbid  waters  should  always  be  fil- 
tered before  the  color  observations  are  made.  The  intensity  of  color 
may  be  determined  by  comparing  with  a  standard  platinum-cobalt  solu- 
tion; the  tint  or  shade  may  be  determined  by  comparison  with  the 
standard  color  disks  of  a  Lovibond  tintometer. 

Platinum-Cobalt  Standaed. — The  standard  solution,  which  has  a 
color  of  500,  is  prepared  as  follows: 

Dissolve  1.246  grams  of  potassium  platinic  chlorid  (PtCl^  2KC1) 
containing  0.5  gram  platinum,  and  one  gram  crystallized  cobalt  chlorid 
(CoCL  6H2O)  containing  0.25  gram  of  cobalt  in  water,  with  100  c.  c. 
concentrated  hydrochloric  acid,  and  make  up  to  one  liter  with  distilled 
water. 

By  diluting  this  solution  with  distilled  water  to  the  100-c.  c.  gradu- 
ation mark  on  the  ISTessler  tubes,  standards  are  prepared  having  colors 
of  0,  5,  10,  15,  20,  25,  30,  35,  40,  50,  60,  and  70.  These  should  be 
kept  in  Xessler  tubes  of  such  diameter  that  the  100-c.  c.  graduation 
mark  is  between  20  and  25  cm.  above  the  bottom,  and  is  uniform  for 
all  tubes.     They  should  be  protected  from  dust  when  not  in  use. 

Procedure. — The  color  of  a  sample  is  observed  by  filling  a  standard 
ISTessler  tube  to  the  graduation  mark  with  the  water  to  be  examined,  to 
a  depth  equal  to  that  of  the  standards,  and  by  comparing  it  with  the 
standards.  The  observation  should  be  made  by  looking  vertically 
downward  through  the  tubes  upon  a  white  surface  placed  at  such  an 
angle  that  light  is  reflected  upward  through  the  column  of  liquid. 

Waters  that  have  a  color  darker  than  70  should  be  diluted  before 
making  the  comparison,  in  order  that  no  diflQculties  may  be  encountered 
in  matching  hues. 

TURBIDITY 

Practically  turbidity  is  synonymous  with  muddiness.  The  turbidity 
of  surface  waters  is  usually  due  to  clay  or  silt,  also  to  finely  divided 
organic  matter,  microscopic  organisms,  and  a  great  variety  of  objects. 
Turbidity  represents  the  amount  of  foreign  substances  in  suspension; 
it  is  frequently,  though  incorrectly,  spoken  of  as  color.  In  a  general 
way  turbid  waters  exist  in  those  regions  where  color  is  not  found;  the 
former  represents  the  washings  of  a  readily  eroded  drainage  basin,  the 
latter  is  mostly  extracted  from  the  decaying  vegetation  of  swamps. 

Pure  water  is  clear  and  sparkling,  in  proportion  to  the  amount  of 
dissolved  oxygen  and  carbonic  acid.  While  brilliancy  and  clearness  do 
not  mean  purity,  on  the  other  hand  turbid  waters  are  not  necessarily 


730  SANITAKY    ANALYSIS    OF    WATER 

dangerous.  A  community  for  years  may  drink  and  seem  satisfied  with 
a  turbid  water  that  is  little  less  than  liquid  mud.  This  was  the  case 
with  Washington  and  the  Potomac  water,  St.  Louis  and  the  Mississippi, 
and  many  other  cities.  \Mien,  however,  such  a  city  once  appreciates 
the  beautiful  appearance  of  a  clean  water,  they  complain  if  the  turbid- 
ity reaches  the  point  of  a  faint  opalescence.  The  turbidity  question  is 
practically  limited  to  river  waters.  Ground  waters  should  never  be 
turbid,  and,  if  so,  should  at  once  excite  suspicion.  Some  ground  waters 
become  more  or  less  turbid  through  the  precipitation  of  iron. 

All  river  waters  are  more  or  less  turbid,  but  the  differences  are 
very  great  indeed.  The  amount  of  turbidity  depends  largely  upon  the 
character  of  the  catchment  areas.  In  general,  rivers  draining  the  large 
areas  of  our  North  and  East,  covered  with  glacial  drift  of  a  sandy 
character,  are  but  little  subject  to  turbidity.  Thus,  on  an  average,  the 
Merrimac  and  Connecticut  Eivers  do  not  carry  more  than  10  parts  per 
million  of  suspended  matter.  In  that  part  of  our  country  which  is  not 
glaciated,  and  this  includes  the  lower  Susquehanna  basin,  much  of  the 
Ohio  basin,  and  the  Missouri  basin,  and  all  to  the  south  of  them,  tur- 
bidity is  often  present  in  large  amounts,  and  consists  largely  of  clay 
in  extremely  fine  particles.  The  water  often  runs  turbid  in  these  streams 
continuously  for  weeks  and  even  months  at  a  time.  The  Missouri  Eiver 
carries  the  largest  amount  of  sediment  of  any  of  our  rivers  largely 
used  for  water  supply.  The  annual  average  runs  as  high  as  1,200  or 
1,500  parts  of  sandy  matter  per  million.  In  winter  it  falls  to  200 
parts  or  less,  while  in  midsummer  it  rises  for  weeks  and  even  months 
to  5,000  parts  or  more. 

If  the  turbidity  is  sufficiently  coarse-grained  it  may  be  removed  by 
sand  filtration  without  previous  chemical  treatment.  Very  turbid  waters 
can  be  cleared,  in  part,  in  settling  basins;  this  lightens  the  work  of 
the  filters  and  reduces  the  cost.  Scrubbers,  which  are  preliminary  rough 
filters,  may  also  be  used  to  protect  the  sand  filters.  In  many  instances 
the  individual  particles  of  clay  which  make  up  the  turbidity  are  much 
smaller  than  the  bacteria.  They  will  not  settle  out,  even  after  pro- 
longed storage,  and  they  cannot  always  be  removed  by  filtration  alone. 
There  is  only  one  known  way  of  removing  such  turbidity,  and  that  is 
by  coagulation  or  chemical  precipitation.  The  substances  most  com- 
monly used  for  this  purpose  are :  aluminium  sulphate,  alum,  or  sulphate 
of  iron  (see  page  794). 

With  reference  to  the  influence  of  the  suspended  matter  upon  health 
we  find  some  conflict  of  opinion.  Kober  states  that  water  containing 
50  parts  per  100.000  or  30  grains  of  solid  matter  per  gallon  is  unflt 
for  drinking  purposes,  on  account  of  its  irritating  effects  upon  the 
gastrointestinal  tract.  Apart  from  this,  turbidity  appears  to  have  no 
special  sanitary  significance. 


EEACTION  731 

Methods  for  Estimating  Turbidity. — There  are  three  methods  by 
which  the  degree  of  turbidity  may  be  determined:  (1)  the  platinum 
wire  method,  which  consists  of  determining  the  depth  of  water  through 
which  a  platinum  wire  of  standard  diameter  may  be  seen;  (2)  com- 
parison with  waters  -of  standard  turbidity,  made  by  adding  1  gram  of 
finely  powdered  diatomaceous  earth  to  1  liter  of  distilled  water;  this  is 
known  as  the  silica  standard;  and  (3)  the  amount  of  suspended  par- 
ticles in  water  may  be  determined  in  special  instruments  known  as 
turbidimeters  or  diaphanometers.  These  instruments  consist  of  a  grad- 
uated glass  tube  with  a  flat  polished  bottom,  inclosed  in  a  metal 
case.  This  is  held  over  an  English  standard  candle,  and  so  arranged 
that  one  may  look  vertically  down  through  the  tube  and  see  the  image 
of  the  candle.  The  observation  is  made  by  pouring  the  sample  of  water 
into  the  tube  until  the  image  of  the  candle  just  disappears  from  view. 
The  graduations  on  the  tube  correspond  to  turbidities  produced  in  dis- 
tilled water  by  certain  numbers  of  parts  per  million  of  the  silica  stand- 
ard. 

The  standard  of  turbidity  adopted  by  the  United  States  Geological 
Survey  consists  of  a  water  which  contains  100  parts  of  silica  per  mil- 
lion, in  such  a  state  of  fineness  that  a  bright  platinum  wire  1  milli- 
meter in  diameter  can  just  be  seen  when  the  center  of  the  wire  is  100 
millimeters  below  the  surface  of  the  water  and  the  eye  of  the  observer 
is  1.2  meters  above  the  wire,  the  observations  being  made  in  the  middle 
of  the  day  in  the  open  air,  but  not  in  sunlight,  and  in  a  vessel  so  large 
that  the  sides  do  not  shut  out  the  light  so  as  to  influence  the  results. 
The  turbidity  of  such  water  is  taken  as  100,  and  all  turbidity  readings, 
by  no  matter  what  method  used,  should  conform  with  this  method. 


REACTION 

The  alkaline  reaction  of  natural  waters  ordinarily  depends  upon  the 
carbonate  and  bicarbonate  of  calcium  and  magnesium.  In  some  waters 
in  the  West  it  also  includes  the  carbonate  of  sodium  and  of  potassium. 
The  alkalinity  of  water  is  determined  by  titrating  100  c.  c.  of  the  sample 
with  JL  sulphuric  acid,  using  0.5  c.  c.  of  a  solution  of  lacmoid  as  an 
indicator.  The  lacmoid  solution  consists  of  2  grams  in  one  liter  of 
50  per  cent,  alcohol.  The  last  cubic  centimeter  or  two  of  acid  must 
be  added  while  the  sample  is  almost  at  the  boiling  temperature,  and 
the  end  reaction  is  not  read  until  a  drop  of  acid,  striking  the  surface  of 
the  liquid,  sinks  to  the  bottom  of  the  dish  without  producing  a  change 
in  the  uniform  reddish  or  purplish  color  of  the  solution.  Erythrosin 
may  be  used  as  an  indicator  when  it  is  desired  not  to  use  heat.  The 
number  of  cubic  centimeters  of  JL  sulphuric  acid  used,  when  multiplied 


733  SANITARY    ANALYSIS    OF    WATEE 

by  ten,  gives  the  muiiber  of  parts  per  million  of  alkalinity  in  terms  of 
calcium  carbonate. 

Under  certain  circumstances  rain  water,  water  from  peat  bogs,  and 
water  from  coal  mines,  tanneries,  etc.,  have  an  acid  reaction.  In  min- 
ing regions  waters  are  frequently  acid  from  high  quantities  not  only 
of  CO..  but  also  of  sulplniric  acid  and  various  sulphates — those  of  iron 
and  aluminium  giving  an  acid  reaction.  When  these  are  present,  the 
total  acidity  is  determined  by  titrating  the  water  in  the  cold  with  a 
standard  sodium  carbonate  solution,  using  phenolphthalein  as  an  indi- 
cator. 

Mine  water  is  that  which  is  constantly  flowing  from  the  coal  and 
surrounding  strata.  It  is  collected  in  ditches  at  one  side  of  the  gang- 
ways and  tunnels,  and  is  allowed  to  flow  to  the  lowest  point  in  the  mine 
or  to  the  foot  of  the  shaft,  from  which  it  is  pumped  to  the  surface. 
Large  quantities  of  this  and  other  water  are  used  to  wash  the  coal.  This 
water  is  acid,  and  it  is  now  well  known,  from  the  researches  of  Dixon, 
Matson,  and  others  in  the  anthracite  coal  regions  of  Pennsylvania, 
that  such  water  has  a  destructive  effect  upon  typhoid,  colon,  and  other 
bacteria.  The  acidity  of  the  streams  in  Pennsylvania  is  a  large  factor 
in  neutralizing  the  pollution  of  the  water  supplies  of  Philadelphia, 
Pittsburgh,  Harrisburg,  and  other  cities.  The  spent  tan  liquors  from 
tanneries  are  also  acid,  and  are  known  to  exert  a  somewhat  similar  in- 
fluence on  sewage  organisms. 

Eain  water  collected  in  the  vicinity  of  towns  has  usually  a  slight 
acid  reaction  and  acts  upon  lead.  •  The  free  acid  in  rain  water  is  ap- 
parently sulphuric,  no  doubt  derived  from  the  sulphur  in  tlie  coal  used. 

Water  from  marshes,  swamps,  and  especially  from  peat  bogs  may 
have  a  markedly  acid  reaction,  especially  in  dry  weather,  when  the 
flow  will  be  comparatively  small.  Heavy  storms  wash  out  the  water 
which  has  long  been  in  contact  with  the  decaying  vegetation.  The  acid- 
ity in  this  case  is  due  to  organic  acids. 

When  the  collection  of  an  acid  water  cannot  be  avoided,  arrangements 
should  be  made  for  filtering  through  some  material  capable  of  com- 
pletely neutralizing  the  acid,  as  without  some  such  arrangement  the 
consumers  of  the  water  run  the  risk  of  lead  poisoning,  provided  lead 
service  pipes  are  used.  A  river  water  suddenly  turning  acid  in  reaction 
plays  havoc  with  a  slow  sand  filter.  This  has  occurred  in  the  Pitts- 
burgh filter. 

TOTAL   SOLIDS 

The  total  solids  or  residue  on  evaporation  is  obtained  by  evaporat- 
ing a  given  quantity  of  water  to  dryness,  when  a  grayish-white  residue, 
composed  of  mineral  and  some  organic  matter  which  has  been  held  by 


HAEDXESS  733 

the  water  in  sus23eiisioii  and  in  solution,  will  be  obtained.  The  amount 
of  this  residue  varies  with  the  character  of  the  water,  and  furnishes  an 
index  of  the  total  quantity  of  foreign  impurities,  and  further  furnishes 
a  rough  index  of  the  relative  quantit}^  of  inorganic  and  organic  sub- 
stances which  make  up  these  impurities. 

Method. — Place  100   c.  e.   of  the  water   in   a   clean  platinum  dish. 

If  the  water  is  of  high  magnesium  content  add  25  c.  c.  of  Jl-  sodium 
°  °  0  0 

carbonate  solution  to  the  water,  and  correct  for  this  addition  in  the 
computation;  evaporate  to  drjTiess  on  a  water  bath,  and  finish  the  evap- 
oration for  half  an  hour  or  to  constant  weight  in  a  toluene  oven  at 
103°  C.  Xow  place  the  platinum  dish  in  a  desiccator  over  sulphuric 
acid  until  cool,  and  weigh.  The  increase  in  weight  gives  the  total  solids, 
or  residue  on  evaporation. 

This  residue  is  now  heated  to  a  dull  red  heat  and  the  platinum 
dish  again  weighed.  The  difference  in  weight  is  called  the  '"loss  on 
ignition,"  and  the  weight  of  the  substances  remaining  in  the  platinum 
dish  is  known  as  the  "fixed  residue."  The  loss  on  ignition  is  an  index 
of  the  amount  of  organic  matter  in  the  water.  A  portion  of  the  loss, 
however,  may  be  due  to  ammonia  or  other  volatile  compounds  and  un- 
stable mineral  salts.  The  fixed  residue  is  an  index  of  the  mineral  con- 
tent of  the  water.  With  waters  low  in  organic  matter,  but  relatively 
high  in  iron,  the  fixed  residue  is  frequently  used  as  a  matter  of  con- 
venience for  the  determination  of  iron.  In  water  analysis  it  is  usual 
to  note  the  character  of  the  odor  upon  ignition  of  the  residue.  This 
may  be  earthy,  or  may  suggest  organic  matter  of  vegetable  origin  or 
animal  origin. 

The  amount  of  total  solids  in  a  water  depends  upon  the  character 
of  the  soil  with  which  the  water  has  been  in  contact,  the  length  of 
exposure,  and  the  amount  of  carbon  dioxid  in  the  water  to  favor  the 
solution  of  inorganic  salts.  Some  mineral  springs  contain  very  large 
amounts  of  total  solids,  derived  from  deeply  situated  natural  deposits, 
as,  for  example,  the  springs  at  Saratoga,  Carlsbad,  Kissingen,  etc. 

The  permissible  amount  of  solids  as  represented  by  the  residue  on 
evaporation,  which  consists  of  the  dissolved  mineral  constituents,  can- 
not be  arbitraxily  stated,  but  500  parts  per  million  are  generally  held 
as  excessive. 

HARDNESS 

The  quality  of  hardness  in  water  is  more  of  an  economic  question 
than  one  of  sanitary  interest,  except,  perhaps,  as  the  encouragement  of 
the  use  of  soap  and  cleanliness  is  of  fundamental  importance  in  hygiene 
and  sanitation.  Hardness  in  water  is  due  to  the  presence  of  the  soluble 
salts  of  the  alkaliiie  earths — especially  calcium  and  magnesium.     These 


734  SANITARY    ANALYSIS    OF    WATER 

salts  form  a  curd  with  soap  instead  of  a  lather,  hence  more  or  less  soap 
must  be  wasted  in  decomposing  the  lime  and  magnesia  compounds 
before  a  lather  will  form.  Thus,  one  grain  of  calcium  carbonate,  for 
example,  will  use  up  8  grains  of  soap  before  a  lather  can  be  produced; 
in  this  way  hard  water  causes  an  enormous  waste  of  soap.  In  Europe, 
hardness  is  usually  expressed  in  degrees.  Each  degree  corresponds  to 
one  grain  of  carbonate  of  lime  or  its  equivalent  of  other  lime  or  mag- 
nesium salts  in  a  gallon  of  water. 

The  hardness  remaining  after  the  water  has  been  boiled  is  called 
"permanent  hardness."  The  hardness  that  may  be  removed  by  boiling 
is  known  as  "temporary  hari'dness."  This  distinction  between  temporary 
and  permanent  hardness  arises  from  the  fact  that  calcium  and  mag- 
nesium carbonates  are  but  slightly  soluble  in  water.  In  the  presence 
of  carbonic  acid  the  so-called  bicarbonates  are  formed,  which  are  much 
more  soluble  than  the  normal  carbonates.  One  gallon  of  pure  water 
will  dissolve  from  2  to  3  grains  of  the  normal  carbonates,  but  when  the 
water  contains  carbonic  acid  it  will  dissolve  20  or  more  grains.  Upon 
heating,  the  CO,  is  driven  off,  and  the  excess  of  normal  carbonates  of 
lime  and  magnesia  is  in  consequence  precipitated,  thus  reducing  the 
hardness  of  the  water. 

Waters  under  4  degrees  of  hardness  may  be  considered  soft,  those 
exceeding  12  degrees  hard.  Fifty  parts  per  million  of  calcium  sulphate 
and  chlorid  of  magnesium  is  usually  regarded  as  excessive.  Boiler  scale 
is  usually  due  to  deposits  of  sulphates  and  carbonates  of  calcium  and 
magnesium. 

Rain  water  is  always  soft;  surface  waters  vary,  but  are  usually  not 
very  hard;  ground  waters  are  apt  to  be  hard. 

Two  conditions  must  be  present  to  make  a  ground  water  hard: 
first,  the  material  through  which  the  water  passes  must  contain  lime 
or  magnesia,  and,  second,  the  conditions  must  be  favorable  for  dis- 
solving it.     The  latter  practically  means  that  CO,  must  be  present. 

Waters  drawn  from  limestone  regions  vary  greatly  in  hardness. 
Rain  water  contains  but  little  carbonic  acid  and,  therefore,  has  little 
power  of  dissolving  lime.  The  principal  source  of  the  carbonic  acid  in 
ground  water  is  from  the  soil,  resulting  from  the  decomposition  of 
organic  matter.  The  hardness  of  water,  therefore,  depends  more  upon 
the  nature  of  the  catchment  area  than  upon  the  amount  of  lime  in 
the  various  materials  over  wliich  the  water  flows.  Thus,  the  water 
supply  of  Vienna  is  comparatively  soft,  notwithstanding  that  it  comes 
entirely  from  limestone  rocks.  The  mountainous  region  which  forms 
the  catchment  area  is  barren  and  sterile,  and  the  water  does  not  get 
the  carbonic  acid  needed  to  dissolve  the  lime.  The  Winnipeg  water 
drawn  from  limestone  underlying  the  rich  prairies  is  excessively  hard. 
It  is  interesting  to  note  that  many  deep  well  waters  of  eastern  Massa- 


HAEDNESS 


735 


chusetts  are  comparatively  soft^  although  they  contain  large  amounts 
of  carbonic  acid. 

Very  hard  water  may  be  softened  upon  a  large  scale  with  iron  and 
lime.  As  a  rule,  methods  of  softening  are  required  with  ground  waters 
rather  than  with  surface  waters. 

The  common  method  in  use  is  the  Clark  process,  in  which  lime  is 
added  to  the  water  either  in  the  form  of  freshly  slaked  lime  or  milk 
of  lime.  The  calcium  hydroxid  unites  with  the  carbon  dioxid  in  the 
water,  forming  calcium  carbonate,  which  is  insoluble,  and  at  the  same 
time  precipitates  the  calcium  carbonate  held  in  solution  in  the  water 
by  the  CO,.  Sodium  carbonate  is  used  to  reduce  the  permanent  hard- 
ness of  water  due  to  sulphates. 

Methods. — The  hardness  of  water,  both  temporary  and  permanent, 
is  determined  by  the  soap  method.  By  far  the  most  accurate  method 
of  determining  the  true  temporary  hardness  due  to  the  bicarbonate 
alkalinity  is  to  titrate  the  original  sample  of  water,  and  also  some  of 
the  water  after  boiling,  with  ^  sulphuric  acid,  using  lacmoid  or  erythro- 
sin  as  an  indicator,  as  already  described  under  Eeaction,  page  731. 

The  soap  method  is  carried  out  as  follows :  Measure  50  c.  c.  of  the 
water  into  a  250-c.  c.  bottle  and  add  the  standard  soap  solution  in 
small  quantities  at  a  time  (from  0.3  to  0.3  c.  c),  shaking  the  bottle 
vigorously  after  each  addition  until  a  lather  forms  over  the  entire  sur- 
face of  the  water,  and  remains  continuous  for  5  minutes  after  the  bottle 
is  laid  upon  its  side.  From  the  amount  of  soap  solution  added,  the 
quantity  of  calcium  carbonate  equivalent  to  each  cubic  centimeter  of 
the  soap  solution  is  indicated  in  the  following  table : 

Table  op  Hardness,  Showing  the  Parts  per  Million  of  Calcium  Carbonate 

(CaCOs)  FOR  Each  Tenth  of  a  Cubic  Centimeter  of  Soap  Solution 

When  50  c.  c.  of  the  Sample  Are  U^ed 


c.  c.  of  Soap 
Solution 


0.0 

0.1 

0.2 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

c.c. 

c.c. 

c.c. 

c.c. 

c.c. 

c.c. 

c.c. 

c.c. 

c.c. 

0.0 

1.6 

4.8 

6.3 

7.9 

9.5 

11.1 

12.7 

14.3 

15.6 

16.9 

19.5 

20.8 

22.1 

23.4 

24.7 

26.0 

27.3 

28.6 

29.9 

32.5 

33.8 

35.1 

36.4 

37.7 

38.0 

40.3 

41.6 

42.9 

45.7 

47.1 

48.6 

50.0 

51.4 

52.9 

54.3 

.55.7 

57.1 

60.0 

61.4 

62.9 

64.3 

65.7 

67.1 

68.6 

70.0 

71.4 

74.3 

75.7 

77.1 

78.6 

80.0 

81.4 

82.9 

84.3 

85.7 

88.6 

90.0 

91.4 

92.9 

94.3 

95.7 

97.1 

98.6 

100.0 

0.9 
c.c. 


0.0 
1.0 
2.0 
3.0 
4.0 
5.0 
6.0 
7.0 


3.2 
18.2 
31.2 
44.3 
58.6 
72.9 
87.1 
101.5 


In  adding  the  soap  solution  to  waters  containing  magnesium  salts 
it  is  necessary  to  avoid  mistaking  the  false  or  magnesium  end-point  for 
the  true  one.  If  the  end-point  was  due  to  magnesium  the  lather  now 
disappears.     Soap  solution  must  then  be  added  until  the  true  end-point 


73G  SANITARY    ANALYSIS    OF    WATER 

is  reached.  Usually  tlie  false  lather  persists  for  less  than  5  minutes. 
Consequently,  after  the  titration  is  apparently  finished,  read  the  burette 
and  add  about  0.5  c.  c.  of  soap  solution. 

At  best  the  soap  method  is  not  a  precise  test  on  account  of  the 
varying  proportions  of  calcium  and  magnesium  present  in  different 
waters.  For  the  determination  of  hardness,  especially  in  connection 
with  processes  for  purification  and  softening,  it  is  advisable  to  use 
volumetric  or  gravimetric  methods. 

ORGANIC    MATTER 

It  is  not  possible  to  determine  the  amount  of  organic  matter  pres- 
ent in  a  sample  of  water  by  any  direct  method.  As  all  proteid  matter 
contains  nitrogen,  methods  have  been  devised  to  determine  the  total 
amount  of  nitrogen  and  also  the  amount  of  nitrogen  in  various  com- 
binations. From  such  data  valuable  information  concerning  the  sani- 
tary history  and  sanitary  quality  of  the  water  may  be  inferred.  The 
nitrogen  is  determined  as  (1)  total  nitrogen;  (2)  nitrogen  as  free 
ammonia;  (3)  nitrogen  as  albuminoid  ammonia;  (4)  nitrogen  as  ni- 
trites;  (5)   nitrogen  as  nitrates. 

The  organic  matter  in  water  is  of  animal  and  vegetable  origin  and 
exists  both  in  solution  and  in  suspension.  Some  of  it  is  in  the  body 
of  living  beings;  some  of  it  is  in  their  dead  bodies;  and  some  of  it 
is  in  various  stages  of  decomposition  until  the  final  stable  compounds, 
such  as  ammonia  and  nitrates,  are  reached.  The  total  amount  of  or- 
ganic matter  present  in  a  sample  of  water  is  represented  by  the  amount 
of  nitrogen  as  free  ammonia  and  albuminoid  ammonia.  The  presence 
of  nitrogen  as  nitrites  and  nitrates  indicates  the  amount  of  self-purifica- 
tion which  the  water  has  undergone.  Their  significance  will  be  dis- 
cussed separately. 

Free  Ammonia. — If  there  is  much  free  ammonia  in  the  water  the 
sample  may  be  nesslerized  directly.  If  tlie  water  contains  compara- 
tively little,  as  is  usually  the  case,  the  ammonia  must  first  be  concen- 
trated by  distillation  and  condensation. 

Place  500  c.  c.  of  the  sample  of  water  in  a  metal  or  glass  still  con- 
nected to  a  tin  or  aluminium  condenser  in  such  a  way  that  the  dis- 
tillate may  be  conveniently  delivered  directly  into  Nessler  tubes.  The 
entire  apparatus  must  first  be  freed  from  ammonia  by  blowing  steam 
through  it  until  the  distillate  shows  no  trace  of  free  ammonia.  When 
this  has  been  done  the  distilling  flask  is  emptied  and  500  c.  c.  of  the 
sample  of  water  measured  into  it.  The  distillation  should  be  carried 
on  at  a  rate  so  that  not  more  than  10  c.  c.  nor  less  than  6  c.  c.  condense 
per  minute;  that  is,  it  should  take  from  5  to  10  minutes  to  distill  50 
c.  c,  which   is  the  quantity  Nessler  tubes  are  ordinarily  graduated  to 


OKGAmC    MATTER  ni 

contain.  Three  Nessler  tubes  of  the  distillate  containing  50  c.  c.  each 
are  collected  from  the  first  portion  that  comes  over;  these  contain 
the  free  ammonia. 

If  the  sample  is  acid,  or  if  the  presence  of  urea  is  suspected,  about 
one-half  gram  of  sodium  carbonate  should  be  added  previous  to  dis- 
tillation, otherwise  the  ammonia  will  not  come  off.  Sodium  carbonate 
is  omitted,  when  possible,  as  it  tends  to  increase  "bumping." 

The  amount  of  ammonia  is  determined  by  adding  2  c.  c.  of  Xessler 
reagent  to  each  tube  and  comparing  the  depth  of  color  with  a  set  of 
standard  tubes  prepared  with  a  known  quantity  of  ammonium  chlorid 
solution,  plus  an  equal  quantity  of  Nessler  reagent. 

Nesslers  reagent  is  prepared  by  dissolving  50  grams  of  potassium 
iodid  in  a  minimum  quantity  of  cold  water.  To  this  add  a  saturated 
solution  of  mercuric  chlorid  until  a  slight  permanent  precipitate  per- 
sists. Then  add  125  grams  of  potassium  hydroxid  dissolved  in  250  c.  c. 
of  water,  allowing  it  to  clarify  by  sedimentation  before  using;  dilute  to 
one  liter,  allow  to  stand,  and  decant.  The  solution  should  give  the  re- 
quired color  with  ammonia  within  5  minutes  after  addition,  and  should 
not  precipitate  with  small  amounts  of  ammonia  within  2  hours.  The 
reaction  between  Xessler's  reagent  and  ammonia  is  an  empyric  one.  The 
Hgig  2KI  KOH,  which  constitutes  the  Nessler's  reagent  in  the  presence 
of  ammonia,  forms  a  broTvmish  compound,  known  as  mercurammonium 
iodid,  and  having  the  formula  NHgoI  HoO. 

Standard  NH^Cl  Solution. — The  standards  for  comparison  con- 
sist of  ammonium  chlorid  dissolved  in  ammonia-free  water.  Dissolve 
3.82  grams  of  ammonium  chlorid  in  1  liter  of  water;  dilute  10  c.  c. 
of  this  to  1  liter  with  the  ammonia-free  water.  One  c.  c.  will  then 
equal  0.00001  gram  of  nitrogen. 

A  gram  molecule  of  XH^Cl  weighs  53.5  grams — that  is: 

N  14+H  4+Cl  35.5=53.5 
The  equation  would  then  be: 

14:53.5::l:x 

x=3.82 

That  is,  if  there  are  14  grams  of  nitrogen  in  53.5  grams  of  am- 
monium chlorid,  then  1  gram  of  nitrogen  is  contained  in  3.82  grams 
of  ammonium  chlorid.  It  is  to  be  noted  that,  while  the  method  deter- 
mines the  amount  of  ammonia,  the  results  are  expressed  in  terms  of 
nitrogen.  In  the  same  way  the  nitrites  and  nitrates  are  also  expressed 
in  terms  of  nitrogen. 

Prepare  a  series  of  16  Nessler  tubes,  which  contain  the  following 
number  of  cubic  centimeters  of  the  standard  ammonium  chlorid  solu- 
tion, namely:  0.0,  0.1,  0.3,  0.5,  0.7,  1.0,  1.4,  1.7,  2.0,  2.5,  3.0,  3.5,  4.0, 


738  SANITARY    ANALYSIS    OF    WATER 

4.5,  5.0,  6.0;  dilute  each  one  with  50  c.  c.  of  the  standard  ammonia- 
free  water.  These  will  contain  0.00001  gram  of  nitrogen  for  each 
cubic  centimeter  of  the  standard  solution  used.  x\dd  2  c.  c.  of  the 
Nessler  reagent  to  each  tube;  do  not  stir  the  contents  of  the  tubes. 

The  color  produced  in  the  distillate  from  tlie  sample  under  exam- 
ination is  now  compared  with  standards  by  looking  vertically  down- 
ward through  them  at  a  white  surface  placed  at  an  angle  in  front  of 
a  window  so  as  to  reflect  the  light  upward.  The  tubes  should  be  al- 
lowed to  stand  at  least  10  minutes  after  nesslerizing  before  making 
the  comparison. 

Tha  last  50  cubic  centimeters  of  the  distillate  examined  should 
contain  no  ammonia,  or  at  most  a  trace,  otherwise  it  may  be  inferred 
that  all  has  not  been  collected,  or  some  error  has  crept  into  the  work. 
It  is  not  uncommon  for  the  last  tube  to  contain  a  little  ammonia  when 
the  organic  matter  is  of  plant  origin.  Ammonia  determinations  should 
be  carried  out  in  a  special  room,  where  at  least  volatile  ammonia  re- 
agents are  not  exposed.  Special  care  must  be  exercised  not  to  con- 
taminate the  Nessler  tubes  with  soiled  fingers,  rags,  etc.  Care  must 
be  exercised  to  thoroughly  wash  the  tubes  free  from  alkaline  soaps. 
The  Nessler  tubes  containing  the  standard  solution  and  the  samples 
for  comparison  should  be  at  the  same  temperature,  and  other  condi- 
tions should  be  as  alike  as  possible. 

Example. — 

The  first  Nessler  tube:=2.5  c.  c.  standard  NH^Cl  solution,  or 
0.000.025   gram   N   as   NH3. 

The  second  Nessler  tube=0.7  c.  c.  standard  NH^Cl  solution,  or 
0.000,007  gram  N  as  NH3. 

Tlie  third  Nessler  tube=0.0  c.  c.  standard  NH4CI  solution,  or 
0.000,000  gram  N  as  NH3. 

Total,  0.000,032  gram  N  as  NH3. 

(Note:  1  CO.  of  the  standard  solution  contains  0.00001  gram  of 
N  as  NH3.) 

Only  500  c.  c.  of  the  sample  of  water  was  distilled.  We  must,  there- 
fore, multiply  by  2  in  order  to  obtain  the  amount  of  N  in  one  liter: 

0.000,032X2=0.000,064  gram  of  N  as  NH3  per  1,000  c.  c. 

If  1,000  c.  c.  contains  0.000,064  gram  of  N  as  NH.,  1.000,000 
parts  will  contain  0.064  part  of  N  as  NH3 — usually  expressed  as  0.064 
part  per  million. 

A  simpler  method  of  making  the  calculation  is  as  follows: 

2.5+0.7X0.02=0.064  part  per  million. 
Significance  of  Free  Ammonia. — The  free  ammonia  which  comes 


OEGANIC    MATTER  739 

o2  with  the  first  part  of  the  distillate  usually  exists  in  the  water  as 
chlorids  or  carbonates.  It  is  called  "free  ammonia^'  because  these  salts 
are  readily  decomposed  and  the  ammonia  is  expelled  by  boiling. 

Eain  water  washes  down  some  free  ammonia  which  is  found  in  the 
atmosphere.  Angus  Smith  and  Boussingault  place  the  average  amount 
of  ammonia  in  the  rain  of  temperate  climates  as  0.5  part  per  million. 

The  amount  of  ammonia  in  rain  water  was  studied  by  Filhol.  He 
found  that  in  the  city  of  Toulouse  the  rain  water  contained  6.60  parts 
per  million,  while  the  rain  water  collected  near  the  city  contained  only 
from  O.i-i  to  0.77  part  per  million.  These  figures  show  the  marked 
difference  between  city  and  country  rain. 

In  a  surface  or  ground  water  free  ammonia  represents  one  of  the 
latter  stages  of  putrefaction  of  organic  matter;  thus,  the  bacterial  de- 
composition of  sewage  yields  ammonia  in  abundance. 

The  ammonia  itself  ordinarily  found  in  drinking  water  is  harmless; 
its  significance  lies  in  the  fact  that  it  indicates  the  presence  of  putre- 
fying organic  matter. 

The  presence  of  free  ammonia  in  clean  and  properly  stored  rain 
water  has  much  less  significance  than  in  a  surface  or  ground  water. 

Free  ammonia  in  water  results  not  only  from  the  decomposition  of 
nitrogenous  organic  matter,  but  is  also  formed  during  the  process  of 
denitrification,  by  which  nitrates  are  again  reduced  to  nitrites  and 
nitrites  to  ammonia.  This  action  only  takes  place  near  the  surface 
of  the  soil,  and  to  a  limited  extent.  Deep  well  waters  of  exceptional 
purit}^  upon  chemical  analysis,  and  practically  sterile  upon  bacteriologi-_ 
cal  examination,  may  contain  a  relatively  high  percentage  of  free  am- 
monia. This  is  supposed  to  come  from  a  chemical  reduction  under 
high  pressure  and  perhaps  temperature  of  the  geological  nitrogenous 
matter  in  coal  and  alluvial  deposits. 

A  definite  permissible  limit  for  the  amount  of  free  ammonia  which 
good  water  should  contain  cannot  be  fixed.  Its  significance  must  be 
judged  from  the  other  constituents  of  the  water  and  a  sanitary  survey 
of  its  source.  As  a  rule,  pure  water  may  contain  from  0.015  to  0.03 
or  even  0.055  part  per  million.  In  general,  free  ammonia  is  less  of 
a  danger  signal  than  the  fixed  or  albuminoid  ammonia. 

Albnminoid  Ammonia. — Xitrogen  as  albuminoid  ammonia  is  always 
determined  in  conjunction  with  and  as  a  continuation  of  the  method 
for  determining  nitrogen  as  free  ammonia.  After  obtaining  150  c.  c. 
(that  is,  3  Xessler  tubes  of  50  c.  c.  each)  from  the  first  portion  of  the 
distillate,  for  the  purpose  of  determining  nitrogen  as  free  ammonia, 
withdraw  the  flame  and  add  40  c.  c.  or  more  of  alkaline  potassium 
permanganate,  and  continue  the  jorocess  until  at  least  4  portions  of 
.  50  c.  c.  each,  or,  preferably,  5  portions,  of  the  distillate  have  been  col- 
lected in  separate  Nessler  tubes. 


740  SANITARY    ANALYSIS    OF    WATER 

The  alkaline  potassium  permanganate  solution  is  made  by  pouring 
1,200  e.  c.  of  distilled  water  into  a  porcelain  dish  holding  2,500  c.  c. ; 
boil  10  minutes  and  turn  oil'  the  gas.  Add  Ifi  grams  of  C.  P.  potas- 
sium permanganate  and  stir  until  dissolved.  Then  add  800  c.  c.  of  50 
per  cent,  clarified  solution  of  potassium  or  sodium  hydrate  and  enough 
distilled  water  to  fill  the  dish.  Boil  down  to  2,000  c.  c.  Test  each 
batch  of  this  solution  for  albuminoid  ammonia  by  making  a  blank  de- 
termination.    Correction  should  be  made  accordingly. 

After  the  readily  decomposed  ammonia  salts  have  been  l)roken  up 
and  the  ammonia  driven  off  in  the  steam  which  condenses  to  form  the 
first  150  c.  c,  the  remainder  of  the  sample  of  water  in  the  still  contains 
nitrogenous  organic  matter  that  requires  a  strong  oxidizing  agent  to 
disintegrate  it.  This  is  accomplished  by  the  alkaline  potassium  per- 
manganate. The  nitrogen  in  the  complex  protein  molecule  finally  forms 
ammonia,  and  hence  this  is  called  albuminoid  ammonia;  the  amount 
of  it  is  determined  by  nesslerization,  precisely  as  for  free  ammonia. 
In  ground  waters  and  surface  waters  containing  but  little  pollution  the 
nitrogen  as  albuminoid  ammonia  usually  approximates  about  one-half 
of  the  total  organic  nitrogen.  In  sewage  and  other  liquids  containing 
considerable  nitrogenous  organic  matter  the  percentage  of  ammonia 
forming  organic  matter  is  variable.  For  this  reason  the  amount  of 
albuminoid  ammonia  obtained  by  the  alkaline  permanganate  method 
is  less  valuable  than  the  total  organic  nitrogen  determined  by  the  Kjel- 
dahl  method. 

If  it  is  desired  to  determine  how  much  of  the  organic  matter  is  in 
solution  and  hoAv  much  in  suspension,  the  sample  of  water  should  be 
passed  through  a  Berkefeld  filter.  The  albuminoid  ammonia  in  the 
filtrate  represents  the  dissolved  organic  matter,  and  the  difference  be- 
tween the  albuminoid  ammonia  in  the  total  sample  and  the  filtered 
sample  gives  the  suspended  nitrogen  as  albuminoid  ammonia. 

The  albuminoid  ammonia  is  a  fairly  correct  index  of  the  amount 
of  organic  pollution  in  the  water.  It  comes  from  minute  organisms, 
both  living  and  dead,  that  are  in  the  sample,  also  from  particles  of 
animal  and  vegetable  matter  in  suspension,  and  finally  from  the  nitrog- 
enous substances  in  solution  and  in  various  stages  of  decomposition. 
The  organic  matter  in  itself  is  not  dangerous  to  health,  but  is  unde- 
sirable because  it  putrefies  and  thus  gives  a  water  disagreeable  tastes 
and  odors;  further,  it  offers  food  for  bacterial  growth.  The  amount 
of  albuminoid  ammonia  is  therefore  an  index  of  pollution,  but  if  of 
vegetable  origin  it  has  much  less  sanitary  significance  than  if  of  animal 
origin.  Organic  matter  of  animal  origin  yields  a  much  larger  amount 
of  albuminoid  ammonia  than  a  similar  amount  of  vegetable  matter. 
Whether  the  organic  matter  comes  from  sewage,  from  a  dead  carcass, 
or  from  the  swamps,  cannot  be  stated  with  certainty  from  this  test,  but 


ORGANIC    MATTER  741 

if  the  albuminoid  ammonia  comes  over  quickly,  that  is,  if  most  of  it 
appears  in  the  first  Nessler  tube,  it  is  presumably  of  animal  origin; 
whereas,  if  the  ammonia  comes  over  more  slowly  and  the  second  and 
third  Nessler  tubes  contain  appreciable  amounts,  the  organic  matter  is 
presumably  of  vegetable  origin. 

No  arbitrary  standard  can  be  set  as  to  the  maximum  amount  of 
albuminoid  ammonia  a  good  water  may  contain.  Waters  considered 
"pure"  often  contain  as  much  as  0.079  to  0.34  part  of  nitrogen  as  al- 
buminoid ammonia  per  million. 

Uitrites. — Nitrites  in  water  are  regarded  as  a  special  danger  sig- 
nal. The  reason  for  this  is  that  nitrites  indicate  that  active  putrefaction 
of  nitrogenous  organic  matter  is  going  on  as  the  result  of  bacterial 
activity.  The  presence  of  nitrites,  therefore,  at  once  suggests  organic 
pollution.  The  presence  of  nitrites  in  water  represents  the  transitional 
stage  in  the  oxidation  of  organic  matter  between  ammonia  and  nitrates, 
and  therefore  indicates  incomplete  oxidation  of  the  protein  and  the  ac- 
tive growth  of  bacteria. 

Nitrites  are  never  present  except  in  small  amounts,  for  they  are  soon 
oxidized  to  the  higher  and  more  stable  nitrates,  but  the  minutest  trace, 
according  to  some  authorities,  is  sufficient  to  condemn  a  water.  As  a 
rule,  pure  water  contains  no  nitrites,  or  traces  only;  on  the  other  hand, 
nitrites  may  be  absent  from  an  impure  water,  owing  to  the  fact  that 
the  oxidation  has  not  reached  this  stage,  or  perhaps  has  entirely  passed 
it.  The  absence  of  nitrites,  therefore,  does  not  mean  that  the  water  is 
necessarily  safe,  while  their  presence  in  any  but  the  smallest  measurable 
amounts  shows  pollution.  We  must  not  give  to  the  nitrites  an  exag- 
gerated importance :  they  are  a  danger  signal  in  the  same  sense  that 
the  colon  bacillus  is  a  danger  signal,  indicating  pollution  but  not  neces- 
sarily infection,  for  they  do  not  tell  the  source  or  nature  of  the  organic 
matter.  It  should  be  remembered  that  the  colorimetric  test  for  nitrites 
with  sulphanilic  acid  and  a-amidonaphthylamin  is  one  of  the  most  deli- 
cate tests  in  chemistry.  With  this  method  we  are  able  to  detect  quan- 
tities as  small  as  one  part  in  a  hundred  million.  When,  therefore,  a 
water  analyst  reports  a  trace  of  nitrites  it  means  an  exceedingly  minute 
quantity. 

Nitrites  are  not  only  formed  by  the  nitrifying  bacteria  in  the  soil 
from  ammonia,  but  are  also  formed  from  the  denitrification  of  nitrates 
by  a  variety  of  microorganisms.  The  typhoid  bacillus,  the  colon  bacillus, 
and  many  other  bacteria  have  the  power  of  producing  nitrites  in  culture 
media. 

Nitrites  are  poisonous,  but  the  minute  amounts  found  in  water  can 
scarcely  have  a  pharmacological  effect. 

Method    for    Estimating    Nitrogen    as    Nitrites. — Reagents: 
(1)   Sulphanilic  acid  solution.     Dissolve  eight  grams  of  the  purest  sul- 
49 


742  SANITARY    ANALYSIS    OF    WATER 

phanilic  acid  in  1,000  c.  c.  of  5  N.  acetic  acid   (sp.  gr.  1.041).     This 
is  practically  a  saturated  solution. 

(2)  a-amidonaphthalene  acetate  solution.  Dissolve  5.0  grams  solid 
a-naphthylamine  iu  1,000  c.  c.  of  5  N.  acetic  acid ;  filter  the  solution 
through  washed  absorbent  cotton. 

(3)  Sodium  nitrite,  stock  solution.  Dissolve  1.1  grams  silver  ni- 
trite in  nitrite-free  water;  preci])itate  the  silver  with  sodium  chlorid 
solution  and  dilute  the  whole  to  one  liter. 

(4)  Standard  sodium  nitrite  solution.  Dilute  100  c.  c.  of  solution 
(3)  to  one  liter;  then  dilute  10  c.  c.  of  this  solution  to  one  liter  with 
sterilized  nitrite-free  water;  add  one  c.  c.  of  chloroform  and  preserve 
in  a  sterilized  bottle.     One  c.  c.  =  0.000.000,1  gram  nitrogen. 

Procedure. — Measure  out  100  c.  c.  of  the  decolorized  sample  (de- 
colorized by  adding  aluminium  hydrate  free  of  nitrite — see  imder 
Chlorin),  or  a  smaller  portion  diluted  to  100  c.  c,  into  a  Nessler  tube. 
At  the  same  time  make  a  set  of  standards  by  diluting  various  volumes 
of  the  standard  nitrite  solution  in  Nessler  tubes  to  100  c.  c.  with  nitrite- 
free  water,  for  example,  0,  1,  3,  5,  7,  10,  14,  17,  20,  and  25  c.  c.  Add 
2  c.  c.  of  reagents  Nos.  1  and  2  (above)  to  each  100  c.  c.  of  the  sample 
and  to  each  standard.  Mix;  allow  to  stand  10  minutes.  Compare  the 
samples  with  the  standards.  Do  not  allow  the  samples  to  stand  over 
one-half  hour  before  being  compared,  on  account  of  absorption  of  nitrites 
from  the  air.  Make  a  blank  determination  in  all  cases  to  correct  for 
the  presence  of  nitrites  in  the  air,  the  water  and  other  reagents.  Dilute 
all  samples  which  develop  more  color  than  the  25  c.  c.  standard  before 
comparing.     Mixing  is  important. 

When  100  c.  c.  of  the  sample  are  used,  then  0.001  times  the  number 
of  c.  c.  of  the  standard  gives  the  parts  per  million  of  nitrogen  as  nitrite. 

Nitrates. — Nitrates  are  the  end  products  of  the  mineralization  of 
organic  matter.  Their  presence,  therefore,  signifies  past  or  distant 
pollution.  While  the  absence  of  nitrates  does  not  necessarily  mean 
purity,  their  presence,  on  the  other  hand,  does  not  necessarily  indicate 
immediate  danger.  If  a  water  contains  an  appreciable  quantity  of  ni- 
trates and  no  nitrites,  it  shows  that  the  source  of  pollution  has  been 
distant  and  that  the  organic  matter  has  been  completely  oxidized.  In 
waters  considered  pure  the  nitrates  are  rarely  less  than  0.3  part,  or 
they  may  run  as  high  as  1.6  parts,  per  million.  Impure  waters  may 
contain  very  much  more,  as  17,  20,  or  more  parts  per  million.  Nitrates 
usually  exist  in  water  as  salts  of  alkaline  bases.  The  test  for  nitrates 
depends  upon  the  fact  that  they  react  with  phenoldisulphonic  acid  to 
form  a  compound  resembling  picric  acid,  which  is  yellow  in  the  presence 
of  an  alkali.  The  amount  of  nitrates  is  determined  colori metrically  l)y 
comparison  with  standard  solutions. 

PiiKXOLSULPHONic   AciD   Metiiod  FOR  NiTRATES. — Reagents:    (1) 


OEGANIC    MATTEE  743 

Phenolsulphonic  acid.  Mix  30  grams  of  synthetic  phenol  with  370 
grams  of  C.  P.  concentrated  sulphuric  acid  in  a  round-bottom  flask. 
Put  this  flask  in  a  water  bath  and  support  it  in  such  a  way  that  it  shall 
be  completely  immersed  in  the  water.     Heat  for  six  hours. 

(2)  Ammonium  hydrate  solution  diluted  with  distilled  water,  1  to  1. 
Potassium  hydrate  may  be  used.  The  ammonia  gives  a  better  color  than 
the  potassium,  but  sho'ald  not  be  used  if  this  test  is  carried  on  in  the 
same  room  where  free  and  albuminoid  ammonia  are  being  determined 
for  fear  of  false  results  from  contamination. 

(3)  Standard  nitrate  solution.  Dissolve  0.73  gram  of  pure  re- 
crystallized  potassium  nitrate  in  one  liter  of  distilled  water.  Evaporate 
cautiously  10  c.  c.  of  this  strong  solution  on  the  water  bath.  Moisten 
quickly  and  thoroughly  with  2  c.  c.  of  phenolsulphonic  acid  and  dilute  to 
one  liter  for  the  standard  solution;  one  c.  c.  of  which  equals  .000,001 
gram  of  nitrogen. 

Procedure. — Evaporate  20  c.  c.  or  less  of  the  sample  of  water  in  a 
small  porcelain  evaporating  dish  on  the  water  bath,  removing  it  from 
the  bath  just  before  it  has  come  to  dryness.  Let  the  last  few  drops 
evaporate  at  room  temperature  in  a  place  protected  from  the  dust. 
When  the  sample  is  suspected  to  contain  a  large  amount  of  nitrate, 
evaporate  less  than  20  c.  c.  If  it  is  suspected  to  contain  but  little,  evap- 
orate more. 

If  the  sample  has  a  high  color,  decolorize  before  evaporating  by  the 
use  of  washed  aluminium  hydrate,  as  directed  in  connection  with  the 
chlorin  determination. 

Add  1  c.  c.  of  phenolsulphonic  acid  and  rub  this  quickly  and  thor- 
oughly over  the  residue  with  a  glass  rod.  x^dd  about  10  c.  c.  of  distilled 
water  and  stir  with  a  glass  rod  until  mixed.  Add  enough  ammonium 
hydrate  solution  (or  potassium  hydrate  if  the  operation  must  of  neces- 
sity be  carried  on  in  a  room  where  ammonia  distillations  are  made)  to 
render  the  liquid  alkaline.  Transfer  the  liquid  to  a  100  c.  c.  N'essler 
tube  and  fill  the  tube  to  the  100  c.  c.  mark  Avith  distilled  water. 

If  nitrates  are  present  there  will  be  formed  a  yellow  color;  this  may 
be  compared  with  permanent  standards  made  for  the  purpose,  which  keep 
satisfactorily  for  several  weeks.  The  series  of  standards  for  comparison 
shall  be  made  by  putting  varying  quantities  of  the  standard  solu- 
tion into  100  c.  c.  tubes  and  making  up  to  the  100  c.  c.  mark  with  dis- 
tilled water,  adding  5  c.  c.  of  strong  ammonia  to  each  tube,  in  accord- 
ance with  the  table  on  page  741:. 

Compare  the  sample  treated  as  above  described  with  these  standards 
by  looking  down  vertically  through  the  tubes  at  a  white  surface  so  placed 
in  front  of  a  window  that  it  will  reflect  the  light  upward  through  them. 

If  the  figures  obtained  by  this  comparison  in  cubic  centimeters  of 
standard  added  be  divided  by  the  number  of  c.  c.  of  the  sample  which 


744 


SANITARY    ANALYSIS    OF    WATER 


were  evaporated,  the  quotient  gives  the  number  of  parts  per  million  of 
nitrogen  in  the  form  of  nitrate. 


Table 


Amount  of 

.\mount  of 

Dilute  Standard 

Standard  Nitrate 

Dilute  Standard 

Standard  Nitrate 

Added 

Added 

C.  C. 

milligram 

C.  C. 

milligram 

0.0 

0.000 

15.0 

0.015 

1.0 

0.001 

20.0 

0.020 

3.0 

0.003 

25.0 

1.025 

5.0 

0.005 

30.0 

0.030 

7.0 

0.007 

35.0 

0.035 

10.0 

0.010 

40.0 

0.040 

CHLORIN 


Chlorin  as  sodium  chlorid  or  common  salt  is  a  normal  constituent 
of  all  waters.  Traces  of  it  are  found  in  rain  water  taken  up  from  the 
air,  especially  near  the  sea-coast.  The  rain  water  collected  at  Troy, 
New  York,  was  found  by  Mason  to  average  1.G4  parts  per  million  of 
chlorin.  The  amounts  varied  from  0.75  part  per  million  in  April  to  3 
parts  per  million  in  October.  The  chlorin  in  surface  and  ground  waters, 
generally  speaking,  comes  from  the  mineral  deposits  in  the  earth;  from 
the  ocean  vapors  and  spray  carried  inland  by  the  wind ;  also  from  pol- 
luting materials  like  sewage  and  trade  wastes,  both  of  which  are  apt  to 
contain  the  common  salt  used  in  the  household  and  in  manufacturing. 
A  comparison  of  the  chlorin  content  of  a  water  with  that  of  other  waters 
in  the  general  vicinity  known  to  be  unpolluted  frequently  affords  useful 
information  as  to  its  sanitary  quality. 

Before  the  water  analyst  is  able  to  properly  interpret  the  significance 
of  the  chlorin  content  of  a  water  it  is  necessary  to  know  the  normal 
amount  of  chlorin  present  in  the  waters  of  that  locality.  Thus,  surface 
waters  near  Provincetown,  on  Cape  Cod,  contain  from  23  to  24  parts 
of  chlorin  per  million,  while  surface  waters  near  Boston  contain  from 
3  to  6  parts  per  million.  Near  the  middle  of  the  state  of  Massachusetts 
(Worcester)  the  surface  waters  contain  only  1.2  to  1.9  parts  per  million, 
wliile  in  the  western  portion  of  the  state,  farthest  from  the  sea,  the 
surface  waters  contain  but  0.7  to  0.9  parts  per  million.  The  amount 
of  normal  chlorin  in  the  waters  of  Massachusetts  has  been  carefully 
studied  by  the  State  Board  of  Health,  and  a  map  has  been  issued  show- 
ing the  isochlors,  or  normal  chlorine  lines. 

In  Massachusetts  the  whole  of  the  surface  of  the  country,  with  the 
exception  of  a  very  small  portion,  is  non-calcareoiis,  and  the  surface 
waters  carry  but  little  chlorin  in  composition,  if  unpolluted,  the  amount 


CHLOEIN  745 

of  chlorin  decreasing  continuously  from  the  coast  inland.  In  a  report 
on  the  State  water  supplies,  1887-1890,  the  Commissioners  state  that 
"in  a  general  way  -1  families  or  20  persons  per  square  mile  will  add,  on 
an  average,  .01  of  a  part  per  100,000  of  chlorin  (.1  part  per  million) 
to  the  water  flowing  from  this  area,  and  that  a  much  smaller  population 
will  have  the  same  effect  during  seasons  of  low  flow." 

The  amount  of  chlorin  in  a  water  of  a  district  varies  with  several 
factors,  such  as  the  distance  from  the  sea,  the  amount  of  rainfall,  the 
amount  of  evaporation,  and  the  direction  of  the  winds ;  an  increase  over 
the  normal  is  an  indication  of  pollution,  and  comes  mostly  from  urine. 
While  the  ammonia  and  the  nitrites  may  have  disappeared  and  the  ni- 
trates may  have  been  largely  taken  up  by  growing  vegetation,  the  chlorin 
salts,  which  are  exceedingly  stable,  will  be  left  to  indicate  remote  or 
passed  pollution. 

The  mixture  of  even  a  small  proportion  of  sea-water  renders  the 
water  hard  and  salty  and  undesirable  for  domestic  use.  Magnesium 
chlorid  also  renders  a  water  unsuitable  for  use  in  boilers.  Wells  driven 
near  the  sea  frequently  become  mixed  with  sea-water,  particularly  if 
sufficient  water  is  withdrawn  to  cause  suction.  When  this  happens  the 
sea-water  passes  back  under  the  wells  as  an  undercurrent  and  gradually 
mixes  with  the  fresh  water  above  it  and  sooner  or  later  appears  in  the 
well.  When  this  happens  it  may  be  a  slow  and  hard  process  to  operate 
the  well  so  as  to  avoid  drawing  sea-water.  In  wells  near  the  sea  it  is 
important  to  draw  no  more  fresh  water  than  would  otherwise  flow  to 
the  ocean.  This  is  often  a  difficult  problem  to  arrange  so  as  to  get  the 
maximum  quantity  of  water  obtainable.  This  sea-water  question  has 
been  more  thoroughly  and  scientifically  studied  in  Holland  than  else- 
where. 

Determination  of  Chlorin. — Reagents.  (1)  Standard  salt  solution. 
Dissolve  16.48  grams  of  fused  sodium  chlorid  in  one  liter  of  distilled 
water.  Dilute  100  c.  c.  of  this  stock  solution  to  one  liter  in  order  to 
obtain  a  standard  solution,  each  c.  c.  of  which  contains  .001  gram  of 
chlorin. 

(2)  Silver  nitrate  solution.  Dissolve  about  2.40  grams  of  silver 
nitrate  crystals  in  one  liter  of  distilled  water.  One  c.  c.  of  this  will 
approximately  equal  .0005  gram  of  chlorin.  Standardize  this  against 
the  standard  salt  solution. 

(3)  Potassium  chromate.  Dissolve  50  grams  of  neutral  potassium 
chromate  in  a  little  distilled  water.  Add  enough  silver  nitrate  to  pro- 
duce a  slight  red  precipitate.  Filter  and  make  up  the  filtrate  to  one 
liter  with  distilled  water. 

(4)  Aluminium  hydrate.  Dissolve  125  grams  of  potash  or  am- 
monium alum  in  one  liter  of  distilled  water.  Precipitate  the  aluminium 
hydrate  by  cautiously  adding  ammonium  hydrate.    Wash  the  precipitate 


746  SANITARY    ANALYSIS    OF    WATER 

in  a  large  jar  by  the  successive  addition  of  distilled  water  and  by  decan- 
tation  until  free  from  chlorin,  nitrites,  and  ammonia. 

Procedure. — For  this  determination  where  the  chlorin  content  is  not 
extremely  low  or  very  high,  titrate  50  c.  c.  of  the  sample  in  a  white  six- 
inch  porcelain  evaporating  dish  with  the  standard  silver  nitrate  solution. 
If  the  chlorin  is  very  high  in  amount,  use  25  c.  c,  or  even  a  smaller 
quantity  if  desired,  diluting  the  volume  taken  with  distilled  water  to 
50  c.  c.  ^^'hen  the  sample  is  very  low  in  its  chlorin  content,  more  ac- 
curate results  may  be  obtained  by  using  50  c.  c.  of  the  sample  and  add- 
ing, prior  to  titration,  one  c.  c.  of  standard  salt  solution. 


OXYGEN 

Oxygen  Consumed. — 'The  oxygen  consumed  means  the  oxygen  which 
the  organic  compounds  in  water  consume  when  treated  in  an  acid  solu- 
tion with  potassium  permanganate.  The  expression  is  synonymous  with 
"ox3-gen  required"  or  "oxygen  absorbed."  Oxygen  consumed  is,  there- 
fore, an  index  of  the  amount  of  putreseible  organic  matter  present  and 
should  carefully  be  distinguished  from  the  expression  "dissolved  oxy- 
gen," which  refers  simply  to  the  amount  of  oxygen  held  in  solution  by 
the  water. 

It  is  the  carbon  and  not  the  nitrogen  in  organic  matter  which  is 
oxidized  by  potassium  permanganate  in  an  acid  solution;  hence  this  de- 
termination is  frequently  referred  to  as  an  indication  of  the  carbonaceous 
organic  matter  present.  The  method  indicates  only  a  certain  portion 
of  the  carbon,  and  this  ratio  varies  in  different  samples  of  water.  Fur- 
ther, it  does  not  differentiate  the  carbon  present  in  unstable  organic 
matter  from  that  in  what  might  be  called  fairly  stable  organic  matter, 
such  as  is  sometimes  referred  to  as  "residual  humus."  The  presence  of 
nitrites,  ferrous  iron,  sulphids,  or  other  unoxidized  mineral  compounds 
causes  oxygen  to  be  taken  up  and  hence  increases  the  amount  of  oxygen 
consumed  by  this  method.  In  case  such  substances  are  present,  a  cor- 
rection should  be  made  when  studying  carbonaceous  organic  matter. 

Determixatiox  of  Oxygen  Consumed. — Reagents.  (1)  Dilute 
sulphuric  acid.  One  part  of  sulphuric  acid  to  three  parts  of  distilled 
water.  This  shall  be  freed  from  oxidizable  matters  by  adding  potassium 
permanganate  until  a  faint  pink  color  persists  after  standing  several 
hours. 

(2)  Standard  potassium  permanganate  solution.  Dissolve  0.4  gram 
of  the  crystalline  compound  in  one  liter  of  distilled  water.  Standardize 
against  an  ammonium  oxalate  solution.  One  c.  c.  is  equivalent  to  0.0001 
gram  of  available  oxygen. 

(3)  Ammonium  oxalate  solution.    Dissolve  0.888  gram  of  the  sub- 


OXYGEN  747 

stance  in  one  liter  of  distilled  water.     One  c.  c.  is  equivalent  to  0.0001 
gram  of  oxygen. 

(4)  Potassium  iodid  solution.    Ten  per  cent,  solution  free  of  iodate. 

(5)  Sodium  thiosulphate  solution.  Dissolve  1.0  gram  of  the  pure 
crystallized  salt  in  one  liter  of  distilled  water.  Standardize  against  a 
potassium  permanganate  solution  which  has  been  standardized  against 
an  ammonium  oxalate  solution.  As  this  solution  does  not  keep  well,  de- 
termine its  actual  strength  at  frequent  intervals. 

(6)  Starch  solution.  Mix  a  small  amount  of  clean  starch  with 
cold  water  until  it  becomes  a  thin  paste;  stir  this  into  150  to  200  times 
its  weight  of  boiling  water.  Boil  for  a  few  minutes,  then  sterilize.  It 
may  be  preserved  by  adding  a  few  drops  of  chloroform. 

Procedure. — Measure  into  a  flask  100  c.  c.  of  the  water,  or  a  smaller 
diluted  portion  if  the  water  is  of  high  organic  content.  Add  10  c.  c.  of 
sulphuric  acid  solution  and  10  c.  c.  of  potassium  permanganate  solution, 
and  allow  the  treated  sample  of  water  to  digest  30  minutes  at  boiling 
temperature  in  a  water  bath. 

Precisely  at  the  end  of  the  period  of  digestion  remove  the  flask  and 
add  10  c.  c.  of  the  ammonium  oxalate  solution.  Titrate  with  the  per- 
manganate solution  until  a  faint  but  distinct  color  is  obtained. 

Each  c.  c.  of  the  permanganate  solution  in  excess  of  the  oxalate  solu- 
tion represents  0.0001  gram  of  oxygen  consumed  by  the  sample. 

At  the  end  of  the  period  of  digestion,  if  not  made  at  the  boiling  tem- 
perature, add  0.5  c.  c.  of  potassium  iodid  solution  to  discharge  the  pink 
color;  mix;  titrate  the  liberated  iodin  with  thiosulphate  until  the  yellow 
color  is  nearly  destro3'ed;  then  add  a  few  drops  of  starch  solution  and 
continue  titration  until  the  blue  color  is  just  discharged. 

Should  the  volume  of  permanganate  solution  be  insufficient  for  com- 
plete oxidation,  repeat  the  analysis,  using  a  larger  volume,  so  that  at 
least  three  c.  c.  of  the  permanganate  solution  will  be  present  in  excess 
when  the  ammonium  oxalate  solution  is  added. 

When  unoxidized  mineral  substances,  such  as  ferrous  sulphate,  sul- 
phids,  nitrites,  etc.,  are  present  in  the  sample,  corrections  should  be 
applied  as  accurately  as  possible  by  procedures  suitable  for  the  samples 
being  analyzed.  Direct  titration  of  the  acidified  sample  in  the  cold,  using 
a  three-minute  period  of  digestion,  serves  this  purpose  quite  well  for 
polluted  surface  waters  and  fairly  well  for  purified  sewage  effluents. 
Paw  sewages  containing  no  trade  wastes  seldom  need  such  a  correction, 
but  when  raw  sewages  contain  "pickling  liquors"  it  is  important.  In 
all  samples  containing  both  unoxidized  mineral  compounds  and  gaseous 
organic  substances  the  latter  should  be  driven  off  by  heat  and  the  sample 
allowed  to  cool  before  applying  this  test  for  the  correction  factor.  "Wliere 
such  corrections  are  necessary  the  fact  should  be  stated,  with  the  amount 
of  correction. 


748  SAXITARY    ANALYSIS    OF    WATER 

This  is  one  of  the  oldest  methods  for  determining  organic  matter 
and  has  been  in  very  wide  use  for  more  than  half  a  century.  It  was 
introduced  as  soon  as  the  fact  was  recognized  that  the  loss  on  ignition 
of  the  residue  upon  evaporation  may  indicate  certain  volatile  mineral 
matters,  as  well  as  organic  matter.  To-day  the  method  of  determination 
of  oxygen  consumed  is  ordinarily  not  included  in  a  water  analysis  for 
the  reason  that  the  results  vary  widely,  depending  on  the  procedure 
as  to  certain  details  of  the  method,  and  from  the  further  fact  that  the 
determinations  of  the  organic  matter  in  water  may  be  more  conveniently 
and  satisfactorily  estimated  from  the  free  and  albuminoid  ammonia. 

Dissolved  Oxygen. — Dissolved  oxygen  is  another  expression  for  the 
degree  of  aeration  or  oxygenation  of  water.  It  varies  from  zero  to  sat- 
uration or  slight  supersaturation.  The  amount  of  oxygen  in  solution  is 
fairly  constant  in  waters  of  uniform  composition  freely  exposed  to  the 
air.  Water  containing  sewage  and  other  oxidizable  matters  uses  up  the 
dissolved  oxygen.  In  badly  polluted  streams  so  much  of  the  dissolved 
oxygen  may  be  lost  in  this  way  that  fish  cannot  breathe.  They  die  from 
suffocation  rather  than  from  the  toxic  effects  of  the  sewage.  Water  may 
contain  practically  no  oxygen  at  depths  of  40  or  50  feet,  but  deep  sound- 
ings show  that  aeration  probably  exists  to  greater  depths,  for  fish  and 
aerobic  organisms  live  at  the  bottom  of  the  sea.  In  this  case  the  oxygen 
may  possibly  be  obtained  from  sources  other  than  the  dissolved  oxygen 
from  the  air. 

Dissolved  oxygen  makes  water  sparkling  and  palatable  and  also  helps 
to  consume  the  organic  matter.  Its  absence  permits  the  growth  of  an- 
aerobic organisms  that  cause  putrefaction  and  impart  putrid  tastes  and 
odors  to  the  water.  Pasteur's  original  conception  of  fermentation  was 
decomposition  in  the  absence  of  oxygen. 

The  amount  of  oxygen  found  in  the  water  of  a  running  stream  taken 
at  different  points  may  furnish  valuable  information  as  to  the  rapidity 
with  which  the  process  of  self-purification  is  taking  place  from  a  chemi- 
cal standpoint. 

The  amount  of  oxygen  dissolved  in  a  water  may  be  measured  by  three 
methods :  viz.,  that  of  Winkler,  Thresh,  or  Le^■y.  The  method  of  Wink- 
ler is  generally  used  in  this  country  and  possesses  the  advantage  of  re- 
quiring only  simple  and  not  readily  breakable  apparatus.  It  is  therefore 
recommended  as  the  standard  method. 

Method. — To  determine  the  amount  of  dissolved  oxygen  it  is  neces- 
sary to  collect  the  sample  with  extreme  care  in  order  to  avoid  the  en- 
trainment  of  any  oxygen  from  the  atmosphere.  The  sample  bottles 
should  be  glass-stoppered,  with  a  narrow  neck,  holding  at  least  250  c.  c. 
The  exact  capacity  of  the  bottle  must  be  determined.  The  bottle  should 
be  filled  through  a  glass  or  rubber  tube  which  reaches  to  the  bottom  of 
the  bottle,  and  the  water  allowed  to  overflow  for  several  minutes,  after 


lEON  749 

which  the  glass  stopper  is  carefully  replaced,  so  that  no  bubble  of  air  is 
caught  beneath  it. 

The  method  depends  upon  the  fact  that  manganous  sulphate  in  alka- 
line solution  is  oxidized  to  a  manganate  in  the  presence  of  oxygen  in 
solution  in  water.  On  neutralization  with  sulphuric  acid  the  man- 
ganese tends  to  revert  to  the  manganous  sulphate  with  the  liberation  of 
oxygen,  and  if  potassium  iodid  is  present  this  is  decomposed  by  the  liber- 
ated oxj^gen,  setting  free  iodin.  The  liberated  iodin  is  titrated  with 
sodium  thiosulphate,  the  end  point  being  made  more  definite  by  the 
use  of  starch  paste,  which  is  added  near  the  end  of  the  titration. 


IRON 

Iron  in  water  influences  its  quality  from  the  standpoint  of  desira- 
bility rather  than  from  the  standpoint  of  health.  After  hardness  there 
is  no  question  of  greater  practical  importance  in  considering  the  quality 
of  a  water.  All  natural  waters  contain  a  certain  amount  of  iron,  and 
ground  waters  are  apt  to  contain  it  in  objectionable  amounts.  Appre- 
ciable amounts  of  iron  render  water  unsuitable  for  domestic  and  techni- 
cal purposes;  it  stains  clothes  in  the  laundry,  and  is  apt  to  cause  head- 
ache and  constipation  if  used  habitually  for  drinking. 

When  iron  is  present  in  water  it  supports  a  fungus  (Crenothrix 
JcueJiniana) ,  an  organism  which  may  grow  in  the  pipes  in  sufficient 
amount  to  obstruct  the  flow  of  water  or  even  completely  choke  the  pipe. 
It  is  chiefly  troublesome  in  ground  waters  containing  organic  matter  and 
iron.  This  was  the  cause  of  the  complete  obstruction  of  the  water  pipes 
in  the  N'ew  York  Custom  House  in  1907.  The  same  sometimes  occurs 
in  the  pipes  of  driven  wells. 

Iron  is  very  widely  distributed  and  exists  in  practically  all  sands, 
gravels,  soils,  and  rocks  with  which  water  comes  in  contact.  The  solu- 
tion of  the  iron  is  brought  about  by  the  organic  matter.  The  iron  exists 
in  the  soil  as  ferric  compounds.  These  are  reduced  by  the  organic  mat- 
ter to  ferrous  salts,  which  are  soluble  in  water  containing  carbonic  acid. 
Trouble  from  iron  is  always  to  be  expected  when  there  is  an  excess  of 
organic  matter  in  the  material  through  which  the  water  passes.  In  a 
well-drained,  pervious  soil  the  oxygen  from  the  air  circulates  in  the 
pores  of  the  soil  and  furnishes  what  is  required  for  the  oxidation  of  the 
organic  matter.  Iron  is  not  dissolved  under  these  conditions,  even  in 
the  presence  of  large  amounts  of  organic  matter,  but  if  the  air  supply 
is  cut  off,  as  for  instance  in  case  the  pores  of  the  soil  are  fllled  with 
water,  the  solution  of  iron  is  sure  to  take  place.  The  iron  is  dissolved 
in  the  form  of  ferrous  salts,  usually  ferrous  carbonate.  When  ground 
waters  containing  iron  are  first  drawn  they  look  clear,  but  the  ferrous 


750  SANITARY    ANALYSIS    OF    WATER 

salts  in  solution  are  soon  oxidized  on  contact  with  the  air  to  insoluble 
ferric  salts,  wliich  are  precipitated  as  red  oxids. 

Iron  Pipes. — Nearly  all  waters  attack  iron  pipes,  corroding  them 
and  foiming  tubercles  on  the  inner  surface.  This  is  objectionable,  be- 
cause it  reduces  the  carrying  capacity  of  the  ])ipe  and  also  influences 
the  quality  of  the  water. 

Tubercles  are  formed  as  follows :  I'he  organic  matter  in  the  water 
settles  in  the  pipe  and  attacks  the  iron  through  a  blow  hole  or  other 
minute  opening  in  the  coating.  The  organic  ma  Iter  decomposes,  form- 
ing carbon  dioxid,  which  acts  upon  the  iron,  causing  some  of  it  to  go 
into  solution  as  ferrous  carbonate.  The  soluble  ferrous  carbonate  for 
the  most  part  passes  on  in  the  flowing  water,  but  some  of  it  becomes 
oxidized  by  the  oxygen  in  the  flowing  water  and  is  precipitated  as  the 
insoluble  ferric  carbonate  and  remains  at  the  surface  of  the  deposit. 
The  iron  precipitated  in  this  way  acts  as  a  coagulant  upon  the  organic 
matter  in  the  flowing  water  at  the  point  where  the  iron  is  precipitated. 
It  thus  attracts  the  organic  matter  from  the  flowing  water  and  binds  it 
to  that  previously  deposited  into  a  firm,  compact,  but  porous  mass,  and 
this  mass  is  the  beginning  of  a  tubercle.  The  process  is  continuous, 
though  slow.  Many  years  may  elapse  before  the  tubercle  reaches  the 
height  of  an  inch.  Tuberculation  starts  more  freely  and  progresses 
more  rapidly  in  waters  from  rivers  or  reservoirs  containing  suspended 
organic  matter.  It  is  less  troublesome  with  filtered  waters,  and  with  lake 
waters  relatively  free  from  such  suspended  nuitter.  Tuberculation  may 
be  prevented  by  improving  the  quality  of  the  water  or  by  thoroughly 
coating  the  inside  of  the  pipes  with  asphaltum  or  tar.  Cement-lined 
pipes  are  not  sul)ject  to  tuberculation,  but  have  defects  in  other  particu- 
lars. Wlien  the  ])rocess  has  advanced  far  it  may  he  corrected  by  pipe 
scrapers.  They  consist  of  appliances  driven  by  the  water  pressure 
through  the  pipes,  with  arrangements  to  scrape  off  the  tubercles.  This 
temporarily  restores  the  original  carrying  capacity  of  the  pipe,  but  the 
process  must  be  repeated  at  intervals.  It  has  the  disadvantage  of  also 
scraping  off  a  large  part  of  the  tar  coating  and  leaving  the  iron  of  the 
pipe  exposed  to  the  action  of  water  to  a  much  greater  extent.     (Hazen.) 

Water  that  passes  through  the  water-backs  of  the  kitchen  stove  to 
the  hot-water  tank  is  particularly  likely  to  collect  iron,  which  accumu- 
lates at  the  bottom  of  the  hot-water  tank.  This  deposit  may  accumulate 
for  days  and  even  weeks  until  some  unusual  draught  of  water  or  other 
disturbance  occurs — perhaps  on  washing  day.  When  this  happens  it  is 
very  objectionable. 

The  household  filter  is  the  most  convenient  and  satisfactory  means 
of  removing  iron  deposits  from  water  that  is  otherwise  good.  The  re- 
moval of  iron  from  a  city's  water  supply  is  a  distinct  process  rarely 
"combined  with   purification.     In  most  cases  iron  may  be  removed  by 


EXPRESSION    OF    CHEMICAL    EESULTS  751 

thoroughly  aerating  the  water  in  order  to  drive  off  the  excess  of  COo 
and  in  order  to  introduce  oxygen  necessary  to  oxidize  the  iron  from  the 
soluble  ferrous  state,  in  which  it  exists,  to  the  insoluble  ferric  state. 
The  precipitated  ferric  salts  can  then  be  removed  by  sedimentation  or, 
better,  by  filtration. 

LEAD 

Tests. — The  presence  of  lead  may  be  discovered  by  chemical  tests  or 
surmised  from  the  symptoms  of  lead  poisoning  among  those  who  use 
the  water.  In  the  amounts  present  it  does  not  affect  either  the  appear- 
ance or  taste  of  the  water. 

It  is  possible  to  determine  the  presence  of  lead  in  clear  water  and 
roughly  estimate  its  amount  by  acidifying  with  acetic  acid,  saturating 
with  hydrogen  sulphid  and  comparing  the  brown  tint  produced  with 
that  produced  by  standard  lead  solutions  contained  in  Nessler  tubes  simi- 
lar to  those  for  containing  the  sample  under  examination.  This  method 
is  not  applicable  if  the  water  is  colored  or  contains-  iron — in  this  case 
special  analytical  procedures  are  necessarj^. 

The  sample  of  water  used  for  testing  lead  should  be  the  first  portion 
(a  pint  or  less)  drawn  after  standing  at  least  one  hour  in  the  pipes. 

No  water  should  be  used  for  drinking  purposes  containing  even  a 
trace  of  lead,  for,  however  minute  it  is,  its  presence  in  the  water  indi- 
cates danger.  Very  often  the  sample  examined  will  not  represent  the 
daily  maximum.    For  lead  poisoning  and  its  relation  to  water  see  p.  810. 


EXPRESSION  OF  CHEMICAL  RESULTS 

Formerly  results  were  expressed  in  grains  per  gallon.  After  the 
introduction  of  the  metric  system  results  were  expressed  in  parts  per 
100,000,  but  now  results  are  commonly  expressed  in  parts  per  million. 
The  latter  method  has  the  advantage  that  1  milligram  is  .000,001  liter, 
and,  therefore,  1  milligram  in  1,000  c.  c.  :=  1  part  per  million.  A  liter 
or  a  fraction  thereof  of  the  water  to  be  analyzed  is  used,  which  greatly 
simplifies  the  calculations. 

Of  course,  the  assumption  is  made  that  a  liter  of  water  weighs  a 
kilogram.  This  is  sufficiently  accurate  for  potable  waters,  but  introduces 
an  error  where  mineral  waters  are  dealt  with  whose  specific  gravities  are 
appreciably  higher  than  unity.  In  such  cases  the  water  may  be  actually 
weighed,  or  else  the  weight  may  be  estimated  from  the  known  specific 
gravity  and  volume. 

The  results  expressed  in  parts  per  100,000  or  in  grains  per  gallon 


752 


SANITARY    ANALYSIS    OF   WATER 


may  be  transformed  to  parts  per  million,  or,  conversely,  by  the  use  of 
the  following  table: 


Parta  per 
100.000 


Parts  per 
1,000,000 


1  )E!Tain  per  U.  S.  gallon 1 .000 

1  grain  per  Imixrial  gallon 0.835 

1  part  per  100,000 0.585 

1  part  per  1,000,000 0.058 


1.71 
1.43 
1.00 
0.10 


17.1 

14.3 

10.0 

1.0 


CHAPTEE    III 
MICROSCOPICAL    EXAMINATION    OF   WATER 

The  chief  object  of  the  microscopic  examination  of  water  is  the  de- 
termination of  the  presence  or  absence  of  those  microorganisms  which 
produce  objectionable  tastes  and  odors.  In  certain  cases  the  determina- 
tion is  also  of  value  as  an  index  of  pollutions  or  as  a  guide  to  the  iden- 
tity of  the  water.  The  microscopical  organisms  comprise  the  Dia- 
tomacese,  Chlorophycese,  Cyanophyces,  Fungi,  Protozoa,  Eotifera,  Crus- 
tacea and  other  organisms  minute  in  size,  but  not  including  the  bacteria. 
Fragments  of  organic  matter,  broken-down  organisms,  zooglea,  etc., 
should  be  termed  amorphous  matter.  Clay,  silt,  oxid  of  iron,  and  mineral 
matter  in  general  are  not  included  under  amorphous  matter  and  are  not 
measured  by  microscopic  examination. 

The  term  "microorganisms"  as  used  by  the  water  analyst  includes 
all  organisms,  whether  plant  or  animal,  that  are  invisible  or  barely 
visible  to  the  naked  eye,  other  than  bacteria.  The  bacteria  are  set  apart, 
inasmuch  as  their  significance  and  the  method  of  studying  them  is  dif- 
ferent from  all  other  microscopic  organisms.  As  Whipple  aptly  phrases 
it,  "Bacteria  make  a  water  unsafe,  microorganisms  make  it  unsavory." 

Methods  of  Microscopical  Examination. — The  standard  method  of 
microscopical  examination  consists  in  concentrating  a  given  quantity  of 
water  (250  or  500  c.  c.)  by  filtration  through  sand.  A  straight  sided 
cylindrical  funnel  two  inches  in  diameter  for  the  first  nine  inches,  taper- 
ing to  one-half  inch  in  the  next  three  inches,  and  concluding  with  a 
one-half  inch  tube  two  and  one-half  inches  long,  is  used.  A  perforated 
rubber  stopper  (size  No.  1)  capped  with  a  circle  of  silk  bolting  cloth 
is  pressed  tightly  into  the  lower  end.  On  top  of  this  "about  five-eighths 
of  an  inch  of  prepared  sand  is  poured,  and  the  filter  is  then  ready  for  use. 

The  sand  used  is  quartz  sand,  washed  and  ignited,  and  of  such  a 
size  that  it  will  pass  through  a  sieve  having  60  meshes  to  the  square 
inch,  but  will  not  pass  a  120-mesh  sieve. 

When  all  the  water  has  passed  off  and  the  sand  begins  to  dry  the 
stopper  is  removed,  and  the  sand  washed  into  a  test  tube  with  five  cubic 
centimeters  of  distilled  water  from  a  pipette.  The  mixture  of  sand, 
organisms,  and  water  is  agitated  and  the  supernatant  suspension  de- 

753 


754        MICROSCOPICAL    EXAMINATION    OF   WATER 

canted  into  a  second  tube,  from  which  one  cubic  centimeter  is  withdrawn 
and  examined  in  a  counting  cell  of  that  capacity,  a  specially  ruled  ocular 
micrometer  and  a  %-inch  objective  being  used.  This  is  the  Sedgwick- 
Rafter  process. 

Significance  of  the  Examination. — The  microscopical  examination 
of  water  is  of  great  value  in  supplementing  the  chemical  and  bacterial 
analyses.  It  may  explain  the  cause  of  odors  and  tastes  in  a  water;  it 
may  explain  certain  chemical  determinations,  as  albuminoid  ammonia, 
dissolved  oxygen,  oxygen  consumed,  carbon  dioxid,  etc. ;  it  may  indicate 
sewage  contamination;  it  nuiy  suggest  the  state  of  self-purification  of 
a  polluted  water;  it  may  identify  the  source  of  the  water. 

Several  of  the  microscopic  organisms,  when  present  in  suflficient  quan- 
tities, give  rise  to  objectionable  odors  and  tastes,  either  when  in  a  vege- 
tative state  or  upon  decomposition.  The  natural  odors  of  organisms  are 
due  to  oils  analogous  to  the  essential  oils  as  in  peppermint  and  in  cer- 
tain fishes.  In  general,  the  diatoms  have  an  aromatic  odor,  increasing 
to  that  of  a  geranium  leaf,  and  even  to  an  intensity  that  is  fishy.  The 
cyanophycese,  or  blue-green  alga^  have  a  grassy  or  moldy  odor.  The 
chlorophyceaj  have  little  odor,  although  some  of  the  motile  forms  give 
rise  to  faintly  fishy  odors.  The  ciliated  protozoa  have  in  general  no 
odor.  Uroglena,  synura,  dinobryon,  and  peridinium  may  and  often  do 
give  rise  to  fishy  odors.  Of  the  other  microorganisms,  the  rotifera  and 
Crustacea,  no  forms  have  been  recorded  as  giving  rise  to  objectionable 
odors.  These  forms  are  present  only  when  there  are  lower  forms  upon 
whicli  to  feed.  Tliey  are  scavengers  and  as  such  may  be  considered 
as  desirable  elements  in  a  water.  Their  presence,  however,  calls  for 
an  investigation  of  the  nature  of  their  food  supply,  as  it  is  often 
furnished  by  pollution.  This  does  not  necessarily  hold  true  in  all 
cases. 

Besides  these  animal  and  plant  forms  there  may  be  present  also 
sponges,  mosses,  yeasts,  and  molds,  the  significance  of  which  is  varied 
and  dependent  upon  local  conditions. 


THE  BACTERIOLOGICAL   EXAMINATION 

Practically  all  natural  waters  contain  bacteria.  This  is  true  of  rain 
water,  ground  water,  and  the  waters  of  lakes,  rivers,  and  oceans.  The 
number  and  variety  of  the  bacteria  vary  greatly  in  different  places  and 
under  different  conditions.  The  bacteria  are  washed  into  the  water  from 
the  air,  from  the  soil,  and  from  almost  every  conceivable  object.  The 
intestinal  contents  of  animals  pollute  waters  with  enormous  numbers 
of  microorganisms,  but  it  is  the  infection  with  certain  species  from  man 
that  makes  water  most  dangerous  when  consumed  by  his  fellowmen. 


THE    BACTEEIOLOGICAL    EXAMINATION  755 


THE    NUMBER    OF    BACTERIA    IN    WATER 

The  number  of  bacteria  is  not  as  important  as  the  kind,  yet  much 
may  be  learned  from  a  simple  enumeration  of  the  bacteria.  Roughly 
speaking,  the  number  of  bacteria  in  water  corresponds  to  the  amount 
of  organic  pollution.  No  known  method  furnishes  a  complete  census 
of  the  bacterial  population  of  a  given  sample  of  water.  Methods  based 
upon  the  direct  microscopic  count  of  the  bacteria  do  not  distinguish  be- 
tween the  live  and  the  dead  ones;  further,  only  those  that  may  readily 
be  seen  by  simple  methods  are  thus  visible.  Many  bacteria,  especially 
those  pathogenic  for  man,  do  not  vegetate  at  20°  C,  so  that  the  usual 
counts  upon  gelatin  may  vary  greatly  from  those  obtained  upon  agar 
at  37°  C.  Some  varieties  require  acid,  others  alkaline  media;  some  are 
aerobic,  others  anaerobic ;  some  will  not  grow  unless  the  medium  contains 
blood  or  other  suitable  pabulum,  and  so  on  through  a  wide  gamut  of 
conditions. 

Although  it  is  not  possible  to  determine  the  total  number,  inferences 
of  importance  may  be  drawn  from  the  differences  in  the  numbers  of 
bacteria  in  a  given  water  obtained  by  different  methods.  Thus  a  water 
containing  great  numbers  of  bacteria,  when  counted  upon  gelatin  at 
20°  C,  and  but  few  colonies  upon  agar  at  37°  C,  has  little  sanitary 
significance,  whereas  a  water  containing  few  bacteria,  but  most  of  them 
varieties  that  grow  upon  agar  at  37°  C,  with  relatively  few  at  20°  C, 
must  be  looked  upon  with  suspicion.  The  distinction  between  polluted 
waters  and  waters  of  good  quality  is  more  sharply  marked  by  counts  at 
37°  C.  than  is  the  case  with  counts  at  20°  C.  Another  advantage  of 
growing  the  plates  at  a  higher  temperature  is  that  the  results  are  avail- 
able in  a  much  shorter  time. 

The  number  of  bacteria  which  grow  at  40°  C.  are  of  special  value, 
since  this  class  includes  the  typhoid  bacillus  and  other  water-borne 
pathogens,  but  excludes  the  common  water  bacteria  of  little  sanitary  im- 
portance. The  significance  of  acid-producing  bacteria  which  grow  at 
40°  C.  upon  litmus  lactose  agar  is  a  well-known  method  in  differentiating 
and  determining  the  number  of  organisms  belonging  to  the  colon  type 
in  a  water. 

From  Germany  we  have  the  arbitrary  standard  based  upon  the  dic- 
tum of  Koch  that  a  good  water  should  not  contain  over  100  bacteria 
per  c.  c.  This  is  a  good  working  rule,  but  should  not  be  taken  too  liter- 
ally. Thus,  water  may  contain  great  numbers  of  the  common  aquatic 
bacteria  which  vegetate  at  room  tem^perature  and  which  are  not  harmful 
to  man.  Surface  waters  contain  the  greatest  numbers  on  account  of 
exposure  to  contamination  to  which  they  are  liable ;  rain  waters  contain 
comparatively  few,  excepting  the  first  shower  through  a  very  dusty  at- 


756         MICROSCOPICAL   EXAMINATION    OF    WATER 

mosphere;  ground  waters  from  the  depths  are  practically  sterile.  Un- 
polluted shallow  well  waters  are  also  exceptionally  free.  The  number 
and  significance  of  the  bacteria,  therefore,  vary  with  the  source  of  tlie 
water.  For  example,  a  hundred  bacteria,  including  a  few  colon  bacilli, 
in  a  well  water  would  be  regarded  with  great  suspicion,  whereas  a  hun- 
dred or  more  bacteria,  witli  an  occasional  colon  l)acillus.  in  a  river  water 
draining  an  uninhabited  watershed  would  be  normal. 

The  number  of  bacteria  in  water  depends  somewhat  uj)on  the  man- 
ner in  which  it  is  stored.  Thus  a  water  containing  a  few  organisms 
placed  in  a  closed  bottle  and  kept  at  room  temperature  may,  at  the  end 
of  24  hours,  contain  hundreds  or  thousands  per  c.  c.  I  once  examined 
a  deep  well  water  that  was  practically  sterile  as  it  came  out  of  the  earth, 
but  when  stored  in  a  cistern  gave  over  a  thousand  organisms  per  c.  c. 
These  came  from  the  multiplication  of  the  bacteria  that  entered  the 
water  from  the  air,  dust,  leaves,  and  other  sources.  On  the  other  hand, 
water  stored  in  impounding  reservoirs  shows  a  marked  diminution  in 
the  number  of  bacteria. 

The  numerical  determination  of  bacteria  in  water  is  of  very  great 
value  when  studying  surface  waters,  such  as  lakes  and  rivers.  As  a 
rule,  the  number  of  bacteria  is  proportional  to  the  pollution  of  a  river — 
not  necessarily  fecal  pollution,  but  pollution  from  dead  organic  matter 
of  one  kind  or  another.  The  bacterial  content  of  a  river  water  varies 
sharply  from  time  to  time.  Contrary  to  the  usual  opinion,  a  river  con- 
tains more  bacteria  in  the  winter  time  than  in  the  warm  weather.  Dur- 
ing times  of  freshets  or  turbidity  the  number  of  bacteria  will  rise  very 
abruptly.  In  other  words,  the  number  of  bacteria  in  a  stream  is  an 
index  of  its  turbidity.  It  is  an  interesting  fact  that  in  the  Potomac  and 
other  rivers  the  bacterial  curve  does  not  correspond  to  the  typhoid  fever 
curve.  Typhoid  in  Washington  is  highest  in  summer,  but  the  bacteria 
are  most  numerous  in  winter.  While  sudden  variations  in  the  number 
of  bacteria  have  a  ready  explanation  in  the  case  of  turbid  and  torrential 
rivers,  in  the  case  of  lakes,  and  especially  in  a  ground  water,  variation 
in  numbers  indicates  nearby  sources  of  pollution  and  is  a  danger  signal. 
For  shallow  wells  the  interpretation  of  numbers  is  not  so  easy,  largely 
because  infection  may  enter  at  the  surface.  Wells  which  are  poorly  pro- 
tected at  the  top  will  always  show  an  unusually  large  number  and  variety 
of  bacteria. 

Numerical  determination  is  also  of  importance  in  tracing  imperfec- 
tions and  leaks  in  a  water  supply.  Thus  Dr.  Shuttleworth,  of  Toronto, 
was  able  through  this  means  to  suspect  a  broken  water  main,  and  upon 
examination  it  was  found  that  a  whole  section  of  the  conduit  had 
dropped  out  of  place,  so  that  the  supply  was  being  taken  from  the  lake 
near  the  shore  instead  of  some  distance  away  where  the  intake  was 
located. 


THE    BACTERIOLOGICAL    EXAMINATION  757 

The  great  value  of  the  numerical  estimate  of  bacteria  is  well  known 
in  determining  the  efficiency  of  filters. 

Method  for  Determining  the  Number  of  Bacteria  in  Water. — Collec- 
tion OF  THE  Sample. — For  a  complete  physical,  chemical,  and  mi- 
croscopical analysis  of  water  one  gallon  is  necessary.  If  the  sample  has 
been  collected  in  a  sterile  container  with  bacterial  precautions,  the  same 
sample  may  serve  for  the  bacteriological  examination.  Usually  the  bac- 
teriological samples  are  collected  separately  in  special  bottles  holding  2 
ounces. 

The  bottles  should  be  of  hard,  clear  white  glass  and  have  a  glass 
stopper.  They  should  be  chemically  clean  and  sterilized  at  160°  C.  for 
1  hour,  or  in  the  autoclave  at  115°  C.  for  15  minutes.  For  transpor- 
tation they  may  be  wrapped  in  sterile  cloth  or  paper,  but,  better,  the 
neck  may  be  covered  with  tinfoil  and  the  bottle  placed  in  a  tin  box. 
When  bacterial  samples  must  of  necessity  stand  12  hours  before  plating, 
bottles  holding  more  than  4  ounces  should  be  used.  Cork  stoppers  should 
never  be  permitted,  except  when  physical  or  microscopical  examination 
only  is  to  be  made.  Earthen  jugs  and  metal  containers  are  entirely 
unsuited. 

The  water  should  be  examined  as  soon  after  collection  as  practicable. 
Generally  speaking,  the  shorter  the  time  elapsing  between  the  collection 
and  analysis,  the  more  reliable  will  be  tlie  analytical  results.  If  too  long 
a  time  intervenes,  it  affects  especially  the  bacterial  tests,  for  bacteria 
multiply  enormously  when  water  is  kept  in  a  bottle  at  ordinary  tem- 
perature. The  oxygen  consimied,  oxygen  required,  and  nitrites  are  also 
materially  affected  by  comparatively  short  delay. 

Care  should  be  taken  to  secure  a  sample  which  is  thoroughly  repre- 
sentative of  the  water  to  be  analyzed.  A  pump  should  be  operated  five 
minutes,  or  water  faucet  allowed  to  run  several  minutes,  before  the 
bottle  is  filled.  In  collecting  samples  of  surface  waters  the  specimen 
should  not  be  obtained  too  near  the  bank  of  the  stream  or  pond.  A  note 
should  be  made  as  to  whether  the  specimen  is  collected  from  the  surface 
or  at  what  depth  under  the  surface  it  is  taken.  It  is  always  advisable 
to  take  the  temperature  of  the  water  at  the  time  of  collection. 

Bacteriological  Method. — The  standard  medium  for  determin- 
ing the  number  of  bacteria  in  water  is  a  nutrient  gelatin  having  a  re- 
action of  -|-1  per  cent.,  using  phenolphthalein  as  an  indicator.  The 
gelatin  is  made  by  using  distilled  water  and  an  infusion  of  fresh  lean 
meat,  and  not  meat  extract.  The  sodium  chlorid  is  omitted.  The  me- 
dium contains  1  per  cent,  of  Witte's  peptone  and  10  per  cent,  of  gelatin. 

The  sample  of  water  must  be  shaken  vigorously  at  least  25  times 
in  order  to  break  up  the  bacterial  clusters  and  to  obtain  a  uniform  sus- 
pension. If  the  water  contains  less  than  200  bacteria  per  c.  c,  1  c.  c.  of 
it  may  be  placed  directly  in  the  petri  dish,  then  add  10  c.  c.  of  the 
50 


758         MICROSCOPICAL    EXAMINATION    OF    WATER 

standard  gelatin.  Mix  well,  congeal,  and  incubate  at  20°  C.  for  48 
hours  in  a  dark,  well-ventilated  incubator  wbere  the  atmosphere  is  prac- 
tically saturated  with  moisture.  If  there  is  reason  to  believe  that  the 
number  of  bacteria  is  more  than  200  per  c.  c,  dilute  by  mixing  1  c.  c. 
of  the  sample  with  9  c.  c.  of  sterilized  tap  or  distilled  water.  Again 
shake  25  times  and  plate  1  c.  c.  of  the  dilution.  Higher  dilutions  may 
be  made  in  99  c.  c.  and  so  on.  In  the  case  of  an  unknown  water  or 
sewage  it  is  customary  to  use  several  dilutions  of  the  same  sample. 
Count  the  colonies  upon  a  Wolffluegel  apparatus  or  a  Jeffcr's  plate.  A 
successful  })late  should  contain  not  more  than  200  colonies.  The  whole 
number  of  colonies  on  a  plate  should  be  counted,  the  practice  of  count- 
ing a  fractional  part  being  resorted  to  only  in  cases  of  necessity. 

When  agar  is  used  for  plating  it  will  be  found  advantageous  to  use 
petri  dishes  with  porous  earthenware  covers  in  order  to  avoid  the  spread- 
ing of  colonies  by  the  water  of  condensation. 

In  order  to  avoid  fictitious  accuracy  and  yet  express  the  numerical 
results  by  a  method  consistent  with  the  precision  of  the  work,  the  table 
below  should  be  followed  in  expressing  the  numbers  of  bacteria  per  c.c. : 

From  1  to  50  recorded  as  found 

"  51  "  100  " 

«  101  "  250  " 

«  251  "  500  " 

"  501  "  1,000  " 

«  1,001  "  10,000  " 

«  10,001  "  50,000  " 

"  50,001  "  100,000  " 

"  100,001  "  500,000 

"  500,001  "  1,000,000 

"  1,000,001  "  10,000,000 

KINDS    OF    BACTERIA    IN    WATER 

Water  analysis  is  in  its  infancy  so  far  as  methods  for  determining 
the  kinds  of  bacteria  are  concerned.  It  is  comparatively  easy  to  isolate 
colon  bacilli  and  to  determine  their  approximate  number  in  a  water. 
It  is  also  comparatively  easy  to  isolate  cholera  vibrio.  Methods  for  de- 
termining whether  a  water  does  or  does  not  contain  typhoid,  dysentery, 
and  other  pathogenic  parasites  are  tedious,  difficult,  and  often  impossible 
in  the  present  state  of  our  knowledge. 

A  certain  amount  of  information  may  be  gleaned  from  the  presence 
and  number  of  organisms  belonging  to  certain  groups,  such  as  chromo- 
genic,  liquefying,  and  fermenting  types.  Chromogenic  organisms  exist 
everywhere  in  surface  waters.  They  should  be  practically  absent  from 
ground  waters.  The  same  is  true  of  organisms  that  are  able  to  liquefy 
gelatin  and  ferment  sugars.    The  chromogenic,  proteolytic  and  ferment- 


to 

the 

nearest 

5 

a 

10 

i( 

25 

(C 

50 

« 

100 

<< 

500 

i( 

1,000 

li 

10,000 

u 

50,000 

ii 

100,000 

THE    BACTEEIOLOGICAL    EXAMIXATIOX  759 

ing  types  are  widespread  in  nature  and  exist  almost  everj-where  in  the 
air^,  the  soil,  and  in  surface  waters.  Their  presence  in  a  ground  water 
signifies  contamination  or  pollution,  often  from  the  surface. 

The  significance  of  the  various  types  of  bacteria  that  grow  at  dif- 
ferent temperatures  has  already  been  discussed. 

THE  COLON  BACILLUS 

The  colon  bacillus  is  very  widely  distributed  in  nature.  Its  normal 
habitat  may  be  regarded  as  the  intestines  of  man  and  many  other  ani- 
mals. It  even  exists  in  some  plants.  The  colon  bacillus  is  usually  taken 
as  an  index  of  pollution.  The  sanitary  significance  of  colon  bacilli  in 
water  varies  with  their  number  and,  further,  with  their  source.  While 
the  colon  bacillus  indicates  pollution,  it  does  not  necessarily  signify 
danger,  that  is,  infection. 

By  common  consent  a  ground  water  should  be  condemned  if  it  con- 
tains even  a  few  colon  bacilli,  for  these  organisms  have  no  business  in 
a  soil-filtered  and  properly  protected  well  or  spring  water.  Surface 
waters  are  not  regarded  as  particularly  suspicious,  provided  they  have 
not  more  than  one  colon  bacillus  per  c.  c,  especially  if  the  surface  water 
is  known  to  drain  an  uninhabited  or  controlled  catchment  area,  llany 
of  the  colon  bacilli  in  a  surface  water  come  from  the  droppings  of  wild 
and  domestic  animals  and,  therefore,  are  infinitely  less  indicative  than 
those  that  come  from  the  intestinal  tract  of  man.  The  source  of  the 
colon  bacillus  can  only  be  determined  by  an  inspection  of  the  watershed. 
A  water  containing  10  colon  bacilli  or  more  per  c.  c.  should  be  regarded 
as  grossly  polluted  and  very  likely  to  contain  infection.  Tests  for  the 
colon  bacilli  in  water  must,  therefore,  be  qualitative  and  quantitative. 

The  absence  of  colon  bacilli  in  water  proves  its  harmlessness  so  far 
as  bacteriology  can  prove  it.  It  is  fair  to  assume  that  typhoid  bacilli, 
dysentery  bacilli,  and  other  intestinal  parasites  could  not  be  present  in 
a  water  in  the  absence  of  the  colon  bacillus.  It  is  possible  to  conceive 
that  in  rare  instances  a  water  may  be  polluted  with  urine  alone  contain- 
ing t^'phoid  bacilli,  but  no  colon  bacilli. 

Presumptive  Tests  for  the  Colon  Bacillus. — Presumptive  tests  or 
partial  tests  are  sometimes  used  to  determine  the  presence  of  B.  coli. 
These  tests,  while  unreliable,  sometimes  afford  useful  information.  They 
consist,  as  a  rule,  in  planting  small  quantities  of  the  water  sample  in 
lactose  bile  or  lactose  bouillon  in  fermentation  tubes  and  incubatino-  at 
40°  C.  Under  these  circumstances  it  may  be  presumed  that  in  the  ab- 
sence of  fermentation  colon  bacilli  are  absent,  and  that  fermentation 
with  gas  production  indicates  their  presence.  Both  these  conclusions 
may  be  misleading.  Grossly  polluted  waters  containing  many  colon 
bacilli  may  be  slow  in  fermenting  sugars  with  the  production  of  gas  on 


760         MICROSCOPICAL    EXAMINATION    OF    WATER 

account  of  the  preponderance  of  other  more  active  species.  On  the  other 
hand,  many  organisms  other  than  the  colon  bacillus  often  found  in  water 
ferment  sugars  with  gas  production.  It  is  therefore  necessary  to  isolate 
the  suspected  organism  in  pure  culture  and  pass  it  through  the  well- 
known  tests  before  it  is  labeled  B.  coli. 

QiTALiTATiVE  Methods. — Isolation. — It  is  comparatively  easy  to  iso- 
late the  colon  bacillus  in  pure  culture.  Before  an  organism  is  labeled 
B.  coli  it  should  correspond  to  the  following:  It  should  be  a  relatively 
small,  non-sporc-bearing  rod  having  rather  sluggish  or  no  motion;  it 
should  not  liquefy  gelatin;  it  should  ferment  dextrose  broth  with  the 
formation  of  about  50  per  cent,  gas,  one-third  of  which  should  be  carbon 
dioxid  and  two-thirds  hydrogen;  it  should  coagulate  milk,  with  the  pro- 
duction of  acid  at  37°  C,  but  without  liquefaction  of  the  coagulum. 
This  coagulation  should  occur  either  spontaneously  or  on  boiling;  it 
should  produce  nitrite  and  iudol  in  peptone  solution  and  reduce  nitrates. 

To  isolate  B.  coli  the  following  method  is  satisfactory.  Either 
plate  the  water  directly  upon  lactose  litmus  agar  and  fish  the  red  colo- 
nies, or  plate  directly  upon  Endo's  medium  and  fish  the  red  colonies. 
An  enriching,  and  hence  a  surer,  method,  especially  where  there  are  very 
few  colon  bacilli  in  a  water,  is  first  to  plant  the  water  in  fermentation 
tubes  containing  lactose  or  dextrose  broth,  incubate  at  37°  to  40°  C.  As 
soon  as  gas  production  is  noted  plate  a  small  quantity  of  the  growth 
upon  lactose  litmus  agar  or  Endo's  medium  and  study  the  red  colonies 
for  cultural  and  morphological  characters. 

The  number  of  colon  bacilli  in  a  water  may  be  determined  by  several 
methods : 

(1)  The  Fermentation  Test. — Add  measured  quantities  of  the 
water  sample  to  fermentation  tubes  containing  lactose  broth.  Ordi- 
narily 0.1,  1.0,  and  10  c.  c.  of  water  are  used  in  this  test.  If  the  water 
is  highly  polluted  smaller  quantities,  such  as  0.01  or  0.001  of  a  cubic 
centimeter,  should  be  used.  If  in  such  a  series  fermentation  with  gas 
production  occurs  in  the  tubes  containing  1  c.  c.  or  more,  but  does  not 
take  place  in  the  tubes  containing  the  smaller  portions,  it  may  then  be 
stated  that  the  water  contains  at  least  one  colon  bacillus  per  cubic  centi- 
meter, provided  the  isolation  tests  show  that  the  fermentation  was 
caused  by  this  organism. 

(2)  The  number  of  colon  bacilli  may  be  determined  approximately 
by  planting  the  water  directly  upon  the  surface  of  lactose  litmus  agar  or 
Endo's  medium.  The  red  colonies  should  then  be  studied  to  determine 
how  many  of  them  are  B.  coli,  and  the  number  may  thus  be  approxi- 
mated per  cubic  centimeter. 


THE    BACTERIOLOGICAL   EXAMINATION  761 


SEWAGE  STREPTOCOCCI 

Fresh  sewage  from  man  and  other  mammalian  animals  usually  con- 
tains streptococci  resembling  the  Streptococcus  pyogenes.  These  intes- 
tinal cocci,  which  are  known  as  sewage  streptococci,  grow  more  readily 
than  the  pyogenic  varieties,  and  produce  a  pinkish  colony  on  lactose 
litmus  agar  at  37°  C,  by  which  their  presence  and  number  may  be  de- 
tected in  water.  These  streptococci  are  not  hardy,  and  therefore  when 
found  in  a  water  represent  immediate  pollution.  The  general  consensus 
of  opinion  is  that  the  occurrence  of  these  organisms  in  a  water  seems 
to  be  of  less  value  than  in  the  case  of  B.  coli,  and  the  streptococcus 
test  is  therefore  of  subordinate  importance. 

TYPHOID   BACILLUS 

The  search  for  a  typhoid  bacillus  in  water  is  frequently  like  looking 
for  a  needle  in  a  haystack.  It  is  probable  that  the  typhoid  bacillus 
rarely,  if  ever,  multiplies  in  natural  waters.  The  dilution  is  usually 
enormous,  and  their  number  is  therefore  comparatively  few.  With 
modern  methods  and  the  use  of  Endo's  medium  it  is  comparatively  easy 
to  isolate  typhoid  bacilli  from  water  richly  seeded  with  these  organisms, 
but  it  is  practically  a  hopeless  task  to  find  them  when  there  are  only  a 
few  in  a  glassful.  Great  care  must  be  exercised  before  an  organism 
isolated  from  water  is  reported  as  B.  typhosus.  There  are  many  or- 
ganisms in  water  closely  resembling  typhoid,  some  of  them  even  giving 
pronounced  agglutination  with  specific  serum.  Thus  B.  proteus,  B. 
fluorescens,  and  even  B.  coli  sometimes  agglutinate  with  typhoid  serum 
and  in  higher  dilutions  than  typhoid  strains  themselves.  An  interesting 
instance  of  this  was  found  in  our  studies  of  the  Potomac  River  water. 
Frost  isolated  an  organism,  the  "Pseudomonas  protea,"  from  the  filtered 
Potomac  River  water  which,  during  the  months  of  August,  September, 
and  October,  1909,  was  more  common  than  B.  coli.  This  organism 
could  not  be  found  in  the  raw  water,  nor  could  it  be  found  in  a  large 
number  of  stools  examined,  which  points  to  a  saprophytic  existence. 
This  organism  may  readily  be  distinguished  from  B.  typhosus,  in  that 
it  has  dijfferent  cultural  characters,  and  further  that  animals  injected 
with  cultures  of  Pseudo7nonas  protea  develop  agglutinins  for  this  or- 
ganism, but  not  for  B.  typhosus. 

CHOLEEA 

The  cholera  vibrio  may  be  detected  in  water  by  making  a  Dunham's 
solution  of  the  water  itself;  that  is,  to  a  large  quantity  of  the  water 
sample  add  sufficient  peptone  to  make  a  1  per  cent,  solution,  and  render 
slightly  alkaline  with  sodium  carbonate.    The  water  should  be  placed  in 


762         MICKOSCOPICAL    EXAMINATION    OF    WATER 

Erlenmeyer,  Fernbach,  or  similar  flasks,  presenting  a  large  surface 
favoring  aerobic  development.  The  flasks  are  then  placed  in  the  thermo- 
stat at  37°  C.  and  in  16,  18,  24  hours,  or  longer,  a  loopful  of  the  sur- 
face growth  is  planted  upon  agar,  Endo's  medium,  or  gelatin.  Cholera 
colonies  upon  gelatin  have  a  ground-glass  appearance  when  examined 
under  a  low  power  of  the  microscope,  with  irregular  margins,  and  the 
gelatin  is  slowly  liquefied.  Upon  agar  the  colonics  are  not  particularly 
distinctive;  upon  the  surface  of  Endo's  medium  cholera  grows  as  faintly 
pinkish,  moist,  translucent  colonies,  not  unlike  typhoid  colonies,  except- 
ing that  they  have  slightly  more  color.  Dependence  cannot  be  placed 
upon  the  appearance  of  the  colonies  nor  upon  the  morphological  charac- 
teristics of  the  organism.  Suspicious  colonies  should  be  isolated  and 
tested  with  an  agglutinating  serum  of  known  specificity  having  a  high 
agglutinating  value.  All  organisms  that  are  agglutinated  with  this 
serum  in  a  dilution  of  1-1,000  or  over  may  be  regarded  as  cholera.  This, 
however,  should  not  be  accepted  as  final,  for,  as  is  the  case  with 
typhoid,  there  are  numerous  cholera-like  organisms  in  water  that  agglu- 
tinate with  a  cholera  senmi,  but  which  upon  further  study  have  charac- 
teristics which  plainly  show  that  they  are  not  the  organism  which  causes 
cholera.  Final  dependence  should  be  placed  upon  Pfeiffer's  phenome- 
non and  upon  cross-agglutinating  tests  or  absorption  tests  to  eliminate 
the  phenomenon  of  group  agglutination. 


CHAPTEE  IV 
INTERPRETATION   OF    SANITARY   WATER   ANALYSIS 

The  interpretation  of  a  sanitary  water  analysis  is  much  more  diffi- 
cult than  the  analysis  itself,  where  everything  may  be  carried  out  by 
rule  of  thumb  in  accordance  with  standard  procedures.  Single  or  occa- 
sional determinations  of  either  the  chemical  or  bacterial  properties  of 
water  are  of  little  value.  A  single  water  analysis  is  often  misleading, 
especially  in  surface  waters,  which  may  vary  greatly  from  time  to  time. 
A  river  water  may  require  repeated  examinations  extending  over  long 
periods  of  time  correlated  with  conditions  of  rainfall,  stream  flow, 
wind,  temperature,  sewage  pollution,  and  other  factors  in  order  to  be 
helpful. 

There  have  been  much  conflict  and  useless  discussion  between  chem- 
ists and  bacteriologists  concerning  the  relative  advantages  of  their 
methods.  The  chemists  were  first  in  the  field,  but  the  limitations  of 
chemical  methods  were  strongly  emphasized  when  it  was  shown  that 
chemistry  can  only  indicate  pollution  but  cannot  discover  infection. 
Much  was  hoped  from  bacteriology,  but  it  is  rather  exceptional  that 
bacteriologists  are  able  to  isolate  pathogenic  microorganisms  from  a 
sample  of  water.  For  the  most  part,  the  routine  bacteriological  exam- 
ination of  water  does  nothing  more  than  the  chemical  examination,  that 
is,  it  shows  pollution  but  does  not  prove  infection.  Both  chemical 
and  bacterial  analyses  of  water  have,  therefore,  distinct  limitations; 
they  do  not  antagonize,  but  supplement  each  other.  From  the  chemical 
side  we  learn  much  of  the  past  history  of  a  water;  the  bacteriology  tells 
us  more  of  its  present  state.  Chemical  methods  reign  supreme  when  we 
desire  to  discover  the  presence  of  lead  or  other  inorganic  poisons;  also 
in  determining  the  hardness,  mineral  and  organic  constituents,  etc. 
From  the  number  and  character  of  the  bacteria  in  water  we  obtain  a 
fair  index  of  the  presence  and  degree  of  pollution.  Occasionally  bac- 
teriologists may  determine  whether  a  water  contains  certain  specific 
agents,  such  as  cholera  vibrio.  It  must,  however,  be  admitted  that  the 
ordinary  routine  chemical  and  bacterial  examination  of  water  affords 
but  meager  information,  especially  when  only  one  analysis  has  been 
made.    Fortunately,  the  inferences  drawn  from  a  sanitary  water  analysis 

763 


764        INTERPRETATION    OF    SANITARY    ANALYSIS 

are  on  the  safe  side,  as  many  good  waters  are  condemned,  so  that  it 
would  be  very  difficult  for  an  unsafe  water  to  pass  the  muster  of  a 
complete  sanitary  analysis.  At  most,  the  information  furnished  is 
only  of  present  conditions  and  is  not  a  guarantee  of  future  safety.  A 
surface  water  or  a  ground  water  may  to-day  be  exceptionally  free  from 
chemical  impurities  and  practically  sterile  bacteriologically,  whereas 
to-morrow  it  may  contain  typhoid,  dysentery,  cholera,  or  other  water- 
borne  infections;  these  may  come  from  sources  that  would  at  once  be 
perfectly  evident  from  a  sanitary  survey  of  the  watershed. 

A  sanitary  survey  of  the  catchment  area  is  frequently  of  much 
greater  practical  importance  than  all  the  information  furnished  by 
the  laboratory.  It  needs  neither  chemists  nor  bacteriologists  to  tell 
us  that  the  water  from  a  creek  with  an  overhanging  privy  a  short 
distance  above  will  some  day  carry  infection;  or  that  the  water  from  a 
shallow  well  in  limestone  or  coarse  gravel  very  near  a  leaking  cess- 
pool must  be  a  source  of  danger.  A  sanitary  survey  is  able  to  discover 
the  sources  of  contamination,  the  kinds  of  pollution,  and  the  degree, 
often  with  greater  precision  than  combined  chemical  or  bacteriological 
tests.  No  sanitary  analysis  of  a  water  can  therefore  be  considered  com- 
plete unless  it  includes  an  examination  of  the  watershed  and  a  study 
of  the  geolog}'  and  topography  of  the  catchment  area. 

From  a  sanitary  standpoint,  the  principal  substances  to  look  for  in 
a  chemical  analysis  are  the  organic  matter,  nitrates,  nitrites,  and  chlorin. 
Of  these  the  nitrites  are  the  greater  danger  signal,  indicating  oxidation 
of  organic  matter  through  bacterial  activity.  High  chlorin  and  nitrates 
without  nitrites  indicate  passed  or  remote  pollution;  this  is  a  frequent 
combination  in  ground  waters.  The  ammonias  (free  and  albuminoid) 
are  a  measure  of  the  amount  of  nitrogenous  organic  matter  in  the  water. 
A  surface  water  may  safely  contain  an  amount  of  albuminoid  ammonia 
that  would  be  suspicious  in  a  ground  water.  The  significance  of  the 
chlorin  varies  with  the  location  and  source  of  the  water.  Ground  waters 
should  contain  fewer  bacteria  than  surface  waters.  Artesian  wells  should 
be  practically  sterile,  and  a  good  surface  water  should  not  contain  over 
100  bacteria  per  cubic  centimeter.  Waters  that  vary  in  composition 
from  time  to  time  without  evident  cause  must  be  regarded  as  unsafe. 
This  applies  particularly  to  ground  waters.  Surface  waters  vary  greatly 
as  the  result  of  freshets,  etc.,  but  a  ground  water,  pond,  or  lake  should 
show  no  such  sudden  variations. 

These  general  statements  may  be  quite  misleading  when  interpret- 
ing the  analysis  of  a  specific  case.  Thesefore  several  selected  analyses 
and  interpretations  have  been  given  below. 

Allowable  Limits. — The  following  are  sometimes  considered  as  the 
allowable  limits  of  the  impurities  commonly  regarded  as  permissible  in 
drinking  water : 


SELECTED    ANALYSIS  765 

Free  ammonia 0.015-0.03  part    per    million 

Albuminoid  ammonia 0.07  -0.35       "       "         " 

Nitrogen  as  nitrites None,  or  at  most  a  trace  (0.0004) 

Nitrogen  as  nitrates 0.16  -0.3-(- 

Chlorin  depends  upon  the  normal  chlorin  content  of  unpolluted  sur- 
face waters  in  the  neighborhood. 

Bacteria  not  over  100  per  cubic  centimeter. 

Colon  bacillus  should  be  absent  from  the  ground  water.  Not  more 
than  1  per  10  c.  c.  in  a  stream  or  in  a  river  water. 

These  figures  must  not  be  taken  literally,  and  are  not  given  as 
standards  of  purity,  but  the  maximum  limits  of  the  impurities  allowable 
under  ordinary  conditions.  It  will  be  seen  from  the  illustrative  analyses 
given  below  that  at  times  these  limits  may  be  exceeded  without  sanitary 
significance,  whereas  at  other  times  a  water  well  within  the  prescribed 
limits  may  contain  infection. 


Much  Organic  Matter 
"      CI 
"     NO  2      &    NOz 

Few  or  No  Bacteria 


Few  or  No  Bacteria 


Fig.  104. — Diagram  Illustrating  the  Character  of  the  Ground  Water  in  Rela- 
tion TO  Soil  Pollution,  to  Assist  the  Interpretation  of  a  Sanitary  Analysis. 
(See  also  Nitrogen  Cycle,  page  676.) 

For  a  better  understanding  a  number  of  sanitary  analyses  of  water 
are  given  with  an  interpretation.  The  student  is  advised  first  to  study 
the  analyses,  draw  his  own  conclusions,  and  then  compare  them  with  the 
interpretation  given. 

Analysis  No.  1 — Gross  Pollution 

Free  ammonia 0.214  part  per  million 

Albuminoid  ammonia   0.810  "  "         " 

Nitrogen  as  nitrites 0.005  "  "         " 

Nitrogen   as   nitrates 21.0  parts  "         " 

Chlorin    47.0  "  "        " 


766        INTKRPlJETxVTlON    OF    SANITAEY    ANALYSIS 

Total  residue   412.0        parts   per  million 

Volatile    residue    279.0  "        " 

Fixed  residue    133.0  "       "        " 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 65,000 

Bacteria  per  c.  c.  upon  agar  at  37°  C 120,000 

Many  liquefying  colonies.  Many  ehromogens  per  c.  c.  Fer- 
mentation in  lactose  bouillon  in  0.001  c.  c.  B.  coli  present  in 
0.01  c.  c. 

This  represents  a  c^rossly  polluted  water  and  should  unhesitatingly 
be  condemned,  no  matter  what  its  source. 

The  following  analysis  of  the  Hamburg  public  supply  from  the 
Elbe  Eiver  during  the  cholera  epidemic  of  1892  is  given  in  Chemical 
News,  LXVI,  144: 

Analysis  No.  2 — Elbe  River  During  Cholera  Epidemic 

Appearance Turbid  and  very  yellow. 

Taste Slightly  unpleasant. 

Odor Extremely  little. 

Deposit Small  and  dirty-looking. 

Chlorin 

Free  ammonia 

Albuminoid  ammonia 

Nitrates 

Required  oxj'gen  (15  minutes) .  . , 

Required  oxygen  (4  hours) 

Total  solids.  .^ 1,160.7         "  " 

This  is  given  simply  as  an  instance  of  a  grossly  polluted  river 
(Elbe)  water,  known  to  be  infected. 

Analysis  No.  3 — Boston  Tap,  Typical  (not  averaged  results) 

Free  ammonia  

Albuminoid  ammonia   

Nitrogen  as  nitrites 

Nitrogen  as  nitrates 

Chlorin   

Total  residue   

Volatile  residue   

Fixed   residue    

Hardness,  13°. 
Bacteria  per  c.  c.  upon  gelatin  at 

B.  coli  None 

This  is  a  surface  water,  collected  in  impounding  reservoirs  and 
stored  about  30  days  before  it  reaches  the  consumer.     The  watershed 


472.0       per 

million 

1.065     " 

0.293     " 

26.43       " 

0.928     " 

3.428     " 

0.010 

part 

per 

million 

0.114 

ii 

iC 

u 

0.000 

(I 

a 

ii 

0.02 

u 

11 

a 

2.7 

parts 

u 

a 

27.0 

u 

(( 

a 

10.0 

ct 

11 

li 

17.0 

(( 

li 

(( 

'C 

...     77 

SELECTED    AXALYSES  767 

is  fairly  well  protected.  The  ehemical  analysis  shows  little  organic 
pollution;  the  ammonias  are  moderate  in  amount,  nitrites  absent; 
nitrates  low;  chlorin  normal;  bacteria  indicate  nothing  suspicious.  The 
water  is  of  good   sanitary  quality,   judged  by   ehemical    and  bacterial 

analysis. 

Analysis  Xo.  -i — A  Suspicious  ^Yater 

Free  ammonia    0.018  part  per  million 

Albimiinoid  ammonia    0.020  "  "  " 

Nitrogen   as  nitrites 0.007  "  "  " 

Nitrogen    as   nitrates 1.5  parts  "  " 

Chlorin    19.3  "  "  " 

Total  residue   106.0  "  "'  " 

Volatile   residue    37.0  "  "  " 

Fixed   residue    69.0  "        "         " 

Hardness,  33.8°. 

(The  residue  did  not  char  and  gave  no  odor  upon  ignition.) 

Bacteria  per  e.  e.  upon  gelatin  at  20°  C 60 

Bacteria  per  e.  c.  upon  agar  at  37°  C 45 

No  liquef^dng  colonies.     One  chromogen   per  c.  c.     No  fer- 
mentation in  lactose  bouillon  in  10  c.  c.     No  B.  coli. 

This  water  came  from  a  driven  well  at  AVenham.  Mass.  Upon  in- 
spection it  was  found  that  the  well  was  -100  feet  from  a  stable,  200 
feet  from  a  cesspool,  and  250  feet  from  the  house. 

The  first  thing  that  strikes  our  attention  in  this  analysis  is  the  high 
chlorin.  This,  however,  lacks  sanitary  significance,  as  it  is  normal  for 
the  ground  waters  of  this  neighborhood.  The  hardness  of  the  water  is 
due  to  the  very  fertile  character  of  the  surrounding  soil  through  which 
the  water  percolates.  The  carbonic  acid  taken  up  by  the  water  from 
the  decomposing  organic  matter  dissolves  the  lime  in  the  soil.  The 
organic  matter  as  represented  by  the  ammonias  is  quite  low.  The 
nitrates  are  high  and  indicate  that  the  water  has  dissolved  this  end 
product  of  the  oxidation  of  organic  matter  in  its  passage  through  the 
soil  and  perhaps  in  seepage  from  the  cesspool.  The  noticeable  quantity 
of  nitrites  indicates  that  all  the  organic  matter  has  not  been  consumed 
and  that  the  mineralization  is  not  complete.  The  small  number  of 
bacteria  present  shows  that  the  filtering  action  of  the  soil  through  which 
the  water  passes  is  effective  in  keeping  out  sewage  contamination  either 
from  the  surface  or  from  the  cesspool.  This  conclusion  is  strength- 
ened by  the  absence  of  fermenting  organisms  and  especially  the  absence 
of  B.  coJi.  The  absence  of  lic|uefying  bacteria  and  the  presence  of  an 
occasional  chromogenic  organism  indicate  that  there  is  little  or  no  con- 
tamination from  the  surface  and,  in  fact,  upon  inspection  the  platform 
covering  the  well  was  found  to  be  tight  and  well  constructed. 


768        INTERPRETATION    OF    SANITARY    ANALYSIS 

This  particular  sample  of  well  water  shows  nothing  injurious  to 
health,  and  if  suhsequent  analyses  are  equally  satisfactory  the  water 
may  be  used  without  fear  for  drinking  purposes.  It  is  plain,  however, 
that  this  well  needs  watching,  for  it  is  evident  that  the  soil  is  already 
surcharged  with  organic  matter,  some  of  wliich  appears  in  the  water, 
and  a  further  loading  of  the  soil  or  a  break  in  the  cesspool  might 
readily  infect  the  well. 

Analysis  No.  5 — Surface  Pollution  of  a.  ^yell 

Free  ammonia   0.022  part  per  million 

Albuminoid  ammonia   0.035  "  "  " 

Nitrogen   as  nitrites 0.007  "  "  " 

Nitrogen  as  nitrates 1.0  "  "  " 

Chlorin 19.0  parts  "  " 

Total  residue   356.0  "  "  " 

Volatile  residue 151.0  "  "  " 

Fixed  residue 205.0 

(Residue  charred  upon  ignition  with  disagreeable  odor.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 9 

Bacteria  per  c.  c.  upon  agar  at  37°  C 275 

Many  liquefying  colonies.  Several  chromogens  per  c.  c.  Fer- 
mentation in  lactose  bouillon  in  0.1  e.  e.  B.  coli  present  in 
1  c.  c. 

This  is  a  shallow  well  in  Washington,  D.  C,  28  feet  deep,  the  water 
standing  4  feet  in  the  well.  There  is  a  sewer  60  feet  from  the  well 
and  a  privy  within  a  block.  The  pump  is  old  and  of  wood  and  the 
cover  to  the  well  is  rotten  at  the  base. 

Although  this  water  contains  a  small  amount  of  organic  matter, 
as  indicated  by  the  ammonias,  every  other  factor  indicates  pollution 
both  present  and  past.  The  nitrates  and  nitrites  are  high ;  the 
chlorin  is  excessive.  It  is  important  to  notice  that  this  water  has  only 
9  bacteria  per  cubic  centimeter  when  judged  by  the  colonies  that  grow 
upon  gelatin  at  20°  C.  Nevertheless,  it  contains  colon  bacilli  in  1  c,  c, 
other  fermenting  organisms,  as  well  as  liquefying  and  chromogenic 
colonies.  It  is  probable  that  most  of  the  contamination  in  this  case 
came  from  the  surface,  as  the  well  had  a  very  poor  and  leaky  platform. 
This  water  should  not  be  used  for  domestic  purposes,  and  if  it  did  not 
materially  improve  after  the  correction  of  the  platform  it  should  be 
condemned. 

Analysis  No.  6 — Well  Water,  Surface  Pollution 

Free  ammonia  0.007       part  per  million 

Albuminoid  ammonia 0.018         "        "         " 

Nitrogen  as  nitrites 0.0005      "       "        " 


SELECTED  ANALYSES  769 

Nitrogen    as   nitrates 2.5  parts  per  million 

Chlorin 14.0             "        " 

Total  residue   62.0 

Volatile  residue   32.0             "        " 

Fixed  residue 30.0             "        " 

(Residue  charred  upon  ignition  and  gave  disagreeable  odor.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 820 

Bacteria  per  c.  c.  upon  agar  at  37°  C 640 

Many  liquefying  colonies.     Many  chromogens  per  e.  c.     Fer- 
mentation in  lactose  bouillon  in  1  c.  e.     B.  coli  in  10  e.  e. 

This  water  came  from  a  shallow  well  in  Washington,  D.  C,  18  feet 
deep,  the  water  standing  3  feet  from  the  bottom.  The  rather  high 
nitrates  and  chlorin  in  this  case  represent  past  pollution.  The  small 
amount  of  organic  matter  with  a  trace  of  nitrites  plus  the  number  and 
character  of  the  bacteria  indicates  surface  pollution.  This  view  is 
strengthened  by  the  fact  that  repeated  examinations  of  the  water  from 
this  well  showed  marked  variations  in  the  number  of  bacteria.  Upon 
inspection  the  pump  and  covering  to  the  well  were  found  in  very  bad 
condition,  leak}',  and  with  surface  drainage  toward  the  well. 

Analysis  jSTo.  7 — Illustrating  Remote  Pollution 

Free  ammonia   0.006  part  per  million 

Albimiinoid  ammonia   0.011  ''  "  " 

Nitrogen  as  nitrites trace  "  "  " 

Nitrogen  as  nitrates 20.0  parts  "  " 

Chlorin 89.0  "  "  " 

Total  residue    430.0  "  "  "    ■ 

Volatile  residue  113.0 

Fixed  residue   317.0  "  "  " 

(No  charring  upon  igiiition;  odor  of  burning  rubber.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 92 

Bacteria  per  e.  c.  upon  agar  at  37°  C 16 

No  liquefj'ing  colonies.     No   chromogens  per  e.  e.     No  fer- 
mentation in  lactose  bouillon  in  10  c.  e.     B.  coli  absent. 

This  is  a  ground  water  from  a  shallow  well  in  "Washington,  D.  C. 
The  well  is  29  feet  deep  and  the  water  stands  4  feet  from  the  bottom. 
Top  is  well  protected,  waste  water  drains  to  sewer  nearby.  There  are 
two  privy  vaults  within  two  blocks  of  the  well. 

The  analysis  shows  high  chlorin  and  nitrates ;  otherwise  nothing 
suspicious.  This  means  remote  pollution.  The  organic  matter  has  been 
completely  mineralized  and  the  bacteria  held  back  by  the  soil. 


770        INTERPRETATION    OF    SANITARY    ANALYSIS 

Analysis  No.  8 — High  Clilorin 

Free  ammonia   0.016       part  per  million 

Albuminoid  ammonia   0.015         "  "         " 

Nitrogen  as  nitrites 0.000         "  "         " 

Nitrog-en  as  nitrates 0.14           "  "         " 

Chlorin 11.20       parts  " 

Total  residue   

Volatile   residue    "  "         " 

Fixed   residue    " 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 48 

Bacteria  per  c.  c.  upon  agar  at  37°  C 12 

No  liquef jdng  colonies.     No  chromogens  })er  c.  c.     No  fer- 
mentation in  lactose  bouillon  in  10  c.  c.     B.  coli  absent. 

This  water  is  from  a  driven  well  at  Beverley,  Mass.  The  analysis 
shows  nothing  suspicious,  excepting  the  high  chlorin,  which  is  normal 
for  this  neighborhood  and  therefore  lacks  sanitary  significance. 

Analysis  No.  9 — High  Free  Ammonia;  Deep  ^Vell 

Free  ammonia   0.170  part  per  million 

Albuminoid  ammonia  0.000  "  "  " 

Nitrogen   as  nitrites trace  "  "  " 

Nitrogen  as  nitrates 0.0  "  "  " 

Chlorin    3.1  parts  " 

Total  residue   115.0  "  "  " 

Volatile    residue    45.0  "  "  " 

Fixed   residue    70.0  "  "  " 

No  bacteria  per  e.  c.  upon   gelatin  at  20°  C. 
No  bacteria  per  c.  c.   upon  agar  at  37°  C. 
No  fermentation  in  lactose  bouillon. 

This  water  is  from  a  driven  well  in  Washington,  D.  C. ;  96  feet 
deep,  water  stands  81  feet  from  the  bottom.  Good  platform  and  drain, 
and  pump  is  in  first-class  condition. 

It  is  exceptionally  pure,  both  chemically  and  bacteriologically,  ex- 
cepting the  large  amount  of  free  ammonia.  This  supposedly  comes 
from  the  reduction  of  nitrates. 

It  is  not  uncommon  to  find  water  from  deep  wells  to  be  high  in  free 
ammonia,  and  it  is  assimied  that  this  comes  from  a  chemical  reduction 
under  high  pressure,  and  perhaps  temperature  of  the  nitrogenous  matter 
in  coal  and  alluvial  deposits. 

Analysis  No.  10 — Bain  ^Vater  Stored  and  Polluted 

Free  ammonia  1.050     parts  per  million 

Albuminoid  ammonia   0.175         "        "         " 


SELECTED    ANALYSES 


'J'71 


Chlorin   2.0         parts  per  million. 

ISTitrogen   as  nitrites strong  trace     "        "         '* 

Nitrogen  as  nitrates 0.0  ''        "         " 

Required    oxygen    2.25  "        "         " 

Total  residue   20.0  "        "         " 

Bacteria  per  c.  c.  upon  gelatin  at  20° 625 

No  fermenting  organisms.     No  B.   coli. 

This  is  rain  water  from  a  dirty  cistern.  In  appearance  the  water 
was  clear  and  good.  The  analysis  shows  that  the  water  is  dirty  and 
contaminated  with  organic  matter.  The  hacteriological  results  indicate 
absence  of  fecal  pollution.  The  water  is  undesirable,  but  not  dangerous, 
as  far  as  infection  is  concerned. 

Analysis  Xo.  11 — Artesian  Well  Waier,  Showing  the  Effects  of  Storage 
(The  figures  are  in  parts  per  mill-ion) 


Water  Directly 
from  the  Well 


Same  Water 

from  the 

Storage  Cistern 


Free  ammonia 

Albuminoid  ammonia 

Nitrogen  as  nitrites 

Nitrogen  as  nitrates 

Chlorin 

Dissolved  oxygen 

Oxygen  required 

Total  residue 

Volatile  residue 

Fixed  residue  (mineral  matter) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 
Fermentation  in  lactose  bouillon  in ...  . 
B.  coli 


.052 
.003 
.000 
.01 

10.4 

10.65 
.10 
111.0 

40.0 

71.0 

6 

none 
absent 


.062 
.016 
.0007 
.01 

10.2 

10.69 
.15 

97. 

30. 

67. 

6500 
in  0.1  c.  c. 

absent 


This  water  is  from  eight  artesian  wells  at  the  Government  Hospital 
for  the  Insane  at  Anacostia,  D.  C,  375  feet  deep.  The  water  is  forced 
out  by  compressed  air  and  flows  by  gravity  to  the  storage  cistern,  which 
is  of  brick  and  cement,  and  has  a  capacity  of  80,000  gallons. 

It  will  be  observed  that  this  water  is  low  in  total  solids  and  is 
almost  free  of  organic  matter  as  represented  by  the  ammonias,  nitrites, 
nitrates,  and  oxygen  required.  The  water  is  clear  as  it  flows  from  the 
ground,  but  soon  turns  slightly  yellowish  on  account  of  a  small  amount 
of  iron  in  the  ferrous  state  that  is  oxidized  to  the  ferric  salt,  which 
is  insoluble  and  is  precipitated  upon  contact  with  the  air.  The 
amount  of  chlorin  is  somewhat  large,  but  has  no  sanitary  significance  in 
this  case.  The  principal  point  in  this  analysis  is  the  bacteriology, 
which  shows  the  water  to  be  practically  sterile  as  it  flows  from  the 
ground,  but  which  contains  over  6,000  bacteria  per  cubic  centimeter  in 


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SELECTED    ANALYSES  773 

the  storage  cistern.  These  come  from  the  air  and  other  contaminating 
objects,  and  illustrate  the  great  gro'O'th  of  the  common  ^ater  bacteria 
in  water  stored  under  these  circumstances.  The  slight  increase  of  the 
ammonias  and  nitrites  in  the  cistern  water,  as  compared  with  the  water 
direct  from  the  well,  indicates  organic  pollution  and  bacterial  activity. 
The  diminution  in  the  residue  results  largely  from  separation  of  the 
iron.  This  water  is  pure  and  wholesome,  despite  the  fact  it  contains 
many  more  bacteria  than  that  usually  allowed.  It  has  been  used  for 
some  years  by  about  3,000  persons,  who  are  singularly  free  from  typhoid 
fever  and  other  water-borne  diseases. 

Analysis  Ko.  12  is  a  good  illustration  of  the  bacteriological  and 
chemical  character  of  a  river  water,  and  illustrates  the  changes  that 
occur  during  short  storage  (3  to  5  days)  and  after  filtration  through  a 
slow  sand  filter. 

It  will  be  seen  from  this  table  that  there  is  a  gradual  diminution 
in  the  amount  of  free  ammonia  and  a  more  marked  diminution  in  the 
amount  of  albuminoid  ammonia.  The  amount  of  organic  matter  as 
represented  by  the  ammonias  is  diminished  just  one-third.  The  nitrites 
show  an  increase  during  storage  of  the  water,  indicating  active  oxida- 
tion, but  a  marked  decrease  after  it  is  filtered,  showing  the  rapid  com- 
pletion of  the  oxidation  of  the  organic  matter  in  the  filter.  The  nitrates 
show  a  tendency  to  increase  in  amount,  which  would  be  expected 
as  the  nitrites  diminish.  It  is  evident  that  storage  and  filtration  have 
little  effect  upon  the  chlorin  content  of  the  water.  The  total  residue 
diminishes  as  the  result  of  storage,  sedimentation,  and  filtration.  It 
will  be  noted,  however,  that  this  diminution  is  more  marked  with  the 
fixed  residue  than  with  the  volatile  residue. 

The  number  of  bacteria  decrease  as  the  result  of  storage,  but  the 
most  marked  decrease  occurs  as  the  result  of  filtration.  It  should  be 
remembered  that  all  the  bacteria  in  the  filtered  water  do  not  represent 
those  which  have  passed  the  filter.  The  effect  of  the  few  days'  storage 
upon  this  water  does  not  very  materially  affect  the  number  of  B.  coli, 
but  there  is  a  marked  diminution  in  their  number  as  the  result  of 
filtration. 

Analysis  No.  13 — Typical  Analysis  of  Surface  Waters 

The  analyses  of  surface  waters,  shown  in  the  table  on  page  774,  with 
diagram  showing  the  locations  from  which  samples  were  obtained,  vrill 
repay  careful  study.  This  table  and  diagram  were  furnished  through 
the  kindness  of  Professor  Whipple. 


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employed  in  Analysis  No.  13. 


CHAPTER  V 
THE   PURIFICATION    OF   WATER 

The  ways  in  which  water  may  be  purified  for  practical  purposes  are 
not  many.  It  is  worth  noting  that  most  of  the  advances  in  water  puri- 
fication come  from  the  development  of  old  empiric  processes.  It  is  only 
at  long  intervals  that  a  new  method  or  principle  of  treatment  is  dis- 
covered that  is  important  enough  to  find  a  permanent  place  in  the  art 
of  water  purification. 

The  principal  methods  at  present  serviceable  for  the  purification  of 
water  upon  a  large  scale  are :  (1)  storage,  (2)  filtration,  (3)  chemicals, 
such  as  ozone,  hypochlorite  of  lime,  sulphate  of  aluminium  or  iron. 

No  method  of  purifying  water  can  be  considered  to  approach  a 
satisfactory  hygienic  standard  that  does  not  first  of  all  practically  elim- 
inate water-borne  diseases.  The  process  must  also  reduce  the  turbidity 
and  color  to  inappreciable  amounts  and  remove  something  like  99  per 
cent,  of  the  bacteria,  when  these  organisms  result  from  sewage  pollution 
and  are  fairly  numerous :  there  is  perhaps  no  final  reason  for  the  bac- 
terial standard.  It  has  been  adopted  by  consent  because  it  represents 
a  purification  that  is  reasonably  satisfactory  and  that  can  be  accom- 
plished at  the  small  cost  of  about  $10.00  per  million  gallons  of  water 
treated.  With  the  further  awakening  of  the  sanitary  conscience  of  the 
community  the  standards  will  inevitably  tend  higher,  and  it  is  probable 
that  in  time  our  standards  will  approach  an  ideal  that  is  now  not  re- 
garded as  necessary.  At  present  there  is  no  evidence  that  the  few  micro- 
organisms left  in  the  water  after  a  satisfactory  method  of  purification, 
such  as  slow  sand  filtration,  are  injurious.  Certainly,  if  injurious  in- 
fluence is  exercised,  it  is  too  small  to  be  determined  or  measured  by 
any  methods  now  at  our  disposal. 

NATURE'S   METHOD    OF   PURIFYING   WATER 

In  nature,  water  is  purified  by  various  methods,  the  chief  of  which 

are:    (a)   evaporation  and  condensation,  which  makes  rain  M'ater  the 

purest  of  natural  waters;   (b)  the  self-purification  of  running  streams, 

which  is  a  variable  and  uncertain  quantity;    (c)    storage  in  lakes  and 

776 


NATUEE'S    METHOD    OF    PUEIFYIXG    WATEE         777 

ponds  which  clarifies  water  and  in  time  eliminates  danger;  and  (d) 
the  physical,  chemical,  and  biologic  action  of  the  soil  upon  water  that 
filters  into  the  earth,  which  is  one  of  nature's  greatest  purifying 
agencies. 

Evaporation  and  Condensation. — The  purifying  action  of  the  dis- 
tilling and  condensing  process  through  which  all  meteoric  water  passes 
is  one  of  nature's  beneficent  processes.  Enormous  quantities  of  -sea 
water,  marsh  water,  and  polluted  waters  of  all  kinds  are  thus  returned 
to  us  suitable  for  domestic  use.  Somerville  estimates  that  "186,24:0 
cubic  miles  of  water  are  annually  raised  from  the  surface  of  the  globe 
in  the  form  of  vapor,  chiefly  in  the  intertropical  seas."  Water  is  thus 
constantly  being  purified  in  nature.  The  ocean  has  been  compared  to  a 
boiler,  the  sun  to  a  furnace,  and  the  atmosphere  to  a  vast  still.  The 
cooler  air  of  the  higher  atmosjDhere  and  of  colder  zones  acts  as  a  con- 
denser, causing  the  precipitation  of  the  distilled  water  as  rain.  About 
three-fourths  of  the  earth's  surface  (14.5,000,000  square  miles)  is  cov- 
ered with  water,  much  of  which  is  in  the  tropical  belt. 

Self-purification  of  Streams. — The  self-purification  of  streams  needs 
special  chscussion.  Streams  become  purer  during  the  course  of  their 
flow.  Of  this  there  can  be  no  doubt.  This  half-truth  based  upon  chemi- 
cal data  has  in  the  past  suffered  sanitarians  to  permit  the  use  of  water 
that  now  we  know  was  responsible  for  much  sickness  and  many  deaths. 
Streams  become  purer,  but  not  pure.  Some  impurities  always  remain, 
that  is,  the  process  is  not  complete  and  final.  All  surface  supplies  are 
now  regarded  with  suspicion  and  are  either  stored,  filtered,  or  other- 
wise purified  before  they  are  used  by  educated  communities. 

It  was  formerly  said  that  a  stream  purifies  itself  in  seven  miles. 
Such  a  generalization  is  absurd.  We  now  know  that  it  is  not  the 
distance  so  much  as  the  time  and  opportumity  for  the  various  factors, 
involved  to  become  effective.  Thus,  Buffalo's  sewage  flows- to  Niagara's 
intake,  a  distance  of  about  16  miles,  in  a  few  hours.  There  is  little 
chance  for  self -purification  to  take  place,  and  despite  the  great  dilution 
the  danger  is  very  great.  Xiagara's  average  typhoid  rate  for  10  years, 
from  1899  to  1908.  was  132.9  per  100,000,  the  liighest  in  the  country. 
On  the  other  hand,  we  have  the  following  facts : 

A  good  instance  of  the  self-purification  of  streams  resulted  from 
the  studies  of  the  Potomac  Eiver  and  its  relation  to  t}-phoid  fever  in 
the  District  of  Columbia.  The  Potomac  Eiver  drains  an  area  of  about 
11,400  square  miles  which,  in  1900,  contained  a  population  estimated 
to  be  about  half  a  million,  or  about  44  per  square  mile.  The  velocity  of 
the  flow  of  the  Potomac  is  extremely  variable.  It  takes  from  4  to  7 
days  for  the  water  to  travel  from  Cumberland  to  Great  Falls  (where 
the  Washington  intake  is  located),  a  distance  of  about  176  miles.  The 
waters  of  the  Potom'ac  are  directly  polluted  by  sewage  at  numerous 


778  THE    PURIFICATION    OF    WATER 

points.  Tlie  direct  pollution  is  contributed  by  about  45,000  individuals, 
or  91  per  cent,  of  the  total  population  on  the  watershed.  Of  this 
pollution  about  80  per  cent,  enters  the  river  at  points  176  or  more 
miles  from  the  intake  at  Great  Falls,  about  15  per  cent,  enters  it  at 
points  between  50  and  170  miles  above  Great  Falls,  and  5  per  cent, 
is  contributed  by  about  2,200  of  the  population  and  enters  the  river  at 
points  between  19  and  50  miles  above  the  intake.  There  is  practically 
no  direct  pollution  of  the  Potomac  within  19  miles  of  the  intake.  Here 
we  have  an  instance  of  a  stream  draining  an  extensive  and  populous 
area  and  receiving  industrial  and  human  wastes  from  many  thousand 
persons.  Xevertheless,  self-purification  has  occurred  to  such  an  extent 
that  little,  if  any,  of  the  typhoid  fever  occurring  in  Washington  could 
be  attributed  to  the  use  of  this  water. 

The  Mississippi  River  is  perhaps  one  of  the  best  examples  of  the 
self-purification  of  a  stream,  for,  after  draining  the  entire  continent 
of  the  United  States  in  a  flow  of  over  15,000  miles,  it  is  exceptionally 
free  of  pathogenic  bacteria  at  Xew  Orleans,  judged  by  the  absence  of 
colon  bacilli. 

The  principal  factors  concerned  in  the  self-purification  of  water  are 
varied  and  interesting.  They  are:  (1)  Chemical,  the  oxidation  of 
nitrogenous  organic  matter,  resulting  in  its  reduction  or  mineraliza- 
tion. (2)  Biologic,  the  death  of  microorganisms  through  symbiosis, 
time,  and  various  means;  and  (3)  physical,  such  as  dilution,  sedimenta- 
tion, sunlight,  etc. 

OxiDATiox. — Organic  matter  is  gradually  oxidized,  thus  diminishing 
the  amount  of  food  for  bacteria.  The  activity  of  the  oxidation  depends 
largely  upon  the  amount  of  dissolved  oxygen  in  the  water.  It  is  there- 
fore favored  by  falls,  rapids,  and  a  turbulent  flow.  It  is  mainly  the 
aerobic  bacteria  which  have  an  active  proteolytic  action,  and  are  thus 
able  to  digest  and  destroy  organic  matter.  During  the  course  of  flow 
the  complex  nitrogenous  substances  are  thus  mineralized.  Chemical 
analyses  show  a  rapid  decrease  in  the  amount  of  organic  matter  and  an 
increase  of  nitrates,  and  diminution  of  nitrites.  It  was  these  facts 
that  led  chemists  to  conclude  that  flowing  rivers  soon  purified  them- 
selves. 

Biological  Factors. — Minute  animals  such  as  infusoria,  amebae, 
water-worms,  water-fleas,  etc.,  which  exist  in  countless  numbers  in 
certain  waters,  feed  upon  the  organic  matter  and  bacteria,  and  are  a 
considerable  factor  in  the  self-purification  of  water. 

Time  and  symbiosis  play  an  important  role  with  self-purification 
of  streams,  as  they  do  elsewhere.  Pathogenic  bacteria  die  more  quickly 
in  a  polluted  water  than  in  a  pure  water.  It  is  probable  that  symbiosis 
here  plays  a  part.  The  saproph}'tic  bacteria  somehow  help  to  kill  off  the 
dangerous  varieties.     Pettenkofer  believed  that  the  greater  part  of  self- 


NATUEE'S    METHOD    OF    PUEIFYING    WATER         779 

purification  is  due  to  the  growth  of  algae  and  other  low  forms  of  vegeta- 
tion which  clear  the  water  of  its  impurities  in  the  same  way  that  the 
higher  plants  utilize  the  decomposing  manure  on  cultivated  fields. 
This  view  is  endorsed  by  Bokorny,  Emerisch,  and  Briiner  and  others 
who  have  studied  the  question.  It  is  proven  that  these  plants  take 
up  all  manner  of  organic  substances.  This  includes  volatile  fatty 
acids,  amino  acids,  glucose,  and  urea.  The  purifying  effects  of  water 
vegetation  are  therefore  placed  near  the  head  of  the  list  of  self-puri- 
fication. 

Dilution"  and  Sedimentation. — Dilution  is  one  of  nature's  real 
sanitary  blessings.  The  superabundance  of  water  and  air  quickly  dilutes 
the  impurities  under  ordinary  conditions  so  as  to  render  them  harm- 
less. A  small  amount  of  infection  in  a  great  volume  of  river  or  lake 
water  soon  becomes  so  diluted  as  literally  to  become  lost.  It  is  true, 
that  one  germ  may  cause  disease  just  as  a  spark  may  start  a  forest  fire, 
but  the  conditions  must  be  exceptionally  favorable.  It  is  fortunate  for 
us  that  a  single  typhoid,  cholera,  or  dysentery  bacillus,  especially  when 
attenuated,  will  not,  as  a  rule,  induce  disease.  It  is  further  clear  that 
the  chances  of  receiving  a  single  bacillus  in  the  few  glasses  of  water 
one  drinks  are  mathematically  very  small  when  the  dilution  is  very 
great.  Owing  to  these  facts  and  to  the  further  fact  that  pathogenic 
spore-free  bacteria  soon  become  attenuated  and  die  in  water,  dilution 
becomes  one  of  our  chief  sanitary  safeguards. 

Sedimentation  is  favored  by  a  slow-moving  stream  containing  in- 
soluble inorganic  particles  such  as  clay.  In  muddy  streams  such  as  the 
Mississippi  and  Potomac  Rivers  the  water  is  purified  in  very  much  the 
same  way  that  the  snow  clears  the  air.  The  particles,  constantly  settling, 
wash  the  water  by  enmeshing  the  bacteria,  which  are  thus  carried  to 
the  bottom,  where  they  are  imprisoned  and  die.  It  is  almost  a  filtration 
process.  The  water  is  swept  or  scoured  many  times  by  the  innumerable 
fine  particles  in  a  turbid  stream.  This  is  the  same  principle  used  to 
clarify  water  with  chemical  coagulants  such  as  sulphate  of  alumina. 

Storage  in  Lakes  and  Ponds. — Nature  makes  use  of  the  purifying 
power  of  time  in  storing  water  in  lakes  and  ponds  and  other  surface 
collections.  Very  few  parasites  pathogenic  for  man  multiply  in  water 
under  natural  conditions.  In  time  they  all  die  out.  Hence  a  stored 
water  is  reasonably  safe.  In  addition,  the  organic  matter  undergoes  decay 
and  returns  to  its  simple  mineral  constituents.  Hence  a  stored  water 
will  in  time  free  itself  not  only  of  harmful  parasites,  but  also  of  most 
of  its  organic  pollution.  The  stagnation  of  stored  water  has  been  de- 
scribed on  page  706. 

The  purifying  power  of  the  soil  has  been  fully  discussed  in  connec- 
tion with  the  nitrogen  cycle    (page  676). 

Sunlight. — The  germicidal   influence   of  sunlight   exerts  its  power 


780  THE    PUKIFICATIOX    OF    WATER 

upon  all  surface  waters.  The  depth  of  penetration,  however,  varies 
with  the  turbidity  of  the  water,  the  strength  and  direction  of  the  sun's 
rays,  and  other  factors. 

DISTILLED   WATER 

The  distillation  of  water  is  the  only  method  known  for  rendering  it 
pure  in  a  chemical  sense.  From  a  hygienic  standpoint  it  is  ideal ;  from 
a  practical  and  economic  standpoint  it  has  several  objections. 

In  the  distillation  of  water  the  first  portion  of  vapor  contains  a 
disproportionate  amount  of  volatile  impurities,  if  such  are  present. 
If  the  distillation  is  continued  to  dryness  or  nearly  so  the  concentrated 
solution  of  mineral  and  organic  matters  suffers  reactions  by  which  more 
volatile  matter  is  formed  and  the  distillate  is  again  contaminated.  For 
these  reasons  standard  distilled  water  usually  includes  only  what  is 
technically  termed  the  "middle  run  of  the  still,"  some  of  the  first 
portion  being  rejected  and  the  distillation  stopped  before  all  the  water 
passes  over. 

Distilled  water,  even  when  obtained  with  precautions,  is  not  always 
acceptable  for  drinking  purposes.  The  taste  is  flat  and  suggestive  of 
scorched  organic  matter.  This  is  often  ascribed  to  the  want  of  aera- 
tion, but  in  many  cases  the  sample  is  not  improved  by  thorough 
aeration.  Even  when  so  improved,  the  additional  operation  adds  ex- 
pense, and  unless  purified  air  is  used  it  adds  organic  matters  living  and 
dead.  Leffmann  believes  that  the  disagreeable  taste  of  distilled  water 
is  often  due  to  volatile  matters. 

The  economic  production  of  a  high-class  distilled  water  is  to  be 
desired  both  from  a  sanitary  and  technical  point  of  view,  such  as  for 
use  by  brewers  and  makers  of  soft  drinks,  laundries,  paper  mills,  and 
many  other  processes  requiring  clean  and  pure  water. 

Statements  are  occasionally  made  that  distilled  water  is  too  pure  and 
hence  not  well  adapted  for  drinking  purposes,  but  these  statements 
are  not  based  upon  physiological  principles  or  clinical  experience. 

BOILED    WATER 

Boiling  renders  water  safe  so  far  as  water-borne  infections  are  con- 
cerned. It  also  destroys  the  toxins  and  probably  renders  most  poisonous 
substances  of  organic  origin  that  may  be  in  the  water  harmless.  Water 
containing  lead  and  other  stable  chemical  substances  injurious  to  health 
would  not,  of  course,  be  rendered  safe  by  boiling. 

For  the  traveler,  the  camper,  and  others  who  must  use  water  of 
various  sources,  the  character  of  which  cannot  be  readily  ascertained, 
the  only  safe  procedure  is  to  have  his  own  tea  kettle  and  little  alcohol 


FILTEKS  781 

lamp.    Enough  water  may  be  boiled  in  a  few  minutes  in  the  morning  or 
evening  to  last  twenty-four  hours  or  more  for  personal  use. 

Boiling  drives  off  the  dissolved  gases,  which  gives  to  boiled  water  a 
flat;,  mawkish  taste.  This  may  be  corrected  b}^  shaking  the  water  in  a 
bottle  or  stirring  with  an  egg-beater,  or  simply  exposing  it  to  the  air 
over  night,  care  being  taken  not  to  recontaminate  it.  The  disagreeable 
taste  of  boiled  water  is  partly  due  to  changes  in  the  organic  matter  which 
take  place  at  100°  C.  As  a  matter  of  fact,  it  is  not  necessary  to  actually 
boil  water  to  render  it  safe  so  far  as  typhoid,  cholera,  dysentery,  and 
other  non-spore-bearing  infections  are  concerned.  A  temperature  of 
60"  C.  for  twenty  minutes  or  70°  C.  or  80°  C.  for  a  few  moments  is 
sufficient.  However,  in  the  kitchen,  where  thermometers  and  scientific 
care  are  not  expected,  it  is  better  to  require  the  water  actually  to  boil 
to  ensure  safety,  especially  in  waters  known  to  be  infected  or  during  epi- 
demics. Boiled  water  may  be  kept  in  covered  pails  or  conveniently 
placed  in  well  stoppered  bottles,  in  which  case  it  may  be  iced  without 
the  risk  of  contamination. 

FILTERS 

Slow  Sand  Filters. — Slow  sand  filters,  also  called  English  filter- 
beds,  consist  of  large,  shallow,  tight  reservoirs  suitably  underdrained 
and  containing  some  five  or  six  feet  of  stratified  filtering  material  of 
progressive  degrees  of  fineness,  beginning  at  the  bottom  with  broken 
stone  or  gravel  and  ending  with  an  upper  layer  of  fine  sand.  The 
water  is  passed  through  such  a  filter  very  slowly,  from  above  down- 
ward, and  the  cleansing  is  done  by  removing  the  surface  layer  of  dirty 
sand. 

Slowly  passing  water  in  this  way  through  sand  purifies  it  biologically, 
physically,  and  chemically;  nearly  all  of  the  objectionable  bacteria  as 
well  as  other  microorganisms  are  removed  and  many  of  the  particles 
in  suspension  are  strained  out  and  much  of  the  organic  matter  is 
oxidized. 

This  process  is  called  "slow"  sand  filtration  to  distinguish  it  from 
the  rapid  process  known  as  mechanical  filtration.  The  slow  sand  filters 
are  spoken  of  as  the  English  method,  or  as  English  filter-beds,  because 
it  was  in  England  that  they  originated;  whereas  the  mechanical  filters 
are  spoken  of  as  the  American  method,  because  this  process  was  de- 
veloped in  this  country  to  meet  our  special  needs.  The  student  should 
have  a  clear  comprehension  of  the  differences  between  these  two  methods. 

The  water  in  the  slow  sand  filter  passes  very  slowly  through  a  layer 
of  sand;  the  filter  chokes  by  the  clogging  of  the  superficial  layer  of 
sand,  and  the  cleansing  of  this  type  of  filter  is  done  by  removing  this 
layer  or  Sdimutzdecke,  as  it  is  called.     Mechanical  filtration,  on  the 


782  THE    PURIFICATION    OF    WATER 

other  hand,  consists  in  first  adding  a  coagulant  such  as  sulphate  of 
alumina  and  then  passing  the  water  rapidly  through  a  layer  of  sand. 
The  sand  is  cleansed  mechanically  by  clever  devices  and  by  a  reversed 
current  of  the  water. 


FiQ.  106. — Section  of  an  Km^ll-h  Filter  Bed. 

The  slow  filtration  of  water  through  sand  originated  as  an  empiric 
process  imitating  nature's  method  of  purifying  water  as  it  slowly  passes 
through  the  soil.  It  was  used  before  the  chemistry  or  bacteriology  of 
the  process  was  understood.  In  fact,  the  intimate  processes  concerned 
in  slow  sand  filtration  are  not  yet  part  of  our  philosophy.  We  know 
that  the  spaces  between  the  sand  are  enormous  when  compared  with 
the  size  of  bacteria;  nevertheless,  over  99  per  cent,  of  the  bacteria  are 
held  in  the  superficial  layers  of  the  sand.  Nitrification  and  oxidation  of 
organic  matter  also  takes  place.  The  process  is  not  a  simple  straining, 
that  is,  a  simple  mechanical  filtration.  It  is  a  "vital"  process  in  which 
bacterial  activity  plays  a  very  large  part.  The  bacteria,  algae,  and  other 
microorganisms  resting  upon  the  upper  layer  of  the  sand  grow  and  form 
a  zoogleal  mass;  each  grain  of  sand  becomes  coated  with  a  gelatinous 
and  adhesive  growth.  The  layer  upon  the  surface  forms  a  carpet-like 
mass  which  constitutes  the  Schmutzdecke.  Tliis  Schmutzdecke  effec- 
tively holds  back  the  bacteria  in  the  water. 

The  removal  of  the  bacteria  then  is  largely  due  to  the  bacteria,  but 
a  visible  Schmutzdecke  is  not  essential  for  successful  sand  filtration.  In 
Hamburg,  Lawrence,  and  other  cities  a  greenish  or  brownish,  slimy 
Schmutzdecke  is  formed  upon  the  surface  of  the  sand,  and  gradually 
becomes  so  thick  and  dense  as  to  offer  much  resistance  to  the  passage 


FILTEES 


783 


of  the  water  itself.  The  Schmutzdeche  is  then  removed.  This  can 
readily  be  done  by  scraping  or  shoveling.  Where  a  visible  SchmutzdecJce 
is  not  formed,  as  in  the  Washington  sand  filters,  it  is  probable  that  the 
microorganisms  which  form  a  zoogleal  mass  do  not  find  favorable  con- 
ditions for  growth.  Nevertheless,  in  this  case  the  surface  layer  of  the 
sand  becomes  clogged  in  the  usual  manner  and  the  underlying  sand  is 
quite  clean.  The  bacteria  that  escape  the  surface  action  are  caught  upon 
and  stick  to  the  mucilaginous  coating  of  the  sand  particles,  where  they 
perish  as  in  a  trap.  The  experiments  of  the  Massachusetts  Board  of 
Health  at  Lawrence  show  that  filtration  may  be  as  ejffective  from  a  bac- 
teriological standpoint  without  the  visible  SchmutzdecJce  as  with  it. 

Construction"  and  Operation. — In  view  of  the  importance  of  the 
subject  the  student  should  be  familiar  with  the  general  principles  and 
some  of  the  details  concerning  the  construction  and  method  of  operat- 
ing a  slow  sand  filter. 

It  is  advisable  to  let  the  water  settle  before  it  is  applied  to  the 
sand  for  the  reason  that  this  prevents  undue  choking  or  clogging  of 
the  filters  and  thus  effects  a  great  economy.  One  of  the  main  items 
in  the  cost  of  maintaining  a  slow  sand  filter  is  the  scraping  of  the  sur- 
face layer  and  the  washing  of  the  dirty  sand.  There  are  other  pre- 
liminary methods  of  treating  the  water  before  it  is  applied  to  the  filter. 
These  methods  differ  with  the  character  of  the  water,  and  consist  in  the 
main  of  screening,  scrubbing,  or  coagulation.  These  processes  are  dis- 
cussed more  in  detail  upon  another  page. 


Fig.  107. — The  Arhangement  of  a  Slow  Sand  Filter. 


A  slow  sand  filter  requires  an  extensive  tract  of  land,  for  it  should  be 
recalled  that  only  two  and  one-half  to  five  million  gallons  of  water  should 
be  filtered  per  acre  per  day.  The  filter  should  be  conveniently  located 
near  the  community  it  is  to  serve,  and  the  high  price  of  urban  property 
is  an  important  economic  consideration.  Thus,  in  Washington  it  re- 
quires 21  acres  alone  for  the  filter  beds  to  furnish  63,000,000  gallons  of 
water  daily  at  a  3-million-gallon  rate  per  acre.  The  settling  basins,  stor- 
age basins  for  the  filtered  water,  sand-washing  apparatus,  pumping  sta- 
tion, laboratory,  and  other  accessories  require  considerably  more  land. 
The  entire  filtering  surface  is  divided  into  units  known  as  filter-beds. 
The  size  of  each  filter-bed  has  grown  with  the  development  of  the  art.  In 
the  filters  recently  constructed  each  bed  occupies  about  one  acre.     Each 


784  THE    PURIFICATION    OF    WATER 

bed  must  he  an  independent  unit,  so  that  the  rate  of  filtration,  the 
cleaning  and  all  other  operations  may  be  carried  on  without  disturbing 
the  other  beds.  The  pipes  carrying  the  effluent  from  each  filter-bed 
must  be  so  arranged  that  the  water  may  be  wasted  or  utilized.  Where 
the  climate  is  cold,  filters  should  be  covered  to  prevent  freezing. 

In  construction  a  filter-bed  is  built  very  much  like  an  ordinary  re- 
inforced concrete  reservoir.  The  bottom  and  sides  must  be  water-tight, 
for  failure  in  this  regard  may  be  annoying  and  dangerous  for  the  reason 
that  there  may  be  considerable  loss  of  filtered  water  or  entrance  of  pollu- 
tion from  the  outside  if  the  pressure  is  reversed.  The  sides  of  the  bed 
are  usually  vertical,  although  it  is  some  advantage  to  make  them  slant- 
ing or  with  horizontal  lediies  in  order  to  diminish  leaks. 

The  sand  may  be  obtained  from  a  river  bed  or  from  sand  banks; 
the  grains  should  be  sharp,  hard  silicates.  If  the  sand  contains  clay 
this  should  be  removed  by  washing  before  it  is  used.  It  is  also  im- 
portant that  the  filtering  sand  should  be  free  from  lime,  which  has  a 
tendency  to  make  the  water  hard.  The  average  diameter  of  the  sand 
best  suited  usually  varies  from  0.2  to  0.3  millimeter.  It  is  especially 
important  that  the  particles  should  be  mainly  of  the  same  size.  This  is 
determined  by  establishing  the  coefficient  of  uniformity. 

The  sand  used  for  filtration  contains  particles  of  various  sizes;  the 
water  is  forced  around  the  larger  particles  and  through  the  finer  inter- 
stices which  occupy  the  intervening  spaces,  so  that  it  is  the  finest  por- 
tion which  mainly  determines  the  efficiency  of  the  sand  for  filtration. 
According  to  Hazen,  a  provisional  basis  which  best  accounts  for  the 
known  facts  considers  the  size  of  grain  such  that  10  per  cent,  by  weight 
of  the  particles  are  smaller  and  90  per  cent,  larger  than  itself.  This 
is  considered  the  effective  size,  and  is  determined  by  sifting  a  weighed 
amount  of  the  sand  through  a  series  of  sieves.  Another  important  point 
in  regard  to  the  sand  is  its  degree  of  uniformity;  that  is,  whether  the 
particles  are  mainly  of  the  same  size  or  whether  there  is  a  great  range 
in  their  diameters.  This  is  shown  by  the  uniformity  coefficient,  a  term 
used  to  designate  the  ratio  of  the  size  of  grain  which  is  60  per  cent, 
of  the  sample'finer  than  itself  to  the  size  which  is  10  per  cent,  finer  than 
itself. 

The  usual  thickness  of  the  sand  layer  varies  from  12  to  48  inches. 
The  Imperial  Board  of  Health  of  Germany  has  fixed  12  inches  as  the 
limit  below  which  the  sand  should  never  be  scraped.  The  higher  limit 
is  advisable  wherever  practicable.  In  this  country  the  usual  depth  of  the 
sand  layer  is  about  3  feet,  and  this  is  reduced  by  successive  scrapings 
for  the  purpose  of  cleaning  until  it  approaches  12  inches,  when  the 
sand  is  replaced.  A  thick  sand  layer  has  a  steadying  action  upon  the 
water  on  account  of  the  increased  friction,  and  thus  aids  in  preventing 
irregularities  in  the  rate  of  filtration. 


FILTERS  785 

The  sand  rests  upon  a  stratified  layer  of  rock  and  gravel  laid  in 
graded  sizes  which  supports  it  so  that  it  does  not  work  its  way  down  into 
the  underdrains. 

The  size,  position,  and  nature  of  the  underdrains  are  a  very  essential 
part  of  the  construction  of  a  slow  sand  filter.  The  underdrains  must 
be  set  so  that  the  rate  of  filtration  will  be  the  same  in  all  parts  of  the 
filter.  If  this  part  of  the  apparatus  is  not  properly  designed  in  a  filter- 
bed  having  the  broad  expanse  of  an  acre  the  water  may  pass  through 
the  sand  in  certain  portions  at  the  rate  of  ten  or  more  million  gallons 
while  at  other  portions  there  may  be  practically  no  flow  at  all. 

The  depth  of  the  water  above  the  sand  is  usually  3  feet.  In 
European  filters  the  depth  varies  from  3  feet  to  52  inches.  It  is  com- 
paratively easy  through  simple  mechanical  devices  to  regulate  the  flow 
of  the  applied  water  so  that  the  depth  of  the  water  above  the  sand  will 
remain  uniform. 

Probably  the  most  important  factor  in  the  operation  of  a  slow  sand 
filter  is  the  rate  of  filtration.  The  tendency  has  been  to  gradually  re- 
duce the  rate  during  the  past  thirty  years.  In  this  country  sand  filters 
are  usually  run  at  a  rate  of  about  2,500,000  to  3,000,000  gallons  per 
acre  per  day.  Three  million  gallons  is  the  maximum  rate  commonly 
allowed.  During  times  of  stress,  however,  or  for  other  reasons,  the 
rate  is  sometimes  speeded  up  to  five  or  six  million  gallons  per  acre 
daily.  In  Hamburg  the  filters  are  not  allowed  to  run  faster  than 
1,600,000  gallons,  and  in  Berlin  2,500,000  gallons.  Water  passed 
through  sand  at  the  rate  of  4,800,000  gallons  per  acre  daily  has  a 
vertical  movement  of  3.94  inches  in  an  hour.  When  the  rate  is  2,400,000 
gallons  the  vertical  motion  is  1.97  inches  per  hour,  and  when  the  rate 
is  slower  the  vertical  motion  is  correspondingly  diminished.  It  will 
thus  be  seen  that  this  process  is  well  named  in  that  the  water  passes 
very  slowly  through  the  filter.  This  is  of  fundamental  importance  be- 
cause the  hour  or  more  during  which  the  water  rests  upon  the  surface 
of  the  sand  and  passes  through  the  superficial  layer  is  the  critical  time 
when  the  bacteria  are  enmeshed  in  the  Schmutzdec'ke  or  adhere  to  the 
particles  of  sand  and  the  other  biological  and  chemical  processes  take 
place.  The  tendency  of  engineers  is  to  increase  the  rate  of  filtration 
on  account  of  the  evident  economy;  the  tendency  of  sanitarians  is  to 
diminish  it  so  as  to  keep  well  within  the  factors  of  safety.  The  rate 
of  filtration  may  be  governed  by  automatic  devices  or  may  be  con- 
trolled by  hand  by  simply  regulating  the  valve  which  governs  the  pipe 
carrying  the  effluent  from  each  filter-bed.  The  friction  of  the  sand 
layer  varies  from  time  to  time,  so  that  careful  attention  is  required  in 
order  to  maintain  a  steady  flow  and  a  constant  rate,  which  is  essential, 
for  sudden  variations  in  rate  are  fatal  to  the  successful  purification 
of  water  by  the  slow  sand  process. 


786 


THE    rURIFICATION    OF    WATER 


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Head 


.0  0  O  O  O  O  O^  0.0  ^ 


Filtered 
Water 


The  friction  of  the  sand  is  measured  by  the  loss  of  head.  The 
loss  of  head  is  the  difference  between  the  level  of  the  water  above  and 
below  the  sand  layer  measured  in  water  gauges.  This  loss  represents 
the  friction  or  resistance  of  the  sand  layer.  It  greatly  increases  as  the 
filter  clogs  up.     When  a  filter  is  new  or  perfectly  clean  the  loss  of 

head  is  usually  about  0.2  foot  or  less; 
when  it  exceeds  4  feet  the  rate  of  filtra- 
tion cannot  be  maintained  at  3,000,000 
gallons  per  acre  daily  with  the  de- 
vices provided,  and  the  filters  must 
be  cleaned. 

The  length  of  time  a  filter  may  run 
before  the  loss  of  head  becomes  so  great 
that  it  becomes  unprofitable  and  requires 
cleaning  varies  from  a  few  days  to  many 
months.  The  time  depends  upon  the 
character  of  the  water,  the  rate  of  filtra- 
tion, and  temperature,  the  formation  of 
Fig.  io8._— Diagram  Illustrating  ^he  ScJimutzdecke  and  many  other  fac- 
tors. In  cleaning  a  filter  it  is  suffi- 
cient to  scrape  off  only  enough  sand  to  a  layer  that  appears  clean.  As 
a  rule  the  sand  immediately  below  the  surface  is  not  apparently  soiled, 
and  usually  it  is  not  necessary  to  take  off  more  than  an  inch  or  so  of 
the  surface  layer.  This  sand  is  removed  to  special  cleaning  devices, 
where  it  is  thoroughly  washed  with  filtered  water  and  then  stored  in 
bins  and  replaced  when  the  sand  layer  reaches  a  depth  of  about  12 
inches.  The  Schmutzdecl-e  and  the  surface  layers  of  the  sand 
are  usually  removed  by  hand  with  broad  shovels.  There  are  also 
mechanical  devices  which  accomplish  the  same  purpose.  After  cleansing, 
the  effluent  from  a  filter-bed  should  be  wasted  until  the  bacteriological 
examination  shows  that  the  filter  is  again  performing  efficient  work. 
This  may  require  several  days,  the  time  varying  with  the  temperature 
and  other  conditions. 

Efficiency  and  Control  of  Slow  Sand  Filters. — The  efficiency 
of  a  slow  sand  filter  is  mainly  measured  by  a  comparison  of  the  number 
of  bacteria  in  the  raw  and  filtered  water.  A  good  filter  should  eliminate 
approximately  99  per  cent,  of  the  bacteria,  provided  the  applied  water 
is  grossly  polluted.  In  any  event  the  filtered  water  should  not  contain 
over  100  bacteria  per  cubic  centimeter  and  very  few  colon  bacilli.  It 
is  to  be  noted  that  all  the  bacteria  in  the  filtered  water  do  not  represent 
those  that  actually  pass  through  the  sand.  Some  of  them  grow  in  the 
underdrains  and  gravel  layer  and  are,  so  far  as  known,  harmless  varieties. 
In  Germany  the  rate  of  filtration  and  other  factors  are  minutely 
regulated   and  controlled   by   official  ordinances.     In  this  country  the 


FILTEES  787 

operation  of  the  filter  is  left  to  the  individual  caprice  of  the  engineer 
in  charge. 

A  slow  sand  filter  cannot  be  effectively  operated  without  skilled 
superintendence  of  an  engineer  expert  in  the  art  of  water  purification. 
It  also  requires  a  small  laboratory  with  a  competent  bacteriologist,  who 
must  make  daily  observations  of  the  applied  water  and  the  effluent 
from  each  filter.  The  effluent  from  a  filter  not  giving  good  results 
should  be  wasted.  The  water  from  a  new  filter,  or  one  just  scraped, 
should  not  be  used  until  the  bacterial  results  show  that  it  is  accom- 
plishing effective  purification. 

There  are  many  ways  in  which  purer  water  may  be  secured,  such  as 
the  use  of  lower  rates  of  filtration,  finer  grained  filtering  materials,  and 
more  complete  preliminary  treatment,  such  as  settling  basins,  storage, 
or  chemical  coagulation.  The  filtered  water  may  be  further  purified 
with  hypochlorite  of  lime  or  ozone.  It  requires  a  surprisingly  small 
amount  of  hypochlorite  to  practically  sterilize  a  filtered  water.  In  Pitts- 
burgh 0.13  part  of  bleaching  powder  (measured  as  available  chlorin) 
per  million  parts  of  water  is  sufficient  for  this  purpose. 

Because  slow  sand  filtration  has  achieved  such  marked  success  with 
some  waters  and  greatly  reduced  the  amount  of  typhoid  is  no  reason 
why  it  should  be  universally  recommended  under  all  circumstances.  To 
recommend  slow  sand  filtration  in  all  cases  would  be  as  irrational  as 
to  recommend  the  use  of  antitoxin  in  every  case  of  sore  throat.  A 
correct  diagnosis  is  essential.  Every  water  cannot  be  successfully  or 
economically  treated  by  this  process  alone.  Thus,  the  very  turbid  waters 
of  our  South  and  West  contain  particles  of  clay  so  fine  that  they  pass 
a  sand  filter.  No  amount  of  sand  filtration  will  take  out  some  of  these 
particles.  The  Potomac  water  in  times  of  high  turbidity  may  be 
passed  through  a  sand  filter  three  or  four  times  without  removing  the 
residual  turbidity  due  to  these  microscopic  particles.  To  apply  a  very 
turbid  water  to  a  sand  filter  soon  chokes  it  and  adds  unnecessarily  to 
the  difficulty  and  expense  of  the  process.  The  particles  may  be  so  fine 
that  they  will  not  all  settle  even  when  the  water  is  given  long  storage. 
There  are  several  ways  of  solving  this  problem,  which  is  of  first  magni- 
tude for  the  purification  of  the  surface  water  of  a  large  part  of  our 
country.  One  of  the  best  ways  is  to  provide  large  storage  reservoirs, 
so  that  the  water  may  be  taken  from  the  river  only  at  favorable  times, 
rejecting  the  flow  during  periods  of  high  turbidity.  Another  is  to  use 
preliminary  coagulation  with  aluminium  sulphate  and  provide  for  sedi- 
mentation before  applying  the  water  to  the  sand.  Much  of  the  turbidity 
may  be  removed  by  a  rapid  preliminary  filtration  through  some  coarse 
material  such  as  charcoal,  sponge,  etc.  This  process  is  known  as  scrub- 
bing. No  general  rule  can  be  set  down.  Waters  differ  radically,  and 
the  same   stream  varies  from  time   to  time.     Each  problem   must  be 


788 


THE    PURIFICATION    OF    WATER 


studied  and  solved  in  relation  to  its  own  special  condition.  Whether 
the  filtered  water  should  be  further  purified  with  bleaching  powder  or 
ozone  depends  upon  circumstances. 

Results  of  Slow  Sand  Filtration. — The  good  results  of  purifying 
water  by  the  slow  sand  method  have  been  abundantly  demonstrated  in 
Altoona,  near  Hamburg,  in  1892.  during  the  cholera  epidemic;  also  in 
Hamburg  since  1893  and  in  Lawrence  also  since  1893;  further  in  Al- 
bany, Philadelphia,  Pittsburgh,  Berlin,  Paris,  and  many  English  cities. 
It  should  be  noted  esjiecially  at  Al'hany  that  tbe  typhoid  rate  did  not 
come  down  immediately  after  filtration.  It  sometimes  requires  one  or 
two  years  to  reach  the  residual  or  "normal"  rate.  In  a  few  instances, 
such  as  Washington,  D.  C,  and  Youngstown,  0..  filtration  of  the  water 
was  not  followed  by  a  noticeable  diminution  in  the  typhoid  rates. 

The  following  American  cities  purify  their  water  supply  by  slow 
sand  filtration: 

Sand  Filters 


Philadelphia,  Penn 

Pittsburgh,  Penn 

Washington,  D.  C 

Providence,  R.  I. 

Indianapolis,  Ind 

Denver,  Colo 

New  Haven,  Conn,  (in  part) 

Albany,  N.  Y 

Reading,  Penn.  (in  part) . . .  . 

Lawrence,  Mass 

Yonkers,  N.  Y.  (in  part) . .  .  . 

Superior,  Wis 

Poughkeepsie,  N.  Y 


Population.  1900 


1,293,697 
321,616 
278,718 
175,597 
169,164 

133,859 

108,027 

94,151 

78,961 

62,559 
47,931 
31,091 
24,029 


Capacity.of  Filters 
in  Gallons  per  Day 


420,000,000 

100,000,000 

87,000,000 

24,000,000 

24,000,000 

30,000,000 

15,000,000 

17,000,000 

5,750,000 

5,000,000 
7,-500,000 
5,000,000 
3,000,000 


And  fully  25  smaller  places. 

The  best  results  in  water  purification,  as  measured  by  the  improve- 
ment in  the  health  and  reduction  of  the  death  rate  among  those  who 
use  the  water,  have  been  obtained  with  slow  sand  filters.  Hazen  believes 
that  this  is  probably  because  the  method  is  an  old  one,  has  been  long 
and  carefully  studied,  and  has  been  applied  on  a  large  scale  in  well- 
perfected  forms  for  many  years,  rather  than  to  any  natural  superiority 
of  the  method. 

The  purification  of  water  through  slow  sand  filtration  not  only 
diminishes  the  amount  of  typhoid  and  other  water-borne  intestinal 
infections,  but  is  believed  also  to  reduce  the  general  death  rate.  This 
fact,  known  as  the  Mills-Reinecke  phenomenon,  is  discussed  on  page  804. 

Mechanical  Filters. — The   essential   and   characteristic    features    of 


FILTEES  789 

mechanical  filtration  are:  (1)  The  addition  of  a  chemical  precipitant 
or  coagulant  to  the  water,  and  (2)  then  passing  the  water  rapidly 
through  a  layer  of  sand.  The  filtering  sand  is  contained  in  a  large 
wooden,  iron,  or  concrete  tank  so  arranged  that  it  can  be  mechanically 
washed.^  These  filters  are  well  named,  not  only  because  the  filtering 
sand  is  washed  mechanically,  but  because  the  action  is  more  strictly  a 
mechanical  straining,  whereas  biological  processes  are  the  main  features 
in  the  purification  of  water  passing  through  a  slow  sand  filter.  In 
the  Hyatt  and  Jewell  filters  the  sand  is  agitated  by  a  revolving  rake 
as  the  reversed  flow  of  water  washes  the  sand.  In  the  Continental  type 
the  sand  is  agitated  by  compressed  air. 

The  coagulants  commonly  used  are  sulphate  of  aluminium,  some- 
times alum,  occasionally  sulphate  of  iron.  The  alkaline  carbonates 
present  in  the  water  decompose  the  aluminium  sulphate  with  the  forma- 
tion of  aluminium  hydrate,  which  is  thrown  out  of  solution  as  a  floc- 
culent,  colloidal,  jelly-like  precipitate.     The  reaction  is  as  follows: 

Al2(SO,)3  +  3Ca(C03)  =  AL(C03)3  +  3CaSO, 
Al2(C03)3  +  6H,0  =  AL(0H)3  +  SH.O  +  SCO^ 

The  calcium  carbonate  is  necessary  to  break  up  the  alum,  and  if  not 
normally  present  in  the  water  some  lime  or  soda  must  be  added.  The 
precipitated  aluminium  hydrate  clears  the  water  very  much  as  white  of 
egg  clears  coffee.  Suspended  matter,  including  bacteria  and  inorganic 
particles,  are  enmeshed  and  deposited  on  the  surface  of  the  sand.  When 
this  deposit  becomes  abundant  enough  to  clog  the  filter  the  filter  is 
washed  by  reversing  the  flow  and  mechanically  agitating  the  sand. 
Thus  it  will  be  seen  that  an  artificially  inorganic  Schmutzdeche  is  pro- 
duced upon  mechanical  filters  instead  of  the  natural  organic  Schmutz- 
deche of  the  slow  sand  filter-bed. 

It  is  advisable  to  provide  coagulating  basins  to  hold  the  water  for 
a  short  time  after  it  has  received  the  coagulant,  in  order  to  allow  the 
chemical  reaction  resulting  from  the  treatment  to  take  place.  Such 
basins  also  serve  to  remove  by  sedimentation  the  greater  part  of  the 
precipitate,  and  the  filters  therefore  do  not  clog  so  readily,  and  cleans- 
ing is  not  required  so  frequently. 

The  rate  at  which  water  is  passed  through  mechanical  filters  is  very 
great  when  compared  with  slow  sand  filters.  Eates  varying  from 
100,000,000  to  150,000,000  gallons  per  acre  per  day  are  used. 

One  hundred  and  twenty-five  million  gallons  per  acre  daily  may  be 

^  Mechanical  filters  date  from  1884,  when  the  process  was  patented  by  J.  W. 
Hyatt  and  Professor  Albert  E.  Leeds.  The  Hyatt  patent  expired  in  1901,  and 
since  then  numerous  inaprovements  in  details  have  been  made  and  patented,  con- 
siderably improving  the  art  of  cleaning  water  through  this  process. 

52 


'{'90  THE    PUIUFICATION    OF    WATER 

taken  as  a  fair  average  of  what  is  to  be  expected  of  them.  On  account 
of  the  rapid  rate  of  filtration  there  is  great  economy  of  space.  However, 
while  the  mechanical  filters  are  cheaper  when  first  cost  is  considered, 
the  advantage  is  with  slow  sand  filters  as  far  as  cost  of  maintenance  is 
concerned. 

The  proper  amount  of  coagulant  is  added  to  the  water  by  means 
of  a  small  automatic  measuring  apparatus.  It  requires,  as  a  rule, 
about  one  or  two  grains  of  alum  or  sulphate  of  aluminium  for  each  gallon 
of  water  to  be  treated.  The  amount  of  alum  added  to  the  water  must 
vary  from  time  to  time,  depending  upon  the  turbidity,  the  reaction^ 
and  also  upon  the  amount  of  calcium  carbonate  in  the  water.  The 
turbidity  and  composition  of  many  of  our  streams  vary  suddenly  and 
require  a  watchful  eye.  If  too  little  alum  is  added  the  effluent  will 
not  be  clear;  if  too  much  is  used  the  effluent  will  contain  the  excess  of 
alum  in  solution.  Mechanical  filters,  therefore,  require  intelligent  and 
constant  supervision  in  order  to  furnish  satisfactory  results. 

Mechanical  filtration  meets  with  special  favor  in  this  country  be- 
cause it  affords  a  comparatively  cheap  method  of  supplying  a  clean- 
looking  water  from  a  very  turbid  source.  The  process  is  particularly 
applicable  to  the  muddy  streams  of  our  South  and  West.  In  fact,  it  is 
the  only  known  method  of  rendering  some  of  these  waters  quite  free 
of  turbidity. 

Mechanical  filters,  when  properly  manipulated,  will  take  out  from 
95  to  99  per  cent,  of  the  bacteria  contained  in  the  raw  water.  The 
bacterial  purification,  however,  is  not  as  constant  and  uniformly' high 
as  that  obtained  by  slow  sand  filtration.  The  aluminium  hydrate  also 
takes  out  much  of  the  soluble  coloring  matter  which  the  water  may 
contain,  as  well  as  its  turbidity. 

Judged  by  the  effects  upon  morbidity  and  mortality,  mechanical 
filtration  of  water  has  in  no  instance  given,  the  same  satisfactory  results 
afforded  by  slow  sand  filtration.  Most  of  the  mechanical  filters  in  use 
in  America  have  fallen  far  short  in  hygienic  efficiency.  This  w^as  espe- 
cially true  with  the  old  and  inferior  plants  which  often  were  without 
skilful  supervision.  According  to  Hazen,  the  mechanical  filters  that 
have  taken  advantage  of  all  the  improvements  in  construction  and  that 
are  operated  with  skill  and  experienced  superintendence  are  doing  as 
good  work,  measured  by  bacterial  efficiency,  as  the  corresponding  slow 
sand  filters,  and  Hazen  believes -that  in  time  the  hj^gienic  efficiency  will 
show  corresponding  results  from  them.  The  sanitarian,  however,  is  com- 
pelled to  regard  the  mechanical  filtration  of  water  as  still  in  the  experi- 
mental stage. 


FILTERS 


791 


The  Differexce  Between  Slott  Saxd  axd  ]\Iechaxical  Filteatiox 


Slow  Sand  Filtration 

English  system  or  English  filter-beds 
— originated  in   England. 

Has  been  long  in  use  and  effective- 
ness  is   established. 


Preliminary  treatment  not  an  essen- 
tial part  of  the  process,  though 
sometimes  desirable. 

"Water  passes  slowly  through  a  layer 
of  sand,  in  large,  shallow,  tight 
reservoirs. 

Usual  rates  from  1.600.000  to  5,000,- 
000  gallons  per  acre  per  day. 

Cleaned  by  scraping  surface  layer  of 
sand — Schmntzdecke. 


The  process  is  mainly  biologir-al. 
partly  a  mechanical  straining. 
Duplicates  nature's  process  of 
purifjing  water. 

First  cost  is  large;  maintenance  com- 
paratively small. 

Especially  serviceable  for  water  hav- 
ing little  turbidity. 

Removes  about  one-third  of  the 
coloring  matter. 

Removes  about  99  per  cent,  of  the 
bacteria;  action  is  uniform. 


Favorable  effect  upon  health  well  es- 
tablished. 


Meclianical  Filtration 

American  system  —  developed  in 
America  to  meet  our  special  needs. 

Comparatively  recent  (since  ISS-i), 
and  effectiveness  not  yet  estab- 
lished. 

A  coagulant  is  first  added  to  the 
water — sulphate  of  aluminium, 
alum,   or  sulphate  of  iron. 

TVater  passes  rapidly  through  a  layer 
of  sand  in  small  wooden,  concrete, 
or  iron  tanks. 

Usual  rates  100  to  200  times  as  rapid 
—100,000.000  to  150.000.000  or 
more  gallons  per  acre  daily. 

Cleaned  by  reversed  flow  of  water  and 
mechanical  agitation  of  the  sand — 
hence  the  name  "mechanical"  filtra- 
tion. 

The  process  is  mainly  a  mechanical 
straining.  An  artificial  imitation 
of  nature's  process. 

First  cost  is  comparatively  small; 
maintenance  large. 

Especially  suitable  for  turbid  waters, 
containing  silt   and  clay. 

Takes  out  nearly  all  of  dissolved 
coloiing  matter. 

AYhen  properly  operated  removes 
from  95  to  99  per  cent,  of  bac- 
teria— less  uniform. 

Hygienic    efficiency    not    established, 
.  but   doubtless  would  be  more  sat- 
isfactoiw   if  well   operated. 


The  following  is  a  partial  list  compiled  by  Hazen  of  places  in  the 
United  States  where  mechanical  filters  are  at  present  in  use  or  under 
construction : 


792 


THE    PURIFICATION    OF   WATER 


Population,  1900 


Capacity  of  Filters 
in  Gallons  per  Day 


Cincinnati,  Ohio ' 

New  Orleans,  La.'     

East  Jersey  Water  Company. 
Hackensack  Water  Company 
Louisville,  Ky.' 

Toledo,  Ohio  i 

Columbus,  Ohio ' 

St.  Joseph,  Mo 

Atlanta,  Ga 

Charleston,  S.  C 

Kansas  City,  Kan 

Harrisburg,  Penn 

Norfolk,  Va 

Youngstown,  Ohio 

Binghamton,  N.  Y 

Augusta,  Ga 

Birmingham,  Ala 

Little  Rock,  Ark 

Terre  Haute,  Ind 

Dubuque,  Iowa 

Quincy,  111 

Elmira,  N.  Y 

Davenport,  Iowa 

Chester,  Penn 

York,  Penn 

Knoxville,  Tenn 

Chattanooga,  Tenn 

East  St.  Louis,  111 

Newcastle,  Penn 

Oshkosh,  Wis 

Lexington,  Ky 

Joplin,  Mo 

Cedar  Rapids,  Iowa 


325,902 
287,104 
250,000 
225,000 
204,731 

131,822 
125,560 
102,979 

89,872 
55,807 

51,418 
50,167 
46,624 

44,885 
39,647 

39,441 
38,415 
38,307 
36,673 
36,297 

36,252 
35,672 
35,254 
33,988 
33,708 

32,637 
30,154 
29,655 
28,339 

28,284 

26,369 
26,023 
25,656 


112,000,000 
44,000,000 
32,000,000 
24,000,000 
37,500,000 

20,000,000 

30,0()(),0()0 

11,000,000 

G,()()(),0()0 

5,000,000 

6,500,000 
12,000,000 

8,000,000 
10,000,000 

8,000,000 

6,000,000 

5,500,6o6 
9,000,000 


4,000,000 
7,000,000 
7,000,000 
4,000,000 
4,000,000 

4,-500,000 
9,000.000 
11,000,000 
4,000,000 
2,000,000 

3,500,000 

2,500,666 


And  fuUy  125  smaller  places. 
^  Building. 


Household  Filters. — The  domestic  filter  as  ordinarily  used  in  the 
household  has  limited  sanitary  value.  The  purification  of  water,  even  by 
so  simple  a  method  as  straining,  requires  a  degree  of  care,  knowledge, 
and  experience  that  is  not  found  in  the  kitchen.  If  a  water  is  infected, 
reliance  should  not  be  placed  upon  any  household  filter  operated 
in  the  usual  way.  It  is  possilile  in  the  laboratory  by  the  use  of  special 
precautions  to  pass  water  through  a  Pasteur-Chamberland  or  a  Berkefeld 
filter  so  as  to  obtain  a  sterile  filtrate.  This  requires  skilled  bacteriolog- 
ical manipulation  of  a  kind  that  cannot  be  attained  in  oidinary  service 
in  the  house.  I  have  seen  janitors  "clean"  a  filter  in  such  a  way  as  to 
actually  contaminate  the  water. 


STORAGE  793 

There  are  two  main  types  of  household  filters :  one  made  of  unglazed 
porcelain  (koalin),  known  as  the  Pasteur-Chamberland,  and  the  other 
made  of  diatomaceous  earth,  the  Berkefeld.  Even  in  the  closest  grained 
unglazed  porcelain  filter  the  pores  of  the  filter  are  larger  than  the  bac- 
teria. The  bacteria  do  not  get  through  on  account  of  the  tortuous 
passage;  they  adhere  to  the  particles  that  make  up  the  filtering  sub- 
stance. But  if  conditions  are  favorable,  bacteria,  such  as  typhoid,  may 
soon  grow  through  its  walls.  The  Berkefeld  filters  of  diatomaceous 
earth  are  more  porous  than  the  Pasteur-Chamberland  filters. 

When  a  water  is  not  infected,  but  turbid,  household  filters  are  service- 
able in  rendering  it  clear.  They  are  specially  useful  when  the  turbidity 
is  due  to  clay  or  to  iron,  or  other  inorganic  particles  that  may  readily 
be  removed  by  simple  straining. 

The  sanitarian  places  no  reliance  upon  the  filtration  of  water  in 
the  household,  and  for  drinking  purposes  such  water  if  infected,  whether 
filtered  or  not,  should  be  boiled.     The  boiling  should  be  the  last  process. 

Filters  of  natural  stone,  charcoal,  asbestos,  and  a  great  variety  of 
porous  substances  are  on  the  market  for  domestic  use.  These  filters 
may  be  useful  in  cleaning  water  that  is  turbid,  but  they  cannot  be 
depended  upon  to  purify  an  infected  supply. 

Scrubbing  or  Roughing  Filters. — Scrubbers  are  rapid  coarse-grained 
filters  through  which  turbid  water  is  passed  at  a  very  high  rate 
in  order  to  remove  coarser  particles  and  some  of  the  turbidity.  This 
process  of  scrubbing  the  water  is  principally  used  as  a  preliminary 
to  sand  filtration.  It  is  designed  to  protect  the  sand  filters  from  clog- 
ging up  too  quickly  and  thus  economize  the  operation.  Scrubbers,  also 
known  as  roughing  filters,  consist  of  some  porous  substances  such  as 
sponge,  coke,  and  lava.  The  principal  difiiculty  connected  with  a  scrub- 
ber is  an  efficient  and  economical  device  for  cleaning  them,  which  must 
be  done  at  frequent  intervals. 

Screening  or  straining  is  used  particularly  to  remove  fish  and  float- 
ing leaves,  sticks,  etc.  Screens  may  consist  of  steel  bars  arranged  so 
that  they  may  be  easily  raked  off,  or  of  wire  cloth  arranged  in  pairs, 
so  that  while  one  screen  is  raised  for  cleaning  its  mate  is  below  in 
service.  Revolving  screens  are  efficient.  The  motion  should  be  con- 
tinuous, and  the  cleaning  is  done  on  that  part  of  the  screen  above  the 
water  by  jets  of  water  playing  upon  it.  Screening  is  of  no  service  in 
removing  algae  or  microorganisms,  and  can  only  be  depended  upon  to 
remove  the  coarse  particles,  and  is  only  necessary  where  the  water  con- 
tains such  material. 

STORAGE 

The  storage  of  water  is  one  of  the  simplest  and  best  means  of  purify- 
ing it.     The  first  cost  may  be  large,  but  the  cost  of  maintenance  is 


794  THE    PURIFICATION    OF    WATER 

coinj)aratively  trifling.  Harmful  bacteria  soon  die  in  a  stored  water,  the 
solid  particles  settle  out,  the  organic  matter  is  largely  oxidized,  the 
color  is  gradually  bleached,  and  other  improvements  take  place.  Storage 
takes  advantage  of  many  of  nature's  methods  of  purifying  water,  viz., 
time,  sunlight,  dilution,  sedimentation,  oxidation,  and  symbiosis. 

A  stored  water  may  deteriorate  in  quality  owing  to  the  growth  of 
alga3  and  the  decomposition  of  organic  matter.  Alga?  and  diatoms  grow 
in  stored  water  exposed  to  sunhght,  particularly  in  warm  weather. 
While  these  organisms  are  not  harmful,  they  impart  disagreeable  tastes 
and  odors  to  the  water.  (See  page  .723.)  The  decomposition  of  the 
organic  matter  in  a  storage  water  may  also  cause  unpleasant  tastes 
and  odors,  especially  at  the  spring  and  fall  overturn.  (See  page  706.) 
Waters  stored  in  a  closed  reservoir  keep  without  deterioration,  and  the 
advantage  is  therefore  manifest.  Filtered  water  should  always  be 
stored  in  covered  reservoirs,  not  only  to  protect  it  from  strong  light,  but 
also  to  prevent  contamination  from  dust  and  other  sources. 


SEDIMENTATION 

Sedimentation  is  of  limited  use  in  improving  the  sanitary  quality  of 
a  water.  Sedimentation  basins  are  frequently  used  as  a  preliminary 
process  in  water  purification.  It  is  the  cheapest  way  of  removing  rela- 
tively large  particles  which  will  settle  out  in  a  moderately  short  time. 
There  is  also  a  sanitary  advantage  in  that  the  suspended  particles 
mechanically  carry  down  with  them  some  of  the  bacteria.  The  water, 
as  a  rule,  does  not  remain  in  the  sedimenting  basins  long  enough  to 
obtain  the  full  effects  of  storage. 

Sedimentation  is  a  very  important  factor  in  the  bacterial  purification 
of  flowing  streams.  The  effect  of  sedimentation  is  most  manifest  when 
the  flow  of  water  is  rapid  enough  to  prevent  accumulation,  at  any  point, 
of  the  products  of  bacterial  multiplication,  but  not  so  rapid  as  to  inter- 
fere with  a  comparatively  rapid  action  of  gravity.  Turbid  streams 
purify  themselves  through  sedimentation  more  quickly  than  clear 
streams,  owing  to  the  washing  or  scouring  action  of  the  particles  as 
they  fall  through  the  water, 

CHEMICAL   METHODS    OF   PURIFYING    WATER 

Ozone. — Ozone  is  one  of  the  most  satisfactorv'  methods  of  purifying 
water  from  a  sanitary  standpoint.  As  a  germicide  it  is  the  most  effective 
of  all  the  methods  used  except  boiling.  A  well-ozonized  water  is  prac- 
tically sterile  and  the  organic  matter  is  partially  oxidized.  It  is  true 
that  a  few  resisting  spores  are  not  killed,  but  these  are  harmless  when 


CHEMICAL    METHODS    OF    PUEIFYING    WATEE       795 

taken  by  the  mouth.  The  limitations  of  the  ozone  process  are  that  it 
does  not  clarify  the  water  in  any  way,  and  that  it  has  practically  no 
effect  upon  the  mineral  salts.  From  a  practical  standpoint  the  expense 
of  producing  ozone  in  sufficient  concentration  is  disproportionately  large, 
but  this  is  an  electrical  engineering  problem  which  is  showing  encourag- 
ing advance. 

As  a  general  rule  it  is  not  desirable  to  add  ozone  to  a  dirty  or  turbid 
raw  water.  It  is  better  first  to  clarify  the  water  by  some  other  method 
before  applying  the  ozone.  The  quantity  of  ozone  required  for  effective 
bacterial  action  depends  upon  the  amount  of  organic  impurities  con- 
tained in  the  water.  Much  of  the  ozone  will  be  used  up  by  these  im- 
purities, and  this  may  happen  so  rapidly  that  it  will  not  have  a 
chance  to  act  upon  the  microorganisms. 

An  impure  water  containing  much  organic  pollution  treated  with 
ozone  may  give  disappointing  results,  from  the  fact  that  unpleasant 
flavors  may  be  developed.  These  are  doubtless  due  to  the  partial 
oxidation  of  the  decomposing  organic  matter  with  the  production  of 
nitrogenous  compounds  not  well  understood. 

For  the  purification  of  water  ozone  is  produced  by  electrical  dis- 
charges in  the  atmosphere,  and  this  ozonized  air  is  then  brought  into  in- 
timate contact  with  the  water.  To  produce  the  ozone  requires  a  brush 
discharge.  If  sparking  takes  place  no  ozone  is  produced.  The  ozonizing 
apparatus  therefore  must  be  carefully  designed,  and  its  operation  needs 
skilled  supervision. 

A  brush  discharge  is  an  electrical  "effluvium,"  that  is,  a  bluish-violet 
glow  in  the  dielectric,  which  in  this  case  is  the  air,  between  the  elec- 
trodes. For  the  production  of  ozone  on  a  large  scale  the  electrodes  must 
be  large  and  placed  close  together.  The  electrodes  may  be  made  of  mica, 
porcelain,  or  glass  covered  with  foil,  etc. ;  one  of  them  may  be  metal. 
The  air  passing  between  the  electrodes  must  be  dry,  otherwise  oxids 
of  nitrogen  will  form,  also  peroxid  of  hydrogen  at  the  expense  of  .the 
ozone.  It  is  therefore  customary  to  first  dry  the  air  by  refrigeration 
or  by  passing  it  over  unslaked  lime  before  it  enters  the  ozonizer.  The 
temperature  of  the  air  in  the  ozonizer  must  not  go  above  a  certain 
degree,  else  ozone  will  not  be  formed.  The  maximum  production  of 
ozone  takes  place  at  about  25°  C.  Overheating  may  be  prevented  by  a 
water  jacket  in  contact  with  the  electrodes.  The  voltage  must  be  high 
— from  8,000  to  20,000  volts;  that  is,  the  current  must  have  a  small 
volume,  but  high  potential. 

The  molecule  of  ozone  (O3)  readily  gives  up  one  atom  of  this  gas  in 
a  nascent  condition.  It  therefore  has  a  very  strong  oxidizing  action 
upon  organic  matter,  decolorizes  many  pigments,  especially  of  vegetable 
origin,  and  has  a  very  powerful  germicidal  action.  In  this  respect  the 
action  of  ozone  corresponds  chemically  to  potassium  permanganate,  the 


79G  TITR    PURIFICATION    OF    WATER 

hypochlorites,   and   otlicr   powerful   oxidizing  chemicals  used   in   water 
purification. 

It  is  necessary  to  get  the  ozone  out  of  the  water  in  order  to  avoid 
the  corrosion  of  pipes.  This  may  be  done  by  aeration,  by  means  of 
fountains  or  cascades.  On  account  of  the  insolubility  of  the  ozone,  it 
soon  disappears.  The  fact  that  ozone  is  largely  insoluble  in  water 
makes  it  necessary  to  bring  it  into  intimate  contact  with  all  portions 
of  the  water  to  be  treated.  This  is  usually  accomplished  by  allowing  the 
water  to  trickle  downward  through  tall  cylinders  filled  with  coke,  lava, 
or  other  similar  substances  while  the  ozone  is  admitted  to  the  bottom 
of  the  cylinder.  The  water  flows  downward,  the  ozonized  air  works 
its  way  upward,  and  in  that  way  the  desired  contact  is  obtained  between 
the  ozone  and  every  portion  of  the  water. 

A  very  small  amount  of  ozone  is  effective  for  the  purification  of 
water.  It  only  requires  a  few  milligrams  per  liter.  The  modern 
machines  produce  concentrations  as  high  as  10  grains  of  ozone  per  cubic 
meter  of  air.  The  ozone  not  taken  up  by  the  water  may  bo  used  over 
and  over  again.  This  is  accomplished  in  some  of  the  ozonizing  processes 
by  conducting  the  air  that  leaves  the  upper  part  of  the  water  cylinder 
back  to  the  ozonizer. 

In  general,  it  may  be  said  that,  owing  to  the  expense  and  the 
electrical  and  engineering  difficulties  involved,  the  ozonizing  process  is 
not  at  present  applicable  to  the  purification  of  water  upon  a  small  scale. 
It  has  been  applied  with  success  upon  a  large  scale  in  a  number  of 
places.  The  first  ozonizing  apparatus  for  the  purification  of  water  on 
a  large  scale  was  installed  by  Siemens-Halske  at  Lille,  France.  Other 
ozonizing  plants  for  purification  of  drinking  water  have  been  in- 
stalled at  Paderborn,  Germany;  at  Ginnekin,  for  Breda,  Holland;  at 
Lille,  France;  at  Wiesbaden,  Germany;  at  Nice,  France;  Lindsay, 
Ontario,  and  other  places.  At  Lindsay  the  ozone  treatment  failed  be- 
cause the  ozone  and  the  water  were  not  properly  mingled.  At  Wies- 
baden much  trouble  was  caused  by  the  oxidation  of  the  iron.  Experi- 
ments at  Ogdensburg,  N.  Y.,  failed  to  remove  the  color  of  the  water. 
Where  water  power  may  be  obtained  for  the  generation  of  the  electricity 
necessary  to  produce  the  ozone  the  cost  is  very  much  lessened.  Tlie 
principal  systems  at  present  used  for  ozonizing  water  are  the  Siemens- 
Halske,  the  Gerhard,  Tindal,  De  Frise,  Otto,  Abraham  Marmier,  Vos- 
maer,  Bridge,  Stynis,  and  others. 

Ozone  treatment  is  best  adapted  to  sewage-polluted  waters,  the  ap- 
pearance of  which  is  satisfactory.  Waters  of  turbid  streams  are  least 
suited  to  this  treatment.  Ozone  must  now  compete  with  bleaching 
powder,  which  has  nearly  the  same  effect  and  is  cheaper  and  simpler. 
One  objection  to  the  treatment  of  water  by  ozone  is  that  the  electric 
apparatus  is  delicate  and  complicated  and  requires  skilled  attendance. 


CHEMICAL    METHODS    OF    PUEIFYING    WATER       797 

The  ozone  processes  are  not  yet  standardized;  at  present  it  is  difficult 
to  determine  what  waters  may  best  be  treated  with  it. 

Chlorinated  Lime — Bleaching  Powder. — Chlorinated  lime,  popularly 
known  as  "chloride  of  lime"  or  bleaching  powder,  also  chlorinated  soda, 
has  been  used  for  years  as  a  sewage  disinfectant.  It  has  recently  at- 
tracted widespread  attention  in  view  of  the  boldness  of  the  Jersey  City 
Water  Company  in  essaying  to  comply  with  its  contract  to  furnish  pure 
water  to  Jersey  City  by  simply  adding  a  little  bleaching  powder. 

The  chief  ingredient  in  chlorinated  lime  so  far  as  water  purification 
is  concerned  is  the  calcium  hypochlorite;  in  chlorinated  soda  it  is  the 
sodium  hypochlorite.  When  bleaching  powder  is  added  to  water  it  is 
in  no  sense  a  "chlorin"  treatment.  The  essential  action  depends  solely 
u|)on  an  oxidation  quite  comparable  to  the  process  of  ozonization.  It 
is  not  the  oxygen  in  the  hypochlorite,  but  the  oxygen  in  the  water,  that 
is  liberated.  Thus  the  calcium  hypochlorite  combines  with  the  COg 
to  form  calcium  carbonate,  and  the  chlorin  liberated  unites  with  the  H 
of  the  water  to  form  HCl,  thus  liberating  the  oxygen,  which  accom- 
plishes the  destruction  of  the  bacteria.  The  reaction  is  expressed  as 
follows : 

Ga/ni^      +  C02  =  CaCOg  +  CI2 

2C1  +  H2O  =  2HC1  +  0 

The  amount  of  hypochlorites  added  is  always  expressed  in  terms  of 
"available  chlorin,"  although  in  reality  this  represents  the  available 
oxygen  liberated  by  the  chlorin.  Thus  a  good  bleaching  powder  will 
average  35  per  cent,  of  available  chlorin,  which  is  the  equivalent  of 
about  7.9  per  cent,  of  available  oxygen.  By  available  chlorin  is  under- 
stood the  chlorin  readily  liberated  from  its  combination  as  determined 
by  the  usual  thiosulphate  titration. 

Upon  exposure  to  the  air  the  hypochlorites  deteriorate  rapidly  to  the 
more  stable  carbonates.  Great  care  must  therefore  be  taken  to  keep  the 
substance  in  air-tight  containers  and  to  know  the  correct  amount  of 
available  chlorin  in  each  lot  of  the  bleach  at  the  time  it  is  used. 

The  amount  of  chlorinated  lime  necessary  to  add  to  a  water  in 
order  to  accomplish  satisfactory  results  varies  with  the  composition  of 
the  water.  Thus  Clark  and  Gage  found  that  0.1  part  of  available  chlorin 
per  100,000  effected  a  satisfactory  purification  of  the  Merrimac  Eiver 
water ;  that  is,  results  were  obtained  equal  to  slow  sand  filtration.  B.  coli 
was  entirely  eliminated.  They  discovered  the  interesting  fact  that  the 
hypochlorite  is  a  differential  germicide,  that  it  destroys  some  bacteria 
more  readily  than  others.  When  small  quantities  are  employed  certain 
species  growing  at  body  temperature  are  only  slightly  affected.  In  Pitts- 
burgh it  was  found  that  0.13  part  of  chlorinated  lime,  measured  in 


798  THE    rrRIFICATIOX    OF    WATER 

terms  of  available  chlorin  per  1.000.000  parts  of  water,  was  sufficient 
to  practically  sterilize  the  Allegheny  River  water  after  it  had  passed 
the  sand  filters.  It  required  as  much  as  1  part  ])er  1,000,000  to  accom- 
plish the  same  results  in  the  raw  water.  In  ^linneapolis  from  2  to  4 
parts  per  1,000.000  have  been  used.  In  the  Jersey  City  case,  already 
referred  to,  5  pounds  of  bleaching  powder,  containing  35  per  cent,  of 
available  chlorin.  are  added  to  each  million  gallons  of  the  water  treated. 
The  raw  water  in  this  case  is  not  highly  polluted,  ranging  as  low  as  30 
bacteria  per  cubic  centimeter,  and  rarely  going  over  15,000.  The  num- 
ber of  bacteria  in  the  treated  water  averages  only  15  bacteria  per  cubic 
centimeter,  and  B.  coli  is  practically  absent.  It  was  found  only  once  out 
of  455  samples. 

Imi)ure  waters  containing  decomposing  organic  matter  or  large 
quantities  of  organic  matter  of  any  kind  held  in  solution  may,  when 
attacked  by  hypochlorites,  give  rise  to  unpleasant  llavors.  These  sub- 
stances appear  related  to  the  amins,  chloramins.  and  other  substances 
the  exact  composition  of  which  requires  further  study.  Hence  the  chem- 
ical sterilization  of  impure  waters  Avithout  subjecting  them  to  some 
preliminary  treatment  may  give  disappointing  results. 

Bleaching  powder  in  no  sense  clarifies  a  water,  and  therefore  can- 
not render  a  turbid  supply  entirely  satisfactory.  Its  cheapness,  relia- 
bility, and  efficiency,  and  the  ease  with  which  it  may  be  applied  make 
it  an  attractive  method.  When  added  in  proper  quantities  it  leaves  no 
undesirable  chemical  substance  in  the  water.  Chlorinated  lime  has  a 
slight  tendency  to  add  a  little  hardness.  Avhile  chlorinated  soda  renders 
the  water  more  soft.  The  latter,  however,  is  more  expensive  than  the 
former.  The  hypochlorite  treatment  of  water  is  suitable  for  the  purifi- 
cation of  supplies  upon  a  large  scale  and  also  for  military  use,  camps, 
tourists,  explorers,  and  others. 

Permanganate  of  Potash. — Permanganate  of  potash  was  much  used 
in  India,  particularly  in  wells  during  cholera  epidemics;  also  in  water 
tanks  on  board  ships,  and  other  places.  Enough  permanganate  is  added 
to  secure  a  faint  pink  tinge,  whicli  indicates  a  slight  excess.  The  per- 
manganate acts  as  an  oxidizing  agent  precisely  as  ozone,  or  similar  to 
the  hypochlorites.  It  is  a  powerful  germicide,  but  not  sufficiently  so 
in  the  strength  used  to  depend  upon  it.  If  too  much  is  added  to 
wells,  springs,  etc.,  so  as  to  kill  the  fish,  frogs,  and  turtles,  the  water 
may  be  spoiled  by  putrefaction  of  their  dead  bodies.  Like  all  chemical 
methods,  the  action  is  not  continuous;  the  agent  expends  itself  in 
oxidizing  organic  matters  before  attacking  the  bacteria,  and  the  amount 
necessary  for  the  purification  of  a  water  depends,  therefore,  upon  its 
character. 

Experiments  by  Clark  and  Gage  show  that  complete  sterilization 
is  not  obtained  by  the  use  of  permanganate  of  potash.     Over  98  per 


CHEMICAL    METHODS    OF    PUEIFYING    WATER       799 

cent,  of  the  bacteria  were  eliminated  by  treating  water  with  0.5  joart 
to  100,000  in  from  4  to  6  hours.  Larger  amounts  of  potassium  per- 
manganate or  longer  times  gave  no  better  results.  The  cost  of  the 
treatment  when  using  5  parts  per  1,000,000  is  from  $3  to  $4  per 
million  gallons.  We  therefore  see  that  potassium  permanganate  has  a 
comparatively  low  efficiency  with  a  relatively  high  cost,  which  will 
always  limit  its  usefulness.  Further,  the  method  is  difficult  of  practical 
application,  being  rather  slow.  Occasionally  it  may  be  serviceable  on 
ships,  in  the  field,  in  an  army  encampment,  or  an  isolated  well. 

Alum  or  Sulphate  of  Aluminium. — ^The  single  and  double  sulphates 
of  aluminium  have  long  been  used  to  clarify  turbid  waters.  In  the 
amounts  used  they  have  no  direct  germicidal  action,  nor  any  direct 
chemical  action  upon  the  water  itself.  The  action  is  entirely  an  in- 
direct one,  and  depends  upon  the  fact  that  the  alkaline  carbonates  react 
upon  the  alum  to  form  aluminium  hydrate.  This  salt  has  a  large  col- 
loidal molecule  and,  being  insoluble,  is  thrown  out  of  solution  as  a 
flocculant  precipitate  which  entangles  much  of  the  suspended  matter 
and  bacteria.  In  a  sense  the  purification  of  water  with  alum  corresponds 
very  much  to  the  clearing  of  coffee  with  the  white  of  egg.  Some  of  the 
aluminium  hydrate  may  also  combine  directly  with  the  organic  matter 
to  form  undetermined  compounds.  The  reaction  is  given  on  page  789. 
By  which  it  will  be  seen  that  if  alum  is  added  in  just  sufficient  quanti- 
ties to  a  water  it  leaves  no  undesirable  constituent  in  the  water.  This  is 
important,  for  there  is  a  great  jjrejudice  against  the  addition  of  a  chemi- 
cal, especially  alum,  to  drinking  water.  In  Washington  it  is  actually 
forbidden  by  law,  despite  the  fact  that  it  has  been  shown  that  in  times 
of  great  turbidity  the  only  known  method  of  clearing  the  Potomac  water 
is  by  the  use  of  a  coagulant  such  as  alum.  It  has  already  been  pointed 
out  that  there  are  many  such  turbid  waters  in  our  country  which  contain 
silt  in  such  fine  subdivision  that  even  prolonged  sedimentation  and  re- 
peated filtration  will  not  entirely  remove  it. 

In  the  use  of  alum  good  results  depend  upon  adding  it  in  just  the 
right  amount.  The  quantity  will  vary  with  the  turbidity  and  the 
amount  of  calcium  carbonate  contained  in  the  water.  This  should  be 
carefully  determined  from  time  to  time,  for  if  not  enough  alum  is 
added  the  result  is  incomplete,  and  if  too  much  is  added  it  remains  in 
the  water  as  such.  The  process  therefore  needs  constant  supervision, 
for  turbid  waters  usually  come  from  turbulent  streams,  which  are  sub- 
ject to  sudden  variations.  If  the  process  is  left  to  automatic  devices 
or  placed  in  incompetent  hands  it  is  sure  to  give  disappointing  results. 

Few  waters  may  be  satisfactorily  purified  by  the  use  of  alum  alone. 
The  alum  should  be  regarded  only  as  one  part  of  the  process.  Subse- 
quent sedimentation,  filtration,  or  hypochlorite,  etc.,  are  necessary,  de- 
pending upon  circumstances.     Alum  alone  should  never  be  depended 


800  THE    PURIFICATION    OF    WATER 

upon  to  purify  a  sewage-polluted  water.  When  properly  combined  with 
filtration  it  will  eliminate  a  large  percentage  of  the  bacteria. 

Sulphate  of  iron  and  alum  in  combination  are  used  in  many  places. 
At  St.  Louis  it  was  introduced  as  an  emergency  installation  to  clarify 
the  muddy  waters  of  the  Mississippi,  to  make  a  good  impression  during 
the. Louisiana  Purchase  Exposition  in  1904.  It  gave  such  satisfactory 
results  that  it  was  decided  to  continue  its  use. 

Lime  and  iron  are  cheaper  than  sulphate  of  aluminium.  Their 
application  is  much  more  difficult  to  control  adequately,  and  it  should 
never  be  undertaken  except  with  the  assistance  of  a  competent  resident 
chemist  and  good  appliances  for  adding  the  lime  in  any  quantity  that 
may  be  required  by  the  composition  of  the  water.  At  St.  Louis  the 
water  is  subject  to  the  iron  and  lime  treatment,  followed  by  subsidence 
in  large  basins  in  which  the  bulk  of  the  precipitate  settles.  This 
partially  purified  water  is  then  sent  to  the  city  without  filtration  or 
other  treatment. 

Metallic  Iron:  the  Anderson  Process. — The  Anderson  process  (pat- 
ented) for  the  purification  of  water  consists  in  agitating  the  water  in 
contact  with  metallic  iron  a  portion  of  which  is  taken  into  solution  as 
ferrous  carbonate.  This  action  is  brought  about  by  the  COg  in  the  water 
which  attacks  the  iron.  Upon  subsequent  aeration  the  ferrous  car- 
bonate is  oxidized  and  precipitated  out  as  the  insoluble  ferric  hydrate, 
which  accomplishes  all  the  good  and  none  of  the  bad  effects  which  fol- 
low the  use  of  alum.  The  precipitate  is  partially  removed  by  sedi- 
mentation, or  filtration  may  complete  the  process.  The  process  is  used 
on  a  large  scale  at  Antwerp,  Belgium,  where  the  water  passes  through 
long  revolving  cylinders  containing  baffle  plates  and  loose  pieces  of 
metallic  iron.  As  the  cylinders  revolve  the  iron  is  continually  carried 
up  and  dropped  through  the  water  in  a  constant  shower.  The  water 
passes  slowly  from  one  end  of  the  cylinder  to  the  other. 

The  process  theoretically  is  an  excellent  one,  but  apparently  enough 
iron  is  not  always  obtained  in  solution  to  accomplish  the  results  when 
applied  on  a  large  scale.  Especially  when  peaty  waters  are  used,  it 
seems  impossible  to  get  enough  iron  into  solution  in  the  time  which 
can  be  allowed;  or  the  inorganic  acids  may  form  soluble  compounds 
with  the  iron,  thus  defeating  the  object  of  the  process.  Other  places 
where  the  Anderson  process  is  used  are  at  Dortrecht,  Holland,  Boulogne- 
sur-Seine,  near  Paris,  and  elsewhere. 

Copper  Sulphate. — The  use  of  copper  sulphate  in  drinking  waters 
was  proposed  by  George  T.  Moore  of  the  United  States  Department  of 
Agriculture  in  1904.  The  original  claim  was  that  copper  sulphate  in 
minute  amounts  would  poison  algae  which  produced  objectionable  tastes 
and  odors,  and  the  further  claim  was  made  that  it  was  also  capable 
of  destroying  typhoid  and  other  pathogenic  microorganisms.     We  know 


ULTEA-VIOLET    EAYS  801 

now  that  copper  sulphate  in  great  dilution  is  a  specific  poison  for  many 
algae  and  other  microscopic  organisms,  but  that  it  has  little  or  no 
effect  upon  typhoid,  cholera,  or  dysentery  bacilli  in  the  amounts  used. 

Copper  sulphate  is  used  in  the  proportion  of  0.1  to  0.25  part  per 
1,000,000  parts  of  water.  Some  algae  require  larger  doses.  Most  of 
the  copper  combines  with  the  bodies  of  the  microorganisms  and  settles 
with  them  to  the  bottom  and  in  this  way  is  removed  from  the  water. 
If  the  water  is  afterwards  filtered  most  of  the  remaining  copper  is  re- 
moved. The  copper  remaining  in  the  water  is  in  such  minute  amounts 
that  there  seems  to  be  no  real  danger  in  using  it  in  this  way  or  even 
in  its  occasional  use  in  somewhat  larger  doses  where  the  water  is  very 
bad. 

The  method  of  applying  the  copper  is  to  place  weighed  quantities 
of  the  copper  sulphate  in  loose  cloth  bags  and  to  tow  them  back  and 
forth  with  rowboats  through  the  water  of  the  reservoir  until  the  material 
is  dissolved.  It  should  be  remembered  that,  while  the  copper  kills 
some  species  of  organisms  in  the  amounts  used,  it  has  no  effect  what- 
ever upon  others.  In  fact,  it  permits  the  growth  of  certain  species  by 
removing  the  retarding  symbiants,  thus  clearing  the  way  for  stronger 
growths  of  the  forms  that  are  not  directly  affected.  Copper  sulphate 
may  therefore  entirely  change  the  flora  in  a  reservoir.  This  change 
is  frequently  accompanied  by  a  great  improvement  in  odors  and  tastes. 
On  the  other  hand,  the  destruction  or  suppression  of  one  species  may 
be  followed  by  an  overgrowth  of  an  equally  objectionable  and  more 
hardy  form.  Therefore  the  results  from  the  use  of  copper  sulphate 
for  the  correction  of  odors  and  tastes  in  water  vary  from  complete  suc- 
cesses to  utter  failure. 

It  is  clearly  established  that  copper  siilphate  does  not  prevent  or 
even  materially  reduce  putrefaction  and  the  tastes  and  odors  resulting 
from  it.  According  to  Hazen,  the  method  of  treating  water  with 
copper  sulphate  is  easily  and  quickly  applied,  and  considerable  good 
has  come  from  it.  The  correction  is  only  partial,  however,  and  is  not 
always  permanent.    It  is  not  therefore  to  be  relied  upon  in  all  cases. 


ULTRA-VIOLET  RAYS 

Recently  the  well-known  germicidal  power  of  the  ultra-violet  rays 
has  been  put  to  practical  use  in  the  sterilization  of  water,  milk,  and 
other  substances.  These  rays,  of  short  wave  length,  may  be  obtained 
from  the  Cooper  Hewitt  mercury  vapor  lamp,  which  is  very  rich  in 
ultra-violet  rays.  Nagier  conceived  the  idea  that  this  lamp  might  be 
used  for  the  sterilization  of  water,  and  the  experiments  made  in  France, 
England,  and  elsewhere  show  this  assumption  to  be  correct.     As  glass 


802  THE    PUWFICATIOX    OF    WATER 

i?  opaque  to  ultra-violet  rays,  it  is  necessary  to  use  qunrtz  or  lamps 
made  of  fused  silica.  The  apparatus  used  iu  the  experiments  '  of  Thresh 
and  Bealle  consists  of  an  aluminium  cylinder  about  12  inches  long  by  6 
inches  in  diameter  containing  a  Cooper  Hewitt  quartz  lamp  with  an  in- 
ternal diaphragm,  Avhich  causes  the  water  entering  at  one  end  to  travel 
along  the  cylinder  in  close  proximity  to  the  lamp.  By  an  ingenious  ar- 
rangement the  moment  the  light  goes  out  the  flow  of  water  is  stopped. 
This  small  apparatus  is  capable  of  sterilizing  50  to  "200  gallons  of  water 
per  hour,  depending  upon  the  character  of  the  water.  In  clear  water 
many  of  the  bacteria  are  killed  in  from  5  to  20  seconds.  The  resisting 
spojes  succumb  in  30  to  60  seconds,  B.  coli  in  15  to  20  seconds,  B. 
iijphosus  10  to  20  seconds,  cholera  vibrio  10  to  15  seconds.  The  pres- 
ence of  colloidal  material  or  turbidity  retards  the  action  of  the  rays. 
The  current  used  in  these  experiments  was  6  amperes  and  130  volts. 
The  results  show  that  a  fairly  clear  and  bright  water  may  be  practically 
sterilized  by  exposure  to  ultra-violet  rays  for  a  brief  time.  The  sim- 
plicity of  the  apparatus  and  its  comparative  cheapness  make  it  attractive, 
so  that  it  doubtless  will  receive  much  attention  in  the  future. 

^Marseilles  recently  adopted  the  ultra-violet  rays  to  purify  its  water 
supplv.  There  are  preliminary  roughing  filters,  and  the  water  passes 
the  quartz  tube  mercury  arc  lamp  three  times.  Xo  B.  coli  were  found 
in  the  treated  water,  and  the  total  bacterial  reduction  was  98.3  per  cent. 
It  is  probable  tliat  the  bacteria  are  killed  by  exposure  to  the  direct 
action  of  the  ultra-violet  rays  themselves.  The  process  does'  not  in  any 
way  clarify  the  water. 

Other  electrical  methods  have  from  time  to  time  been  devised  for 
the  purification  of  water,  using  the  water  itself  as  an  electrolyte. 
These  processes  have  not  yet  been  developed  to  give  successful  results  on 
a  large  scale,  but  much  may  be  hoped  from  them,  and  they  are  worth 
careful  study. 

"■Lancet,  Dec.  24,  1910. 


CHAPTEE  yi 
WATER    AND    ITS    RELATION    TO    DISEASE 

Water  is  a  vehicle  for  certain  infections  such  as  cholera,  typhoid 
fever,  dysentery,  and  other  diseases,  having  their  primary  seat  in  the 
digestive  tract.  It  may  carry  inorganic  poisons  such  as  lead.  It  is 
responsible  for  a  large  group  of  nutritional  and  dietetic  disorders  less 
well  understood.  It  may  contain  qualities  which  bring  about  derange- 
ments of  metabolism  resulting  in  such  conditions  as  goiter;  further,  it 
may  be  the  medium  for  carrying  infections  now  not  generally  regarded 
as  water-borne,  or  it  may  lower  resistance  so  as  to  favor  infections  not 
water-borne.  It  is  also  occasionally  resjDonsible  for  conveying  animal 
parasites,  amebse,  worms,  etc. 

While  water  has  an  established  place  among  the  carriers  of  certain 
infections,  it  has  not  a  supreme  or  exclusive  place,  and  this  should  be 
kept  carefully  before  us.  The  tendency  to  exaggerate  the  importance 
of  water  as  a  bearer  of  disease  and  death  has  sometimes  led  to  over- 
statement. The  facts  are  bad  enough  and  do  not  require  extravagant 
language  to  emphasize  their  imj^ortance.  The  greatest  danger  in  water 
is  pollution  from  human  sources.  All  the  discharges  from  the  body: 
urine,  feces,  expectoration,  secretions  from  the  nose,  and  washings  from 
the  skin,  find  their  way  sooner  or  later  into  our  streams,  especially 
where  modern  water-carriage  systems  are  installed  for  the  disposal  of 
wastes.  All  sewage-polluted  water  must  be  regarded  as  dangerous, 
whether  there  are  any  known  cases  of  t3^phoid  fever  on  the  water- 
shed or  not.  It  is  highly  probable  that  the  sewage  of  large  communi- 
ties always  contains  t}'phoid  bacilli  in  larger  or  smaller  numbers, 
because  in  large  communities  typhoid  fever  does  not  die  out  com- 
pletely at  any  time,  and  carriers  and  missed  cases  are  growing  in  interest 
and  importance. 

Water  differs  in  several  essential  particulars  from  any  other  article 
of  diet.  Above  all,  it  is  partaken  of  raw,  while  perhaps  90  per  cent,  of 
all  our  other  food  is  disinfected  by  cooking  before  it  is  used.  Again,  it 
is  a  vehicle  which  comes  in  contact  with  many  objects  spread  over  broad 
acres,  and  it  is  the  natural  vehicle  for  the  removal  of  wastes  from  these 
areas.    Its  great  solvent  and  erosive  powers  favor  this  action. 

803 


804  RELATIOX    OF    WATER    TO    DISEASE 

The  relation  of  water  supply  to  sickness  and  death  has  been  shown 
with  force  in  many  cities,  notably  at  Lowell  and  Lawrence,  ilass. ;  in 
Alban}',  N.  Y. ;  at  Jersey  City  and  Newark,  N".  J. ;  at  Philadelpliia 
and  Pittsburgh,  Pa. ;  at  Chicago,  111. ;  and  abroad  at  London,  Paris, 
Hamburg,  Altona,  Berlin,  and  many  other  cities. 


THE  MILLS-REINCKE   PHENOMENON 

Following  the  filtration  of  the  water  supply  of  Lawrence,  Mass.,  in 
September,  1893,  Mr.  Hiram  F.  Mills,  a  member  of  the  State  Board 
of  Health  of  Massachusetts,  noted  that  a  marked  decrease  in  the  general 
death  rate  of  the  city,  and  not  merely  in  the  death  rate  from  typhoid 
fever,  was  taking  place.  About  the  same  time  (May,  1893)  filtered 
Elbe  River  water  was  furnished  the  city  of  Hamburg,  and  Dr.  J.  J. 
Reincke,  health  officer  of  that  city,  in  his  successive  annual  reports, 
noticed  that  the  general  death  rate  was  declining  more  rapidly  than 
could  possibly  be  accounted  for  by  the  deaths  from  typhoid  fever  alone. 
To  this  important  discovery  Sedgwick  and  MacXutt  have  given  the 
name  of  the  "Mills-Reincke  phenomenon."^  In  1904  Mr.  Allen  Hazen, 
a  sanitary  engineer,  formulated  a  numerical  expression  for  the  com- 
parative effect  of  water  purification  upon  typhoid  fever  mortality  and 
total  mortality.  He  said  that,  "where  one  death  from  typhoid  fever  has 
been  avoided  by  the  use  of  a  better  water,  a  certain  number  of  deaths, 
probably  two  or  three,  from  other  causes  have  been  avoided."  The 
Mills-Reincke  phenomenon  and  Hazen's  theorem  have  been  searchingly 
studied  by  Sedgwick  and  ]\IacXutt,  and  the  student  is  advised  to  read 
the  original  article  referred  to  in  the  footnote.  These  authorities  exam- 
ined the  vital  statistics  of  the  cities  of  Lawrence,  Mass.,  and  Hamburg, 
Germany,  and  also  of  Lowell,  ]\Iass.,  Albany,  Binghamton,  and  Wa- 
tertown,  X.  Y.  They  found  abundant  evidence  of  the  great  life-saving 
power  of  a  purified  water  in  preventing  many  diseases  other  than  typhoid 
fever  in  the  cities  studied,  except  Watertown,  and  in  this  case  it  is 
possible  that  the  purification  of  the  public  water  supply  has  been  as  yet 
relatively  imperfect.  It  is  further  to  be  noted  that  the  method  of 
purification  used  at  Watertown  is  mechanical  filtration. 

SedgAvick  and  MacXutt  express  the  opinion  that  ]\Ir.  Hazen's 
theorem  applied  to  the  cities  they  studied,  with  the  exception  of  Water- 
town,  appears  to  be  sound  and  conservative.  In  Hamburg  the  saving 
in  typhoid  mortality  was  slight  in  comparison  with  the  saving  of 
mortality    in    other    diseases    combined ;    that    is.    roughly,    only    about 

'W.  T.  Sedgwick  and  J.  S.  MacNutt:  "The  Mills-Reincke  Phenomenon  and 
Hazen's  Theorem  Concerning  the  Decrease  of  ^lortality  from  Diseases  Other 
Than  Typhoid  Fever  Following  the  Purification  of  Public  Water  Supplies,"  Jour. 
Infect.  Bis.,  Vol.  VII,  No.  4,  Aug.  24,  1910,  pp.  489-.'564. 


THE    MILLS-REIN^CKE    PHENOMENON  805 

1  to  16.  In  the  other  cities  the  ratios  differed  widely  from  this. 
Thus,  at  Lawrence  it  was  1  to  4.4,  at  Lowell  1  to  6.0,  in  Albany  abont 
1  to  4.1,  and  in  Binghamton  only  about  1  to  1.5.  It  is  clear,  therefore, 
that  Hazen's  theorem  is  merely  a  convenient  formula  rather  than  a 
precise  methematical  expression. 

One  of  the  most  surprising  results  of  these  studies  is  the  disclosure 
of  the  remarkable  relation  subsisting  between  j)olluted  water  and  infant 
mortality.  This  was  emphasized  especially  by  Dr.  Reincke  at  Hamburg. 
Closely  associated  with  infant  mortality  stand  diarrhea  and  gastro- 
intestinal disorders  in  relation  to  polluted  water,  which  now  bids  fair 
to  assume  a  causal  importance  in  these  diseases  second  only  to  that  of 
contaminated  milk. 

In  regard  to  tuberculosis  the-  evidence,  though  less  striking,  is  in- 
teresting and  suggestive.  Sedgwick  and  MacNutt  state  that,  "inasmuch 
as  they  have  been  unable  even  after  the  most  careful  investigation  to 
discover  any  other  possible  explanation  of  the  figures,  they  are  forced 
to  the  conclusion  that  a  considerable  ]3ortion  of  the  decline  in  mortality 
from  tuberculosis  in  Lawrence  and  Lowell  during  the  years  immediately 
following  a  change  from  a  polluted  water  supply  was  due  to  that  change, 
and  in  line  with  this  conclusion  a  similar  explanation  appears  more  than 
probable  for  Hamburg.  A  somewhat  similar  relation  stands  for  pneu- 
monia, bronchitis,  and  the  acute  respiratory  diseases." 

The  question  naturally  arises  as  to  what  such  decline  of  mortality 
observed  in  the  Mills-Eeincke  phenomenon  for  diseases  other  than 
typhoid  fever  is  due.  The  natural  suggestion  is  that  it  either  results 
from  an  increased  vital  resistance  resulting  from  the  use  of  purer 
water  or  an  exclusion  of  the  disease  germs,  or  perhaps  the  phenomenon 
might  be  due  to  a  combination  and  cooperation  of  these  two  factors. 

McLaughlin  ^  has  also  stated  the  relation  of  a  sewage-polluted  water 
to  infant  mortality,  and  concludes  that  it  is  certain  that  in  practically 
every  instance,  in  addition  to  a  lessened  number  of  deaths  from  typhoid 
fever,  the  substitution  of  a  safe  for  a  polluted  water  supply  results  in 
the  saving  of  many  lives  from  diseases  which  are  not  reported  as  typhoid 
fever.  Hazen's  theorem  has  also  been  studied  by  Arthur  Lederer,-  who 
finds  a  large  number  of  afBirmative  statistical  results  from  which,  to- 
gether with  our  direct  and  indirect  proof  of  the  prevalence  of  water- 
borne  diseases,  it  seems  safe  to  assume  that  the  influence  of  an  improved 
water  supply  upon  the  death  rate  in  general  is  correct.  The  theorem 
seems  well  borne  out  by  the  figures  in  the  following  table : 

^Puh.  Bealtli  Reports,  Vol.  XXVII,  No.  17,  Apr.  26,  1912. 

^Arthur  Lederer:     Amer.  Journal  Public  Hygiene.     June,  1910,  p.  304. 


53 


806 


RELATIOX    OF    WATER    TO    DISEASE 


City 


Providence,  R.  I.  . 

St.  Louis,  Mo 

Youngstown,  O .  .  . 

Ithaca,  N.  Y 

Paducah,  Ky 

Watertown,  N.  Y. 
Paterson,  N.  J. .  .  . 
Binghamton,  N.  Y 

Average 


General 
Death 
Rate 
Before 
Change  of 
Water 
Supply 


19.3 
18.0 
15.6 
16.4 
23.4 
15.5 
17.2 
17.6 


17.8 


Same 
After 


19.0 
16.1 
15.1 
15.1 
17.8 
17.2 
16.5 
17.6 


16.8 


1    Typhoid 

Fever 

Percent- 

Death 

age  Re- 

Rate 

duction 

Before 

Change    of 

Supply 

+  1.6 
+  10.6 
+  3.2 
+  7.9 
+23.9 
—11.1 
+  4.1 
0 


+  5.7 


21.8 
39.2 
96.1 

108.8 
82.1 

100.6 
28.2 
40.8 


64.7 


Same 
After 


13.7 
19.1 
39.1 
25.3 
78.7 
38.2 
11.9 
13.4 


Percent- 
age Re- 
duction 


+37.2 
+51.3 
+59.4 
+76.8 
+  4.2 
+62.1 
+57.8 
+67.2 


29.9     i   +53.8 


NON-SPECIFIC    DISEASES     DUE     TO     WATER 


Impure  water  is  responsible  for  disorders  other  than  the  specific 
gastrointestinal  infections,  but  these  disorders  are  often  obscure  or  over- 
looked. It  is  not  ahvays  plain  just  what  quality  or  what  impurity  in 
the  water  is  responsible  for  these  non-specific  disorders,  and  the  dis- 
eases themselves  may  present  a  vague  and  ill-defined  clinical  picture. 
The  relationship  has  been  worked  out  in  only  a  few  instances. 

A  turbid  or  malodorous  water  may  not  in  itself  be  particularly 
injurious  to  health,  but,  on  account  of  its  unattractive  appearance  or 
repulsive  condition,  less  may  be  taken  than  is  necessary  for  the 
maintenance  of  good  health.  In  this  way  water  may  be  indirectly  re- 
sponsible for  much  harm.  The  drinking  of  too  little  water  is  a  very 
common  dietetic  error. 

While  a  polluted  water  may  not  carry  specific  germs,  it  may  so 
undermine  health  or  lower  resistance  as  to  favor  infections  not  usually 
associated  with  the  digestive  tract,  such  as  pneumonia  and  tuberculosis 
and  the  diseases  responsible  for  infant  mortality. 

From  the  nature  of  the  case  the  effects  of  an  impure  water  cannot 
always  be  measured  by  gross  results,  but  the  cumulative  or  separate 
action  of  small  effects  often  repeated  may  result  in  deranged  digestion, 
altered  metabolism,  irritation  of  delicate  membranes  or  sensitive  organs 
and  structures,  which  may  lead  to  or  hasten  the  course  of  chronic 
diseases. 

The  organic  matter  in  the  quantities  usually  contained  in  a  natural 
water  is  not  of  itself  harmful.  This  organic  matter,  however,  does  not 
stay  in  its  native  state,  but  soon  putrefies,  and  it  is  suspected  that  some 
of  the  intermediate  products  of  putrefaction  may  have  toxic  potency. 
Ordinarily  these  toxic  sulistances  are  in  minute  quantities,  or  at  least 


NOJ^-SPECIFIC    DISEASES    DUE    TO    WATEE  807 

in  great  dilution,  but  under  certain  circumstances  they  may  accumulate 
in  noticeable  concentration.  Further,  while  persons  habitually  taking 
such  toxic  substances  may  soon  become  immune,  the  new-comer  will 
not  be  so  fortunate.  The  case  of  organic  matter  in  water  is  not  a  clear 
one,  and  sanitarians  have  ever  erred  on  the  safe  side  in  condemning 
waters  containing  much  organic  matter.  It  is  well  known  that  if  the 
organic  matter  is  not  derived  from  sewage  it  is  jirobably  harmless.  Thus, 
in  the  case  of  organic  matter  of  vegetable  origin,  Mason  has  been  able 
to  find  but  few  cases  of  illness  traceable  to  jDcaty  waters.  In  such  in- 
stances the  patients  suffered  from  a  mild  and  transient  form  of  diar- 
rhea. I  am  familiar  with  an  outbreak  of  diarrhea  traced  to  a  dead  fish 
caught  in  the  water  meter  of  a  hospital.  This  is  probably  a  type  of 
water-borne  disease  due  to  organic  pollution  which  is  not  infrequent. 
Whether  in  such  cases  the  trouble  is  due  to  bacteria  or  to  bacterial 
toxins,  or  to  the  degradation  products  of  protein  decomposition,  cannot 
always  be  made  out. 

As  far  as  the  inorganic  impurities  usually  found  in  water  are  con- 
cerned, the  chlorids,  carbonates,  sulphates,  and  silicates,  and  lime,  mag- 
nesia, and  aluminium  can  scarcely  be  harmful  in  the  amounts  ordinarily 
found.  It  is  commonly  stated  that  water  containing  500  parts  per 
million,  or  30  grains  per  gallon,  of  clay  and  silt  is  unfit  for  drinking 
purposes,  on  account  of  its  irritating  effects  upon  the  gastrointestinal 
tract;  but  beyond  this  probability,  turbidity  is  of  no  special  sanitary 
significance,  unless  the  water  also  contains  metallic  poisons  or  objection- 
able chemicals. 

An  attempt  has  frequently  been  made  to  correlate  the  formation  of 
concretions  such  as  urinary  and  biliary  calculi  with  the  inorganic  salts 
in  water.  We  now  know  that  biliary  calculi  usually  form  about  a  colon 
bacillus  or  a  typhoid  bacillus  or  about  some  joathological  particle  as  a 
nucleus,  and  that  urinary  calculi  jDrobably  have  a  similar  pathogenesis. 
There  is  no  known  relation  between  these  concretions  in  the  body  and 
the  inorganic  salts  in  water,  even  those  in  a  very  hard  water.  The 
relation  of  inorganic  substances  in  water  to  goiter  will  be  discussed 
separately. 

Goiter. — Goiter  or  struma  is  a  chronic  enlargement  of  the  thyroid 
gland.  It  occurs  as  epidemics,  is  endemic  in  places,  and  sporadic  cases 
may  arise  anywhere.  Goiter  has  many  of  the  earmarks  of  an  infectious 
disease,  although  it  is  not  communicable  from  person  to  person,  the 
cause  being  derived  from  his  environment.  The  epidemics  are  usually 
of  short  duration,  limited  extent,  and  commonly  occur  in  goiter  regions. 

The  classic  home  of  endemic  goiter  is  in  the  Swiss  Alps.  In 
certain  regions  of  these  mountains  it  is  very  prevalent.  Thus,  in  Pied- 
mont it  sometimes  affects  more  than  two  out  of  every  three  of  the  in- 
habitants.    It  also  occurs  in  the  mountains  of  Austria,   France,   and 


808  RELATION    OF    WATER    TO    DISEASE 

Germany,  and  tliere  are  a  few  endemic  centers  in  Norway,  Sweden, 
Finland,  and  the  Baltic  provinces.  The  traditional  seat  of  goiter  in 
England  is  in  Derbyshire,  while  Sussex  and  Hampshire  have  also  been 
affected.  There  are  many  endemic  centers  in  the  mountains  of  Asia, 
Japan,  the  Asiatic  Islands,  Africa,  Mexico,  and  South  America.  The 
early  explorers  found  it  among  the  North  American  Indians,  as  Mun- 
sen  has  in  more  recent  times  in  the  Eskimos.  According  to  Osier, 
Dock,  and  Adami,  the  region  of  our  Great  Lakes  shows  considerable 
numbers,  but  in  the  L^nited  States  and  Canada  the  goiters  are  not  large 
and  cretinism  is  rare.  The  absolute  number  of  goiter  subjects  in 
countries  with  endemics  of  severe  degree  is  of  great  social  and  economic 
importance.  In  France,  Mayet  (1900)  estimates  the  number  at  400,000. 
The  drain  on  the  country  is  better  expressed  by  the  number  of  cretins. 
In  Cisleithan,  Austria,  there  were  in  1883  a  total  of  12,815,  or  71  per 
100,000;  in  one  district  in  Styria  a  proportion  of  1,045  in  100,000.  In 
Piedmont,  Lombardy,  and  Venetia  there  were  in  1883  12,882  cretins 
in  a  population  of  9,565,038  (Dock).  It  will  therefore  be  seen  that 
this  disease,  which  is  undoubtedly  preventable,  but  the  cause  of  which 
has  not  yet  been  satisfactorily  unraveled,  deserves  careful  study. 

Goiter  is  a  disease  which  is  caused  by  some  poison  or  possibly  in- 
fection taken  into  the  system  with  the  water  or  perhaps  some  other 
article  of  diet.  There  is  much  evidence  that  drinking  water  is  re- 
sponsible; also  some  that  it  is  not.  There  is  no  doubt  that  remarkably 
good  effects  have  been  obtained  in  Switzerland  and  Italy  by  the  intro- 
duction of  good  drinking  water.  For  a  long  time  glacial  waters  were 
believed  to  be  responsible,  but  this  view  has  now  been  abandoned  as 
the  cause  of  goiter.  Suspicion  has  fallen  upon  certain  inorganic  con- 
stituents of  water,  but  all  these  studies  have  resulted  negatively.  Thus 
the  magnesium  limestone,  iron,  and  iodin  have  each  in  turn  been  accused. 
It  is  known  that  goiter  may  occur  where  water  is  hard  or  soft,  or  in 
water  with  or  without  iron.  The  relation  of  iodin  in  water  to  goiter  is 
an  attractive  theory.  It  is  known  that  iodin  under  certain  circumstances 
stimulates  the  function  of  the  thyroid  gland  and  produces  the  train  of 
symptoms  associated  with  exophthalmic  goiter.  As  goiters  occur  in 
regions  in  which  the  water  does  not  contain  unusual  amounts  of  iodin, 
this  relationship  is  therefore  doubtful. 

It  is  assumed  that  some  constituent  in  the  water  is  responsible  for 
goiter  from  the  well-known  fact  that  there  are  goiter  wells  in  France 
and  Switzerland.  These  waters  are  used  successfully  for  the  intentional 
production  of  the  disease  with  the  view  of  escaping  compulsory  military 
service. 

The  relation  of  water  to  goiter  is  also  illustrated  in  A^ienna.  This 
city  long  boasted  of  the  best  water  among  all  European  cities.  It  is 
brought  in  long  aqueducts  and  subterranean  pipes  from  the  Schneeberg, 


NON-SPECIFIC    DISEASES    DUE    TO    WATEE  809 

a  mountain  groujD  about  6.000  feet  high  and  85  miles  to  the  north  of  the 
city.  This  water,  used  since  1872,  put  a  stop  to  typhoid  and  other 
gastrointestinal  diseases.  The  water  comes  from  limestone  formations, 
and  has  a  low  degree  of  hardness,  owing  to  the  absence  of  vegetation 
upon  the  catchment  area.  Since  18T3  the  number  of  goiters  in  Vienna 
have  increased  200  per  cent,  and  popular  belief  always  pointed  to  the 
water  as  the  cause.  The  water  used  by  the  inhabitants  in  many  of  the 
goiter  regions  in  Switzerland  comes  from  similar  limestone  formations. 

It  has  recently  been  shown  that  '"goiter"  is  xevj  common  in  trout 
in  certain  regions.  Thus,  in  our  own  endemic  area  about  the  Great 
Lakes  many  trout  have  enlarged  thyroid  glands.  In  trout  hatcheries 
almost  all  the  fish  may  suffer  from  goiters,  some  very  large,  provided 
three  conditions  are  present.  These  are:  (1)  overcrowding;  (2)  over- 
feeding: and  (3)  pollution  of  the  water.  It  is  stated  that  in  the  absence 
of  any  one  of  these  three  conditions  the  thyroid  glands  do  not  enlarge. 
These  enlarged  glands  have  been  described  by  Gaylord  as  cancers. 

For  the  reason  that  no  definite  correlation  has  been  demonstrated 
between  any  inorganic  impurity  in  a  water  and  the  occurrence  of  goiter, 
investigators  such  as  Kocher.  Ewald,  Bircher,  and  others  are  inclined  to 
think  that  a  microorganism  is  the  cause  of  the  trouble.  This  theory 
would  exjjlain  the  definite  endemic  distribution  of  the  disease. 

Bircher^  has  shown  that  goiter  occurs  essentially  upon  marine  de- 
posits or  paleozoic,  triassic,  and  tertiary  periods,  whereas  volcanic  forma- 
tions, crystalline  rock  of  archaic  age,  stratified  deposits  of  the  Jura  and 
Kreidemeer.  and  all  fresh-water  deposits  are  free.  These  facts  led 
Wilms-  to  assume  that  the  cause  of  goiter  is  not  a  living  organism,  but 
that  it  is  due  to  unknown  substances  derived  from  the  bodies  of  marine 
animals.  He  speculates  that  these  substances  may  be  toxalbumins  or 
ferments.  Experiments  upon  rats  show  that  water  from  a  goiter  well 
in  Basel  produces  hypertrophy  of  the  th}Toid.  This,  however, 
does  not  occur  if  the  water  is  heated  above  80°  C.  The  hypertrophy 
takes  place  in  the  rats  who  drink  this  water  which  has  been  passed 
through  a  Berkefeld  filter.  The  water  looks  clear  and  fine,  has  a 
moderate  hme  content,  and  is  slightly  high  in  ammonia. 

Lobenhoffer  ^  studied  the  presence  of  goiter  in  the  I'nterfranken 
district.  In  some  of  the  town  21  to  26  per  cent,  of  the  inliabitants  are 
affected.  The  endemic  regions  correspond  to  certain  geological  formations 
from  which  the  drinking  water  is  derived.  "Water  from  shell  limestone 
is  the  main  goiter  producer,  but  in  a  milder  degree  red  sandstone 
and   other   formations  are   involved.     Boiling  the   water   seems   to   do 

^Med.  EJinik,  1908,  Heft,  6. 

'■'Deutsche  med.   Wochenschr.,  March  31,   1910,  p.   604. 

^  Lobenhoff er,  W. :  ' '  Die  Verbreitung  des  Kropf  es  in  I'nterf  ranken, ' "  Mit- 
teilung  aus  den  Grenzgehieten  der  Med.  und  Chir.,  Jena,  XXr\^,  No.  3,  pp.  383- 
606. 


810  in^LATION    OF    WATER    TO    DISEASE 

away  with  its  goiter-prodiicinij  properties.  Lobenhoffer  believes  that 
the  hi  test  researclies  in  re<iar(l  to  the  causal  a*i'ent  of  goiter  seem  to 
demonstrate  tb;it  it  is  a  purely  chetnieal  substratum  substance  which 
enters  the  water  as  a  toxin,  but  which  is  certainly  destroyed  at  70°  C. 
He  also  believes  that  it  is  possible  that  filtering  through  certain  sub- 
stances or  treating  witli  ultra-violet  rays  may  have  the  same  effect. 

The  prevention  of  goiter  therefore  consists  in  the  elimination  of 
factors  that  are  known  or  sus])ected  of  being  able  to  produce  the 
disease,  such  as  water  from  certain  sources.  If  possible,  persons  in 
predisposed  families  should  leave  goiter  districts  and  live  in  healthy 
localities.  The  drinking  water  should  be  boiled,  for  experimental  evi- 
dence demonstrates  that  the  "poison,"  whatever  it  may  be,  in  water  is 
destroyed  by  boiling.  Filtration  is  not  sufficient,  for  experiments  have 
shown  that  it  will  pass  a  Berkefeld  filter.  Tight  collars  and  occupa- 
tions that  induce  congestion  of  the  head  should  be  avoided.  The  satis- 
factory control  of  the  disease  must  await  further  studies  into  its  causa- 
tion. In  the  meantime  improved  sanitation  in  its  broadest  sense 
woiild  doubtless  diminish  the  incidence  to  this  disease. 

Lead  Poisoning. — Lead  is  practically  never  found  in  natural  waters. 
The  source  of  tiie  lead  in  the  water  is  almost  always  lead  service  pipes,  or 
some  other  lead  object  used  in  collecting,  storing,  or  delivering  the 
water.  Lead  is  the  most  dangerous  inorganic  substance  with  which 
our  drinking  water  is  ordinarily  contaminated.  Lead  poisoning  from 
this  source  is  much  more  common  than  it  is  given  credit  for.  A 
celebrated  instance  of  lead  poisoning  occurred  in  Lancashire  and  York- 
shire, England.  The  water  came  from  peaty  moorlands  and  was  de- 
livered through  lead  pipes.  The  citizens  of  these  towns  experienced 
a  mysterious  bodily  derangement  for  some  years,  until  it  was  finally 
discovered  that  lead  poisoning  was  prevalent.  In  many  other  places, 
as  Somerfeld,  Germany,  and  Lowell,  Mass.,  numerous  cases  of  lead 
poisoning  due  to  the  action  of  water  in  lead  pipes  have  been  reported. 

Enormous  quantities  of  lead  service  pipes  are  still  in  use,  not  only 
in  the  old  plumbing,  but  in  the  newer  installations.  It  is  so  pliable 
that  plumbers  find  it  much  easier  to  bend  it  around  corners  and 
angles  than  to  make  the  usual  connections  with  iron  or  brass  pipe, 
and  it  is  therefore  a  great  temptation  to  put  in  short  lengths  of 
it  in  difficult  places.  Lead  poisoning  may,  under  certain  circumstances, 
come  from  a  few  feet  of  lead  pipe.  The  various  factors  that  determine 
the  corrosive  action  of  water  u})on  lead  are  very  complex.  It  is  not 
possible  to  determine  by  chemical  tests  whether  or  not  a  water  has 
plumbo-solvcnt  action.  All  natural  waters  have  some  solvent  power. 
The  only  sure  method  of  determining  to  what  degree  a  given  water 
will  take  up  lead  is  by  testing  the  question  experimentally  under  prac- 
tical conditions  and  establishing  the  amount  of  lead  taken  up. 


KON-SPECIFIC    DISEASES    DUE    TO    WATER  811 

The  way  by  which  water  takes  up  lead  is  first  through  the  formation 
of  lead  oxid.  This  oxidation  is  favored  by  the  amount  of  oxygen 
carried  in  the  water,  possibly  aided  by  the  nitrates  and  nitrites  serving 
as  oxygen  carriers.  The  lead  oxid  may  then  be  dissolved,  more  rapidly 
if  the  water  is  acid,  or  may  be  washed  away  by  the  currents  in  the  state 
of  a  fine  powder  in  suspension. 

As  a  general  rule  clean  (pure)  waters  have  a  greater  corrosive  action 
upon  lead  than  turbid  waters.  This  is  partly  for  the  reason  that  the 
mud  coats  the  pipes  and  protects  them  mechanically.  Acid  waters  are 
almost  sure  to  take  up  lead  if  allowed  to  come  in  contact  with  that 
metal.  Even  so  feeble  an  acid  as  carbonic  acid  may  under  certain  cir- 
cumstances greatly  increase  the  plumbo-solvent  action  of  water.  Soda 
water  (highly  charged  with  CO2  under  pressure)  takes  up  relatively 
large  quantities;  as  if  lead  pipes  are  used  in  soda  water  fountains  or 
"syphon"  bottles.  "Waters  containing  carbonates  or  sulphates  are  not 
apt  to  take  up  lead  because  the  corresponding  salts  of  lead  are  in- 
soluble, and  thus  form  a  protecting  coating.  Even  though  a  water  has 
no  plumbo-solvent  action,  the  use  of  lead  piping,  lead  cooking  utensils, 
lead-lined  cisterns,  etc.,  is  entirely  unjustified  for  domestic  service,  for 
the  reason  that  under  certain  circumstances  electrolytic  action,  changes 
in  the  character  of  the  water,  or  other  causes  may  lead  to  lead  poisoning. 

Various  conditions  affect  the  plumbo-solvent  action  of  water,  such 
as  the  duration  of  contact,  the  temperature,  the  pressure,  the  season  of 
the  year,  the  purity  of  the  lead,  etc.  Water  remaining  in  the  pipes 
all  night  naturally  takes  up  more  lead  than  the  water  that  flows  more 
or  less  rapidly  during  the  day.  Lead  pipes  were  formerly  used  in  soda 
water  fountains  and  the  employee  who  took  the  first  drink  in  the  morn- 
ing before  the  proprietor  arrived  received  a  concentrated  dose.  Hot 
water  has  a  greater  solvent  action  than  cold  water;  so,  also,  increase  in 
pressure  up  to  140  pounds  to  the  square  inch.  For  some  unexplained 
reason  more  lead  is  often  found  in  the  water  during  the  winter  than 
during  the  summer.  The  purer  the  lead  in  the  pipes  the  freer  the 
solvent  action.  ISTew  pipes  give  up  more  lead  than  old  pipes.  However, 
in  some  cases  the  poisoning  manifested  itself  only  after  the  pipe  had 
been  in  use  for  years.  Lead  pipes  are  purer  now  than  formerly,  owing 
to  profitable  methods  of  extracting  the  silver  and  other  metals  with 
which  it  is  frequently  associated.  If  the  lead  is  combined  with  copper, 
zinc,  or  tin  the  lead  passes  into  the  water  more  quickly  in  consequence 
of  galvanic  action  than  when  pure  lead  is  used.  Electrolytic  action 
favors  the  solution  of  lead,  and  the  modem  method  of  grounding  electric 
currents  adds  to  the  danger. 

The  various  conditions  of  water  that  favor  plumbo-solvent  action  are : 
Those  containing  free  acid,  such  as  soft,  peaty  waters;  those  containing 
much  oxygen   and  little   dissolved  salts,  that  is,   soft  waters,  such  as 


812  EELATION    OF    WATER    TO    DISEASE 

rain  water;  those  containing  organic  matter,  nitrites,  and  nitrates,  that 
is,  sewage-contaminated  water  in  the  stage  of  oxidation;  those  contain- 
ing chlorids,  because  chlorids  dissolve  the  protecting  film  of  carbonates. 
Waters  that  act  least  upon  lead  are  turbid  waters  and  hard  waters, 
especially  those  containing  free  COo,  for  here  again  carbonates  are 
formed  which  protect  the  water  with  an  insoluble  film.  However,  if 
CO,  is  present  in  excess  or  under  pressure  the  carbonates  are  redissolved. 

It  will  therefore  be  seen  that  the  purest,  softest,  and  best  aerated 
waters  are  especially  prone  to  act  upon  lead.  Distilled  water  will  take 
up  lead  even  from  impure  zinc  pipes  (containing  some  lead)  used  on 
board  ships.  Absolutely  pure  water  probably  has  no  appreciable  action 
upon  metals  such  as  lead,  iron,  and  zinc,  but  absolutely  pure  waters 
are  not  found  in  nature.  The  plumbo-solvent  action  is  in  part  a 
mechanical  erosion,  in  part  a  chemical  solution,  and  in  part  results 
from  electrolytic  action. 

Symptoms. — The  symptoms  of  lead  poisoning  are  sometimes  vague 
and  readily  overlooked.  Fatal  poisoning  may  be  caused  when  very  little 
lead  is  taken  with  the  water  each  day;  the  action  is  cumulative  and  the 
course  of  the  intoxication  is  chronic;  the  immediate  and  remote  effects 
are  serious. 

The  usual  symptoms  of  chronic  lead  poisoning  are  anemia,  dyspepsia, 
depression,  constipation,  colic;  various  forms  of  paralysis,  especially 
paralysis  of  the  extensor  muscles  of  the  forearm  leading  to  wrist- 
drop; a  blue  line  along  the  edges  of  the  gums,  due  to  the  formation 
of  sulphid  of  lead  deposited  in  the  tissues.  Optic  neuritis  may  come 
on.  There  is  an  increase  in  the  blood  pressure.  Chronic  lead  poisoning 
leads  to  arteriosclerosis,  fibrosis  of  the  kidneys,  and  the  remote  conse- 
quences of  these  changes.  Muscular  paresis,  pain  and  swelling  of  the 
joints,  often  occur  and  may  be  mistaken  for  "rheumatism."  In  some 
cases  gout  is  closely  simulated.     The  pain  is  usually  worse  at  night. 

The  individual  susceptibility  to  lead  poisoning  varies  remarkably. 
Of  a  number  of  individuals  equally  exposed  some  will  suffer  and  others 
escape.  Of  those  who  suffer  the  degree  of  intoxication  varies  con- 
siderably. It  is  quite  common  to  find  that  among  the  members  of  a 
family  using  a  water  containing  lead  only  one  is  stricken,  while  the 
others  seem  to  be  immune;  that  is,  they  either  do  not  absorb  the  lead 
or  are  able  to  eliminate  it. 

Mild  cases  of  lead  poisoning  may  show  only  symptoms  of  anemia, 
vague  or  fugitive  pains,  or  a  mild  type  of  peripheral  neuritis.  This  stage 
of  lead  poisoning,  which  does  not  vary  essentially  from  other  intoxica- 
tions of  mild  degree,  is  readily  overlooked  clinically. 

Lead  is  absorbed  from  the  intestines  and  eliminated  by  the  kidneys 
and  the  liver.  It  therefore  may  appear  in  either  the  urine  or  feces. 
Lead  in  the  urine  is  always  associated  with  albumin,  and  may  be  inter- 


SPECIFIC    DISEASES    DUE    TO    WATEE  813 

mittent.  That  is,  a  well-marked  case  of  lead  poisoning  may  excrete 
urine  free  from  both  lead  and  albumin.  However,  if  the  feces  are 
examined  they  will  be  found  to  contain  lead. 

Lead  poisoning  may  occur  when  a  comparatively  small  surface  of 
lead  is  exposed  to  the  solvent  action  of  the  water.  This  is  well  illus- 
trated in  the  following  cases  :^ 

Case  1. — A  man  about  fifty  years  old  contracted  lead  poisoning  from 
using  cistern  water.  Twelve  feet  of  the  service  pipe  was  lead,  and 
almost  wholly  in  the  water,  as  it  was  bent  at  right  angles  and  ran 
across  the  cistern  under  the  water. 

Case  2. — Mrs.  W.,  sixty-six  years  of  age,  contracted  lead  poisoning 
from  a  well  water  which  was  contaminated  from  an  old  lead  clock 
weight  which  had  been  accidentally  dropped  into  the  well.  The  clock 
weight  had  been  in  the  water  about  fourteen  months  before  the  appear- 
ance of  symptoms.  The  well  was  pumped  free  of  water  and  the  clock 
weight  found  and  removed.  In  two  weeks  from  this  time  Mrs.  W. 
noticed  an  improvement  in  her  lameness,  and  in  four  months  she  was 
entirely  well. 

Case  3. — In  this  case  the  patient  was  poisoned  by  cistern  water 
pumped  through  10  feet  of  lead  pipe.  The  symptoms  were  acute  mul- 
tiple peripheral  neuritis,  with  extensive  paralysis.  After  the  lead  in 
the  water  was  removed  recovery  was  only  partial  after  a  period  of 
two  years. 

SPECIFIC  DISEASES  DUE  TO  WATER 

The  principal  diseases  of  man  contracted  by  drinking  infected  water 
are  typhoid  fever,  cholera,  and  dysentery.  Water-borne  epidemics  of 
these  diseases  have  frequently  occurred  in  the  history  of  the  world. 
It  should  be  remembered  that  endemic  and  sporadic  cases  may  also  con- 
tract their  infections  through  water.  The  great  water-borne  tragedies 
have  for  a  time  occupied  an  exaggerated  position.  They  overshadowed 
the  less  dramatic,  but  more  insidious,  and  nevertheless  frequent  modes 
of  transmission  of  infection  through  other  channels,  especially  "con- 
tacts." It  is  only  in  recent  years,  since  the  water  supplies  of  most  of 
our  large  communities  have  been  very  much  improved,  so  that  water- 
borne  epidemics  have  been  excluded,  that  sanitarians  have  appreciated 
the  quantitative  role  played  by  water  as  a  medium  of  convection  in 
distributing  pathogenic  microorganisms. 

It  is  worthy  of  note  that  almost  all  the  large  water-borne  outbreaks 
that  have  been  investigated  have  been  traced  to  a  quick  transfer  of  the 
infected  material  from  the  patient  to  the  victim.  The  greater  the 
distance  and  the  longer  the  time  between  the  source  of  the  infection 

*  Bull.  State  Board  of  Health,  Maine,  Jan.,  1909,  Vol.  I,  No.  21. 


814  RELATION    OF    WATER    TO    DISEASE 

and  the  use  of  the  water,  the  less  are  the  chances  of  harm.  This  we 
now  understand  as  the  result  of  several  factors  which  have  heen  dis- 
cussed. 

It  is  doubtful  wliether  typhoid,  cholera,  or  dysentery  bacilli  multiply 
in  water  under  natural  conditions,  certainly  to  no  great  extent.  Almost 
all  the  great  water-l)orne  epidemics  of  typhoid  fever  occur  in  the  spring, 
winter,  or  fall  of  the  year,  when  the  water  is  very  cold.  Water-borne 
epidemics  of  typhoid  in  the  summertime,  when  the  conditions  seem 
favorable  for  multiplication  of  the  bacilli,  are  relatively  infrequent. 
Assuming  that  in  the  case  of  typhoid  there  is  no  multiplication  of  the 
bacilli  in  the  water,  the  dilution  must  have  been  enormous  in  many  of 
the  cases  recorded ;  that  is,  there  must  have  been  very  few  typhoid 
bacilli  in  a  tumblerful  of  water.  If  these  facts  are  correct  it  illustrates 
how  very  few  bacteria,  when  fresh  and  virulent,  may  induce  disease. 
The  experimental  data  from  the  laboratory  indicate  that  the  healthy 
organism  may,  as  a  rule,  successfully  overcome  small  doses  of  infection. 
Feeding  experiments,  especially  upon  the  lower  animals,  under  labora- 
tory conditions,  indicate  that  very  large  numbers  of  microorganisms 
are  usually  necessary  to  induce  disease  when  administered  by  the 
mouth.  This  is  only  one  of  the  many  discrepancies  between  laboratory 
and  natural  conditions.  Many  large  epidemics  have  been  traced  to  in- 
dividual instances  of  pollution.  In  the  typhoid  epidemics  at  Butler, 
Plymouth,  New  Haven,  in  jSTanticoke  and  Beading,  there  were  collec- 
tively 3,929  cases  of  typhoid  fever,  with  361  deaths,  resulting  from 
the  careless  treatment  of  the  discharges  of  but  five  individual  patients. 

Outbreaks  due  to  water  are  usually  caused  by  the  contamination 
of  surface  supplies;  less  often  by  wells  and  springs.  It  is  self-evident 
that  the  great  epidemics  have  always  been  caused  by  polluted  river  or 
lake  waters,  and  not  by  ground  waters.  Ground  water  is  sometimes 
responsible  for  outbreaks  of  typhoid  fever,  especially  in  limestone  dis- 
tricts, as  at  Lausen,  Switzerland ;  Paris,  France,  etc.  Usually  when 
a  well  becomes  badly  infected  it  is  from  a  nearby  privy  or  broken  sewer 
underground,  as  in  the  instance  of  the  Broad  Street  cholera  epidemic  in 
London. 

Epidemics  from  public  water  supplies  result  from  contamination  by 
various  factors.  The  use  of  a  raw  water  into  which  is  continually  dis- 
charged the  sewage  of  other  towns  has  occurred  at  Pittsburgh,  Lawrence, 
and  Philadelphia.  A  city  may  drink  the  water  of  a  lake  which  has  be- 
come its  own  cesspool,  as  did  Chicago,  Cleveland,  and  Burlington.  The 
pollution  may  come  from  the  wastes  of  individual  houses,  as  at  Ply- 
mouth, or  from  institutions  or  factories;  or  the  pollution  may  come 
from  privies  situated  directly  over  the  stream  or  on  its  banks,  as  at 
Ithaca ;  or  the  pollution  may  come  indirectly  after  the  offending  matter 
has  been  deposited  on  the  surface  of  the  ground,  later  gaining  access 


SPECIFIC    DISEASES    DUE    TO    WATEE  815 

to  tlie  water  course  by  the  washing  of  rain  or  seepage  through  ground 
seams.  In  some  instances  epidemics  originate  through  criminal  thought- 
lessness in  a  town  that  has  been  supplied  with  a  pure  or  purified  water. 
Thus  a  water  pipe  laid  through  a  polluted  pond  may  become  sufficiently 
disjointed  to  permit  admission  of  the  infected  water,  as  occurred  at 
Baraboo,  Wis.,  and  Palmerton,  Pa.  The  admission  of  polluted  water 
to  a  pure  city  supply  at  any  time  is  inexcusable.  Epidemics  have 
originated  as  a  result  of  the  unusual  drain  upon  the  water  supply  at 
times  of  fire,  as  in  the  case  of  Lawrence;  or  through  failure  of  valves 
to  operate,  as  in  the  case  of  Wilkinsburg,  Pa.,  when  the  ordinary  water 
supply  was  judged  to  be  insufficient  and  no  public  warning  was  given 
of  the  substitution  as  at  Newburyport;  or  when  polluted  water  was  fur- 
nished temporarily  while  the  filter  plant  was  undergoing  repair,  as  at 
Lawrence,  Mass.,  in  1902 ;  in  Brewer,  in  Poughkeepsie,  IST.  Y.,  and  Mill- 
inocket,  Me.  Various  public  wells  have  become  infected  through  ground 
seams,  and  have  thus  caused  epidemics  of  typhoid  fever  at  Trenton, 
Newport,  and  Mt.  Savage,  Md.^ 

In  addition  to  the  usual  sources  of  pollution  of  a  surface  water, 
the  following,  while  relatively  infrequent,  may  be  particularly  dangerous, 
for  the  reason  that  they  are  apt  to  take  place  near  the  source  of  supply: 
discharges  from  water-closets  of  railroad  trains  while  crossing  bridges 
or  passing  the  banks  of  reservoirs  and  streams ;  picnic  parties ;  camping 
parties;  construction  gangs;  fishermen;  ferryboats  and  other  craft  upon 
navigable  streams.  The  large  boats  plying  our  Great  Lakes  may  dis- 
charge dangerous  and  obnoxious  material  very  near  an  intake. 

Cholera. — Cholera  in  London  in  1854 — The  Case  of  the  Broad 
Street  Pump. — Cholera  was  prevalent  in  London  in  1854,  but  prevailed 
with  epidemic  intensity  in  the  district  about  Broad  Street.  This  focus 
was  conspicuously  circumscribed  in  area,  and  the  disease  was  virulent, 
with  great  fatality.  This  case  has  become  classic  because  it  was  one 
of  the  earliest  instances,  if  not  the  first,  in  which  water  was  proved 
to  convey  a  specific  disease.  The  circumstances  were  studied  by  Dr. 
John  Snow  and  by  Mr.  John  York,  Secretary  and  Surveyor  of  the 
Cholera  Inquiry  Committee.^  No  less  than  700  deaths  occurred  in  St. 
James  Parish  during  the  seventeen  weeks  that  the  cholera  raged.  The 
death  rate  was  220  per  10,000  in  the  parish,  which  contained  a  popula- 
tion in  1851  of  36,406.  In  the  adjoining  districts  the  death  rate  varied 
from  9  to  33  per  10,000. 

Dr.  Snow  made  a  careful  epidemiological  study  of  the  outbreak  and 

^  Harold  B.  Wood :  * '  The  Economic  Value  of  Protecting  the  Water  Sup- 
plies."    J.  A.  M.  A.,  Oct.  2,  1909,  p.  1093. 

^  The  complete  original  report  is  entitled  ' '  Report  on  the  Cholera  Outbreak 
in  the  Parish  of  St.  James,  Westminster,  during  the  Autumn  of  1854.  Presented 
to  the  Vestry  by  the  Cholera  Inquiry  Committee,  July,  1855. ' '  London,  J. 
Churchill,  1855. 


81G 


KELATION    OF    WATER    TO    DISEASE 


compiled  a  statistical  statement  of  special  value,  which  is  here  given  in 
its  original  form. 

The   Broad    Stiieet    (London)    Well  and   Deaths    from    Asiatic 
Cholera  Near  It  in  1854 


Date 


Aug.  19. 
Aug.  20. 
Aug.  21. 
Aug.  22. 
Aug.  23. 
Aug.  24 . 
Aug.  25 . 
Aug.  26. 
Aug.  27. 
Aug.  28. 
Aug.  29 . 
Aug.  30 . 
Aug.  31 . 
Sept.  1 . 
Sept.  2. 
Sept.  3. 
Sept.  4. 
Sept.  5. 
Sept.  6. 
Sept.  7. 
Sept.  8. 
sept.  9. 
Sept.  10. 


Number 

of  Fatal 

Peaths 

Attacks 

1 

0 

2 

0 

0 

0 

2 

0 

0 

0 

1 

0 

1 

8 

2 

56 

3 

143 

70 

116 

127 

54 

76 

46 

71 

36 

45 

20 

37 

28 

32 

12 

30 

11 

24 

5 

18 

Date 


Sept.  11 

Sept.  12 

Sept.  13 

Sept.  14 

Sept.  15 

Sept.  16 

Sept.  17 

Sept.  18 

Sept.  19 

Sept.  20 

Sept.  21 

Sept.  22 

Sept.  23 

Sept.  24 

Sept.  25 

Sept.  26 

Sept.  27 

Sept.  28 

Sept.  29 

Sept.  30 

Date  unknown 

Total 


Number 
of  Fatal 
Attacks 


0 

0 

0 

45 


616 


Deaths 


15 
6 

13 
6 
8 
6 
5 
2 
3 
0 
0 
2 
3 
0 
0 
2 
0 
2 
0 
0 
0 


616 


Many  of  the  facts  of  this  epidemic  are  taken  from  Sedgwick's  excel- 
lent account  in  his  "Principles  of  Sanitary  Science  and  the  Public 
Health/'  1902,  which  the  student  is  advised  to  read. 

It  will  be  seen  that  the  disease  broke  out  with  special  intensity  upon 
August  30  and  declined  noticeably  after  September  10.  The  pump 
had  been  removed  on  September  8.  Dr.  Snow's  inquiry  showed  that 
most  of  the  victims  had  preferred  or  had  access  to  the  water  of  the 
Broad  Street  well,  and  only  in  a  few  cases  was  it  impossible  to  trace 
any  connection  with  that  source.  Thus,  with  regard  to  73  deaths  occur- 
ring in  the  locality  of  the  pump  and  studied  especially  with  reference 
to  this  point,  it  was  found  that  there  were  61  instances  in  which  the 
deceased  persons  used  to  drink  the  water  from  the  pump  in  Broad 
Street,  either  constantly  or  occasionally.  In  6  instances  no  information 
could  be  obtained,  and  in  6  cases  it  was  stated  that  the  deceased  persons 
did  not  drink  the  pump  water  before  their  illness. 

On  the  other  hand,  Dr.  Snow  discovered  that,  while  a  workhouse 
(almshouse)  in  Poland  Street  was  three-fourths  surrounded  by  houses 
in  which  cholera  deaths  occurred,  out  of  535  inmates  of  the  workhouse 


SPECIFIC    DISEASES    DUE    TO    WATER 


817 


only  5  cholera  deaths  occurred.  The  workhouse^  however,  had  a  well  of 
its  own  in  addition  to  the  city  supply,  and  never  sent  for  water  to  the 
Broad  Street  pump.  If  the  cholera  mortality  in  the  workhouse  had 
been  equal  to  that  in  its  immediate  vicinity  it  should  have  had  50 
deaths. 

A  brewery  in  Broad  Street  employing  seventy  workmen  was  entirely 
exempt,  but,  having  a  well  of  its  own,  and  allowances  of  malt  liquor 
having  been  customarily  made  to  the  employees,  it  appeared  likely  that 


Fig.  109. 

the  proprietor  was  right  in  his  belief  that  resort  was  never  had  to  the 
Broad  Street  well. 

It  was  quite  otherwise  in  a  cartridge  factory  at  No.  38  Broad  Street, 
where  about  200  workpeople  were  employed,  two  tubs  of  drinking  water 
having  been  kept  on  the  premises  and  always  filled  from  the  Broad 
Street  well.  Among  these  employees  eighteen  died  of  cholera.  Similar 
facts  were  elicited  for  other  factories  on  the  same  street,  all  tending  to 
show  that  in  general  those  who  drank  the  water  from  the  Broad  Street 
well  suffered  either  from  cholera  or  diarrhea,  while  those  who  did  not 


818  RELATION    OF    WATER    TO    DISEASE 

drink  that  Avater  escaped.  The  whole  chain  of  evidence  was  made 
absolutely  conclusive  by  several  remarkable  and  striking  cases  in  Dr. 
Snow's  report  like  the  following : 

"A  gentleman  in  delicate  health  was  sent  for  from  Brighton  to 
see  his  brother  at  Xo.  6  Poland  Street  who  was  attacked  with  ciiolera 
and  died  in  twelve  hours,  on  the  first  of  September.  The  gentleman 
arrived  after  his  brother's  death,  and  did  not  see  the  body.  He  only 
stayed  about  twenty  minutes  in  the  house,  where  he  took  a  hasty  and 
scanty  luncheon  of  rump  steak,  taking  with  it  a  small  tumbler  of  cold 
brandy  and  water,  the  water  being  from  the  Broad  Street  pump.  He 
w^ent  to  Pentonville,  and  was  attacked  with  cholera  on  the  evening  of 
the  following  day,  September  2,  and  died  the  next  evening." 

"The  deaths  of  Mrs.  E.  and  her  niece,  who  drank  the  water  from 
Broad  Street  at  the  West  End,  Hampstead,  deserve  especially  to  be 
noticed.  I  was  informed  by  Mrs.  E.'s  son  that  his  mother  had  not 
been  in  the  neighborhood  of  Broad  Street  for  many  months.  A  cart  went 
from  Broad  Street  to  West  End  every  day,  and  it  was  the  custom  to 
take  out  a  large  bottle  of  the  water  from  the  pump  in  Broad  Street,  as 
she  preferred  it.  The  water  was  taken  out  on  Thursday,  the  31st  of 
August,  and  she  drank  of  it  in  the  evening  and  also  on  Friday.  She 
was  seized  with  cholera  on  the  evening  of  the  latter  day,  and  died  on 
Saturday.  A  niece  who  was  on  a  visit  to  this  lady  also  drank  of  the 
water.  She  returned  to  her  residence,  a  high  and  healthy  part  of 
Islington,  was  attacked  with  cholera,  and  died  also.  There  was  no 
cholera  at  this  time,  either  at  West  End  or  in  the  neighborhood  where 
the  niece  died.  Besides  these  two  persons  only  one  servant  partook  of 
the  water  at  West  End,  Hampstead,  and  she  did  not  suffer,  or,  at  least, 
not  severely.    She  had  diarrhea." 

Mr.  York,  Secretary  and  Surveyor  of  the  Cholera  Inquiry  Commit- 
tee, was  instructed  to  survey  the  locality'  and  examine  the  well,  cess- 
pool, and  drains  at  Xo.  40  Broad  Street.  His  report  revealed  the  fol- 
lowing condition  of  affairs:  The  well  was  circular  in  section,  28  feet 
10  inches  deep,  6  feet  in  diameter,  lined  with  brick,  and  when  examined 
(April,  1855)  contained  7  feet  6  inches  of  water.  It  was  arched  in  at 
the  top,  dome  fashion,  and  tightly  closed  at  a  level  3  feet  6  inches 
below  the  street  by  a  cover  occupying  the  crest  of  the  dome.  The  bot- 
tom of  the  main  drain  of  the  house  from  Xo.  40  Broad  Street  lay  9  feet 
2  inches  above  the  water  level,  and  one  of  its  sides  was  distant  from 
the  brick  lining  of  the  well  only  2  feet  8  inches.  This  was  an  old- 
fashion  drain  12  inches  wide,  with  brick  sides;  the  top  and  bottom  were 
made  with  old  stone.  It  had  a  small  fall  to  the  main  sewer.  The 
mortar  joints  of  the  old  stone  bottom  were  found  to  be  perished,  as 
was  also  the  jointing  of  the  brick  sides,  which  had  brought  the  brick- 
work into  the  condition  of  a  sieve,  and  through  which  the  house  drain- 


SPECIFIC    DISEASES    DUE    TO    WATER 


819 


LINE   OF  FRONT. 


rr 


PAVEMENT. 


"<0    -J 

n 


!-/+> 


L_. 


WATER      LINE. 


age  must  have  percolated  for  a  considerable  period.     Dr.   Snow  found 

the  cesspool  intended  for  a  trap,  but  misconstructedj  and  upon  and  over 

a  part  of  the  cesspool  a  common  privy,  without  water  supply,  for  the 

use  of  the  house  had  been  erected.     The  brickwork  of  the  cesspool  was 

found    to    be    in    the    same 

decayed    condition    as    the 

drain.       Dr.     Snow     states 

that,     "from    the     charged 

condition    of    the    cesspool, 

the    defective    state    of    its 

brickwork,  and  also  that  of 

the  drain,  no  doubt  remains 

upon  my  mind  that  constant 

percolation,  and  for  a  con- 
siderable  period,   had   been 

conveying  fluid  matter  from 

the  drains  into  the  well.    A 

washed   appearance    of   the 

ground  and  gi"avel  flow  cor- 
roborated   this    assumption. 

The    ground    betvreen    the 

cesspool   and   the   well   was 

black,   saturated,   and  in   a 

swampy    condition,    clearly 

demonstrating     the     fact." 

This    evidence,    while    only 

circumstantial, '  is   sufficient 

to  connect  the  cesspool  with 

the  well,  and  can  leave  no  doubt  in  the  minds  of  those  who  study  this 

interesting  and  instructive  instance  that  the  water  became  infected  with 

cholera  germs  through  this  channel.     It  should  be  remembered  that  this 

outbreak  occurred  before  the  days  of  bacteriology,  so  that  direct  proof  is 
not  at  hand.  As  far  as  could  be  determined,  the  infection  of  the  well 
came  from  an  unrecognized  case  of  cholera  in  the  house  at  No.  -iO  Broad 
Street.  There  were  four  severer  cases  of  cholera  subsequently  in  the 
same  house. 

The  Cholera  Epidemic  in  Hambueg  in  1892. — This  epidemic 
stands  out  clearly,  not  only  as  one  of  the  most  devastating  of  modem 
times,  but  as  one  of  the  most  instructive.  The  relation  between  the 
infected  water  and  the  disease  was  conclusively  proven,  and  the  value 
of  slow  sand  filtration  placed  upon  a  strong  foundation.  The  conditions 
of  the  epidemic  were  equal  to  those  of  a  well-controlled  laboratory  ex- 
periment, and  the  bacteriological  and  epidemiological  evidence  corrobo- 
rated each  other  in  every  essential  particular. 


ASIATIC    CHOLERA 

AND 

THE  BROAD  STREET  WELL. 

LONDON    ISS4. 
W. .WELL. 

d main  drain  of  h0u8c  n0.40. 

VandV.!.cellars  unocr  stbect. 
c- cesspool.. 

R„. PRIVY» 

CaFTER   Ma  YORkb  original   DRAWINGS.) 


Fig.  110. 


820 


DELATION    OF    WATER    TO    DISEASE 


From  August  17  to  October  23,  1892,  a  little  over  two  months,  there 
were  nearly  17,000  cases  of  cholera  in  Hamburg  (population  640,000), 
with  8,605  deaths.  On  one  day  during  the  height  of  the  epidemic  over 
1,000  new  cases  occurred.  This  was  a  pandemic  year  for  cholera  in 
the  sense  that  it  showed  a  remarkable  tendency  to  spread  to  all  parts 
of  the  world.  It  traveled  from  the  valley  of  the  Ganges  through  Per- 
sia, to  Russia,  Germany,  Austria,  France,  Belgium,  Holland,  and  the 
disease  was  brought  to  our  own  doors  and  several  cases  occurred  in 
New  York  City. 

Hamburg  is  a  separate  city,  and  at  the  time  of  the  epidemic  had  a 
population  of  640,000.  Altona  (population  143,000)  is  in  Prussia. 
Politically  Hamburg  and  Altona  are  separate,  but  geographically  and 
actually  they  form  one  large  city.  The  boundary  runs  through  a  street 
on  one  side  of  which  is  Hamburg,  on  the  other  Altona.  Wandsbeck 
(population  20,000)  is  a  nearby  suburban  town.  Each  of  these  three 
places  at  the  time  of  the  epidemic  had  a  separate  water  supply.  Wands- 
beck drank  filtered  water  from  a  spring  little  subject  to  pollution. 
Hamburg  and  Altona  were  both  furnished  with  water  from  the  Elbe 
Eiver,  which  is  a  grossly  polluted  stream.  Both  the  cities  of  Hamburg 
and  Altona  rest  upon  the  bank  of  the  Elbe  River,  but  Altona  is  below 
or  downstream.  At  the  time  of  the  epidemic  the  intake  for  the  water 
supjjly  of  each  city  was  directly  at  the  river  front,  and  the  sewers  of 
the  city  emptied  into  the  river  at  various  points  along  the  same  river 
fronts.  It  will  therefore  be  seen  that  Altona  had  Elbe  River  water  plus 
Hamburg's  sewage.  Altona,  however,  first  filtered  this  water  by  the 
slow  sand  process;  Hamburg,  however,  furnished  its  citizens  with  the 
raw,  unfiltered  Elbe  River  water.  This  water  was  first  pumped  to  a 
single  reservoir,  which  at  one  time  held  approximately  a  day's  supply, 
but  had  long  outgrown  its  i;sefulness.  It  will  therefore  be  seen  that 
these  three  cities,  with  a  homogeneous  population,  with  the  same  climate, 
the  same  low-lying  site,  and  all  other  conditions  similar,  differed  only 
in  their  water  supply. 

During  the  epidemic  the  deaths  in  the  several  cities  were  as 
follows : 


Population 

Deaths 

Deaths 
per  10,000 
Inhabitants 

Hamburg 

Altona 

Wandsbeck 

640,400 

143,000 

20,000 

8,605 

328 

43 

134.4 
23.0 
22.0 

Relatively  few  cases  occurred  in  Altona,   and   most  of  these  were 
on  the  boundary,  where  the  people  probably  had  access  to  the  raw,  un- 


SPECIFIC    DISEASES    DUE    TO    WATEE 


821 


filtered  Elbe  Eiver  water.  In  Kocli's  own  words,  "cholera  in  Hamburg 
went  right  up  to  the  boundary  of  Altona  and  there  stopped.  In  one 
street,  which  for  a  long  way  forms  the  boundary,  there  was  cholera  on 
the  Hamburg  side,  whereas  the  Altona  side  was  free  from  it." 

Further  evidence  consisted  in  the  fact  that  at  one  point  close 
to  and  on  the  Hamburg  side  of  the  boundary  line  between  Hamburg 
and  Altona  is  a  large  yard  known  as  the  Hamburger  Platz.  It  con- 
tains two  rows  of  large  and  lofty  dwellings  containing  seventy-two  sepa- 
rate tenements  and  some  400  people  belonging  almost  wholly  to  those 


yfANDSBECK 


Fig.  111. — Hamburg  received  its  water  supply  from  the  River  Elbe  (unfiltered)  at  G. 
The  sewage  of  Hamburg  and  Altona  entered  the  Elbe  at  ABC.  Altona  received 
its  water  supply  from  the  Elbe  at  D,  about  8  miles  below  ABC.  The  sand  filters  which 
purified  this  water  were  located  at  Blankenese.  Wandsbeck  had  an  independent  water 
supply  from  a  small  lake. 


classes  who  suffer  most  from  cholera  elsewhere  in  Hamburg.  While 
cholera  prevailed  all  around  no  single  case  occurred  among  the  many 
residents  of  this  court  during  the  whole  epidemic.  Koch  found  tha,t, 
owing  to  local  difficulties,  water  from  the  Hamburg  mains  could  not 
easily  be  obtained  for  the  dwellings  in  question,  and  hence  a  supply  had 
been  obtained  from  one  of  the  Altona  mains  in  an  adjacent  street. 
This  was  the  only  part  of  Hamburg  that  received  Altona  water,  and  it 
was  also  the  only  spot  in  Hamburg  in  which  was  aggregated  a  population 
of  the  class  in  question  which  escaped  the  cholera.  The  source  of  the 
epidemic  was  traced  to  Eussian  immigrants  crowded  in  barracks  on  one 
of  the  wharves  pending  their  embarkation  for  the  United  States,  and 
"at  the  time  of  the  outbreak  there  were  on  an  average  about  1,000  of 
these  people  on  hand  all  the  time.  Many  of  them  came  from  districts 
in  Eussia  which  had  been,  and  were  then,  suffering  severely  from 
cholera,  and  all  were  well  supplied  with  dirty  clothing  and  blankets, 
54 


822  RELATION    OF    WATER    TO    DISEASE 

some  of  which  they  washed  while  they  were  being  detained.  It  is  be- 
lieved that  among  those  that  had  arrived  there  must  have  been  some 
mild  cases  of  the  disease,  or  at  least  some  convalescents  with  cholera 
germs  still  in  their  evacuations  two  or  three  weeks  after  recovery.  All 
of  the  sewage  matters  of  every  descrijition  from  these  people  were  dis- 
charged directly  into  the  river  at  the  wharf."  After  the  Elbe  River 
once  became  seeded  with  the  cholera  vibrios  the  people  in  Hamburg  who 
drank  this  infected  water  took  the  disease,  and  their  discharges,  return- 
ing to  the  river,  added  fuel  to  the  flames.  A  vicious  circle  was  thus 
set  up,  so  that  the  infection  became  exceedingly  concentrated  and  in- 
tense, and  as  the  circle  was  a  short  one  the  time  interval  was  corre- 
spondingly brief  and  the  virulence  unusually  severe. 

The  Hamburg  outbreak  will  ever  remain  classic  on  account  of  the 
clearness  of  the  circumstances  and  the  fact  that  there  is  no  missing 
link  in  the  chain  of  evidence  as  the  specific  organism  was  readily  isolated 
from  the  Elbe  River  water. 

Typhoid  Fever. — The  Influence  of  Pure  Water  Upon  Typhoid 
Fever. — The  effect  of  an  improved  water  supply  appears  to  have  a 
more  favorable  influence  upon  typhoid  fever  than  upon  any  other  dis- 
ease. The  relation  between  water  and  typhoid  fever  has  long  been 
known,  and  the  attention  of  vital  statisticians  has  been  focused  upon 
the  improvement  in  morbidity  and  mortality  of  this  disease  following 
the  purification  of  a  water  supply.  There  is  now  reason  to  believe 
that  the  good  effects  of  a  pure  water  in  ])reventing  other  diseases  may 
possibly  outweigh  the  good  effects  in  typhoid  alone.  The  typhoid  figures 
present  such  clear  and  often  dramatic  proof  of  the  value  of  clean  water 
in  the  conservation  of  health  that  a  few  of  the  striking  tables  and  charts 
are  shown  upon  the  following  pages,  and  should  be  carefully  studied 
by  the  student. 

For  the  general  character  of  water-borne  epidemics  of  typhoid  fever 
see  page  87.  For  the  relation  of  ice  and  cold  water  to  typhoid  see 
page  837. 

The  table  on  page  823,  compiled  by  Kober,^  clearly  shows  the  effect 
of  improving  the  water  supply  in  typhoid  fever  death  rates  in  American 
cities. 

From  this  table  we  learn  that  the  combined  average  annual  rate 
from  typhoid  fever  in  cities  with  a  polluted  supply  was  69.4,  and  after 
the  substitution  of  a  purer  water  fell  to  19.8  per  100,000 — a  reduction 
of  70.5  per  cent.  The  Bulletin  of  the  New  York  State  Health  Depart- 
ment for  April,  1908,  shows  that  the  death  rate  from  typhoid  fever 
in  ten  cities  of  that  state  has  been  reduced  53.4  per  cent,  by  an  im- 
proved water  supply.    Many  similar  instances  are  cited  in  the  literature. 

' ' '  Conservation  of  Life  and  Health  by  Improved  Water  Supply, ' '  George  M. 
Kober,  1908. 


SPECIFIC    DISEASES    DUE    TO    WATER 


823 


TABLE  SHOWING  THE  AVERAGE  TYPHOID  DEATH  RATE  PER  100,000  FOR  A  PERIOD 
PRIOR  TO  THE  IMPROVEMENT  IN  THE  WATER  SUPPLY,  THE  AVERAGE  TYPHOID 
DEATH  RATE  PER  100,000  SINCE  THE  CHANGE  IN  THE  WATER  SUPPLY,  AND  THE 
PERCENTAGE  OF  REDUCTION  CAUSED  BY  THE  IMPROVEMENT; 


Average 

Average 

Per  Cent. 

Place 

Before 

After 

Reduction  in 

Improvement 

Improvement 

Death  Rate 

1 

Albany 

88.8 

23.7 

73.0 

2 

Binghamton 

39.3 

11.7 

72.2 

3 

Elmira 

54.9 

41.5 

24.4 

4 

Hornell 

42.2 

24.7 

41.4 

5 

Hudson 

64.3 

31.9 

50.5 

6 

Ithaca 

67.2 

14.6 

78.3 

7 

Rensselaer 

95.5 

54.4 

43.0 

s 

Schenectady 

25.0 

58.2 

14.4 
31.0 

42.6 

q 

Troy 

46.8 

10 

Watertown 

94.7 

36.9 

61.8 

The  Typhoid  Epidemic  at  Lausen,  Switzerland. — The  epidemic 
of  typhoid  fever  which  occurred  in  Lausen,  Switzerland,  in  1872,  was  the 
first  to  attract  general  attention,  "and,  because  of  certain  peculiar  condi- 
tions connected  with  it,  and  especially  because  of  its  influence  upon 
the  theory  and  practice  of  the  purification  of  water  by  filtration,  it  de- 
serves the  most  careful  consideration  by  all  students  of  sanitation." 
It  is  also  interesting  because  of  the  remoteness  and  unusual  method 
by  which  the  infection  reached  the  water  supply.  The  following  ac- 
count of  this  epidemic  is  from  the  description  by  Sedgwick,  quoting 
Dr.  Hagler's  report: 

The  epidemic  occurred  in  the  little  village  of  Lausen  in  the  canton 
of  Basel  in  Switzerland  in  August,  1872.  Lausen  was  a  well-kept  village 
of  90  houses  and  780  inhabitants,  and  had  never,  so  far  as  known,  suf- 
fered from  a  typhoid  epidemic.  For  many  years  it  had  not  had  even 
a  single  case  of  typhoid  fever,  and  it  had  escaped  cholera  even  when  the 
surrounding  country  suffered  from  it.  Suddenly,  in  August,  1872,  an 
outbreak  of  typhoid  fever  occurred,  affecting  a  large  part  of  the  entire 
population. 

A  short  distance  south  of  Lausen  is  a  little  valley,  the  Fiirlerthal, 
separated  from  Lausen  by  a  hill,  the  Stockhalden,  and  in  this  valley,  on 
June  19,  upon  an  isolated  farm,  a  peasant,  who  had  recently  been  away 
from  home,  fell  ill  with  a  very  severe  case  of  typhoid  fever,  which  he 
had  apparently  contracted  during  his  absence.  In  the  next  two  months 
there  occurred  three  other  cases  in  the  neighborhood — a  girl,  and  the 
wife  and  son  of  the  peasant. 

No  one  in  Lausen  knew  anything  of  these  cases  in  the  remote  and 
lonely  valley,  when  suddenly,  on  August  7,  ten  cases  of  typhoid  fever 
appeared  in  Lausen,  and  by  the  end  of  9  days  57  cases.  The  number 
rose  in  the  first  four  weeks  to  more  than  one  hundred,  and  by  the  end 


TYPHOID   FEVER 

DEATH    RATES    PER    100,000    OF    POPULATION 

885  1890  1895 1900 


Si^ 


1905 


120 

100 

80 

60 

40 

20 

0 

160 

i40 

120 

too 

80 

80 

40 

20 

0 

100 

30 

80 

40 

20 

0 

100 

30 

SO 

40 

20 

0 

40 

20 

0 

ISO 

140 

120 

100 

80 

SO 

40 

20 

0 


ajaiiH^N 


f^lrJJiS: 


Fig.  112. — Change  in  Water  Scpplt, 

l.-From  unfiltered  river  supply  to  filtered  river  supply. 

2. -From  unfiltered  river  supply  to  wells. 

3. -From  polluted  river  supply  to  conserved  river  supply. 

824 


10       20       30      40      50      60      70      80       90      100     HO 


Vienna 
Hevlni 

ZUTltll 

rtiniliuio 
^aiis  ■ 
,  .oiidoii 
■Ri(f!rs()i« 
!'inyliaiiit(in 
Alhaiiu 
Liiwrence 
Walcrtuwii 
RiclnnofidlHinuigh 
Quefiislioruuuh. 
Camden 
Linvell 
Fiichbura 
Camhridoc 
Soinervitlf 
\M)rce?ter 
Britknurr 
HariiohJ 
Malaen 
Boston 
Chelsea. 
NcwBed/onrf 
Waterbury 
'Holiioke 
Broiixborouoh 
Manliattuiihuroanh 
Pawtutket        ^ 
MewarK 
Jer^Citu 
Baliimore 
Rochesto* 
Suracust! 
FSIiTJiver 
Brocton 
TauDton 
HaverhiU 
Pomand 
SaJem 
MflwauXce 
Detroit 
Chicaoo 

Bugafc 

Erie 

Oeveland 

iDululh 

St.Paut 

mtoii 
_;ookiu.._,. 

.  ColUlDDUS 

_  McKeesport 
Mimicapulis 
Seattle 
NewOileans 
Toledo 
Eva»isyi\ie 
(pringfieKt 
-ovinmon  , 
GranaRapids 
Wtlminglon 
RtctiiDond 
Cincinnati 
Lcmsvitte 
PtiitadelplVia 
LaiKasJfr 
Atlanta 
Harrtstjura 
Wtieetina 
Allejlienij 
P^iisn^it^ 

Fig.  113. — Mean  Death  Rates  from  Typhoid  Fever,  1902  to  1906,  in  66  American 
Cities  and  7  Foreign  Cities.  Grouped  According  to  their  Drinking  Water. 
The  rates  for  foreign  cities  are  taken  from  James  H.  Fuertes. 


825 


826  RELATION    OF    WATER    TO    DISEASE 

of  the  epidemic  in  October  to  about  130,  or  seventeen  per  cent,  of  the 
population.  Besides  these,  fourteen  children  who  had  spent  their  sum- 
mer vacation  in  Lausen  fell  ill  with  the  same  disease  in  Basel.  The 
fever  was  distributed  quite  evenly  throughout  the  town,  with  the  excep- 
tion of  certain  houses  which  derived  their  water  from  their  own  wells 
and  not  from  the  public  water  supply.  Attention  was  thus  fixed  upon 
the  latter,  which  was  obtained  from  a  well  at  the  foot  of  the  Stockhalden 
hill  on  the  Lausen  side.  The  well  was  walled  up,  covered,  and  appar- 
ently protected,  and  from  it  the  water  was  conducted  to  the  village, 
where  it  was  distributed  by  several  public  fountains.  Only  six  houses 
used  their  own  wells,  and  in  these  six  there  was  not  a  single  case  of 
typhoid  fever,  while  in  almost  all  the  other  houses  of  the  village,  which 
depended  upon  the  public  water  supply,  cases  of  the  disease  existed. 
Suspicion  was  thus  directed  to  the  water  supply  as  the  source  of 
the  t)Tohoid,  very  largely  because  no  other  source  could  well  be  im- 
agined. 

There  had  long  been  a  belief  that  the  Lausen  well  or  spring  was 
fed  by  and  had  a  subterranean  connection  with  a  brook  (the  Fiirler 
brook)  in  the  neighboring  Fiirler  valley;  and  since  this  brook  ran  near 
the  peasant's  house  and  was  known  to  have  been  freely  polluted  by  the 
excreta  of  the  typhoid  fever  patients,  absolute  proofs  of  the  connection 
between  the  well  of  Lausen  and  the  Fiirler  brook  could  not  fail  to  be 
highly  suggestive  and  important.  Fortunately,  such  proofs  were  not 
far  to  seek.  Some  ten  years  before  observations  had  been  made  which 
had  shown  an  intimate  connection  between  the  brook  and  the  well. 
At  that  time,  without  any  known  reason,  there  had  suddenly  appeared 
near  the  brook  in  the  Fiirler  valley  below  the  hamlet  a  hole  about  eight 
feet  deep  and  three  feet  in  diameter,  at  the  bottom  of  which  a  consider- 
able quantity  of  clear  water  was  flowing.  As  an  experiment  the  water 
of  the  little  Fiirler  brook  was  at  that  time  turned  into  this  hole,  with 
the  result  that  it  had  all  flowed  away  underground  and  disappeared,  and 
an  hour  or  two  later  the  public  fountains  of  Lausen,  which,  on  account 
of  the  dry  weather  prevailing  at  the  time,  were  not  running,  had  begun 
flowing  abundantly.  The  water  from  them,  which  was  at  first  turbid, 
later  became  clear;  and  they  had  continued  to  flow  freely  until  the 
Fiirler  brook  was  returned  to  its  original  bed  and  the  hole  had  been 
filled  up.  But  every  year  afterward,  whenever  the  meadows  below  the 
site  of  the  hole  were  irrigated  or  overflowed  by  the  waters  of  the  brook, 
the  Lausen  fountains  soon  began  to  flow  more  freely.  In  the  epidemic 
year  (1872)  the  meadows  had  been  overflowed  as  usual  from  the  middle 
to  the  end  of  July,  which  was  the  very  time  when  the  brook  had  been 
infected  by  the  excrements  of  the  typhoid  patients.  The  water  supply 
of  Lausen  had  increased  as  usual,  had  been  turbid  at  the  beginning,  and 
had  had  a  disagreeable  taste.    And  about  three  weeks  before  the  begin- 


SPECIFIC    DISEASES    DUE    TO    WATEE  827 

ning  of  the  irrigation  of  the  Fiirler  meadows  typhoid  fever  had  broken 
out,  suddenly  and  violently,  in  Lausen. 

In  order  to  make  matters,  if  possible,  more  certain  the  following 
experiments  were  made,  but  unfortunately  not  until  the  end  of  August 
when  the  water  of  the  Lausen  supply  had  again  become  clear.  The  hole 
which  had  appeared  ten  years  earlier,  and  had  afterward  been  filled  up, 
was  reopened,  and  the  little  brook  was  once  more  led  into  it ;  three  hours 
later  the  Lausen  fountains  were  yielding  double  their  usual  volume.  A 
quantity  of  brine  containing  about  eighteen  hundred  pounds  of  common 
salt  was  now  poured  into  the  brook  as  it  entered  the  hole,  whereupon 
there  appeared  very  soon  in  the  Lausen  water  first  a  small,  later  a  con- 
siderable, and  finally  a  very  strong  reaction  for  chlorin,  while  the  total 
solids  increased  to  an  amount  three  times  as  great  as  before  the  brine 
was  added.  In  another  experiment  five  thousand  pounds  of  flour 
(Mehl),  finely  ground,  were  likewise  added  to  the  brook  as  it  disap- 
peared in  the  hole;  but  this  time  there  was  no  increase  of  the  total 
solids,  nor  were  any  starch  grains  detected  in  the  Lausen  water. 

It  was  naturally  concluded  from  these  experiments  that  while  the 
water  of  the  brook  undoubtedly  passed  through  to  Lausen  and  carried 
with  it  salts  in  solution,  it  nevertheless  underwent  a  filtration  which 
forbade  the  passage  of  suspended  matters  as  large  as  starch  grains.  Dr. 
Hagler,  from  whose  report  the  foregoing  facts  are  taken,  was  careful, 
however,  to  state  that  "it  is  not  denied  that  small  organized  particles, 
such  as  typhoid  fever  germs,  may  nevertheless  have  been  able  to  find  a 
passage."  As  a  matter  of  fact  Dr.  Hagler's  minute  account  does  to-day 
give  us  some  indication  that  such  germs  might  easily  have  passed  from 
the  brook  to  Lausen,  for  the  turbidity  of  which  he  repeatedly  speaks  is 
evidence  of  the  passage  of  particles  as  small  as,  and  possibly  smaller 
than,  the  germs  of  typhoid  fever.^ 

Unfortunately  this  was  before  pure  cultures  of  bacteria  were  known, 
and  no  experiments  were  made  with  suspended  matters  as  small  as  bac- 
teria. The  conclusion  was  inevitable  that  although  filtration  had  in  this 
case  sufficed  to  remove  starch  grains,  it  had  been  powerless  to  remove  the 
germs  of  typhoid  fever;  and,  accordingly,  filtration  as  a  safeguard 
against  disease  in  drinking  water  fell  for  a  time  into  disrepute.^ 

The  Typhoid  Epidemic  in  Plymouth,  Penn. — In  1885  the  mining 
town  of  Plymouth,  Penn.,  with  a  population  of  about  8,000,  suffered 
with  a  severe  outbreak  of  typhoid  fever  which  involved  one  in  every 
eight  of  the  inhabitants.    Plymouth  received  its  water  from  a  mountain 

^ ' '  Typhus  und  Trinkwasser, ' '  Vierteljahresschrift  fur  offentliche  Gesund- 
heitspflege,  VI,  154;  also  Sixth  Eeport,  Rivers  Pollution  Commission  of  1868, 
London,  1874. 

^  See  paper  by  Sedgwick  on  ' '  The  Eise  and  Progress  of  Water-Supply  Sani- 
tation in  the  Nineteenth  Century,"  Journal  New  England  Water  Works  Associa- 
tion, XV,  1901,  p.  330,  No.  4. 


828 


RELATIOX    OF    WATER    TO    DISEASE 


4TS  RESERVOIR 


HOUSE  TROM  WWICH 
"^THE  INFECTION  CAME. 


brook  which  drained  an  ahiiost  uninhabited  watershed.  The  stream 
was  dammed  at  intervals  and  the  water  was  stored  in  a  series  of  four 
small  impounding  reservoirs.  The  source  of  the  infection  was  traced 
to  a  citizen  who  spent  his  Christmas  holidays  in  Philadelphia  and  re- 
turned home  in  January.  He  contracted  typhoid ;  the  excreta  were  not 
disinfected,  but  were  thrown  either  into  the  frozen  creek  or  upon  its 
banks  within  25  or  30  feet  of  the  edge  of  the  stream.     (See  map.)     At 

this  time  the  brook  was 
frozen  and  remained  so  un- 
til spring.  There  came  a 
thaw  in  March  and  the 
entire  accumulation  was 
washed  into  the  brook  and 
thence  into  the  water-main. 
Three  weeks  thereafter 
cases  of  typhoid  by  the 
score  made  their  appearance 
throughout  the  to^Ti.  On 
some  days  more  than  100 
new  cases  occurred.  In  all 
1,004  cases  were  reported. 
Some  estimates  placed  the 
number  at  1,500,  that  is,  1 
in  every  5  of  the  inhabitants. 
There  were  114  deaths.  The 
epidemic  was  limited  to  the 
houses  supplied  with  the 
town  water  or  to  persons 
who  drank  of  the  public 
water  supply.  The  distinc- 
tion was  particularly  empha- 
sized on  one  street  where 
the  houses  on  one  side  had 
one  or  more  cases  while  the  houses  on  the  other  side  had  none  at  all. 
The  former  were  supplied  by  the  town  water,  the  latter  depended  upon 
wells. 

This  epidemic  will  ever  stand  out  in  the  literature  as  a  clear-cut 
instance  of  water-borne  typhoid  caused  by  the  quick  transfer  of  virulent 
material  from  a  single  case.  It  proves  further  that  freezing  alone  was 
not  sufficient  to  destroy  the  typhoid  infection,  and  on  account  of  the 
coldness  of  the  water  it  is  exceedingly  unlikely  that  any  multiplication 
of  the  typhoid  bacilli  occurred.  The  infection,  although  greatly  diluted, 
was  nevertheless  sufficiently  virulent  to  induce  the  disease  in  most  of 
those  who  drank  the  water.     It  further  teaches  the  lesson  how  one  per- 


MAP  OF 

PLYMOUTH,  PENN. 

IN     1665. 


Fig.   114. 


SPECIFIC    DISEASES    DUE    TO    WATER  829 

son  is  sufficient  to  defile  the  "pure  waters  of  a  mountain  brook  draining 
an  almost  uninhabited  territory."  This  epidemic  was  the  first  large 
outbreak  in  America  where  the  cause  was  definitely  traced  to  the  water 
supph'.  It  stands  out  sharply  in  the  sanitary  annals  of  our  country  on 
account  of  the  lessons  it  taught  and  the  good  influence  it  had  in  stimu- 
lating other  cities  to  safeguard  and  improve  their  water  supplies. 

The  Typhoid  Epidemic  at  Xew  Havex. — Yery  similar  to  the  Ply- 
mouth outbreak  was  that  at  Xew  Haven.  Conn.,  during  April,  May,  and 
June  of  1901,  when  51-1  cases  of  typhoid  fever  occurred,  resulting  in  73 
deaths.  The  outbreak  was  carefully  studied  by  Professor  Herbert  E. 
Smith,  who  found  that  it  was  unquestionably  due  to  an  infection  of  one 
of  the  sources  of  joublic  water  supph'. 

The  water  supply  in  Xew  Haven  was  drawn  from  five  distinct  sys- 
tems. It  was  all  surface  water  and  was  used  without  filtration.  One  of 
the  sources  was  known  as  the  Dawson  supply.  Dawson  Lake  was  a 
storage  reservoir  located  on  West  Eiver  in  Woodbridge,  five  miles  from 
JSTew  Haven.  Dawson  Lake  had  an  area  of  60  acres  and  a  capacity  of 
300,000,000  gallons.  There  was  no  direct  sewage  pollution  upon  the 
catchment  area  and  the  rural  population  was  only  25  per  square  mile. 

A  mile  and  a  half  above  the  Dawson  Lake  a  small  stream  flowed  into 
the  river,  and  about  half  a  mile  up  this  stream  there  was  a  farmhouse 
situated  at  an  elevation  of  about  180  feet  above  the  water  in  the  lake. 
Several  cases  occurred  in  this  house  during  January  and  February,  1901. 
The  excreta  was  thrown  into  a  shallow  privy  vault  without  disinfection 
(for  the  reason  that  tyj^hoid  fever  was  not  at  first  recognized).  Here 
they  accumulated  and  remained  more  or  less  frozen  for  six  weeks  or 
more.  This  privy  was  325  feet  from  the  brook  and  10  feet  above  it. 
On  March  10  and  11  there  was  a  heavy  rainfall  (2.16  inches)  and  a 
sudden  thaw.  The  flow  was  so  large  that  in  spite  of  the  intervention 
of  the  storage  reservoir  the  water  in  the  city  was  in  a  turbid  condition 
on  the  afternoon  of  March  11.  The  typhoid  fever  outbreak  began  about 
10  days  later,  and  there  seems  to  be  little  doubt  that  infection  took 
place  at  this  time.  Professor  Smith  found  that  96  per  cent,  of  the  cases 
that  occurred  were  in  the  districts  supplied  with  water  from  the  Dawson 
Lake.      ("VThipple.) 

This  outbreak  again  illustrates  the  resistance  of  the  typhoid  infection 
to  freezing,  and  the  danger  from  a  surface  supply  that  for  years  may  run 
satisfactorily.  Even  the  storage  reservoir  failed  in  this  case,  as  in  the 
Pl}Tnouth  case,  to  check  the  quick  transfer  of  the  infection.  Had  the 
Dawson  supply  been  flltered  or  otherwise  purified  the  epidemic  could 
have  been  averted. 

The  Typhoid  Epidemic  at  Ashlaxd,  Wiscoxsix. — This  outbreak 
is  cited  from  Harrington  and  is  one  of  peculiar  interest,  in  that,  in 
addition  to  serving  as  an  excellent  illustration  of  the  danger  of  using 


830 


RELATION    OF    WATER    TO    DISEASE 


the  same  body  of  water  as  a  place  for  the  disposal  of  sewage  and  as  a 
source  of  drinking  water,  it  was  made  the  basis  of  an  action  at  law,  which 
established  the  liability  of  water  companies  and  municipalities  in  case 
of  sickness  and  death  caused  by  the  distribution  and  use  of  infected 
water. 

The  city's  supply  is  derived  from  an  arm  of  Lake  Superior,  Che- 
quamegon  Bay,  upon  which  the  city  is  situated.  This  bay,  which  is 
about  twelve  miles  long,  and  of  an  average  width  of  five,  varies  from 
eight  to  thirty-six  feet  in  depth.    North  of  the  city,  and  extending  out- 


FiG.  115. 

ward  in  a  northwestwardly  direction,  is  a  breakwater  constructed  for  the 
protection  of  the  harbor  against  northerly  gales ;  and  between  it  and  the 
city  the  mouth  of  the  water  intake  is  located  about  a  mile  from  the 
shore.  (See  Fig.  115.)  The  sewage  of  the  city  is  discharged  further  to 
the  west  and  south.  The  currents  in  the  bay  follow  the  course  indicated 
by  the  arrows  in  the  figure,  and  carry  the  sewage  toward  the  breakwater 
and  over  the  mouth  of  the  intake.  This  condition  of  affairs  was  brought 
to  the  attention  of  the  company  by  the  health  boards  of  the  city  and 
state  repeatedly,  but  without  results.  That  the  water  was'  polluted  was 
evident  on  mere  ocular  inspection,  for  it  was  often  cloudy  or  markedly 
turbulent.  During  the  winter  of  1893-94  typhoid  fever  made  its 
appearance    in    the    city,    and    from    the    initial    cases    a    disastrous 


SPECIFIC    DISEASES    DUE    TO    WATER  831 

epidemic  developed,  which  led  to  the  establishment  of  a  model  filtering 
plant. 

The  action  at  law  referred  to  abo^e  was  brought  by  the  widow  of 
one  of  the  victims.  In  evidence  it  was  shown  that  he  lived  continuously 
in  Ashland,  and  drank  no  water  other  than  that  supplied  by  the  water 
company;  that  previous  to  his  seizure  the  disease  had  prevailed  in  the 
cit}^,  and  that  the  discharges  from  the  antecedent  cases  had  passed  into 
the  waters  of  the  bay  by  way  of  the  city  sewers.  The  court  found  for  the 
plaintiff  in  the  sum  of  $5,000. 

The  Typhoid  Epidemic  in  Mankato,  Minn. — Mankato  (popula- 
tion 11,553)  receives  its  water  supply  from  four  deep  artesian  wells  on 
Washington  Street.  Two  of  these  wells  are  within  from  16  to  18  feet 
of  the  pumping  station.  The  main  outlet  of  the  sewer  runs  down  Wash- 
ington Street,  emptying  into  the  river.  A  great  flood  occurred  May  20 
to  24,  1908.  The  gate  in  the  main  trunk  of  the  sewer  was  let  down  on 
the  night  of  June  24,  1908,  in  order  to  keep  the  river  from  backing  up 
into  the  sewers.  This  caused  a  backing  up  or  stasis  of  the  sewage,  which 
in  turn  backed  up  into  a  well  pit  of  the  new  artesian  well  near  the 
pumping  station,  hence  sewage  was  pumped  into  the  water  system.  Two 
of  the  other  wells  and  suction  mains  were  rusty  and  leaked  and  had 
not  been  properly  looked  after  for  a  number  of  years.  Then  came  a 
sudden  sharp  epidemic  of  diarrhea,  June  26.  Probably  2,000  persons 
were  affected.  It  soon  developed  that  the  prevailing  disease  was  typhoid 
fever.  The  epidemic  lasted  from  June  26  and  gradually  died  out  by 
Nov.  20,  1908.  From  July  7  to  Nov.  20  464  cases  of  typhoid  fever  were 
reported  to  the  Health  Officer.  Four  hundred  and  one  of  these  cases 
were  considered  primary  and  57  secondary  or  contact  cases  and  6  outside 
or  imported  infection. 

This  water-borne  outbreak  of  typhoid  fever  is  particularly  instructive 
from  the  fact  that  Delia  McKeever  and  Kate  Flanagan,  administratrices 
of  the  estates  of  their  husbands,  who  had  died  of  the  fever,  sued  the  city 
of  Mankato  for  damages.  The  city  demurred  to  this  complaint  on  the 
grounds  that  as  a  government  it  could  not  be  sued  and  was  exempt 
because  it  was  carrying  out  a  government  function.  The  Supreme  Court 
of  Minnesota  held  that  "the  state  is  liable  if  damages  can  be  proved." 
The  decision  of  the  Supreme  Court  in  holding  the  city  liable  sets  an  ex- 
cellent precedent  which  places  the  responsibility  where  it  should  be. 
Citizens  are  evidently  as  much  entitled  to  reasonable  sanitary  protection 
as  they  are  to  police  protection,  or  to  protection  from  accidents  at  grade 
crossings.  It  is  a  fortunate  day  for  preventive  medicine  when  the  prin- 
ciple is  recognized  that  sanitary  negligence  is  just  as  culpable  as  the 
negligence  which  fails  to  place  a  red  flag  or  a  red  lantern  to  warn  against 
a  pitfall  in  the  public  highway. 

The  Typhoid  Epidemic  in  Ithaca,  Nevp^  York. — In  the  winter  of 


832  RELATION    OF    WATER    TO    DISEASE 

1903  Ithaca,  New  York,  the  seat  of  Cornell  University,  was  visited  by  a 
severe  epidemic  in  the  course  of  which  1,350  cases  of  typhoid  fever 
occurred  in  a  poindation  of  al)out  13,156.  The  population  included 
about  3,000  students  at  the  university.  More  than  500  homes  were  vis- 
ited and  there  were  cS"^  deaths.  The  epidemic  covered  a  period  of  about 
3  months  ami  extended  from  al)out  the  11th  of  January,  1903,  to  the  1st 
of  April,  although  for  several  months  before  the  epidemic  began  ty])h()id 
fever  had  been  unduly  prevalent.  The  epidemic  was  carefully  studied 
by  Dr.  George  A.  Soper,  who  clearly  showed  that  the  disease  was  due 
to  the  public  water  sui)ply,  although  the  original  case  or  cases  which 
gave  rise  to  the  epidemic  were  not  ascertained.  Ithaca  had  at  that  time 
three  separate  sources  of  Avater  sup])ly.  The  larger  one  was  derived 
from  Six-Mile  Creek  and  the  second  supply  from  Buttermilk  Creek,  and 
the  third  was  an  independent  supply  for  the  university.  The  conditions 
on  the  two  streams  were  similar.  Both  streams  were  considerably  pol- 
luted by  the  population  which  lived  largely  in  villages  bordering  on  the 
streams.  The  nearest  of  these  villages  was  5  miles  above  the  intake. 
Soper  found  numerous  other  sources  of  contamination  on  the  water- 
shed, and  some  even  in  the  city  of  Ithaca  a  few  rods  above  the  intake  of 
the  water-works  where  there  were  no  less  than  17  privies  located  on  the 
precipitous  banks  of  the  creek.  It  was  known  that  during  the  year 
previous  to  the  c])idemic  there  had  been  at  least  6  cases  of  typhoid  fever 
on  the  watershed.  The  typhoid  epidemic  in  Ithaca  followed  a  flood  in 
the  river. 

One  episode  of  the  epidemic  is  worthy  of  special  mention,  namely, 
a  secondary  outbreak  which  resulted  from  the  infection  of  a  well.  This 
well  had  become  popular  among  the  residents  of  a  certain  district  at  the 
time  when  the  public  supply  came  to  be  distrusted,  and  its  good  quality 
was  taken  for  granted.  But  the  wife  of  the  owner  was  taken  sick  with 
typhoid  fever  during  the  epidemic,  and  her  dejecta  passed  without  disin- 
fection through  the  water-closet,  and  into  a  drain-pipe  which  ran  within 
three  or  four  feet  of  the  well.  The  joints  of  the  drain-pipe  were  inse- 
cure ;  and  the  well  water,  which  had  probably  been  for  some  time  grossly 
contaminated,  finally  became  infected.  As  a  result  about  fifty  cases  of 
typhoid  fever  and  five  deaths  were  traced  to  people  who  iised  this  well 
water.     (Whipple.) 

The  TynroiD  Epidemic  in  Butler,  Penn. — Butler,  Penn.  (popu- 
lation 16,000),  had  an  epidemic  of  typhoid  fever  in  1903.  There  were 
1,270  cases,  that  is,  about  8  per  cent,  of  the  population  were  attacked. 
Infection  in  this  ease  was  clearly  water-borne  and  was  traced  to  one  of 
various  points  of  the  stream,  small  tributaries,  or  creeks.  One  house  in 
particular,  provided  with  an  overhanging  privy,  emptied  into  the  creek 
within  a  short  distance  of  the  pumping  station. 

The  Typhoid  Epidemics  of  Lawrence  and  Lowell. — During  the 


SPECIFIC    DISEASES    DUE    TO    WATEE  833 

years  1890-91  a  typhoid  fever  epidemic  occurred  in  LoT^'ell  and  Law- 
rence, Mass.  This  epidemic  illustrates  with  great  clearness  what  occurs 
on  streams  which  are  used  both  as  sources  of  water  supply  and  as  re- 
ceptacles for  sewage.  Both  cities  are  on  the  Merrimac  Eiver,  which  was 
grossly  polluted  by  the  sewage  of  Manchester  (population  44,126), 
Haverhill  (population  27,412),  Nashua  (population  19,311),  Concord 
(population  17,004),  Fitchburg  (population  22,037),  jSTewburyport 
(population  13,947),  Marlborough  (population  13,805),  Clinton  (popu- 
lation 10,424),  and  from  other  sources  of  pollution.  In  Lowell  550 
cases  of  typhoid  fever  occurred  from  Sept.,  1890,  to  Jan.,  1891.  The 
epidemic  was  carefully  studied  by  Professor  William  T.  Sedgwick,  who 
made  a  most  thorough  investigation. 

A  short  time  after  the  epidemic  in  Lowell  typhoid  fever  broke  out 
in  Lawrence,  nine  miles  downstream,  and  rapidly  increased.  The  rela- 
tion between  these  two  epidemics  was  most  striking.  Lowell  discharged 
its  sewage  into  the  river,  Lawrence  drank  the  water  without  filtration. 
The  climax  of  the  Lawrence  epidemic  occurred  about  one  month  after 
that  in  Lowell.  In  1892  there  was  a  repetition  of  this  episode.  Typhoid 
fever  in  Lowell  was  again  responsible  for  an  increase  of  typhoid  fever 
in  Lawrence.  As  a  consequence  of  these  occurrences  Lowell  abandoned 
the  river  and  introduced  a  ground  water  supply,  while  at  Lawrence  a 
filtration  plant  was  constructed  which  has  materially  reduced  the 
amount  of  typhoid  fever  in  that  city.     (Whipple.) 

The  Typhoid  Epidemics  of  Pittsburgh  and  Alleghany. — These 
two  Pennsylvania  cities  are  situated  at  the  junction  of  the  Alleghany 
and  Monongahela  Eivers,  where  they  unite  to  form  the  Ohio.  In  1900 
Pittsburgh  had  a  population  of  321,616  and  Alleghany  129,896.  Pitts- 
burgh takes  its  water  from  the  Alleghany  Eiver  at  Brilliant  Station,  six 
miles  above  the  junction  of  the  rivers,  and  from  the  Monongahela  Eiver 
at  a  point  three  miles  above  the  junction.  Alleghany  receives  its  water 
supply  from  the  Alleghany  Eiver  at  Montrose,  ten  miles  from  the  point ; 
it  is  drawn  from  a  rock-filled  crib.  It  is  practically  unfiltered  water. 
Both  the  Monongahela  and  the  Alleghany  Eivers  are  grossly  polluted 
streams,  receiving  the  sewage  from  a  populous  watershed;  in  addition 
the  sewers  of  the  cities  of  Alleghany  and  Pittsburgh  empty  directly  into 
these  streams,  and  on  account  of  the  rapid  growth  of  these  cities  much 
of  this  sewage  entered  the  river  dangerously  near  to  the  water  intakes. 
The  records  of  the  Board  of  Health  show  that  at  this  time  there  oc- 
curred annually  upward  of  5,000  cases  of  typhoid  fever. 

For  about  ten  years  centering  around  1900  Pittsburgh  and  Alleghany 
had  the  unenviable  distinction  of  having  the  highest  typhoid  death  rate 
of  any  city  in  this  country  and  probably  of  any  large  city  in  the  world. 
At  times  the  rates  ran  above  150  per  100,000.  The  conditions  have 
recently  been  improved  by  the  introduction  of  slow  sand  filtration  for 


834  RELATIOX    OF    WATER    TO    DISEASE 

the  city  of  Pittsburgh.  Allegliany,  now  officially  known  as  North  Pitts- 
burgh, is  just  being  furnished  (1912)  with  filtered  water. 

The  Typhoid  Epidemic  at  Chicago. — The  Chicago  epidemic  is  an 
illustration  of  a  city  using  a  lake  water  which  is  infected  with  its  own 
sewage.  The  water  in  1892  was  taken  from  Lake  Michigan  opposite  the 
city  at  several  "cribs"  which  were  1.5  to  4  miles  off-shore.  The  Chicago 
sewage  was  discharged  all  along  the  water-front,  while  the  Chicago  River 
penetrated  the  city  with  its  north  and  south  branches  and,  polluted 
almost  beyond  endurance,  flowed  out  into  the  lake  about  midway  be- 
tween the  upper  and  lower  cribs.  The  pollution  of  the  lake  water  was 
at  times  so  intense  that  the  foul  river  water  could  be  traced  to  the  in- 
takes with  the  eye.  This  intolerable  situation  resulted  in  the  building 
of  the  Chicago  drainage  canal,  the  object  of  which  was  to  keep  the 
sewage  out  of  the  lake  and  carry  it  down  the  Des  Plaines  and  Illinois 
Rivers  into  the  Mississippi.  By  the  construction  of  this  canal  the  flow 
of  the  Chicago  River  was  reversed  so  that,  instead  of  the  sewage  entering 
the  lake  and  polluting  the  water  supply,  the  water  of  Lake  Michigan 
now  flow^s  westward  to  the  Mississippi  and  to  the  Gulf  of  Mexico.  Dur- 
ing the  years  1890,  1891,  and  1892  typhoid  fever  was  unusually  preva- 
lent in  Chicago.  In  1890  1,008  of  the  inhabitants  died  from  typhoid 
fever,  in  1891  the  death  toll  from  this  preventable  disease  was  997  and 
in  1892  1,489.  The  present  conditions  in  Chicago,  owing  to  the  improve- 
ments in  the  water  supply,  in  the  milk  supply,  and  an  attack  upon  the 
residual  typhoid  as  contact  infection,  have  reduced  the  death  rate  to 
about  12  per  100,000,  which  is  now  among  the  lowest  death  rates  from 
typhoid  fever  in  any  large  city  in  this  country,  and  compares  favorably 
with  some  of  the  European  figures. 

The  above  water-borne  typhoid  fever  epidemics  have  been  selected 
as  examples.  Many  more  may  be  found  in  the  literature.  Whipple,  in 
his  book  on  "Typhoid  Fever,"  cites  numerous  instances  and  gives  in 
tabular  form  an  impressive  list  of  such  outbreaks,  with  references  to 
the  literature. 

Dysentery. — Both  bacillary  dysentery  and  amebic  dysentery  may  be 
transferred  through  drinking  water.  The  infection  in  both  types  of 
dysentery  is  discharged  in  the  feces  and  taken  in  by  the  mouth;  there 
is,  therefore,  every  opportunity  for  water  to  play  the  same  role  in  dysen- 
tery that  it  plays  in  typhoid.  However,  comparatively  few  water-borne 
epidemics  of  bacillary  dysentery  have  been  reported ;  these  few,  neverthe- 
less, are  sufficiently  conclusive  to  be  convincing.  Amebic  dysentery  does 
not  occur  in  epidemic  form,  but  the  known  facts  are  sufficient  to  in- 
criminate water  as  one  of  the  vehicles  of  convection. 

Shiga  reports  outbreaks  in  Japan  from  the  use  of  well  and  river 
water.  Eldridge  states  that  dysentery  is  a  rural  disease  in  Japan;  the 
use  of  human  feces  as  a  fertilizer  and  the  frequency  of  the  infection  of 


SPECIFIC   DISEASES    DUE    TO    WATEE  835 

the  numerous  small  streams  and  wells  render  it  preeminently  a  water- 
borne  disease.  The  epidemic  described  by  Duprey  which  occurred  at 
Grenada  Island  in  1901  is  one  of  the  best  examples  of  a  water-borne 
epidemic  of  dysentery.  Shiga^  in  Osier's  "Modern  Medicine,"  gives  the 
following  instance : 

In  a  village  called  Momma-Mura,  at  Nobechi,  in  Japan,  in  1900,  a 
dysentery  epidemic  broke  out  in  houses  situated  near  each  other.  It  was 
proved  that  the  well,  used  by  all  the  households  suffering  from  the  dis- 
ease, was  infected  with  the  dysentery  bacillus.  We  have  also  an  in- 
teresting example  of  river-water  infection  in  Japan.  There  is  a  village 
called  Mitake-Mura  in  the  district  Miyagi-Ken,  through  which  a  river 
flows.  Fishing  and  swimming  are  prohibited  in  it  because  of  fish  breed- 
ing. In  the  late  summer  of  1899,  the  prohibition  having  been  removed, 
the  men  of  the  village  were  very  glad  to  be  allowed  to  fish  and  swim 
once  more  in  the  river.  However,  after  four  or  five  days  an  epidemic  of 
dysentery  broke  out  with  10  patients  on  the  first  day,  and  increasing 
numbers  daily  afterward.  There  were  in  all  413  cases,  of  which  115 
were  boys  under  ten  years  of  age.  After  investigation  it  was  found 
that  there  was  an  epidemic  of  dysentery  in  a  village  higher  up  the  river, 
and  the  water  had  been  soiled  with  the  infected  clothes. 

Epidemics  of  bacillary  dysentery  in  this  country  in  institutions  have 
not,  as  a  rule,  been  associated  with  water. 

The  Entameba  histolytica,  causing  amebic  dysentery,  was  recovered 
by  Musgrave  and  Clegg  ^  from  17  of  61  samples  of  the  public  water 
supply  of  Manila  and  was  found  in  tanks  used  for  holding  distilled 
water  and  also  in  many  wells.  Eecently  Allan  -  has  reported  a  small 
outbreak  of  amebic  dysentery  in  North  Carolina  due  to  an  infected  well. 

Diarrhea. — Polluted  waters  not  infrequently  cause  diarrhea,  some- 
times as  widespread  epidemics,  sometimes  as  small  outbreaks  or  sporadic 
cases.  Whenever  there  is  a  water-borne  outbreak  of  typhoid  fever  or 
cholera  there  are  also  a  large  number  of  cases  of  diarrhea  and  gastro- 
intestinal disturbances  in  which  the  precise  etiological  factor  has  not 
been  discovered.  Some  of  these  cases  may  be  mild  instances  of  the 
major  disease.  Infantile  diarrheas  are  especially  prevalent  at  such  times 
and  very  likely  are  due  to  the  contaminated  water.  Thus  Eeincke  states 
that  infantile  diarrhea  was  greatly  lessened  after  the  improvement  in 
the  water  supply  of  Hamburg.  The  same  phenomenon  was  noted  by 
Hiram  0.  Mills  after  the  filtration  of  the  water  supply  of  Lawrence, 
Mass.  Sedgwick  noted  an  excessive  prevalence  of  both  typhoid  fever 
and  diarrhea  in  Burlington  and  attributed  the  diarrhea  to  the  sewage 
contamination   of  the   water   supply.     Whipple   states   that  in   Albany 

^Mus^ave  and  Clegg:  Bull.  18,  Bu.  Gov.  Lab.,  P.  I.,  93;  Eep.  Bd.  Health, 
P.  I.,  1904-05,  10. 

'Allan:  J.  A.  M.  A.,  Chicago,  1909,  LIII,  1561. 


836  RELATION    OF    WATER    TO    DISEASE 

there  was  a  reduction  of  57  per  cent,  in  the  mortality  from  diarrheal 
diseases  after  the  introduction  of  filtration  in  1898.  Chapin  questions 
wliether  sucli  statistical  evidence  is  sufficient  to  incriminate  water  as 
an  influence  to  tlie  causation  of  diarrheal  diseases. 

It  is  generally  believed  that  diarrhea  may  be  brought  on  by  changes 
from  a  hard  to  a  soft  water;  also  by  organic  and  inorganic  im- 
purities. 

Numerous  outbreaks  of  diarrhea  have  been  attributed  to  the  follow- 
ing microorganisms  in  water,  viz. :  B.  coJi,  B.  enteritidis  of  Gaertner, 
B.  pyocyaneus,  B.  proteus,  B.  aerogenes  capsuJatus  of  Welch,  B.  meseri'- 
tericus,  and  streptococci.  Water  containing  these  and  other  organisms 
is  not  infrequently  regarded  as  the  cause  of  outbreaks  of  gastrointestinal 
irritation.  The  symptoms  vary  greatly  in  intensity,  but  usually  the  dis- 
ease is  not  fatal  excepting  in  the  young  and  feeble.  The  relation  be- 
tween the  diarrhea  and  the  water  is  usually  based  upon  the  fact  that 
some  species  of  microorganisms  are  found  both  in  the  water  and  in  the 
stools.  Corroborative  evidence,  such  as  the  finding  of  specific  agglutinins 
and  other  antibodies  in  the  blood,  lends  countenance  to  the  claim  that 
the  particular  microorganism  is,  in  fact,  the  cause  of  the  complaint. 
While  the  evidence  is  not  conclusive,  it  is  suggestive,  and  in  many  cases 
doubtless  correct. 

Malaria. — Malaria  in  relation  to  drinking  water  is  mentioned  only 
for  its  historical  interest.  Laveran  himself,  and  even  Ross,  considered 
this  not  improbable.  Celli  attempted  to  demonstrate  this  relationship 
by  administering  water,  from  the  most  malarious  regions  of  Italy,  to 
human  beings,  daily  up  to  a  month.  He  failed  completely.  According 
to  Craig  all  other  similar  experiments  have  similarly  proved  negative, 
except  one  instance  studied  by  Ross,  in  which,  however,  the  conditions 
of  the  experiment  were  far  from  conclusive. 

Laveran  based  his  judgment  upon  the  facts  that : 

(1)  "There  have  been  observed  cases  in  which,  in  the  same  locality, 
persons  living  in  identical  conditions,  but  using  drinking  waters  from 
different  sources,  the  one  group  being  attacked  in  large  proportion  while 
the  other  group  of  persons  are  scarcely  affected  at  all. 

(2)  "In  certain  otherwise  unhealthy,  localities  the  paludal,  fevers 
have  been  seen  to  disappear  by  supplying  pure  drinking  water  instead 
of  the  previously  stagnant  waters. 

(3)  "In  localities  otherwise  healthy  one  can  contract  intermittent 
fever  from  drinking  the  water  from  an  unhealthy  locality. 

(4)  "Travelers  in  malarial  countries  have  found  that  on  boiling 
their  drinking  w^ater  they  escaped  the  disease  in  a  large  proportion  of 
cases." 

These  conclusions  are  especially  instructive,  as  they  illustrate  some 
of  the  sources  of  error  in  epidemiological  studies.     Similar  errors  were 


ICE  837 

made  in  the  case  of  yellow  fever  before  the  discovery  of  mosquito  trans- 
mission; and  in  other  diseases. 

Yellow  Fever. — Yellow  fever  was  formerly  associated  with  drinking 
water,  but  we  now  know  that  water  plays  no  part  in  the  transmission  of 
yellow  fever  other  than  breeding  the  Stegomyia  calopus.  In  my  studies 
at  Vera  Cruz  I  crushed  a  large  number  of  infected  yellow  fever  mos- 
quitoes^ mixed  the  mass  in  some  water  which  was  then  given  by  the 
mouth  to  several  volunteers,  with  entirely  negative  results. 

Animal  Parasites.^ — The  eggs,  larvse,  or  other  stages  in  the  life  cycle 
of  various  intestinal  parasites  may  enter  the  body  in  drinking  water. 
Thus  the  eggs  of  Ascaris  lumhricoides  are  discharged  in  the  feces,  which 
may  contaminate  streams  and  then  be  returned  to  the  mouth.  Some 
eases  of  infection  with  this  parasite  probably  occur  in  this  way.  Oxyuris 
vermicularis,  the  pinworm.  and  TricJiiuris  trichiura,  the  whipworm, 
may  similarly  be  contracted  through  drinking  water.  The  guinea  worm, 
Dracunculus  medinensis,  invades  the  skin  during  bathing  and  may, 
perhaps,  also  be  contracted  by  the  mouth  in  drinking  water.  The  living 
embryos  of  this  worm  are  liberated  and  find  their  way  into  fresh  water. 
There  they  enter  the  bodies  of  the  common  fresh-water  flea,  Cyclops 
quadricoriiis,  which  acts  as  the  intermediate  host. 

It  is  fairly  well  established  that  the  eggs  of  the  hookworm  may  be 
taken  into  the  stomach  through  drinking  water,  and  the  same  is  as- 
sumed of  the  similar  parasite  of  Cochin  China  diarrhea. 

The  Billiarzia  hcEmatohia,  and  very  possibly  other  intestinal  parasites, 
may  likewise  be  transmitted  through  drinking  water. 

ICE 

Ice  was  not  suspected  of  being  a  vehicle  by  which  infection  could  be 
spread  until  it  was  shown  in  bacteriological  laboratories  that  typhoid  and 
other  cultures  are  not  killed  by  freezing.  Leidy  in  1848  showed  that 
water  derived  from  melted  ice  contained  not  only  living  infusoria,  but 
also  rotifers  and  worms.  MacFayden  proved  that  the  temperature  of 
liquid  air  (—  315°  F.)  does  not  kill  bacteria.  In  fact,  some  bacteria 
and  molds  grow  and  multiply  at  temperatures  as  low  as  0°  C. 

Sedgwick  and  Winslow  ^  (1902)  were  the  first  to  make  quantitative 

studies  on  the  effect  of  freezing  upon  pathogenic  bacteria.     They  used 

cultures  of  the  typhoid  bacillus  and  showed  that  50  per  cent,  of  the 

organisms  die  at  the  end  of  the  first  week.  90  per  cent,  at  the  end  of 

the  second  week,  and  practically  all  at  the  end  of  12  weeks.     They  con- 

'  Sedgwick,  W.  T.,  and  Winslow,  C.  E.  A.:  (1)  "Experiments  on  the  Effect 
of  Freezing  and  Other  Low  Temperatures  upon  the  Viabilitr  of  the  Bacillus  of 
Typhoid  Fever,  with  Considerations  Begarding  Ice  as  a  Vehicle  of  Infectious  Dis- 
ease.''  (2)  "Statistical  Studies  on  the  Seasonal  Prevalence  of  Typhoid  Fever  in 
Various  Countries  and  Its  Eelation  to  Seasonal  Temperature."  Mem.  Am.  Acad. 
Arts  and  Sci.,  Vol.  XII,  No.  5,  Aug.,  1902.  Summary,  Boston  Soc.  Med.  Sci., 
1899-1900,  Vol.  IV,  p.  181. 
55 


838 


RELATION    OF    WATER    TO    DISEASE 


sider  that  we  may  be  sure  that  in  nature  the  destruction  would  exceed 
rather  .than  fall  short  of  these  figures,  for  the  experiments  were  made 
in  a  test-tube  where  all  the  bacteria  are  imprisoned,  while  in  nature  per- 
haps 90  per  cent,  are  extruded  during  the  purifying  process  of  freezing. 

As  water  crystallizes  it  excludes  suspended  matter  and  even  dissolves 
substances.  The  extent  to  which  water  thus  purifies  itself  depends,  how- 
ever, upon  conditions,  for  under  certain  circumstances  the  impurities 
may  be_  entangled  or  even  concentrated  during  the  process  of  freezing. 

It  is  necessary  to  distinguish  between  natural  ice  and  manufactured 
ice. 

Natural  Ice. — Natural  ice  should  be  harvested  from  water  of  good 
sanitary  quality  and  handled  in  a  cleanly  manner.  Even  when  natural 
ice  is  obtained  from  a  polluted  water  the  danger  is  greatly  reduced,  not 
only  because  ice  purifies  itself  in  freezing,  but  because  natural  ice  is 
usually  stored  weeks  and  months  before  it  is  used.  There  are  plenty 
of  clean,  fresh  streams,  lakes  and  ponds  from  which  an  abundant  supply 
may  be  obtained.  It  is  comparatively  easy  to  protect  most  ponds,  from 
which  ice  is  harvested,  from  undesirable  pollution.  Under  natural  con- 
ditions the  surface  layer  of  ice  contains  most  of  the  impurities  and  the 
lower  layers  are  relatively  purer,  for  the  reason  that  ice  grows  from 
above  downward  and  extrudes  both  suspended  and  dissolved  matters, 
the  surface,  however,  receives  additional  contamination  from  the  dust, 
snow,  flooding  and  other  sources.  It  is,  therefore,  good  practice  to  plane 
the  surface  of  snow  ice. 

The  fact  that  natural  ice  is  usually  purer  than  the  water  from  which 
it  is  taken  is  shown  by  the  following  analyses  which  give  the  chemical 
and  bacterial  composition  of  natural  ice  and  the  water  from  which  it 
was  frozen.     In  this  case  the  water  was  a  sewage-polluted  stream: 


3  to  6  Inches  Thick 

Water 

Free  ammonia 

Albuminoid  ammonia 

.008—         .034 
.156—       .214 
.05  —       .20 
2.0     —    3.0 
11.0     —28.5 
30.       —210. 
10 c. c— 10  CO. 

.016—       .136 

.46  —            .084 
.146—             .276 

Nitrates 

Chlorin 

Hardness 

Bacteria 

Bacillus  coli  in 

Free  ammonia 

.350—             .480 

4.500—           6.000 

57.000—        60.000 

.5200         —      13,000 

1.000—          0.100 

.006—             .038 

Albuminoid  ammonia 

.230 —       .726 

.116—             .166 

Nitrates 

.0     —       .050 
0.8    —    3.50 
18.0    —  34.0 
2.       —  60. 
0.       —    0. 

.260—             .400 

Chlorin 

5.500— 

Hardness 

58 .  500—        62 .  000 

Bacteria 

2500        —         3900 

Bacillus  coli  in 

1000—     0.1c. c. 

The  chemical  figures  in  this  table  are  in  parts  per  million. 


ICE 


839 


The  reduction  in  the  number  of  bacteria  is  noteworthy.  It  will  be 
noticed  that  there  was  no  diminution,  rather  an  increase  in  the  free  and 
albuminoid  ammonia. 

Manufactured  Ice. — Manufactured  ice  is  now  universally  made  by 
the  ammonia  process.  The  condensed  ammonia  in  expanding  requires 
heat  which  it  takes  from  surrounding  objects  and  in  this  way  the  water 
is  frozen.  There  are  two  distinct  processes ;  one  known  as  "can  ice"  and 
the  other  as  "plate  ice."  In  the  first  case  the  freezing  takes  place  in 
rectangular  cans,  the  water  freezes  from  the  sides  of  the  can  toward  the 
center,  and  the  impurities  are  extruded  and  concentrated  in  the  core, 
which  is  often  visible  in  a  cake  of  can  ice.  In  making  can  ice  the  water 
must  first  be  distilled  or  boiled  in  order  to  drive  out  the  air,  else  the 
resulting  product  will  contain  air  bubbles.  Plate  ice  is  made  by  freezing 
water  in  large  shallow  tanks.  The  water  freezes  upon  the  surface  and 
when  of  sufficient  thickness  is  cut  out  and  removed  in  blocks.  In  this 
method  it  is  not  necessary  to  distill  or  boil  the  water  for  the  reason  that 
the  air  is  extruded  naturally  during  the  process  of  freezing.  Plate  ice 
should  be  made  from  water  of  good  sanitary  quality,  especially  as  it  is 
not  usually  stored  a  long  time  before  it  is  used. 

When  ice  is  made  from  distiUed  or  boiled  water  it  should  be  above 
reproach.  I  have  found,  however,  that  manufactured  ice  may  contain 
more  bacteria  than  the  water  from  which  it  was  made.  This  is  due  to 
uncleanly  methods.  Thus  six  specimens  of  plate  ice  made  from  water 
containing  64  microorganisms  per  cubic  centimeter  and  no  colon  bacilli 
gave  the  following  results : 


Number  of 
Sample 

Manufacturer 

Organisms  per 
Cubic  Centimeter 

Colon  Bacillus 

24 
29 

26 
27 

C.  P.  Co 

C.  P.  Co 

G.  Ice  Co 

G.  Ice  Co 

455 
5,000 
230 
650 
470 
8 

Absent 
In  1  c.c. 
In  10  c.  c. 

Absent 

32 
34 

C.-S.  Co 

P.  Ice  Co 

Absent . 
In  1  c.  c. 

The  laborers  who  work  "on  ice,"  as  it  is  termed,  scrape  considerable 
amounts  of  dirt  from  their  shoes  in  walking  over  the  cans  and  tanks, 
and  pollution  takes  place  from  other  sources. 

The  chemical  examination  of  manufactured  ice  may  show  conspicu- 
ously less  total  solids,  less  chlorin  and  less  nitrates  than  found  in  the 
water  from  which  it  was  made.  On  the  other  hand,  it  may  be  very  high 
in  free  ammonia.  This  is  accounted  for  by  the  fact  that  there  is  always 
some  leakage  of  this  gas  about  ice  factories  using  the  ammonia  process. 
Sometimes  ammonia  occurs  in  such  quantities  as  to  impart  a  distinctly 
alkaline  taste  to  the  manufactured  ice. 


840  RELATION    OF    WATER    TO    DISEASE 

There  is  no  excuse  for  uncleanly  methods  in  handling  ice  that  is 
used  on  or  in  our  foods.  The  fact  that  surface  impurities  may  be  washed 
from  a  cake  of  ice  is  no  reason  for  dragging  it*over  sputum-laden  pave- 
ments, over  dirty  railroad  platforms,  and  similar  methods  familiar  to 
all.  The  general  use  of  ice  is  a  modern  innovation.  It  has  come  into 
vogue  within  the  past  100  years.  For  the  uses  of  ice  as  a  preservative 
see  page  474. 

Properties  of  Ice. — Latent  Heat. — If  one  pint  of  water  at  the  tem- 
perature of  0°  C.  be  mixed  with  one  pint  of  water  at  79°  C.  the  tem- 
perature of  the  mixture  will  be  the  mean,  39.-5°  C.  If,  however,  ice  be 
substituted  for  the  cold  water,  the  whole  of  the  ice  will  melt,  but  the 
temperature  of  the  resulting  mixture  will  not  be  39.5°  C,  but  0°  C.  It 
therefore  requires  considerable  heat  to  convert  ice  into  water.  This  heat 
becomes  latent  during  the  process  of  liquefaction,  and  is  again  given  off 
when  water  freezes.  Wlien  the  surface  of  water  freezes  the  latent  heat 
liberated  by  the  new-formed  ice  raises  the  temperature  of  the  remaining 
water,  and  thus  retards  the  process  of  freezing  or  solidification.  Thresh 
points  out  that  were  not  this  the  case  water  would  freeze  with  great 
rapidity  in  winter  and  the  ice  so  formed  would  as  rapidly  melt  when 
the  weather  became  warmer. 

In  the  act  of  freezing  water  expands  one-eleventh  of  its  volume, 
and  with  an  almost  irresistible  force.  Thick  iron  shells  filled  with 
wat€r  and  securely  plugged  are  easily  burst  by  exposure  to  the  cold  of  a 
Canadian  winter  night.  Water  reaches  its  greatest  density  at  4°  C. 
It  expands  if  heated  above  or  cooled  below  this  temperature.  It  is 
owing  to  this  property  that  in  large  lakes  and  rivers  the  temperature 
of  the  deep  water  never  falls  below  4°  C.  during  the  winter.  If  water 
reached  its  greatest  density  at  freezing  point,  which  is  the  common 
property  of  other  fluids,  freezing  would  take  place  from  the  bottom 
instead  of  at  the  top.  The  result  would  be  that  during  a  severe  winter 
our  streams  and  lakes  would  become  one  mass  of  ice,  which  all  the  heat 
of  the  ensuing  summer  would  be  unable  to  melt. 

Ice  and  Disease. — A  search  of  the  literature  discloses  but  few  in- 
stances of  disease  attributable  to  impurities  in  ice.  While  the  experi- 
mental evidence  indicates  that  there  is  a  quantitative  reduction  of  the 
number  of  bacteria  in  freezing,  and  that  the  imprisoned  bacteria  gradu- 
ally die,  nevertheless  experience  has  shown  that  low  temperatures  alone 
cannot  be  depended  upon  to  remove  the  danger  of  typhoid  infection. 
For  example,  we  have  the  water-borne  epidemic  in  Pl}'mouth,  Pa.,  in 
1885,  presumably  produced  from  the  frozen  accumulation  of  typhoid 
excrement  from  a  single  case.  Very  similar  to  the  Plymouth  outbreak 
was  that  at  New  Haven.  Conn.,  in  1901.  In  only  a  few  isolated  in- 
stances, however,  has  ice  itself  been  accused  of  being  the  vehicle  by 
which  the  infection  of  t}^hoid  fever  has  been  spread.     It  appears  prob- 


ICE  841 

able  that  milder  intestinal  diseases  may  be  caused  by  highly  polluted  ice, 
of  which  the  Eye  Beach  epidemic,  carefully  studied  by  Nichols^  of 
Boston  in  1875,  is  a  point  in  evidence. 

Park  -  (1901)  described  an  epidemic  which  was  believed  to  have  had 
its  origin  in  ice  obtained  from  a  pond  in  which  it  was  shown  that  the 
excrement  from  a  patient  sick  with  typhoid  fever  had  been  thrown  while 
the  pond  was  covered  with  ice. 

In  the  second  annual  report  of  the  Board  of  Health  of  Connecticut 
for  1882  an  interesting  single  case  of  typhoid  fever  is  cited  as  probably 
derived  from  ice. 

Derange"  (1898)  described  an  epidemic  of  typhoid  fever  attributed 
to  ice  among  eight  lieutenants  in  a  regiment  stationed  at  Eennes  in  the 
autumn  of  1895.  The  implication  of  the  ice  in  this  instance  rests  upon 
a  doubtful  chain  of  evidence,  however,  and  no  mention  is  made  of 
other  possible  factors. 

Hutchins  and  \^Tieeler  *  (1903)  report  an  epidemic  of  typhoid  fever 
in  the  St.  Lawrence  State  Hospital,  three  miles  below  Ogdensburg, 
N.  Y.,  which  seems  to  have  been  due  to  impure  ice.  The  disease  was 
endemic  in  the  hospital  for  ten  years,  increasing  from  two  cases  with 
the  opening  of  the  hospital  in  1890  to  forty  cases  in  1900.  Although 
the  water  supply,  tested  bacteriologically  and  chemically,  gave  negative 
results,  all  observers  agreed  that  the  disease  was  water-borne.  In  De- 
cember, 1900,  the  source  of  the  water  supply  was  changed  to  the  Oswe- 
gatchie  Eiver,  a  small  Adirondack  stream  supplying  Ogdensburg.  This 
practically  put  a  stop  to  the  disease,  for  there  were  no  cases  of  typhoid 
that  were  not  clearly  contracted  elsewhere  until  October,  1903. 

Following  this  eight  persons  were  attacked,  seven  of  whom  were 
employees  in  the  dining-room.  It  seems  the  milk  "could  not  have 
been  infected."  The  water  was  excluded  and  other  sources  studied,  with 
negative  results.  The  ice  fell  under  suspicion.  It  had  recently  been 
taken  from  a  newly  opened  ice-house.  The  ice  had  been  harvested  from 
the  St.  Lawrence  Eiver  at  about  the  same  spot  as  the  ice  previously 
used.  It  was  gathered  in  February,  and  consequently  had  been  stored 
for  seven  months.  This  ice  disclosed  a  contamination  of  30,400  bacteria 
per  cubic  centimeter  on  agar  plates  and  50,400  on  gelatin.  Of  eight 
fermentation  tubes  three  showed  evidence  of  contamination  by  the 
presence  of  the  colon  bacillus. 

The  stock  of  ice  was  then  examined.     In  the  center  of  certain  cakes 

^  Nichols,  A.  H. :  "  Report  on  an  Outbreak  of  Intestinal  Disorder  Attribut- 
able to  the  Contamination  of  Drinking  Water  by  Means  of  Impure  Ice, ' '  Seventh 
Ann.  Sep.,  S.  B.  H.,  Mass.,  1876,  p.  467. 

^Park,  W.   H. :      Virchow-TIirsch's  JahrhericM  f.   1901,  p.   16. 

'Dorange:  "  Epidemie  de  Fievre  Typhoide  du  a  1 'Ingestion  de  Glace  Im- 
pure," Eev.  d'Hyg.,  Vol.  XX,   1898,  p.   295. 

*  Hutchins,  E.  H.,  and  Wheeler,  A.  W. :  "An  Epidemic  of  Typhoid  Fever 
Due  to  Impure  Ice,"  Am.  Jour.  Med.  ScL,  Vol.  CXXVI,  1903,  p.  680. 


842  RELATION    0¥    WATER    TO    DISEASE 

were  found  foreign  substances  in  the  form  of  black  or  dark  brown 
granular  matter.  Examined  under  the  microscope,  this  matter  was 
found  to  be  teeming  with  bacteria,  from  which  both  the  colon  and 
typhoid  bacillus  were  isolated  in  pure  culture. 

With  the  discontinuance  of  the  use  of  this  infected  ice  the  epidemic 
gradually  subsided.  There  were  in  all  thirty-nine  cases.  The  evidence 
of  this  outbreak  was  studied  by  Hill,  who  doubted  the  relation  of  the 
ice  to  the  disease. 

REFERENCES 

Standard  Methods  of  Water  Analysis;  Report  of  the  Committee  of 
the  American  Public  Health  Association;  second  edition  American 
Journal  of  Public  Health.  289   Fourth  Ave..  N.  Y. 

Mason :  "The  Examination  of  Water."  Wiley  &  Sons,  N.  Y.,  1899. 
(Hygienic  Laboratory.) 

Leffman :  "The  Examination  of  Water  for  Sanitary  and  Technical 
Purposes."    5th  Ed.,  Blakiston's,  Phila.,  1903. 

Richards  and  Woodman:  "Air,  Water,  and  Food."  Wiley  &  Sons, 
N".  Y.,  1901. 

Whipple :  "The  I\Iicroscopy  of  Drinking  Water,"  Wiley  &  Sons,  N.  Y. 

For  typical  and  composite  analyses  see  also : 

Clarke :  "The  Data  of  Geochemistry."  Bulletin  No.  330,  Series  E, 
Chemistry  and  Physics,  54,  U.  S.  Geological  Survey,  1908. 

"The  Municipal  Water  Supplies  of  Illinois."  Bulletin  of  the  Illinois 
State  Board  of  Health,  1908,  Vol.  IV,  No.  6,  June. 

Whipple :  "Typhoid  Fever."    Wiley  &  Sons,  N.  Y.,  1908. 

Turneaure  and  Russell:  "Public  Water  Supplies."  Wiley  &  Sons, 
N.  Y.,  1907. 

Hazen :  "The  Filtration  of  Public  Water  Supplies."  3rd  Ed.,  Wiley 
&  Sons,  N.  Y.,  1900. 

Thresh,  J.  C. :  "The  Examination  of  Waters  and  Water  Supplies." 
Blakiston's,  Phila.,  1904. 

Thresh,  J.  C. :  "Water  and  Water  Supplies."  3rd  Ed.,  Blakiston's, 
Phila.,  1901. 

^lason :  "Water  Supply."    3rd  Ed.,  Wiley  &  Sons,  X.  Y.,  1902. 

Hazen :  "Clean  Water  and  How  to  Get  It."    Wiley  &  Sons,  N.  Y. 

Whipple :  "The  A^alue  of  Pure  W^ater,"  Wiley  &  Sons,  N.  Y. 


SECTION  VII 

SEWAGE  DISPOSAL 

By  Geokge  C.  Whipple 
Professor  of  Sanitary  Engmeering  in  Harvard  University 

Importance  of  Speedy  Removal  of  Fecal  Matter. — The  basic  princi- 
ple that  underlies  all  methods  of  sewage  disposal  is  to  get  rid  of  the 
sewage  as  speedily  as  possible,  with  the  least  nuisance  to  the  smallest 
number  of  people,  with  the  least  damage  to  health  or  property,  and  at 
the  smallest  cost.  Experience  has  shown  that  failure  to  remove  human 
escrementitious  matter  from  a  community  promptly  or  properly  is  a 
menace  to  the  public  health.  Privies  and  cesspools  should  not  be 
tolerated  in  a  closely  built  up  area.  Unless  more  than  ordinary 
care  is  exercised  their  existence  may  give  opportunity  for  the  spread  of 
disease  by  insects  and  animals  and  by  the  pollution  of  local  wells. 
Statistics  show  that  the  abandonrdent  of  privies  and  the  substitution  of 
sewerage  systems  have  reduced  the  general  death  rate  in  many  a  city. 
Thus  Dr.  Boobyer  has  reported  that  at  jSTottingham,  England,  in  a 
period  covering  ten  years  typhoid  fever  cases  occurred  in  2.7  per  cent, 
of  the  houses  that  were  provided  with  privies,  in  0.83  per  cent,  of  the 
houses  where  pail  closets  were  used,  and  in  only  0.18  per  cent,  of  the 
houses  that  had  water-closets  connected  with  the  sewers.  Similarly,  Dr. 
Porter  has  stated  that  in  Stockport,  England,  during  the  years  1893-7 
typhoid  fever  occurred  in  3.4  per  cent,  of  the  houses  where  there  were 
privies,  but  in  only  1.2  per  cent,  of  the  houses  that  had  sewer  connec- 
tions, these  figures  being  based  on  a  study  of  over  18,000  houses.  In 
Munich,  when  sewers  were  constructed  in  1856-9  the  typhoid  fever  death 
rate  fell  from  242  to  166  per  100,000;  later,  after  an  improved  water 
supply  and  other  sanitary  reforms  had  been  brought  about,  the  typhoid 
fever  death  rate  fell  to  a  much  lower  figure. 

By  taking  special  precautions  against  the  spread  of  infection  through 
the  agency  of  flies,  either  by  preventing  their  breeding  or  preventing 
them  from  obtaining  access  to  fecal  matter,  and  by  closing  polluted  wells 
in  crowded  districts,  the  dangers  from  privies  and  cesspools  may  be 
greatly  reduced.^  Sometimes  it  is  wiser  to  do  this  in  villages  and 
^  For  the  dangers  of  polluting  the  soil  with  feces  see  chapter  on  "Soil." 

843 


841  SEWAGE    DISPOSAL 

small  towns  than  to  go  to  tlie  exjjonse  of  introducing  sewerage  sys- 
tems, with  perhaps  tlie  attendant  difliculty  and  expense  of  purifying  the 
sewage  after  collection. 

Ordinarily  in  this  country  sewerage  systems  and  public  water  sup- 
plies are  introduced  in  towns  where  the  poi)ulation  exceeds  about  3,000, 
and  in  smaller  places  if  the  population  is  concentrated.  This  is  so 
generally  true  that  towns  that  have  less  than  2,500  or  3,000  population 
are  classed  as  "rural,"  the  larger  towns  being  called  "urban." 

Dry  Earth  System. — The  dry  earth  system,  much  in  vogue  before 
the  general  introduction  of  the  water  carriage  system,  is  now  but 
little  used;  yet  under  some  conditions  it  has  advantages.  With  this 
method  the  water-closets  are  replaced  by  removable  water-tight  re- 
ceptacles, or  pails,  in  which  the  fecal  matter  is  kept  covered  with  dry 
earth,  ashes,  or  some  similar  material.  The  pails  are  collected  at  fre- 
quent intervals,  preferably  daily,  and  a  clean,  empty  pail  substituted. 
The  material  is  usually  buried  in  the  ground.  For  isolated  houses,  for 
temporary  camps  of  laborers,  for  small  scattered  summer  colonies,  and 
for  houses  situated  near  streams  or  lakes  used  for  public  water  supplies 
this  method  is  satisfactory,  and  is  often  the  best  possible  method,  pro- 
vided that  proper  care  is  taken  by  the  user  and  the  collector.  Cleanli- 
ness in  handling,  the  protection  of  the  material  against  flies,  regular 
and  frequent  collection,  occasional  disinfection  of  the  pails,  and  prompt 
burial  in  proper  soil  are  essential  to  success. 

Water  Carriage  System. — So  accustomed  are  we  to  present  methods 
of  sewerage  that  it  is  hard  to  realize  that  the  system  of  water  carriage 
of  fecal  matter  is  less  than  a  century  old.  Up  to  1815  the  public  drains 
of  London  were  not  permitted  to  receive  excreta;  in  Boston  fecal 
matters  were  rigidly  excluded  from  the  sewers  until  1833;  and  in  Paris 
this  was  the  case  even  up  to  1880. 

Following  the  report  of  the  Health  of  Towns  Commission  in  Eng- 
land in  1844,  water-closets  were  rapidly  introduced,  and  in  1847  their 
connection  with  the  sewers  was  required  by  law.  The  modern  sewerage 
system,  therefore,  dates  from  about  the  middle  of  the  last  century. 
Chesbrough  designed  a  general  sewerage  system  for  Chicago  in  1855. 
Boston's  first  sewerage  commission  was  appointed  in  1875.  Baltimore 
was  without  a  sewerage  system  until  within  a  few  years,  and  even 
now,  1912,  the  system  has  not  been  fully  completed,  nor  have  many 
houses  been  connected  with  it. 

The  introduction  of  the  water  carriage  system  accomplished  its  pur- 
pose and  effectually  did  away  with  the  offensive  accumulations  of  filth 
around  city  dwellings,  but  it  gave  rise  to  a  series  of  other  problems 
that  sanitarians  are  now  endeavoring  to  solve.  The  sewers  were  naturally 
built  to  discharge  their  contents  into  the  nearest  available  body  of  water 
— into  river,  lake,   or  harbor,  according  to  the  situation  of  the  city. 


SYSTEMS    OF    SEWAGE    DISPOSAL  845 

Where  the  streams  were  relatively  large,  no  nuisance  was  caused  by 
doing  this,  but  Avhere  the  streams  were  relatively  small  foul  conditions 
soon  arose,  and  it  became  necessary  to  reduce  the  amount  of  organic 
matter  discharged  from  the  sewers  into  them.  Water  supplies  also 
became  infected  and  in  some  instances  great  epidemics  followed,  while 
infection  was  spread  in  other  minor  ways.  Thus  the  problem  of  the 
removal  of  fecal  matter  was  sometimes  solved  at  one  place  only  to  re- 
appear elsewhere.  Litigation  also  arose  between  riparian  owners  along 
the  water  courses,  involving  damages  caused  by  tlie  pollution  of  the 
water. 

The  problem  has  thus  broadened  from  a  local  one  to  one  in  which 
different  cities  and  even  different  states  have  become  involved.  It  is  to 
the  solution  of  these  problems  of  maintaining  our  streams  and  lakes 
and  harbors  in  a  satisfactory  condition  that  sanitarians  are  now  earnestly 
devoting  themselves. 

Separate  and  Combined  Systems. — The  sewers  and  drains  of  a  city 
are  used  for  various  purposes,  the  two  most  important  ones  being  the 
removal  of  domestic  house  sewage,  and  the  rain  water  that  falls  on 
roofs,  yards,  sidewalks,  and  streets.  Sometimes  the  same  system  of 
sewers  is  used  to  carry  both  domestic  sewage  and  storm  water.  Such  is 
called  a  comMned  system.  Sometimes  the  storm  water  is  carried 
in  relatively  large  drains,  or  allowed  to  flow  along  in  the  street  gutters, 
while  the  domestic  sewage  is  carried  in  a  separate  system  of  sewers  of 
smaller  size.  The  choice  of  the  two  systems  depends  upon  the  local 
situation,  but  in  general  the  following  conditions  control. 

The  combined  system  is  the  older  and  the  one  more  commonly  used 
in  large  cities  and  crowded  communities,  for  it  is  cheaper  than  a  dual 
system,  where  both  separate  sewers  for  the  house  sewage  and  drains 
for  the  storm  water  are  required.  Where  the  storm  water  can  be  allowed 
to  flow  off  in  the  gutters  without  serious  inconvenience  from  flooding 
the  separate  system  is  cheaper,  as  the  pipes  are  smaller.  Wliere  the 
sewage  must  be  pumped  or  carried  long  distances  in  pipes  or  purified  by 
expensive  methods  the  advantages  lie  with  the  separate  system,  as  the 
quantity  of  sewage  is  less  and  its  flow  more  constant.  From  the 
sanitary  standpoint  either  method  is  satisfactory.  The  choice  of  the 
two  systems  depends  upon  various  engineering  questions  involving  cost, 
so  that  the  matter  is  one  that  should  be  submitted  to  an  engineer. 

Sewerage  systems  consist  of  house  sewers  or  house  drains  that  convey 
the  sewage  to  the  street  sewers  or  lateral  sewers.  These  unite  in  what 
are  termed  district  sewers,  and  the  latter  sometimes  unite ^  in  one  or 
more  trunk  sewers  of  large  size.  Belief  sewers  are  sometimes  built 
parallel  to  old  sewers  of  inadequate  capacity,  and  storm  sewers  are  some- 
times built  to  carry  away  surface  water,  while  under  drains  may  be 
used  in  connection  with  the  separate  system  to  remove  some  of  the 


846  SEWAGE    DISPOSAL 

ground  water.  Intercepting  sewers  are  sometimes  built  parallel  to  a 
stream  for  collecting  the  sewage  from  a  number  of  district  sewers  and 
conveying  it  to  a  safer  point  of  discharge.  When  intercepting  sewers 
are  used  with  the  combined  system  they  are  not  designed  to  carry  all 
of  the  flow  at  times  of  storm,  but  are  provided  with  overflows,  so  that 
the  excess  of  storm  water  discharges  into  the  river  at  various  points  of 
overflow.  This  is  a  matter  of  importance  and  one  to  be  remembered 
in  connection  with  the  purification  of  sewage,  for  the  quantity  of  sewage 
that  passes  these  overflows  at  times  of  heavy  rain  may  amount  to  25 
per  cent,  or  50  per  cent,  or  more  of  the  sewage,  and  during  the  course 
of  the  year  may  amount  to  from  2  per  cent,  to  5  per  cent.,  or  even 
more,  of  the  entire  sewage  of  the  city.  Such  overflow  water  is  almost 
never  purified.  At  Birmingham,  England,  Watson  has  estimated  that, 
in  spite  of  the  elaborate  provisions  for  purification,  a  large  part  of  the 
city's  sewage  is  at  times  discharged  untreated,  and  at  Milwaukee  the 
Sewerage  Commission  estimated  that  nearly  2  per  cent,  of  the  sewage 
would  fail  to  be  collected  by  a  very  liberally  designed  system  of  inter- 
cepting sewers. 

Cluantity  of  Sewage. — The  volume  of  sewage  flowing  in  a  separate 
system,  or  in  a  combined  system  during  dry  weather,  does  not  differ 
materially  from  the  water  consumption  of  the  city.  In  small  towns 
this  may  be  as  low  as  40  or  50  gallons  per  capita  daily,  although  ordi- 
narily it  is  rather  more  than  this.  In  large  cities  it  may  amount  to 
from  100  to  200  gallons  per  capita,  and  more  than  this  in  extreme 
cases. 

Intercepting  sewers  are  commonly  designed  to  provide  for  a  flow  of 
300  to  400  gallons  per  capita  daily.  The  amount  of  storm  water  depends 
upon  climatic  conditions,  and  for  this  subject  engineering  books  should 
be  consulted.  The  flow  of  sewage  fluctuates  hourly,  and  the  maximum 
may  be  from  50  to  100  per  cent,  of  the  daily  average,  while  greater 
fluctuations  may  be  found,  especially  in  cities  where  large  quantities 
of  water  are  used  in  manufacturing. 

Composition  of  Sewage. — A  city's  sewage  consists  of  the  public  water 
supply  soiled  with  the  waste  products  of  human  life  and  refuse  from 
household  and  factory,  increased  by  a  certain  amount  of  ground  water 
which  leaks  into  the  sewers,  and,  in  the  combined  system,  by  varying 
quantities  of  rain  water  and  street  wash.  Disintegrating  and  decom- 
posing as  it  flows,  the  sewage  gradually  becomes  a  more  or  less  homo- 
geneous suspension  of  fine  particles  in  water,  with  organic  and  mineral 
matter  in  solution.  The  longer  the  sewage  flows  or  stands,  the  more  its 
constituents  become  disintegrated;  fecal  matter  and  paper  become  un- 
recognizable as  such;  bacteria  increase  enormously,  and  assist  in  the 
breaking  down  of  the  complex  organic  compounds.  The  oxygen  orig- 
inally  present  in  the  water  becomes  reduced  and  finally  disappears. 


COMPOSITION    OF    SEWAGE  847 

so  that  from  a  fresh  condition  the  sewage  becomes  first  stale  and  then 
"septic."  Mixed  with  the  putrefying  organic  matter  and  the  swarming 
hosts  of  bacteria  harmlessly  engaged  in  their  beneficent  work  of  de- 
stroying the  organic  matter,  there  may  be  also  bacteria  which  have  come 
from  persons  sick  with  typhoid  fever,  dysentery,  tuberculosis,  and  other 
diseases. 

Sewage  is  obnoxious  to  the  senses  because  of  its  decomposing  organic 
matter,  but  it  is  dangerous  to  health  because  of  the  possible  presence 
of  these  pathogenic  bacteria. 

Among  the  important  constituents  of  sewage  from  the  standpoint 
of  purification  are  urea,  various  proteid  substances  such  as  albumin, 
fibrin,  casein,  starch,  sugar,  and  other  carbohydrates,  fats,  soaps,  and 
other  organic  substances.  Important  among  the  elements  present  in  the 
easily  decomposable  matter  are  nitrogen  and  sulphur.  The  concentra- 
tion of  these  substances,  that  is,  the  amount  present  in  a  given  volume 
of  sewage,  depends  upon  the  per  capita  volume  of  the  sewage,  and  varies 
widely  in  difi^erent  places.  Somewhat  more  constant,  however,  are  these 
constituents  when  compared  with  the  number  of  persons  dwelling  in 
houses  connected  with  the  sewers. 

The  following  figures  show  the  approximate  constituents  of  sewage 
expressed  in  terms  of  grams  per  capita  daily  and  in  parts  per  million 
when  the  volume  of  sewage  amounts  to  100  gallons  per  capita  daily. 

Estimated  Constituents  of  Average  Sew^age 

(After  Fuller) 

Grams  per      Parts  per 

Capita  Daily .^     Million.^ 

_,  T  (    Two  minutes  boiline 15.0  39.6 

Oxygen  consumed  j    ^.^^  ^^^^^^  ^^.^^^ 22.0  58.0 

{Free  ammonia  7.0  18.5 

Albuminoid  ammonia 2.5  6.6 

Organic   8.0  21.1 

Total   15.0  39.6 

Chlorin 19.0  50.2 

Fats   19.0  50.2 

(   Total  136.0  359.0 

Dissolved  matter   •)    Mineral   99.0  261.0 

(    Organic  and  volatile 37.0  98.0 

cj           .   .              (    Total    66.0  246.0 

mattet                ]   Mineral   58.0  140.0 

(    Organic  and  volatile 40.0  106.0 

I   Total  229.0  605.0 

Total  solids             ]   Mineral 152.0  402.0 

'    Organic  and  volatile 77.0  203.0 

Bacteria,  322  billion  per  capita  daily. 

^  These  figures  also  indicate  parts  per  million  if  the  per  capita  volume  of 
sewage  is  264  gallons  per  day. 

^  Assuming  a  per  capita  volume  of  100  gallons  per  day. 


848  SEWAGE    DISPOSAL 

The  methods  of  sewage  analyses  at  present  are  practically  the 
same  as  tliose  used  in  the  analyses  of  water.  (See  p.  72.)  They  are 
not  in  all  respects  satisfactory. 

Ventilation  and  Flushing  of  Sewers. — The  old  bugal)oo  of  sower  gas 
that  frigiitened  mir  fathers  before  tlie  days  of  l)aeteriology  is  no  longer 
feared  by  sanitarians,  although  its  influence  still  })ervades  the  antique 
plumbing  regulations  in  force  in  many  places.  It  is  indeed  desirable 
to  keep  the  air  of  sewers  from  mixing  with  the  air  we  breathe — the 
debilitating  influence  of  all  impure  air  sliould  be  avoided — luit  the 
danger  of  any  one's  becoming  infected  with  the  germs  of  disease  by 
breathing  sewer  air  is  ordinarily  so  extremely  small  as  to  be  quite  neg- 
ligible. 

The  water  carriage  system  offers  practically  no  danger  to  the  public 
health  during  the  transmission  of  sewage.  In  many  cities  the  sewers 
are  ventilated  by  allowing  a  free  flow  of  air  from  the  sewers  through 
the  house  drains,  the  individual  house  fixtures  only  being  trapped. 
This  method  is  apparently  safe,  provided  the  plumbing  is  of  substantial 
character.  If  it  is  not,  it  is  better  to  place  a  trap  upon  the  main  house 
drain.  It  is  believed  that  in  the  future  plumbing  will  develop  along 
the  lines  of  simplicity  and  improved  quality  of  materials  and  work,  and 
that  the  present  complicated  system  of  traps  and  vents  will  be  abandoned. 

The  catch-basins,  through  which  the  street  wash  enters  the  sewers, 
are  trapped  against  the  egress  of  sewer  air.  The  water  that  stands  in 
them  is  a  prolific  breeding  place  for  mosquitoes.  Unless  catch-basins 
are  frequently  cleaned,  the  accumulating  organic  matter  putrefies  and 
the  odor  from  it  may  be  worse  than  that  of  the  air  of  the  sewer.  Catch- 
basins  are  being  omitted  from  some  of  the  best  designed  modern  sewer- 
age systems. 

Combined  sewers  are  sufficiently  flushed  by  the  storms.  Separate 
sewers,  if  hiid  on  proper  grades,  need  little  or  no  flushing.  It  has  been 
common  in  the  past  to  employ  flush  tanks  at  the  end  of  lateral  sewers, 
but  these  are  troublesome  and  waste  much  water. 


STREAM   POLLUTION 

Sewage  Disposal  by  Dilution. — The  readiest  method  of  sewage  dis- 
posal, and  the  one  which,  until  within  the  last  few  years,  has  been 
universally  practiced  in  this  country,  is  to  allow  the  sewage  to  flow 
without  treatment  into  the  nearest  stream  or  lake  or  harbor.  This 
method  is  known  as  disposal  by  dilution.  It  is  a  proper  and  satisfactory 
method  of  disposal  where  the  dilution  is  sufficient.  It  is,  however, 
capable  of  abuse,  and  from  its  abuse  water  supplies  may  become  polluted, 
oyster  beds  may  become  infected,  and  in  severe  cases  streams  may  be  so 


STREAM    POLLUTION  849 

overloaded  with  sewage  as  to  become  an  offense  to  sight  and  smell. 
Properly  restricted,  however,  the  sewage  is  effectively  disposed  of,  the 
heavy  particles  settle  to  the  bottom,  the  organic  matter  is  oxidized  by 
the  oxygen  dissolved  in  the  water,  and  the  bacteria  are  gradually  dis- 
persed, consumed  by  other  organisms,  killed  by  sunlight,  or  otherwise 
destroyed.  These  agencies  bring  about  the  phenomenon  known  as  the 
self-purification  of  streams. 

"Wliile  it  is  true  that  hygienic  and  sanitary  considerations  materially 
affect  the  use  of  rivers  and  waterways  as  vehicles  for  the  reception,  trans- 
mission, and  ultimate  disposal  of  sewage,  the  c^uestion  is  primarily  an 
economic  one.  The  power  of  streams  to  transport  suspended  matter  and 
the  abilit}'  of  natural  bodies  of  water  to  oxidize  and  destroy  offensive 
substances  represent  a  natural  resource  that  should  be  utilized  just  as 
far  as  this  can  be  done  with  safety  and  without  off'ense.  For  each  river 
there  is  a  limit  to  the  amount  of  permissible  pollution.  The  reasons  for 
this  limit  are  not  the  same  in  all  cases,  but  vary  according  to  the  use 
that  is  made  of  the  water  of  the  river,  and  no  universal  standard  can 
be  wisely  set  up  or  maintained,  ^^len  the  extent  of  the  pollution  is 
such  as  to  affect  public  health  in  any  way  by  any  reasonable  use  of  the 
river  the  sanitary  aspect  of  the  situation  should  control. 

The  minimum  amount  of  water  required  to  dilute  sewage  in  streams 
is  usually  considered  to  be  from  2.5  to  4  cubic  feet  per  second  for  the 
sewage  of  one  thousand  people.  The  Chicago  Drainage  Canal  was  de- 
signed on  the  basis  of  3.3  cubic  feet  per  second  for  one  thousand  people. 
Eapidly  flowing  streams-  require  less  than  this,  as  much  oxygen  is  ab- 
sorbed from  the  air.  Stagnant  streams  may  require  considerably  more 
water.  The  presence  of  certain  trade  wastes  in  the  sewage  may  materi- 
ally increase  the  dilution  required.  For  example,  oily  matters  that  float 
on  the  surface  and  form  scums  may  interfere  with  the  absorption  of 
oxygen  from  the  air. 

In  lakes  the  relation  between  the  sewer  outfall  and  the  intake  of 
the  water  works  must  be  carefully  considered,  and  the  dispersion  of 
bacteria  by  currents  induced  by  the  wind  and  temperature  must  be 
studied.    In  harbors  the  effects  of  the  tides  must  be  taken  into  account. 

Dissolved  Oxygen"  in  Water. — The  amount  of  oxygen  dissolved 
in  water  depends  largely  upon  its  temperature,  as  shown  by  the  figures 
in  the  table  on  page  850. 

Water  near  the  freezing  point  will  hold  nearly  twice  as  much  oxygen 
as  at  prevailing  summer  temperatures.  The  dilution  required  in  sum- 
mer is  therefore  greater  than  in  winter,  and  in  some  situations  it  would 
be  logical  to  construct  purification  plants  to  be  operated  during  the 
summer  only,  thus  making  a  material  saving  in  cost. 

Sea  water  dissolves  about  20  per  cent,  less  oxygen  than  fresh  water. 

In  order  that  the  dissolved  oxygen  may  be  used  to  its  best  advantage. 


850 


SEWAGE   DISPOSAL 

SOLUBILITY  OF  DISSOLVED  OXYGEN  IN  WATER. 

Parts  per  JNlillion 


Temp.  "  C. 

Oxygen 

Temp.  '  C. 

Oxygen 

Temp.  •  C. 

Oxygen 

0 

14.70 

10 

11.31 

20 

9.19 

1 

14.28 

11 

11.05 

21 

9.01 

2 

13.88 

12 

10.80 

22 

8.84 

3 

13.50 

13 

10.57 

23 

8.67 

4 

13.14 

14 

10.35 

24 

8.51 

5 

12.80 

15 

10.14 

25 

8.35 

6 

12.47 

16 

9.94 

26 

8.19 

7 

12.16 

17 

9.75 

27 

8.03 

8 

11.86 

18 

9.56 

28 

7.88 

9 

11.58 

19 

9.37 

29 

7.74 

it  is  necessary  to  have  the  sewage  thoroughly  and  quickly  diffused 
through  the  water.  Otherwise  the  oxygen  near  the  point  of  discharge 
may  be  too  greatly  reduced,  and  nuisance  may  result,  even  though  there 
be  plenty  of  unused  oxygen  near  by. 

Necessity  of  Biological  Equilibrium. — It  is  becoming  recognized 
that  the  problem  of  sewage  disposal  by  dilution  is  largely  a  biological 
one.  The  decomposition  and  oxidation  of  the  organic  matter  in  sewage 
are  brought  about  by  bacteria,  and  the  bacteria  serve  as  food  for  protozoa 
and  other  forms  of  microscopic  animal  life.  The  dissolved  organic 
matter  in  sewage  serves  as  food  for  algae.  These  algae  and  protozoa  are, 
in  turn,  consumed  by  rotifers  and  Crustacea,  while  the  latter  form  the 
basis  of  the  food  supply  for  various  aquatic  animals  and  fishes.  Thus 
there  is  a  continuous  biological  cycle.  Again,  animal  forms  require 
oxygen  and  produce  carbonic  acid,  while  plants  consume  carbonic  acid 
and  produce  oxygen.  Wliere  these  processes  occur  normally  and  with  a 
proper  equilibrium  maintained  between  animal  and  plant  life,  offensive 
conditions  do  not  result,  but  where  abnormal  conditions  are  produced, 
as,  for  example,  by  the  discharge  of  excessive  quantities  of  sewage  or 
trade  wastes  into  a  stream,  a  depletion  of  the  dissolved  oxygen  may 
follow,  or  there  may  be  an  over-production  of  algae,  so  that  the  condi- 
tions become  offensive.  It  is  coming  to  be  realized  that  in  order  to 
properly  determine  the  dilution  required  in  any  particular  case  the  con- 
ditions required  to  bring  about  this  condition  of  biological  equilibrium 
must  be  determined. 

Hygienic  Aspects  of  Stream  Pollution. — Considering  the  hygienic 
aspects  of  stream  pollution  with  special  reference  to  the  pollution  of 
water  supplies,  it  is  important  to  remember  that  the  typhoid  fever  bacilli 
do  not  multiply  in  the  ordinary  water  of  our  streams,  but,  on  the  con- 
trary, when  discharged  into  water  they  rapidly  diminish  in  number. 
After  a  week  not  more  than  10  per  cent,  may  remain  alive,  and  after  a 
month  not  more  than  1  per  cent. 

It  follows  that  recent  pollution   is   the  most  dangerous,   and  that 


STREAM    POLLtJTiOK  851 

water  stored  in  reservoirs  and  lakes  becomes  more  and  more  safe  for 
use  as  time  of  storage  increases.  The  longevity  of  the  typhoid  bacillus 
is  much  greater  in  cold  water  than  in  warm  water.  Hence,  typhoid 
fever  epidemics  are  more  common  in  winter  than  in  summer,  and  in 
northern  climates  than  in  southern  climates. 


PROTECTION  AGAINST  POLLUTION 
WATEE    FILTRATION 

Long  experience  in  this  country  and  a  much  longer  experience  in 
England  and  Germany  have  demonstrated  clearly  and  unmistakably 
that  polluted  waters  can  be  and  are  being  constantly  purified  by  means 
of  filtration  to  such  an  extent  that  they  are  reliably  wholesome.  In 
Germany  the  typhoid  fever  death  rates  in  the  large  cities  have  been 
reduced  to  figures  far  below  those  of  American  cities.  In  Europe  it 
is  not  at  all  uncommon  for  the  typhoid  death  rate  to  remain  less  than 
10  per  100,000  for  ten  and  even  twenty  years  in  succession,  the  rate 
not  infrequently  dropping  as  low  as  3  and  4  per  100,000.  There  the 
filtration  of  surface  water  is  required  by  law,  and  the  efficiency  of  the 
filters  is  likewise  required  to  rise  to  a  certain  fixed  standard.  It  is 
worth  remembering  also  that  the  streams  of  Germany  are  far  from 
being  unpolluted  with  sewage,  and  that  no  general  attempt  is  made  to 
provide  sewage  purification  works  of  high  bacterial  efficiency.  Only  in 
case  of  actual  epidemics  is  the  practice  of  disinfection  of  sewage  fol- 
lowed. The  theory  that  water  filtration  is  superior  to  sewage  purifica- 
tion as  a  means  of  protecting  water  supplies  against  infection  appears 
to  prevail.    The  success  of  this  policy  has  been  amply  demonstrated, 

TEEATMENT    OF    SEWAGE 

By  appropriate  processes  sewage  can  be  artificially  purified  so  that 
the  decomposable  organic  matter  is  removed  or  oxidized  and  the  bacteria 
removed  or  killed.  A  complete  purification  is  not  attempted  even  in 
the  best  conducted  plants,  as  the  processes  demanded  are  too  elaborate, 
too  expensive,  and  too  uncertain  of  results.  More  often  the  purifica- 
tion is  incomplete,  the  degree  of  purification  secured  being  adjusted  to 
the  particular  needs  of  the  situation.  In  the  past  sewage  treatment 
works  have  been  built  to  remove  as  much  of  the  decomposable  organic 
matter  as  was  necessary  to  enable  the  effluent  to  be  discharged  into  some 
waterway  without  causing  offensive  conditions.  This  was  the  case  in 
Europe,  and  especially  in  England,  where  the  streams  are  relatively 
small  and  the  cities  relatively  large  and  the  amounts  of  trade  waste 
considerable. 

In  some  places  greater  emphasis  has  been  placed  on  the  removal  or 


852  SEWAGE    DISPOSAL 

destruction  of  pathogenic  bacteria,  with  the  object  of  protecting  oyster 
beds,  bathing  beaches,  or  reducing  tlie  "load"  on  water  filters. 

The  degree  of  purification  thus  required  varies  all  the  way  from 
a  nearly  complete  purification  down  to  a  mere  straining  out  of  the 
grosser  solids. 

Fundamental  Principles  of  Sewage  Treatment. — 'riie  fundamoilnl 
processes  in  sewage  treatment  are : 

(1)  Separation  of  the  suspended  matter  from  the  li(|ui(l  sewage. 

(2)  Destruction  of  the  putrescible  organic  matter  in  the  liquid 
sewage  looking  to  final  mineralization  by  the  processes  of  oxidation  and 
bacterial  action. 

(3)  The  transformation  of  the  sewage  sludge  to  a  condition  of 
stability  and  inertness  by  bacterial  action,  with  or  without  oxidation. 

(4)  Destruction  or  removal  of  the  bacteria  from  the  liquid  effluent. 
The  processes  involved  may  be  classified  as  follows : 

(1)  Preparatory  processes,  such  as  screens,  detritus  tanks,  plain 
settling  tanks,  septic  tanks,  digestion  tanks,  chemical  precipitation 
tanks,  roughing  filters. 

(2)  Purification  processes,  such  as  sub-surface  irrigation,  broad 
irrigation,  intermittent  filtration,  contact  beds,  and  trickling  filters. 

(3)  Finishing  processes,  such  as  sedimentation  or  coarse  filtration, 
land  treatment,  disinfection. 

(4)  Sludge  disposal  by  digestion  tanks,  filter  presses,  drying  on 
land,  dumping  at  sea. 

These  processes  are  by  no  means  clear  cut.  They  overlap  at  many 
points;  they  are  used  singly  or  in  all  sorts  of  combinations. 

Preparatory  Processes. — Screening. — Sewage  is  screened  to  remove 
the  larger  substances  that  might  injure  pumps,  clog  filters,  or  appear 
as  unsightly  litter.  Coarse  screens  consist  of  gratings  of  iron  bars; 
fine  screens  of  wire  cloth.  The  amount  of  material  screened  from 
sewage  varies  from  0.1  to  1.0  cubic  yard  per  million  gallons  of  sewage, 
according  to  the  fineness  of  the  screens.  It  is  pressed  and  burned  under 
a  boiler  or  buried  in  land.  Screening  has  attained  its  greatest  develop- 
ment in   Germany. 

Sedimentation. — Sedimentation  is  the  most  important  of  the  pre- 
paratory processes.  By  allowing  the  sewage  to  flow  slowly  through 
basins  in  which  the  velocity  is  checked  some  of  the  suspended  matter  is 
deposited  and  the  sewage  clarified  accordingly.  There  are  five  types 
of  sedimentation  basins:  (1)  grit  chambers  or  detritus  tanks,  (2)  plain 
settling  tanks,  (3)  septic  tanks,  (4)  digestion  tanks,  and  (5)  chemical 
precipitation  tanks. 

(1)  Grit  Chambers. — Grit  chambers  are  small  settling  basins  in 
which  the  sewage  remains  for  a  brief  interval,  often  not  more  than  ^ 
few  minutes,  and  where  the  velocity  is  commonly  between   10  and  30 


STREAM    POLLUTION 


853 


inches  per  minute.  They  require  frequent  cleaning.  The  material  col- 
lected consists  largely  of  sand  and  gravely,  but  usually  with  enough 
organic  matter  to  make  the  sludge  offensive. 

(2)  Plain  Settling  Tanks. — Plain  settling  basins  retain  the  sewage 
from  one  to  twelve  hours.  The  velocity  of  flow  is  commonly  from 
0.1  to  0.5  inch  per  minute.  Sludge  is  removed  at  frequent  intervals  in 
order  to  prevent  bacterial  decomposition. 

(3)  Septic  Tanks. — Septic  tanks  are  settling  tanks  large  enough  to 
retain  the  flow  of  sewage  from  eight  to  twenty-four  hours  or  longer,  the 
velocity  of  flow  varying  from  0.1  to  0.3  inch  or  more  per  minute.  The 
sludge  is  allowed  to  remain  in  the  tanks  for  long  periods,  giving  oppor- 
tunity for  intensified  bacterial  action  to  take  place  in  the  absence  of 
oxygen;  that  is,  under  anaerobic  conditions.  As  a  result  some  of  the 
solid  organic  matter  is  liquefied  or 
gasified  and  the  amount  of  sludge 
reduced.  This  process  is  spoken  of 
as  digestion.  It  is  accompanied  by 
the  presence  of  a  scum  on  the  sur- 
face of  the  tank  and  a  continual  ris- 
ing and  falling  of  sludge  through 
the  liquid.  The  amount  of  solid 
organic  matter  thus  digested  varies 
from  10  per  cent,  to  40  per  cent., 
being  greatest  in  strong  domestic 
sewage.  Septic  action  does  not  ma- 
terially improve  the  quality  of  the 
effluent.  It  may,  in  fact,  make  it 
more  objectionable.  Septic  action 
cannot  be  depended  upon  to  render 
sewage  safe  so  far  as  infections  are 
concerned. 

(4)  Digestion  Tanks. — The  best 
known  type  of  digestion  tank  is  the 
Imhoff,  or  Emscher,  tank.  This  is 
a  deep  septic  tank  divided  by  sloping  partitions  into  an  upper  and  a 
lower  compartment,  so  arranged  that  the  sewage  flows  through  the  upper 
compartment,  while  the  sludge  settles  through  openings  in  the  partition 
walls  into  the  lower  compartment,  where  digestion  takes  place.  The, 
advantage  of  this  type  of  septic  tank  is  that  the  sludge  alone  is  submitted 
to  septic  action  without  allowing  the  products  of  decomposition  to  mix 
with  the  flowing  sewage  above,  while  more  complete  digestion  improves 
the  character  of  the  sludge  from  the  standpoint  of  subsequent  disposal. 

The  following  figures  show  the  approximate  percentage  of  suspended 
matter  removed  by  sedimentation: 
56 


Fig.  116. — Typical  Section  of  an  Im- 
hoff Tank. 

a.  Compartment    for    flowing    sewage. 

/.  Sludge  digestion  compartment. 

g.  Baffle  to  prevent  gases  and  sludge 
from  rising  into  compartment  a,  but 
permitting  sediment  to  fall  into  the 
sludge  compartment. 

b-c.  Pipe  for  withdrawing  sludge. 


854 


SEWAGE    DISPOSAL 

PERCENTAGE  REMOVAL  OF  SUSPENDED  MATTER. 


Kinds  of  Sedimentation 

Period, 
Hours 

Weak 
Sewage 

Medium 
Sewage 

Strong 
Sewage 

Grit,  or  detritus  tanks 
Plain  sedimentation 
Plain  or  septic  sedimentation 
Septic  sedimentation 
Septic  sedimentation 

1 

6 
12 

24 
48 

10% 

25 

30 

40 

50 

15% 

40 

50 

65 

75 

25% 
60 
75 
80 

85 

(5)  Chemical  Precipitation. — Sedimentation  may  be  hastened  and 
increased  by  the  use  of  chemicals.  Lime,  copperas  (ferrous  sulphate), 
and  alum  (aluminium  sulphate)  are-  commonly  used.  The  active 
coagulants  are  the  hydroxids  of  iron  and  aluminum.  When  the  sewage 
itself   contains    the   necessary    amount    of   iron,   lime   only    is    needed. 


Fig.  117. — Imhoff  Tanks  and  Sludge  Drying  Beds,  Emscher  District,  Germany. 

When  alum  is  used  500  to  1,500  pounds  are  required  per  million  gal- 
lons. At  London  the  sewage  is  treated  with  500  pounds  of  lime  and 
120  pounds  of  copperas  per  million  gallons;  at  Worcester,  Mass.,  with 
1,000  pounds  of  lime  and  no  copperas;  at  Providence,  R.  I.,  with  600 
pounds  of  lime  and  no  copperas;  at  Glasgow  with  GOO  pounds  of  lime 
and  1,000  pounds  of  copperas. 

Sludge  Disposal. — The  disposal  of  sludge  is  one  of  tlie  most  difficult 
parts  of  sewage  purification.  Grit  chambers  collect  from  0.1  to  1  cubic 
yard  of  wet  sludge  per  million  gallons  of  sewage;  plain  settling  tanks 
from  1  to  4  cubic  yards;  septic  tanks  from  1  to  2  cubic  yards.  Sludge 
deposited  in  plain  settling  tanks  contains  from  90  to  95  per  cent,  of 
water;  septic  tank  sludge,  after  storage,  contains  from  80  to  85  per 
cent.;  chemical  precipitation  sludge  from  90  to  92  per  cent.;  Imhoff 
tank  sludge  from  80  to  90  per  cent.  Sludge  after  pressing  contains 
from  25  to  50  per  cent,  of  water.     It  has  some  manurial  value,  and  is 


STEEAM    POLLUTIOX 


855 


used,  to  some  extent,  on  land.     As  a  general  proposition,  however,  the 
attempt  to  '"utilize"  the  sludge  has  not  met  with  financial  success. 

Purification  Processes. — Sub-sueface  Ieeigatiox. — For  small  instal- 
lations a  satisfactory  method  of  disposing  of  sewage  after  sedimentation 


Fig.  118. — Chemical  Precipitation  Plant  at  Worcester,  AIass.,  Inlet. 

is  to  discharge  it  through  3-inch  or  4-inch  tile  pipes  laid  in  the  ground 
10  to  18  inches  deep  in  rows  Si/o  to  3  feet  apart.  In  sandy  soils  this 
method  o-iYes   saticf action,   and  under  favorable  conditions  the  sewage 


Fig.  119. — Chemical  Precipitation  Plant  at  Worcester,  Mass.,  Outlet. 

of  150  to  250  people  can  be  applied  to  an  acre,  the  rate  of  application 
being  commonly  one  to  two  gallons  per  lineal  foot,  or  20.000  to  30.000 
gallons  per  acre  daily.  With  tight  soils  larger  areas  are  required. 
With  clav  soils  the  method  cannot  be  used. 


856 


SEWAGE    DISPOSAL 


This  method  of  sewage  disposal  is  particularly  applicable  to  suburban 
and  rural  conditions. 

Broad  Irrigation. — Broad  irrigation  consists  in  the  application  of 
crude  sewage  to  land,  making  it  serve  as  food  for  crops,  the  principal 
value,  however,  being  in  the  water  itself.  It  is  distributed  by  means 
of  ditches  and  other  channels  as  in  ordinary  irrigation.  The  sewage 
farms  of  Berlin  and  Paris  are  very  extensive,  the  Berlin  farms  covering 
nearly  20,000  acres.  The  rate  of  application  varies  from  3,000  to  15,000 
gallons  per  acre  daily,  an  acre  serving  for  the  sewage  of  from  100  to 
300  persons.  The  crops  raised  on  sewage  farms  frequently  pay  the 
expenses  of  operation,  but  seldom  pay  the  interest  on  the  investment 
except  in  arid  regions,  where  irrigation  is  profitable.     Broad  irrigation 


Fig.  120. — Triple  Contact  Beds  at  Hampton,  England. 


cannot  be  successfully  used  with  clayey  soils.     The  purification  obtained 
is  usually  very  satisfactory,  both  chemically  and  bacteriologieally. 

Intermittent  Sand  Filtration. — With  this  method  the  sewage  is 
applied  intermittently  to  beds  of  sand,  especially  prepared  for  the  pur- 
pose, in  such  quantities  that  it  quickly  soaks  away,  leaving  the  bed  ex- 
posed to  the  air  for  a  period  of  several  hours  or  several  days,  thus  giving 
opportunity  for  aeration  and  oxidation  of  the  organic  matter.  The 
results  obtained  are  usually  very  satisfactory,  provided  that  the  filters 
are  not  overloaded.  Wlien  raw  sewage  is  applied  directly  to  the  beds 
the  rates  of  application  vary  from  50,000  to  150,000  gallons  per  acre 
daily,  the  population  served  per  acre  being  from  300  to  1,200.  With 
preliminary  treatment  higher  rates  may  be  used,  and  the  sewage  of 
1,500  to  2,000  people  applied  per  acre.  The  filters  are  usually  divided 
into  beds  by  means  of  earth  embankments  which  cover  the  distributing 
pipes.     Often  they  are  underdrained  with  tiles  laid  20  to  SO  feet  apart 


STEEAM    POLLUTION 


857 


in  fine  material,  or  100  feet  apart  in  coarse  material,  their  depth  below 
the  surface  varying  from  3  to  8  feet.  Crops  are  sometimes  grown  on 
these  beds,  but  agricultural  operations  are  regarded  as  a  secondary  mat- 
ter. In  winter  the  beds  are  plowed  into  ridges  or  the  sludge  is  collected 
into  piles  so  that  ice  may  form  and  be  supported  upon  them,  leaving 
channels  beneath  the  ice  by  which  the  sewage  can  be  distributed.  After 
a  few  weeks  or  months  the  beds  become  clogged  and  it  is  necessary  to 
rake  the  surface.  At  intervals  the  accumulated  deposit  on  the  sand 
has  to  be  scraped  off. 

The  efficiency  of  intermittent  sand  filtration  is  higher  than  that  of 
any  other  process.  Well  operated  plants  are  capable  of  removing  from 
95  to  98  per  cent,  of  the  suspended  matter  and  bacteria,  while  the  effluent 


FiQ.  121. — Inclined  Screen  Operated  by  Water  Wheel,  Birmingham,  England, 


is  quite  clear  and  non-putrescible.     The  method  is  limited,  however,  to 
regions  where  suitable  and  convenient  areas  of  sandy  soil  exist. 

Contact  Beds. — Contact  beds  are  water-tight  compartments  filled 
with  porous  material,  such  as  broken  stone  or  coke,  and  operated  as 
follows:  The  bed  is  slowly  filled  with  sewage,  which  has  previously 
passed  through  a  septic  tank,  and  allowed  to  remain  full  for  a  brief 
period,  after  which  it  is  emptied  and  allowed  to  remain  empty  for  a 
longer  period.  A  cycle  commonly  employed  is  to  allow  one  hour  for 
filling,  two  hours  for  contact,  one  hour  for  emptying,  and  four  hours 
for  rest.  During  the  period  of  contact  the  suspended  matter  tends  to 
settle  upon  and  adhere  to  the  exposed  surfaces  of  the  broken  stone  or 
coke,  thus  forming  a  film.  While  standing  full  septic  action  occurs  and 
organic  matter  is  absorbed  by  the  film.  During  the  resting  period 
oxidation  of  this  organic  matter  takes  place.  The  purification  obtained 
in  this  way  is  partial.     Commonly,  two  or  three  contact  beds  are  used 


858  SEWAGE    DISPOSAL 

in  series,  the  effluent  from  the  first  passing  to  the  second,  and  that  of  the 
second  to  the  third.  The  depth  of  contact  beds  varies  from  3  to  6  or 
8  feet,  the  broken  stone  or  coke  being  from  y^  inch  to  2  inches  in  size. 
The  rate  of  application  is  usually  between  300,000  and  800,000  gallons 
per  acre  daily,  one  acre  serving  a  population  of  about  5,000.  When 
properly  operated  and  receiving  the  sewage  of  septic  tanks  contact  beds 
are  capable  of  removing  about  65  to  70  per  cent,  of  the  organic  matter, 
80  to  85  per  cent,  of  bacteria,  and  85  to  90  per  cent,  of  suspended  mat- 
ter. Contact  beds  become  clogged  with  use,  and  after  periods  varying 
from  five  to  eight  years  it  is  necessary  to  remove  the  stone  or  coke  and 
clean  them. 

Trickling  Filters. — Trickling  filters,  otherwise  called  "sprinkling 


FiQ.  122. — Trickling  Filters  and  Final  Settling  Basin  and  Roughing  Filter  at 

Hyde,  England. 

filters"  or  "percolating  filters,"  consist  of  beds  of  porous  material  such 
as  broken  stone,  coke,  or  clinkers  upon  which  the  sewage  is  sprinkled 
and  through  which  it  percolates  to  underdrains  laid  on  a  tight  floor  be- 
neath. The  entire  bed  is  arranged  with  reference  to  complete  aeration 
throughout,  in  order  that  the  organic  matter  of  the  sewage  may  become 
thoroughly  oxidized.  The  suspended  matter  of  the  sewage  is  not  perma- 
nently retained  in  the  beds,  but  is  carried  out  in  the  effluent,  which  is 
turbid  and  requires  subsequent  clarification.  The  object  of  the  trickling 
filter  is  to  change  the  character  of  the  organic  matter  so  as  to  render 
it  non-putrescible.  The  sewage  is  applied  to  the  beds  by  sprinkling 
through  fixed  sprinklers  or  by  use  of  traveling  sprinklers,  rotary  or 
rectangular,  operated  by  the  discharging  sewage  or  by  power.  The  rate 
of  application  varies  from  0.5  to  2.0  million  gallons  per  acre  daily, 
one  acre  of  trickling  filter  serving  a  population  of   10,000   or  more. 


strea:\i  pollutiois^ 


859 


The  beds  vary  in  depth  from  5  to  10  feet,  coarser  material  being  used 
for  the  deeper  beds.  Well-operated  sprinkling  filters  receiving  the 
effluent  from  plain  sedimentation  or  septic  tanks  are  capable  of  remov- 
ing from  85  to  90  per  cent,  of  the  suspended  matter  and  from  90  to  95 
per  cent,  of  bacteria,  yielding  an  effluent  that  is  non-putrescible.  This 
method  is  useful  when  sandy  areas  of  sufficient  size  are  not  available 
for  intermittent  filtration  or  are  too  expensive. 

Finishing  Processes. — Disixfectiox  of  Sewage. — The  best  disin- 
fectant for  sewage  or  sewage  effluents  is  "chlorid  of  lime,"  or  bleaching 
powder,  which  is  usually  applied  in  the  form  of  a  1  per  cent,  to  2  per 
cent,  solution.  The  quantities  required  are  25  to  75  pounds  per  million 
gallons  for  good  effluents  from  sprinkling  filters  or  contact  beds,  75  to 


Fig.   123. — Tricexixg  Filter  at  Biemixgham,  England. 


125  pounds  for  poor  effluents,  125  to  250  pounds  for  crude  sewage,  and 
250  to  375  pounds  for  septic  sewage,  the  time  of  contact  required 
varying  from  about  %  hour  to  2  or  more  hours.  By  properly  applying 
the  chemicals  in  these  quantities  it  is  possible  to  destroy  from  95  to  99 
per  cent,  of  the  bacteria. 

Choice  of  Methods. — The  choice  of  methods  to  be  used  in  any  case 
depends  upon  various  considerations,  such  as  the  nature  of  the  sewage 
to  be  treated,  the  allowable  character  of  the  effluent  considered  with  refer- 
ence to  the  use  made  of  the  water  into  which  it  is  to  be  discharged, 
the  availability  of  suitable  areas  of  land  at  proper  elevation,  and  finally 
the  cost,  both  of  construction  and  operation. 

Where  suitable  areas  of  sandy  soil  are  available  the  method  of 
intermittent  filtration  is  ordinarily  the  most  satisfactory  one  that  can 
be  adopted.  This  is  the  case  in  many  parts  of  Xew  England  and  in 
some  other  parts  of  our  country.     Over  much  of  the  United  States, 


860  SEWAGE    DISPOSAL 

however,  the  soil  is  far  too  heavy  to  allow  this  method  to  be  used  satis- 
factoril)-,  and  when  this  is  the  case  some  of  the  newer  methods  must  be 
resorted  to,  such  as  sedimentation  followed  by  oxidation  in  trickling 
filters,  contact  beds,  etc.  Under  some  special  conditions  broad  irrigation 
may  be  desirable,  but,  generally  speaking,  this  method  is  falling  into 
disuse.  When  the  effluent  is  to  be  discharged  into  a  stteam  used  for  a 
nearby  supply  of  drinking  water,  or  into  the  ocean  or  a  harbor  in  the 
vicinity  of  oyster  beds,  disinfection  may  properly  form  a  part  of  the 
process.  Chemical  precipitation  is  seldom  used  where  the  sewage  is  of 
a  strictly  domestic  character,  but  it  may  be  used  to  advantage  when  the 
sewage  contains  large  amounts  of  trade  wastes. 

Methods  for  the  purification  of  sewage  are  quite  elastic  inasmuch  as 
the  different  processes  may  be  combined  in  different  ways.  A  study  of 
the  works  that  have  been  built  in  the  United  States  during  the  last 
generation  shows  that  not  infrequently  they  have  been  made  more 
elaborate  than  was  necessary.  Often  a  simpler  design  with  a  large 
capacity  gives  better  results  than  an  elaborate  combination  of  processes 
of  limited  capacity.  Important  engineering  problems  are  almost  always 
involved  in  the  laying  out  of  sewage  treatment  works  that  require  the 
services  of  a  specialist  in  sanitary  engineering. 

Relative  Bacterial  Efficiency  of  Different  Processes. — By  way  of  re- 
capitulation the  following  figures  are  given  to  show  the  relative  sanitary 
efliciency  of  various  processes  employed  in  sewage  treatment : 

Percentage 
Removal  of  Bacteria 

Coarse  screens  0  to    5 

Fine  sex'eens 10  "  20 

Grit  chambei-s   10  "  25 

Sedimentation 25  "  75 

Septic   sedimentation    25  "  75 

Chemical  precipitation   40  "  80 

Contact   beds    80  "  90 

■     Trickling  filters   90  "  95 

Intei-mittent  sand  filters 95  "  98 

Broad  irrigation    97  "  99 

Disinfection  of  raw  or  settled  sewage 90  "  95 

Disinfection  of  filter  effluents 98  "  99 

These  figures  are  mere  approximations,  but  they  serve  to  show  how 
some  forms  of  treatment,  very  desirable  from  many  points  of  view, 
have  a  low  sanitary  efficiency.  The  septic  treatment,  for  example,  does 
not  greatly  reduce  the  number  of  bacteria  in  sewage;  in  fact,  if  the 
period  of  detention  of  the  sewage  in  the  tank  is  long  the  numbers  of 
bacteria  in  the  effluent  may  be  greater  than  those  in  the  raw  sewage. 

Management  of  Sewage  Treatment  Works. — Proper  management  of 
sewage  treatment  works  is  as  important  as  proper  design,  and  is  more 


STEEAM    POLLUTION 


861 


difficult  to  secure.  It  is  a  most  regrettable  fact  that  many  treatment 
works  in  the  United  States  have  been  badly  neglected^  and,  in  conse- 
quence, have  given  inefficient  service.  Neglect  not  only  results  in  mak- 
ing the  effluent  unsatisfactory,  but  leaves  the  works  themselves  in  an 
offensive  condition.  Neglect  of  small  plants  is  more  common  than  of 
plants  large  enough  to  require  the  entire  time  of  one  or  more  attendants. 
Another  frequent  cause  of  failure  is  that  treatment  works  are 
allowed  to  become  outgrown,  so  that  the  plant  becomes  overloaded  and 
the  process  becomes  inefficient.  The  sewers  of  a  city  are  usually  designed 
for  a  long  period  in  advance — forty  or  fifty  years — but  this  is  not  the 
case  with  treatment  works,  for  the  reason  that  such  works  can  ordi- 
narily  be    enlarged    when   necessary.      This    is    sound   policy,    for   the 


Fig.  124. — Removing  Sludge  from  a  Septic  Tank  at  Manchester,  England.' 

reason  that  the  methods  of  purification  are  constantly  improving,  and  it 
is  desirable  to  take  advantage  of  these  improvements  as  far  as  possible 
whenever  enlargement  is  necessary.  But,  if  the  works  are  to  operate 
satisfactorily,  the  enlargement  must  be  made  as  the  tributary  population 
increases,  taking  advantage  of  the  state  of  the  art  at  the  time. 

The  purification  of  sewage  is  so  largely  a  chemical  and  biological 
matter  that  it  is  desirable  to  have  the  works  in  charge  of  men  trained 
in  sanitary  engineering,  with  a  laboratory  equipment  at  their  dis- 
posal. Tests  of  the  sewage  before  and  after  treatment  should  be  made 
regularly  in  order  to  ascertain  the  efficiency  of  the  process.  Tests  should 
also  be  made  of  the  water  into  which  the  sewage  is  discharged.  In  the 
case  of  plants  of  large  size,  provided  with  laboratories,  such  tests  are 
made  daily,  but  in  the  case  of  plants  too  small  to  constantly  employ  a 
chemist  tests  should  be  made  regularly  by  some  controlling  authority. 
Herein  lies  one  of  the  functions  of  the  State  Board  of  Health, 


862  SEWAGE    DISPOSAL 

Treatment  Plants  as  Nuisances. — If  sewage  treatment  works  are 
properly  designed  and  carefully  operated,  and  if  they  are  enlarged 
from  time  to  time  to  meet  the  needs  of  the  growing  community,  they 
need  not  be  the  cause  of  offensive  conditions,  but  often  they  are,  as  a 
matter  of  fact,  a  source  of  nuisance  in  themselves.  There  is  a  natural 
opprobrium  attached  to  a  region  where  such  works  exist  that  results 
in  a  recognized  deterioration  of  property  values.  The  processes  used 
for  the  treatment  of  sewage  not  infrequently  result  in  odors  that  may 
be  objectionable  over  considerable  areas.  Wliere  the  treatment  works 
are  entirely  covered,  as  some  kinds  of  works  may  be,  little  or  no 
nuisance  may  result,  but  where,  for  example,  the  sewage  is  first  sub- 
mitted to  putrefaction   in  a   septic  tank  and   the   septic   effluent   then 


Fig.  125. — Septic  Tank  and  Chemical  Precipitation  Tanks  at  Rochdale,  England. 

sprayed  into  open  air  upon  the  surface  of  sprinkling  filters,  this  ex- 
posure of  the  atomized  liquid  results  in  the  liberation  of  odors  that  may 
reach  distances  up  to  perhaps  half  a  mile  from  the  plant,  depending 
upon  the  amount  and  character  of  sewage  treated,  the  local  topography, 
prevailing  direction  of  the  wind,  humidity  in  the  atmosphere,  and  other 
conditions. 

Frequently  high  winds  will  carrv'  the  spray  itself  for  several  hundred 
feet  with  inevitable  bacterial  pollution  of  the  air.  In  the  operation 
of  sprinkling  filters  also  it  has  been  found  that  at  certain  seasons  of 
the  year  swarms  of  flies  breed  in  the  porous  beds.  These  are  very 
troublesome,  if  not  dangerous,  in  the  immediate  vicinity  of  such  works. 
In  considering  the  need  of  sewage  treatment  it  is  proper  to  balance  these 
possible  nuisances  against  those  resulting  from  the  discharge  of  un- 
purified  sewage  into  a  body  of  water.    It  not  infrequently  happens  that 


COOPERATIVE    SANITATION 


863 


the    installation    of    sewage    treatment    works    merely    substitutes    one 
nuisance  for  another. 

Nuisances  Caused  by  Trade  "Wastes. — It  not  infrequently  happens 
that  the  greatest  nuisance  in  streams  is  due  not  so  much  to  domestic 
sewage  as  to  the  presence  of  trade  wastes  that  may  be  discharged  into 
the  stream  directly,  or  that  may  be  allowed  to  flow  into  the  stream 
through  the  sewers.  For  example,  the  discharge  of  spent  dye  liquors 
may  color  the  water  of  a  stream  for  many  miles;  petroleum  wastes 
from  gas  works  may  cause  iridescent  films  to  form  upon  the  surface 
of  the  water,  producing  an  unsightly  appearance  and  increasing  the 
odor  directly,  as  well  as  indirectly,  by  excluding  air  from  the  water; 
the  acid  iron  wastes  from  galvanizing  works  may  cause  a  rusty  discolora- 


"FiQ.  126. — Burying  Sludge  from  Htdholttic  Tank  at  Hampton,  England. 

tion  that  not  only  imparts  a  brown  color  to  the  water,  but  paints  the 
rocks  and  submerged  stumps  along  the  shores  for  many  miles.  When 
nuisances  of  this  character  arise  it  is  wise  and  proper  to  install  sewage 
clarification  plants,  and  sometimes  more  elaborate  works,  for  such 
nuisances  cause  real  damage  to  property  and  to  personal  comfort.  Trade 
waste  pollution  may  interfere  with  the  filtration  of  water  even  more 
than  sewage  itself.  Illustrations  of  this  are  the  paper-mill  pollutions  in 
New  York  State  and  the  acid-iron  wastes  in  Pennsylvania. 


COOPERATIVE   SANITATION 


What  appears  to  be  needed  at  the  present  time  is  some  method 
of  cooperation  by  which  needed  sanitary  reforms  can  be  brought  about 
at  least  expense.     It  is  unbusinesslike  to  compel  the  purification  of  the 


864  SEWAGE    DISPOSAL 

sewage  of  a  large  upstream  city  in  order  to  protect  the  water  supply  of 
a  small  city  lower  down,  if  pure  water  can  be  furnished  tlie  latter  in 
some  better  and  cheaper  way.  Legislation  that  clothes  the  State  authori- 
ties witli  power  to  prevent  the  pollution  of  streams  by  sewage,  but  does 
not  give  them  power  to  compel  the  purification  of  water  or  to  control 
pollution  by  trade  wastes,  is  unfortunate.  It  naturally  leads  to  litigation 
rather  than  cooperation,  and  may  retard  rather  than  hasten  necessary 
sanitary  reforms.  If  our  State  authorities  cannot  be  trusted  in  this 
matter  it  may  be  that  a  proper  solution  of  the  difficulty  Avill  be  found 
in  the  establishment  of  district  boards  similar  to  those  in  England  and 
Germany,  such  boards  having  jurisdiction  over  the  limits  of  particular 
catchment  areas.  In  some  respects  these  natural  hydrographic  boun- 
daries have  advantages  over  artificial  State  boundaries.  In  the  near 
future  also  our  national  govermnent  will  doubtless  take  a  hand  in  the 
matter.  In  whatever  form  the  authority  may  be  constituted  the  idea  of 
cooperation  should  prevail,  and  ironclad  rules  against  stream  pollution 
should  give  way  to  a  rational  distribution  of  the  burden  of  water  puri- 
fication and  sewage  treatment,  and  an  equitable  adjustment  of  cost  made 
between  the  parties  interested,  thus  decreasing  the  total  expense  of 
sanitary  measures  required  and  utilizing  natural  resources  for  the 
purification  of  sewage  in  water  as  far  as  this  is  safe. 

If  the  system  of  water  carriage  of  sewage  continues  in  use  the  time 
will  some  day  come  when  the  sewage  of  all  of  our  cities  will  be  purified, 
partially  or  completely,  and  all  surface  water  supplies  filtered.  It  is 
proper  to  anticipate  this  consummation  as  far  as  our  means  permit, 
but  meantime  it  is  good  business  and  sound  common  sense  to  spend  our 
money  first  where  it  will  go  furthest  and  do  the  most  good,  building 
water  filters  and  sewage  treatment  works,  sometimes  one,  sometimes 
both,  as  they  may  be  needed. 

Adequate  remedies  against  stream  pollution  from  the  standpoint  of 
nuisance  have  been  usually  obtained  by  an  appeal  to  the  principles  of 
common  law.  Cases  involving  bacterial  pollution  by  sewage  have  been 
thus  far  too  few  to  establish  definite  precedents.  It  will  be  interesting 
to  see  whether,  in  view  of  our  increasing  population,  and  especially 
the  increasing  growth  of  our  cities,  the  courts  will  ultimately  decide  that 
the  use  of  unfiltered  river  water  as  a  source  of  water  supply  by  riparian 
owners  is  a  reasonable  use  of  the  water. 

THE  RURAL  PROBLEM   OF   SEWAGE   DISPOSAL 

One  of  the  most  difficult  problems  of  modem  sanitation  is  to  secure 
proper  disposal  of  fecal  matter  in  rural  communities,  at  summer  hotels, 
at  temporary  camps  of  laborers,  at  summer  colonies  at  beach  and  moun- 
tain, and  at  individual  houses  in  villages  and  on  the  farm.    It  is  difficult 


THE    EUEAL    PEOBLEM    OF    SEWAGE    DISPOSAL      865 

because  the  necessary  structures  are  so  small  and  simple  that  they  have 
been  thoughtlessly  constructed,  because  adequate  care  of  the  processes 
is  more  or  less  disagreeable  and  therefore  neglected,  but  chiefly  because 
the  inherent  dangers  have  not  been  understood  or  appreciated. 


Fig.  127. — Chemical  Precipitation  Tanks  at  Glasgow,  Scotland.     Lower  End. 

One  of  the  most  needed  reforms,  and  one  that  is  happily  making 
progress,  is  that  of  the  protected  privy,  that  is,  one  where  the  fecal 
matter  is  received  in  a  tisrht  vault  so  constructed  that  the  contents  can- 


FiG.  128. — Chemical  Precipitation  Tanks  at  Glasgow,  Scotland.     Upper  End. 

not  be  reached  by  flies,  insects,  -  rats,  hens,  or  pigs,  yet  so  ventilated  as 
to  prevent  disagreeable  odors  and  give  opportunity  for  evaporation  of 
liquids.     This  necessitates  the  liberal  use  of  screens  around  the  vault 


866 


SEWAGE    DISPOSAL 


and  on  the  windows  and  doors,  and  tlio  use  of  a  self-closing  cover  for 
the  seat.  The  privy  vault  may  be  constructed  of  concrete,  with  bottom 
and  walls  3  incbes  to  G  iucbcs  in  thickness,  or  the  vault  may  be  re- 
placed with  a  tight,  removable  receptacle  of  metal  or  wood  ])laced 
in  a  screened  compartment.  Properly  constructed  privies  of  this  charac- 
ter may  be  located  near  dwellings,  the  only  conditions  being  those  con- 
trolling offensive  odors,  but  this  presupposes  greater  care  than  is  ordi- 
narily given  to  such  matters.  Preferably,  therefore,  they  should  be 
located  at  some  reasonable  distance  from  dwellings. 

Privies  that  are  not  provided  with  water-tight  vaults,  but  are  so 
arranged  that  tbc  fecal  matter  falls  upon  the  soil,  may  be  safe,  so  far 
as  water  pollution  is  concerned,  if  the  soil  is  of  proper  character  and 


Fig.   129. — Intermittent  Sand  Filtration  Bed  at  Brockton,  Mass. 

if  the  privy  is  sufficiently  removed  from  the  house  well;  but  are  unde- 
sirable for  other  reasons.  No  arbitrary  rules  as  to  the  necessary  mini- 
mum distance  of  a  privy  from  a  well  can  be  laid  down,  as  everything 
depends  upon  the  character  of  the  soil,  the  slope  of  the  ground,  the 
elevation  of  the  natural  ground  water,  and  the  draught  of  water  from 
the  well.  A  distance  of  at  least  25  feet  should  be  secured  with  sandy 
soils,  whenever  possible,  and  preferably  50  feet  or  more.  With  clay  soils, 
liable  to  dry  and  crack,  and  in  limestone  regions,  liable  to  contain 
cTevices  in  the  rock,  leaching  privies  sliould  not  be  used,  as  wells  may 
be  polluted  100  feet  or  even  a  mile  or  more  away. 

Cesspools  are  holes  dug  in  the  ground  to  receive  not  only  fecal 
matter,  but  also,  perhaps,  sink  wastes  and  water-closet  discharges.  They 
are  often  lined  with  loose  stones  to  prevent  caving,  but  this  permits  the 
liquids  to  leach  into  the  soil,  ^^^len  the  soil  is  sandy' there  is  no  objec- 
tion to  this  method  of  disposal ;  in  fact,  it  is  like  the  method  of  sub- 


THE    EUEAL    PROBLEM    OF    SEWAGE    DISPO>SAL     867 

soil  disposal  previously  described,  except  that  the  sewage  is  discharged 
into  the  soil  below  the  depth  where  the  soil  bacteria  are  at  work.  This 
may  be  an  important  difference,  however,  and  the  oxidation  of  the  dis- 
solved organic  matter  proceeds  by  a  slow  and  incomplete  process.  Leach- 
ing cesspools,  however,  should  not  be  located  near  wells  used  for 
drinking  water  supplies.  In  sandy  soils  the  danger  of  bacterial  con- 
tamination is  small  if  the  distance  is  more  than  25  feet,  but.  even  so,  the 
idea  of  infiltration  of  sewage  into  a  well  is  repugnant,  and  often  the 
water  may  be  so  tainted  as  to  have  a  disagreeable  odor,  even  when  analy- 
sis shows  it  to  be  bacterially  safe. 

Ordinarily  leaching  cesspools  should  not  be  constructed  in  clav  soils 
or   in  limestone   regions,   for  they   are   liable   to   seriously   pollute   the 


Fig.  130. — Filter  Bed  with  SA>rD  Ridged  for  Wixter  Operatiox  at  Brockton, 
Mass.  The  ice  sheet  rests  on  the  ridges.  The  photograph  shows  the  accxunulatioii 
of  suspended  matter  during  the  winter. 

ground  water  and  are  almost  sure  to  overflow.  If  cesspools  are  neces- 
sary under  such  conditions  they  should  be  made  water-tight  and  treated 
as  septic  tanks  and  the  effluent  taken  care  of  by  subsurface  irrigation 
or  some  form  of  land  treatment. 

In  cesspools  the  organic  matter  undergoes  septic  action  and  the 
amount  of  sludge  that  accumulates  is  often  small.  Nevertheless,  clean- 
ing is  necessary  at  intervals  in  the  case  of  all  cesspools.  The  disposal 
of  the  contents  is  one  of  the  most  troublesome  questions  connected  with 
this  form  of  sewage  disposal.  The  common  method  is  to  spread  it  upon 
the  land  as  a  topdressing.  The  work  is  apt  to  be  done  in  the  winter, 
when  other  farm  work  is  not  pressing,  and  not  infrequently  when  the 
ground  is  frozen.  Thus  opportunity  is  given  for  fecal  bacteria  of  human 
origin  to  be  washed  into  a  well  or  some  public  water  supply.     If  spread 


868  SEWAGE    DISPOSAL 

on  the  ground  during  the  summer  flies  have  access  to  it.  If  used  for 
fertilizer  for  crops  eaten  raw,  as  celery  or  lettuce,  opportunity  is  offered 
for  transmission  of  infection  by  such  foods.  Tlie  only  i)roper  melliod  of 
disposal  for  cesspool  sludge  is  by  burial  or  disinfection.  In  laborers' 
camps,  and  in  army  camps,  disposal  of  fecal  matter  by  cremation  is 
practiced  with  advantage. 

In  the  South,  where  hook-worm  disease  is  prevalent,  the  scattering 
of  human  fecal  matter  upon  the  surface  of  the  ground  is  one  of  the 
greatest  elements  of  danger.     The  danger  of  transmission  of  infection 


Fig.   131. — Discharge  of  Sewage  upon  a  Filter  Bed  at  Brockton,  Mass. 

by  flies  from  fecal  matter  to  food  is  likewise  greater  in  the  South,  as 
the  warm  season  is  longer,  so  that  greater  care  needs  to  be  exercised  in 
the  construction  and  care  of  protected  privies  than  in  the  aSTorth. 

REFERENCES 

1890-1910. — Annual  Eeports  of  the  Massachusetts  State  Board  of 
Health.  (Summary  of  Eesults  Obtained  at  the  Lawrence  Experiment 
Station  during  Twenty-one  Years  Is  Given  in  the  Report  of  1908.) 

1905-1910. — Contributions  from  the  Sanitary  Research  Laboratory 
of  the  Massachusetts  Institute  of  Technology.  Eight  volumes,  contain- 
ing papers  by  Professors  Sedgewick,  Winslow,  Phelps,  and  others. 

1908. — Dunbar:  "Principles  of  Sewage  Treatment."  Translated  by 
H.  T.  Calvert.     Charles  Griffin  &  Co.,  Ltd.,  London. 

1910. — Follwell,  A.  Prescott:  "Sewerage."  John  Wiley  &  Sons, 
New  York. 

1910. — Kinnicutt,  Winslow,  and  Pratt:  "Sewage  Disposal."  John 
Wiley  &  Sons,  New  York. 


EEFEEENCES  869 

1910. — Schmeitzner,  Eudolf:  "Clarification  of  Sewage,"  translated 
by  A.  E.  Kimberly.  Engineering  ISTews  Publishing  Company,  Xew 
York. 

1911. — Kershaw,  G.  Bertram:  "Modern  Methods  of  Sewage  Purifi- 
cation."    Charles  Griffin  &  Co.,  Ltd.,  London. 

1912.^Elsner,  Alexander :  "Sewage  Sludge  Treatment."  Translated 
by  Kenneth  Allen.    McGraw-Hill  Book  Co.,  Xew  York. 

1912.— Fuller,  G.  W. :  "Sewage  Disposal."  McGraw-Hill  Book  Co., 
New  York. 

1912.— Ogden,  Henry  K.,  and  Cleveland,  H.  B. :  "Practical  Methods 
of  Sewage  Disposal." 

For  references  to  recent  works  for  the  treatment  of  sewage  see  files 
of  Engineering  News  and  Engineering  Becord. 


57 


SECTION   VIII 
REFUSE   DISPOSAL 


By  George  C.  Whipple 
Professor  of  Sa?iitary  Engineering  in  Harvard  University 

The  general  term  "refuse"'  is  applied  to  all  of  the  solid  waste  ma- 
terial not  carried  by  the  sewers,  such  as  ashes,  rubbish,  garbage,  street 
sweepings,  manure,  and  dead  animals.  The  quantity  of  this  waste 
material  that  has  to  be  gotten  rid  of  in  a  city  is  very  large.  For  exam- 
ple, in  the  Borough  of  Manhattan,  Xew  York  City,  the  ashes  amount 
to  about  1.200  pounds  per  capita  per  year,  the  rubbish  100  pounds,  the 
street  sweepings  300  pounds,  and  the  garbage  200  pounds,  the  total 
amount  of  refuse  being,  in  round  numbers,  a  ton  per  capita  per  year. 
In  smaller  cities  the  per  capita  quantities  of  collected  refuse  are  less 
than  half  of  this,  sometimes  considerably  less.  The  amount  of  garbage 
alone  varies  from  less  than  100  to  upward  of  200  pounds  per  capita 
per  year.  Both  the  quantity  and  character  of  the  refuse  vary  with  the 
seasons,  the  maximum  amount  of  ashes  occurring  in  the  winter  and  the 
maximum  amount  of  garbage  in  the  summer.  This  fact  has  an  im- 
portant bearing  on  the  problem  of  ultimate  disposal. 

Ashes  weigh  from  900  to  1,200  pounds  per  cubic  yard,  garbage 
from  900  to  1,100  pounds,  street  sweepings  from  700  to  1,800  pounds, 
and  rubbish  from  150  to  250  pounds.  The  following  figures  serve  to 
indicate  approximately  the  constituents  of  the  principal  classes  of  refuse: 

CONSTITUENTS  OF  CITY  REFUSE. 


Water 

Volatile 
Matter 

Ash 

Carbon 

Heat  Units 

per  Pound 

of  Refuse 

B.  T.  U. 

Ashes 

Garbage 

Rubbish 

Street  sweepings 

7-25  per  cent. 
70-80  per  cent. 

5-15  {)er  cent. 
35-^5  per  cent. 

8-10  per  cent. 
15-25  per  cent. 
40-65  per  cent. 
20-30  per  cent. 

50-60  per  cent. 

5-15  per  cent. 

5-15  per  cent. 
25-95  per  cent. 

18-25  per  cent. 
4-8    per  cent. 
15-^0  per  cent. 
18-25  per  cent. 

3,700 
2,000 
6,000 
4,000 

The  refuse  problem  is  to  a  slight  extent  a  hygienic  one,  but  it  is  more 
a  problem  of  economy,  convenience,  and  general  cleanliness.    Bad  smells 
870 


EEFUSE    DISPOSAL  871 

from  fermenting  garbage  do  not  directly  injure  the  public  health,  yet 
they  are  an  offense,  and  their  elimination  is  an  important  matter. 
Ashes  and  street  dust  may  irritate  the  eyes,  nose,  and  throat  and 
predispose  to  bacterial  infection.  Accumulating  rubbish  is  not  only  un- 
sightl}^,  but  may  provide  conditions  favorable  for  mosquito  breeding, 
while  accumulating  manure  may  breed  flies.  Garbage  attracts  flies  and 
may  breed  them  if  the  cans  are  left  uncleaned  from  week  to  week,  but 
ordinarily  garbage  does  not  stand  uncollected  long  enough  to  give  oppor- 
tunity for  the  larvae  to  hatch. 

There  are  two  general  methods  of  collection  and  disposal  of  city 
refuse:  the  mixed  system  and  the  separate  system.  With  the  mixed 
system,  which  is  the  one  most  generally  used  in  Europe,  all  of  the 
refuse,  ashes,  garbage,  and  rubbish  is  put  together  by  the  householder  in 
a  single  can,  conveyed  by  wagon  to  the  disposal  plant,  where  it  is  all 
burned  together  and  the  organic  matter  thus  destroyed.  The  com- 
bustible matter  in  the  rubbish  and  the  unburned  coal  in  the  ashes  are 
usually  sufficient  to  evaporate  the  water  in  the  garbage,  so  that  the 
material  is  self-consuming.  This  method  is  known  as  incineration,  or 
cremation,  or  destruction.  With  the  separate  system  the  garbage,  rub- 
bish, and  ashes  are  kept  separate  by  the  householder  and  collected  in 
separate  wagons  and  disposed  of  in  different  ways.  The  ashes  are  used 
for  filling  low  land,  the  rubbish  carried  to  the  dump,  and  the  garbage 
taken  to  sea  and  dumped  or  buried,  or  fed  to  hogs,  or  taken  to  a  re- 
duction plant,  where  it  is  cooked  and  treated  for  the  recovery  of  fats 
and  other  products. 

The  separate  system  is  commonly  used  in  America,  but  with  numer- 
ous combinations  of  processes  of  collection  and  disposal.  Whichever 
method  of  disposal  is  adopted  determines  the  manner  of  collection  and 
the  treatment  of  the  refuse  by  the  householder.  The  choice  of  the 
system  to  be  used  is  one  to  be  determined  for  each  community,  largely 
on  the  basis  of  cost.  Generally  speaking,  an  incineration  plant  entails 
a  greater  initial  outlay  than  a  reduction  plant.  Its  products  are  ashes 
and  steam.  The  ashes  transported  are  commonly  used  for  filling  near 
the  plant ;  the  steam  is  used  for  power  to  run  the  works,  and  the  excess 
steam  is  sold  or  converted  into  electricity  and  conveyed  to  places  where 
it  can  be  utilized  to  advantage.  In  cities  where  power  is  expensive 
the  receipts  for  the  sale  of  power  may  be  sufficient  to  throw  the  balance 
in  favor  of  this  method  of  disposal.  Where  power  is  cheap,  however, 
the  opposite  may  be  the  case  and  the  reduction  process  prove  the  cheaper. 
With  the  reduction  process  the  salable  products  are  grease  and  tanlvage. 
The  former  is  sold  for  soap  manufacture,  and  the  latter,  which 
consists  of  the  solid  particles  of  the  cooked  garbage,  is  pressed, 
dried,  and  ground,  and  used  as  a  filler  for  fertilizers.  As  time  goes 
on    other    useful    products    are    likely    to    result    from    this    process. 


872  EEFUSE    DISPOSAL 

iis  the  materials  wasted  or  sold  contain  much  sugar  and  proteid 
l)<)dics. 

Incineration  Plants. — There  are  two  general  types  of  destructors. 
The  mutual  assistance  type,  where  there  are  several  grates  and  divided 
ash  pits,  the  products  of  combustion  commingling  above,  thus  combining 
several  furnaces  into  one,  and  the  separate  unit  type. 

The  temperature  of  combustion  varies  from  about  1,200°  to  2,000° 
F.  and  the  capacity  is  from  1,200  to  1,500  pounds  of  mixed  refuse  per 
day  for  each  square  foot  of  grate  surface.  Each  pound  of  mixed  refuse 
is  capable  of  evaporating  from  one  to  two  pounds  of  water.  So-called 
cremation  plants  are  operated  at  lower  temperatures  and  are  less  satis- 
factory. 

The  best  illustration  of  an  incinerator  in  this  country  is  the  one 
recently  constructed  at  Milwaukee.  This  was  designed  by  Dr.  Eudolph 
Hering,  and  a  description  of  it  may  be  found  in  the  Engineering  News 
for  August  26,  1910.  It  has  a  capacity  of  300  tons  of  mixed  refuse 
per  day.  The  Milwaukee  incinerator  receives  street  sweepings  and 
manure  as  well  as  ashes,  rubbish,  and  garbage.  The  manure  has  been 
found  fully  as  difficult  to  burn  as  the  garbage,  and  on  general  principles 
it  would  appear  to  be  wasteful  to  dispose  of  it  in  that  way.  With  a  well- 
arranged  incinerator  there  are  practically  no  objectionable  odors  and 
very  little  disagreeable  smoke. 

Reduction  Plants. — This  method  of  garbage  disposal  is  used  in 
many  of  our  largest  American  cities,  including  New  York,  Boston, 
Buffalo,  the  plants  as  a  rule  being  owned  and  operated  by  private 
companies  under  contract  with  the  city.  Eecently  an  excellent  plant  of 
the  reduction  type  has  been  constructed  by  the  city  of  Columbus  and 
is  now  operated  by  the  city.  A  description  of  this  plant  may  be  found 
in  the  Engineering  Becord  of  November  19,  1910.  When  the  garbage 
reaches  a  plant  of  this  type  it  is  sorted  to  remove  foreign  substances, 
such  as  tin  cans,  glass  bottles,  etc.,  and  conveyed  to  a  series  of  digestors, 
where  it  is  cooked  for  from  six  to  ten  hours  under  pressure  of  about  60 
pounds.  It  then  passes  through  presses  which  separate  the  water  and 
fats  from  the  solid  part,  called  tankage.  The  water  and  grease  are 
allowed  to  pass  through  settling  tanks,  where  the  grease  is  skimmed 
off  the  top.  The  water  flows  away  to  the  sewer  or  is  evaporated,  and 
the  solids  added  to  the  tankage.  The  latter  is  sometimes  treated  for 
fat  recovery  by  the  use  of  hot  naphtha.  Ultimately  the  tankage  is 
ground  and  dried  and  used  as  a  filler  for  fertilizers.  The  per  cent,  of 
grease  recovered  may  amount  to  from  1  to  3  per  cent,  and  the  market- 
able tankage  to  about  20  per  cent,  of  the  garbage.  Unless  a  plant  of 
this  type  is  Avell  designed  and  carefully  managed  offensive  odors  will 
result,  but  these  can  be  almost  completely  done  away  with  if  proper 
precautions  are  taken. 


EEFEEENCES  873 

Feeding  Garbage  to  Hogs. — In  man}'  small  cities,  especially  those  of 
iSTew  England,  the  garbage  is  fed  to  hogs.  This  requires  frequent  col- 
lection and  careful  management  at  the  piggery.  If  the  garbage  is 
sterilized  with  steam,  and  if  the  feed  is  supplemented  with  grain,  and 
the  garbage  feed  stopped  a  few  weeks  before  the  hogs  are  killed,  there 
seems  to  be  no  sanitary  objection  to  this  method,  while  it  may  be 
a  profitable  one  on  account  of  the  large  food  value  of  the  garbage. 

Collection  of  Garbage. — From  a  sanitary  standpoint,  and  even  from 
the  standpoint  of  nuisance,  the  problem  of  garbage  collection  is  even  a 
more  difficult  one  than  that  of  garbage  disposal.  A  strong  argument  in 
favor  of  the  incinerator  method  is  that  the  method  of  mixed  collection 
can  be  carried  on  with  less  nuisance  than  separate  collection.  When 
garbage  is  mixed  with  the  ashes  in  a  single  can  the  water  of  the  garbage 
is  absorbed  by  the  ashes,  fewer  flies  are  attracted  to  it,  and  the  odor 
is  reduced.  The  absorption  of  water  by  the  ashes  also  tends  to  reduce 
the  dust  nuisance.  Mixed  collection  is  also  more  economical,  as  fewer 
carts  are  required  and  collections  need  not  be  as  frequently  made.  Much 
depends,  however,  upon  local  conditions. 

Garbage  disposal  plants  are  best  located  near  the  outskirts  of  the 
city,  where  no  nuisance  will  result.  This  ordinarily  involves  a  long 
haul.  If  favorable  opportunities  exist  for  dumping  ashes  within  the 
limits  of  a  short  haul  the  separate  collection  of  refuse  may  prove  the 
cheaper.  At  Minneapolis  the  householders  are  required  to  wrap  each 
day's  garbage  in  paper.    This  method  is  said  to  be  very  satisfactory. 


REFERENCES 

1905. — Hering,  EudoliDh :  "Eeview  of  General  Practice  of  Disposal 
of  Municipal  Eefuse."  Transactions  American  Society  of  Civil  En- 
gineers, A^ol.  LIA^  Part  E,  p.  263. 

1906. — Parsons,  H.  deB. :  "Disposal  of  Municipal  Eefuse.''  John 
Wiley  &  Sons,  Xew  York. 

1906. — Amenable,  W.  M. :  "Garbage  Crematories  of  the  United  States." 
John  Wiley  &  Sons,  New  York. 

1910.— Morse,  W.  F. :  "Collection  and  Disposal  of  Wastes."  Pub- 
lished by  the  Municipal  Journal,  ISTew  York. 

1911. — Greeley,  Samuel  A.:  "Investigations  for  Municipal  Eefuse 
Disposal."  Proceedings  New  Jersey  Sanitarj^  Association,  jSTovember, 
1911. 


SECTION    IX 
VITAL    STATISTICS 

By  Cressy  L.  Wilbur,  M.D. 

Chief  Statistician,  Bureau  of  the  Census,  Department  of  Commerce  and 
Labor,  Washirigton,  D.  C. 

In  the  broadest  sense  vital  statistics  may  be  defined  as  the  statistics 
relating  to  any  forrii  of  life  or  to  the  growth  and  development  of  any 
living  organism.  In  this  sense  they  may  constitute  a  part  of  biometrical 
methods  as  applied  to  biological  problems  of  every  character,  dealing 
both  with  plant  and  animal  life.  In  the  more  limited  and  usual  sense, 
however,  vital  statistics  are  the  statistics  based  upon  the  chief  events 
of  human  life,  and  the  events  that  are  commonly  studied  by  statistical 
methods  are  births,  marriages,  and  deaths.  Of  minor  importance  are 
stillbirths,  now  usually  distinguished  from  living  births,  and  also  from 
deaths  of  persons  born  alive. 

The  statistical  method  involves  the  study  of  masses  or  considerable 
numbers  of  events  rather  than  that  of  individual  or  few  cases.  Nothing 
is  more  uncertain  than  the  prediction  of  the  future  life  of  an  individual 
at  birth,  but  the  probability  that  a  certain  proportion  of  individuals  will 
die  in  infancy  or  reach  adult  years,  will  be  married  or  remain  single, 
will  succumb  to  certain  diseases  or  will  survive  to  approximately  a  cer- 
tain age,  may  be  established  within  reasonable  limits  by  the  observa- 
tion of  large  numbers  of  similar  cases  existing  under  like  conditions. 
Changes  occur  in  the  vital  statistics  of  large  groups,  both  suddenly  and 
of  a  periodic  character,  but  on  the  whole  there  is  a  considerable  stability 
among  the  averages  shown  for  cities,  states,  and  countries,  and  the  trend 
of  future  events  may  often  be  anticipated  from  the  results  of  the  past. 

Unfortunately,  perhaps,  statistics  are  obliged  to  deal  to  a  consider- 
able extent  with  figures  and  tables.  This  fact  may  account  for  a 
certain  degree  of  unpopularity  of  the  subject  because  arithmetical  opera- 
tions are  distasteful  to  many  minds.  There  is  much  drudgery  con- 
nected with  the  work  of  statistical  compilation,  and  it  is,  of  course, 
very  necessary  that  each  step  connected  with  the  collection  and  com- 
874 


NECESSITY    OF    VITAL    STATISTICS  875 

pilation  of  data  be  performed  with  precision  and  accuracy,  as  otherwise 
the  results  and  conclusions  based  thereupon  may  be  vitiated.  It  fol- 
lows, therefore,  that  vital  statistics  are  not  infrequently  neglected  in  the 
work  of  a  public  health  service,  and  perhaps  relegated  to  the  charge  of 
persons  unfitted  by  training  or  taste  properly  to  discharge  the  important 
duties  of  registration  officials. 

Necessity  of  Vital  Statistics  in  Public  Health  Work. — The  first  duty 
of  a  newly  appointed  officer  of  public  health  should  be  to  inform  himself 
thoroughly  as  to  the  character  and  conduct  of  the  vital  statistics  of  the 
state  or  city  of  which  he  has  charge.  The  movement  of  the  vital  sta- 
tistics of  the  past  should  be  examined,  and  he  should  remember  that  the 
ultimate  judgment  of  the  success  of  his  work  and  of  the  methods  of 
sanitary  betterment  that  he  may  introduce  will  be  based  upon  the  care- 
ful analysis  of  the  vital  statistics  collected  during  his  term  of  office. 
Dr.  Hurty  has  well  called  vital  statistics  the  "bookkeeping  of  humanity," 
and  the  health  officer,  charged  with  control  over  the  precious  treasure 
of  human  life,  must  again  and  again  appeal  to  the  vital  records  to  show 
how  well  he  has  discharged  his  trust. 

There  is  a  danger  here.  The  health  officer  must  be  entirely  candid 
in  his  use  of  vital  statistics,  must  thoroughly  understand  the  fallacies 
to  which  he  is  liable  by  the  improper  use  of  registration  data  or  by  the 
use  of  imperfect  or  inaccurate  returns.  No  great  degree  of  mathe- 
matical attainment  is  necessary  for  some  of  the  most  important  prac- 
tical applications  of  vital  statistics.  The  ordinary  ratios  or  "rates" 
employed  in  vital  statistics  are  as  easily  computed  and  understood 
as  the  "percentages"  so  familiar  to  the  baseball  public.  A  little  common 
sense  in  avoiding  comparisons  of  data  that  are  not  comparable,  and 
absolute  honesty  in  accepting  and  using  the  results — if  based  upon  effi- 
cient registration — are  alone  necessary  to  make  the  vital  statistics  of 
indispensable  service  in  public  health  work. 

It  should  not  be  necessary  to  warn  against  the  tendency  to  warp 
the  statistical  data  in  the  direction  of  preconceived  or  desired  conclu- 
sions. The  compilation  of  vital  statistics  can  be  manipulated  in  many 
ways,  and  by  overestimates  of  population  or  exclusion  of  deaths  for 
various  reasons  the  death  rates  may  be,  apparently,  reduced  so  that 
boastful  claims  of  the  "healthiest  city"  may  seem  to  be  justified.  Such 
claims  are  usually  open  to  question,  and  frequently  will  be  found  to 
depend  either  upon  grave  deficiencies  in  registration,  the  unjustifiable 
omission  of  certain  deaths,  overestimates  of  population,  or,  perhaps 
most  frequently  of  all,  the  utter  ignoring  or  lack  of  knowledge  of  the 
fact  that  general  or  crude  death  rates  are  unreliable  criteria  of  sanitary 
efficiency,  and  that  the  age,  sex,  or  other  peculiar  constitution  of  the 
population  must  be  taken  into  consideration.  The  most  crying  needs  of 
American  registration  at  the  present  time  are:  (1)  better  registration. 


876 


VITAL    STATISTICS 


that  is,  more  complete  registration,  especially  of  births,  and  (2)  prac- 
tical knowledge  of  the  uncertainty  of  the  crude  or  general  death  rates 
as  compared  with  death  rates  properly  corrected  for  sex,  age,  or  other 
modifviiiuf   constitution   of   the  population. 

Neglected  Condition  of  Vital  Statistics  in  the  United  States. — The 
United  States  is  exceptional  among  the  countries  of  the  civilized  world 
in  that  there  are  no  national  system  of  vital  statistics  and  no  complete 
records  of  births  and  deaths  for  the  country  as  a  whole.  This  results 
from  the  fact  that  the  control  of  registration  is  entirely  a  function  of 
state  government,  or  of  municipal  government  in  states  where  no  gen- 
eral laws  on  this  subject  are  in  force. 

Reports  on  vital  statistics  have  been  published  by  the  Federal  gov- 
ernment for  many  years.  The  subject  was  first  introduced  in  the 
Seventh  Census  and  a  report  on  the  mortality  statistics  of  the  United 
States  for  the  census  year  ended  May  31,  1850,  was  published  in  1855. 
This  report  was  based  on  the  deaths  collected  by  the  assistant  marshals 
while  enumerating  the  population.  It  will  readily  be  understood  that 
it  is  quite  impossible  to  obtain  a  complete  list  of  deaths  by  this  method, 
and  the  statistics  were  far  too  imperfect  to  afford  any  reliable  rates. 
Nevertheless,  the  plan  of  attempting  to  collect  deaths  by  enumeration 
after  the  close  of  the  year  to  which  they  relate  was  continued  for  suc- 
cessive censuses  until  it  was  finally  done  away  with  in  the  law  for  the 
Thirteenth  Census  (1910). 


Population  of 

Deaths  in 

Registration  Area 

Registration  Area 

Population  of 

Year 

Continental 
United  States 

Rate  per 

Number 

Per  Cent. 

Number 

1,000 
Population 

Census  year  1879-1880 

50,155,783 

8,538,366 

17,0 

178,645 

19.8 

Census  year  1889-1890 

62,622,250 

19,659,440 

31.4 

386,212 

19.6 

Census  year  1899-1900 / 

75.994.575 

(  28,807,269 
1  30,765,618 

37.9 

512,669 

17.8 

Calendar  year  1900 ( 

40.5 

639,939 

17.6 

Calendar  year  1901 

77,747,402 

31,370,952 

40.3 

518,207 

16.5 

Calendar  year  1902 

79,365,396 

32,029,815 

40.4 

508,640 

15.9 

Calendar  year  1903 

80,983,390 

32,701,083 

40.4 

524,415 

16.0 

Calendar  year  1904 

82,601,384 

33,345,163 

40.4 

551,354 

16.5     • 

Calendar  year  1905 

84,219,378 

34,052,201 

40.4 

545,533 

16.0 

Calendar  year  1906 

85,837,372 

41,983,419 

48.9 

6.58,105 

15.7 

Calendar  year  1907 

87,455,366 

43,016,990 

49.2 

687,034 

16.0 

Calendar  year  1908 

89,073,.360 

46,789,913 

52.5 

691,574 

14.8 

Calendar  year  1909 

90,691,354 

50,870,518 

56.1 

732,538 

14.4 

92,309.348 

53,843,896 

58.3 

805.412 

15.0 

Vital  statistics  should  be  collected  only  by  immediate  registration,  as 
distinguished  from  enumeration  after  the  close  of  the  period  covered. 
Many  states  established  systems  of  registration  about  the  middle  of  the 
last  century,  but  of  these  only  two,  Massachusetts  and  New  Jersey,  were 
found  to  possess  returns  of  sufficient  value  for  inclusion  in  the  registra- 
tion area  for  deaths  which  was  established  in  the  mortality  reports  of 


NEGLECTED  CONDITION  IN  UNITED  STATES         877 

the  Tenth  Census  (1880).  This  area,  which  was  based  upon  the 
requirement  of  approximately  complete  registration  enforced  by  burial 
permits,  embraced  only  these  states  and  certain  cities  in  other  states 
with  an  aggregate  population  of  8,538,366  persons,  or  about  one-sixth 
(17  per  cent.)  of  the  estimated  population  of  the  continental'  United 
States.  The  growth  of  this  area,  together  with  the  deaths  and  death 
rates  for  succeeding  years,  is  shown  on  page  876. 

For  the  year  1910  the  registration  area  for  deaths  had  thus  increased 
to  a  population  of  53,843,896,  or  nearly  three-fifths  (58.3  per  cent.)  of 
the  total  estimated  population  of  the  country  in  the  middle  of  1910. 
The  following  list  comprises  the  registration  states  for  that  year  :^ 

California  New  Jersey 

Colorado  New  York 

Connecticut  North  Carolina  (municipalities 

Indiana  of  1,000  population  and  over) 

Maine  Ohio 

Maryland  '  Pennsylvania 

Massachusetts  Ehode  Island 

Michigan  Utah 

Minnesota  Vermont 

Montana  Washington 

New  Hampshire  Wisconsin 

Eeturns  were  also  received  from  the  District  of  Columbia  (city  of 
Washington)  and  forty-three  other  cities  in  non-registration  states.  The 
registration  of  deaths  is  not  equally  efficient  in  all  of  these  states.  Some 
of  them  are  sparsely  settled  and  the  returns  for  certain  counties  are 
practically  worthless.  This  fact  is  indicated  in  the  annual  report  on 
mortality  statistics  prepared  by  the  Bureau  of  the  Census,  and  it  is 
a  question  whether  it  would  not  be  preferable  to  omit  entirely  the  re- 
ports for  counties  in  which  the  State  authorities  appear  to  be  unable 
to  enforce  the  law.  The  total  population  belonging  to  such  areas  is 
small,  however,  and  the  general  completeness  of  the  returns  for  certain 
states  may  not  be  materially  depressed  thereby. 

Eegistration  of  births  is  more  difficult  than  registration  of  deaths. 
This  is  proved  by  the  fact  that  after  many  years  of  experience  with  the 
operation  of  registration  laws  no  state  or  city  in  the  United  States 
claims  complete  birth  registration.  It  is  not  difficult  to  obtain  by 
enumeration  or  imperfect  registration  a  considerable  proportion  of  the 
births  that  occur  in  a  given  area.  Up  to  the  limit  of  one-half  or 
perhaps  two-thirds  of  the  actual  births  the  collection  of  births  may  be  as 
easy  as  or  even  easier  than  that  of  deaths.  But  such  returns  are  worth- 
less for  statistical  purposes,  however  useful  the  records  may  be   for 

^  Kentucky  and  Missouri  were  added  for  1911. 


878 


VITAL    STATISTICS 


legal  purpose?.  When  complete  returns  of  deaths  are  obtained  by  means 
of  that  essential  requirement  the  burial  permit  it  invariably  happens 
that  the  completeness  of  the  registration  of  births  does  not  rise  to  the 
level  attained  by  the  registration  of  deaths.  Consequently,  it  was  not 
possible  to  establish  a  registration  area  for  births  as  early  as  that  for 
deaths  (1880),  and  the  tentative  birth  registration  area  established  for 
1908  includes  a  much  smaller  rej)orting  population  than  the  death 
registration  area.  The  following  table  shows  the  births  and  birth  rates 
for  this  area,  which  represents  about  one-fourth  of  the  aggregate  popu- 
lation of  continental  United  States : 


Year 

Estimated  Midyear 
Population 

Birtha  (exclusive  of 
stillbirths) 

Birth  Rate  per 
1,000  Population 

1908 

1909 

1910 

21,296,119 
21,759,262 
22,222,404 

547,665 
543,185 
555,486 

25.7 
25.0 
25.0 

The  figures  for  1910  are  provisional,  but  approximately  complete; 
that  is,  so  far  as  the  registration  returns  are  accurate  for  the  areas  in- 
cluded. These  are  the  six  New  England  states,  Pennsylvania,  Michigan, 
the  District  of  Columbia,  and  New  York  City. 

Collection  of  Vital  Statistics. — The  vital  statistics  of  greatest  im- 
portance to  the  sanitary  administration,  namely,  those  of  births  and 
deaths,  must  be  collected  under  a  registration  law.  The  births  and 
deaths  must  be  registered  immediately  or  very  soon  after  their  occur- 
rence, or  some  will  be  omitted  and  the  records  and  statistics  will  be 
inaccurate.  For  a  long  time  the  movement  for  better  legislation  with 
respect  to  vital  statistics  in  the  United  States  proceeded  without  any 
general  direction  and  supervision,  and  as  a  result  of  the  lack  of  a  definite 
policy  and  understanding  of  the  necessary  provisions  of  an  adequate 
registration  law  many  bills  were  presented  to  State  legislatures,  and 
some  of  them  were  given  effect  as  laws,  that  were  predestined  to  failure 
in  practical  operation.^  Some  of  these  laws,  as,  for  example,  the  recent 
Tennessee  enactment,  may  prove  to  be  of  service  in  preparing  the  way 
for  better  laws,  but  others  stand  in  the  path  of  progress  and  remain 
obstacles  to  effective  legislation. 

About  1902  the  question  of  the  improvement  of  registration  legisla- 
tion was  taken  up  in  a  practical  way  by  a  special  committee  of  the 
American  Public  Health  Association  and,  in  conjunction  with  the 
Bureau  of  the  Census,  a  circular  was  issued  in  which  certain  essential 
principles  were  defined  as  necessary,  according  to  American  experience, 
for  successful  results  in  the  registration  of  deaths.     The  committee  and 

*An  improved  law  was  recently  enacted  in  Tennessee,  which  will  soon  be 
effective. 


COLLECTION    OF    VITAL    STATISTICS 


879 


the  Bureau  of  the  Census  did  not  go  so  far  as  to  define  the  require- 
ments for  successful  birth  registration  because  there  was,  in  fact,  no 
complete  birth  registration  in  the  United  States  upon  which  to  base 
their  recommendations — nor  to  draft  bills  embodying  those  require- 
ments. It  seemed  to  be  a  distinct  step  in  advance  to  point  out  some 
solid  basis,  however  limited,  which  would  serve  as  a  foundation  upon 
which  to  build  better  laws. 

Later  a  bill  was  drafted  for  the  registration  of  deaths,  and  subse- 
quently, in  order  to  carry  out  the  desire  expressed  by  Congress  for  co- 
operation by  the  state  authorities  in  the  more  effective  registration  of 
births  and  deaths,  drafts  of  a  bill  for  the  registration  of  births  and  for 
the  registration  of  both  births  and  deaths  were  prepared. 

The  essential  principles  upon  which  these  drafts  were  based,  having 
stood  the  test  of  practical  criticism  in  the  construction  and  administra- 
tion of  registration  laws,  were  adopted  as  "Eules  of  Statistical  Practice" 
by  the  American  Public  Health  Association.  The  requirements  for 
effective  registration  of  births  and  deaths  may  be  compared  by  means 
of  the  following  tabular  statement : 

Necessary  Peovisions  foe  the  Eegisteation  of  Deaths  and  Births 


DEATHS 

1.  Deaths  must  be  registered  imme- 

diately after  their  oceurrenee. 

2.  Certitieates  of  death  should  be  re- 

quired. 

3.  Burial   or  ee^ioval  permits   are 

essential  to  the  enforcement  of 
the  law. 

4.  Efficient  local  registrars  are  neces- 

sary. 

5.  The    responsibility   for  reporting 

deaths  to  the  local  registrars 
should  be  fixed. 

6.  The     central     registration     office 

should  have  full  control  of  the 
local  machinery,  and  its  rules 
should  have  the  effect  of  law. 

7.  The    transmission    and    preserva- 

tion of  returns  should  be  pro- 
vided for. 

8.  Penalties  should  be  pro^dded  and 

enforced. 


BmTHS 

1.  Births   must  be  registered  imme- 

diately after  their  occurrence. 

2.  Certificates  of  birth  should  be  re- 

quired. 

3.  Some   check  is  necessary  to  se- 

cure enforcement  of  the  law. 

4.  Efficient  local  registrars  are  nec- 

essary. 

5.  The   responsibility   for   reporting 

births  to  the  local  registrars 
should  be  fixed. 

6.  The     central     registration     office 

should  have  full  control  of  the 
local  machinery,  and  its  rules 
should  have  the  effect  of  law. 

7.  The  transmission  and  preservation 

of  returns  should  be  pro\ided 
for. 

8.  Penalties  should  be  provided  and 

enforced. 


The   Model   Eegistration"   Law. — IMuch   of   the   improvement  in 
methods  of  registering  vital  statistics  in  the  United  States  has  been 


880  VITAL    STATISTICS 

due  to  the  active  interest  and  cooperation  of  the  medical  profession.  The 
American  Medical  Association  has  taken  an  especially  prominent  part 
in  this  movement  and  has  circulated  literature  upon  the  subject  and 
copies  of  what  is  known  as  the  "model  bill"  or  "model  law"  drafted 
in  accordance  with  the  essential  requirements  of  registration.  The 
following  is  an  extract  from  the  American  Medical  Association  Bulletin, 
September  15,  1910: 

"In  The  Bulletin  for  January  15,  1909,  appeared  the  model  l)ill 
drafted  by  a  committee  appointed  at  the  1906  conference  on  medical 
legislation.  At  the  1907  conference  held  in  Chicago  in  December  of 
that  year  the  committee  submitted  its  report,  which  consisted  of  a 
model  bill  patterned,  in  the  main,  after  the  Pennsylvania  law.  This 
bill  has  since  been  endorsed  by  the  Census  Department  of  the  United 
States  Government,  the  Section  on  Hygiene  and  Sanitary  Science,  and 
the  House  of  Delegates  of  the  American  Medical  Association,  the  Ameri- 
can Public  Health  Association,  the  American  Statistical  Association,  the 
Committee  on  Uniform  Laws  of  the  American  Bar  Association,  the 
American  Association  for  the  Study  and  Prevention  of  Infant  Mor- 
tality, and  the  general  officers  of  the  American  Federation  of  Labor, 
as  well  as  by  numerous  local  and  state  associations  and  other  public 
health  bodies.  It  can  therefore  be  said  to  represent  the  combined 
judgment  of  all  those  interested  in  securing  better  vital  statistics  legis- 
lation and  registration  for  the  United  States,  as  well  as  tlie  knowledge 
and  experience  of  those  best  qualified  to  speak  with  authority  on  the 
subject.  As  this  bill  has  been  carefully  prepared,  it  is  especially  urged 
that  no  changes  be  made  in  its  verbiage  or  provisions,  as  apparently  slight 
and  unimportant  changes  may  seriously  affect  the  operation  of  the  law." 

The  best  general  idea  of  the  mode  of  operation  of  a  modern  registra- 
tion law  may  be  obtained  by  a  careful  examination  of  the  provisions  of 
this  bill  ^  or  of  the  state  laws,  e.  g.,  those  of  Pennsylvania,  Ohio,  Mis- 
souri, Kentucky,  that  are  practically  identical  with  it. 

The  administration  of  a  registration  law  is  a  matter  of  infinite 
detail.  The  State  Registrar  must  be  in- constant  touch  with  his  corps 
of  local  registrars  scattered  throughout  the  state.  It  is  extremely  im- 
portant in  the  organization  of  the  system  that  there  shall  be  a  suffi- 
cient number  of  such  local  registrars  and  so  distributed  in  each  county 
that  there  will  be  no  great  difficulty  in  the  carrying  out  of  the  essential 
requirement  of  the  law,  namely,  that  all  deaths  shall  be  registered  and 

'Copies  of  this  bill  can  be  obtained  from  Dr.  Frederick  R.  Green,  Secretary, 
Council  on  Health  and  Public  Instruction  of  the  American  Medical  Association, 
535  Dearborn  Avenue,  Chicago.  The  bill  has  been  again  revised  by  a  special 
committee  composed  of  representatives  of  the  American  Medical  Association, 
American  Public  Health  Association,  American  Bar  Association,  and  Bureau  of 
the  Census,  with  aid  from  the  committee  on  vital  and  penal  statistics  of  the 
conference  of  Commissioners  on  Uniform  State  Laws  and  the  Children  's  Bureau. 


COLLECTIOISr    OF    VITAL    STATISTICS  881 

permits  for  burial  or  removal  issued  in  advance  of  any  disposition  of 
the  body.  If  this  requirement  is  neglected  in  a  few  cases  the  number  of 
violations  will  increase  and  soon  the  law  will  become  a  dead  letter. 
But  in  sparsely  settled  districts  the  difficulty  of  communication  may  be 
very  great  at  times,  hence  some  provision  is  necessary  as  a  safety-valve, 
especially  during  the  first  trial  of  such  a  law  in  a  state  in  which  no 
formalities  have  been  observed  relative  to  the  burial  of  the  dead.  A 
plan  whereby  any  registrar  may  issue  a  provisional  permit  for  deaths 
not  occurring  in  his  district,  afterwards  seeing  that  the  certificate  is 
filed  with  the  proper  local  registrar  in  time  for  his  monthly  return,  or  a 
special  exemption  for  sparsely  settled  districts,  with  requirement  of  re- 
turn within  ten  days  after  death,  may  be  employed.  A  practical  diffi- 
culty is  found  in  rural  districts  where  no  undertakers  are  employed, 
interments  being  made  by  the  relatives  or  friends  of  decedents.  To 
secure  complete  returns  under  such  circumstances  will  require  long  and 
patient  education  of  the  people  as  to  the  importance  of  such  records, 
and  also  some  check  upon  the  sale  of  coffins  by  furniture  dealers,  so 
that  a  blank  certificate  and  a  copy  of  the  law  requiring  registration  may 
accompany  each  one  sold. 

The  enforcement  of  the  law  for  the  registration  of  births  is  espe- 
cially difficult  because  there  is  no  ready  check,  analogous  to  the  burial 
permit  for  deaths,  which  will  indicate  at  once  that  the  law  has  not 
been  complied  with.  In  some  cities  special  enumerations  of  births  are 
made  and  the  registration  records  are  supplemented  by  the  additional 
births  thus  found.  Local  registrars  may  also  "keep  tab"  on  births  re- 
ported in  the  press  or  otherwise  coming  to  their  knowledge,  but  prob- 
ably the  most  effective  method  is  the  systematic  examination  of  all 
returns  of  deaths  of  infants  under  one  year  of  age  in  order  to  see  whether 
their  births  were  duly  registered.  For  example,  it  is  stated  in  the 
weekly  vital  statistics  report  for  the  District  of  Columbia.,  October  14, 
1911,  that  "there  were  14  District-born  babies  who  died  during  the 
week  covered  by  this  report.  Of  these  11  had  their  births  reported. 
The  other  three  are  now  being  investigated  with  a  view  to  ascertain,  if 
possible,  who  is  responsible  for  the  failure  to  make  these 
reports."  In  New  York  City,  beginning  in  October,  1910,  many 
physicians  and  midwives  were  prosecuted  and  fined  for  failing  to  register 
births.  A  state  inspector  is  constantly  employed  in  Pennsylvania  and 
has  been  instrumental  in  securing  many  thousands  of  births  that  would 
otherwise  not  have  been  recorded.  Success  depends  mainly  upon  the  en- 
forcement of  the  law  by  means  of  the  penalties  provided  therein,  and 
if  the  law  is  not  enforced  it  does  little  good  to  ascertain  the  fact  of 
violation  and  receive  the  more  or  less  hackneyed  excuses  of  the  delin- 
quents. So  much  injury  is  done  to  the  legal  and  personal  interests  of 
children  and  their  parents  by  the  unjustifiable  neglect  of   physicians 


882  VITAL    STATISTICS 

and  midwives  who  are  charged  with  the  duty  of  reporting  births  that 
it  would  seem  that  public  sentiment  should  demand  rigorous  enforce- 
ment of  registration  laws. 

The  compensation  of  physicians  and  midwives  for  the  reporting  of 
births  is  not  provided  for  in  the  model  law  recommended  by  the 
American  Medical  Association.  This  may  perhaps  be  taken  as  an  ex- 
pression of  medical  opinion  in  general  throughout  the  country,  but  in 
some  localities  the  sentiment  of  the  profession  is  urgent  for  a  small  fee, 
to  be  paid  out  of  the  county  funds.  The  Michigan  birth  registration  law 
of  1905,  originally  with  no  provision  for  fee,  was  amended  in  1907  to 
give  a  compensation  of  fifty  cents  to  the  physician  or  midwife  for  re- 
porting each  birth.  The  Kentucky  act  of  1909  provides  a  fee  of  twenty- 
five  cents  to  physician  or  midwife  for  births  and  of  twenty-five  cents 
to  the  physician  for  making  out  a  certificate  of  cause  of  death.  So  far 
no  provisions  for  fees  to  the  undertakers,  upon  whom  the  chief  burden 
of  filing  certificates  of  death  is  imposed,  has  been  provided  in  any 
registration  law.  Some  of  the  authorities  in  charge  of  the  most  pro- 
gressive state  systems  believe  that  a  fee  to  the  physician  or  midwife 
for  birth  or  death  registration  is  not  only  unnecessary  but  harmful,  so 
far  as  securing  complete  returns  is  concerned.  Physicians  may  suppose, 
in  a  given  case  of  neglect  to  register  a  birth,  that  if  the  fee  is  not  paid 
the  omission  is  excused.  The  payment  of  a  fee  would  have  no  detri- 
mental influence,  and  might  perhaps  with  some  individuals  smooth  the 
course  of  registration,  provided  it  were  understood,  and  the  law  ex- 
pressly stated,  that  the  failure  to  receive  compensation  on  account  of 
delayed  or  incomplete  returns  should  not  interfere  with  the  prosecution 
of  every  such  case  and  the  recovery  of  the  penalty  provided  by  the  law. 
The  work  of  a  registration  office,  in  addition  to  the  responsibility 
for  the  thorough  and  uniform  enforcement  of  the  registration  law  and 
the  proper  preservation,  binding,  and  indexing  of  the  records,  is  really 
a  continuous  statistical  investigation  and  should  be  conducted  throughout 
with  direct  reference  to  the  statistical  data  which  it  is  purposed  to  show. 
The  chief  processes  of  such  an  investigation  may  be  summarized  as 
follows : 

(1)  Planning  the  investigation,  which  includes  the  preparation  of 
the  schedules  or  forms  used  for  the  "returns" — the  technical  term  de- 
fining the  filled  out  blanks  or  reports  which  are  received  at  the  statisti- 
cal office  as  the  result  of  the  inquiry. 

(2)  Scrutiny  and  correction  of  the  returns.  The  thoroughness  with 
which  this  is  done  obviously  depends  upon  the  time  at  the  disposal  of  the 
registrar  and  the  accessibility  and  reliability  of  the  persons  reporting. 

(3)  Hand  or  mechanical  compilation.  "Compilation"  may  com- 
prehend the  whole  process  of  obtaining  "statistics"  from  raw  material, 
but  is  here  restricted  to  the  technical  procedure  of  transferring  the  facts 


COLLECTION    OF    VITAL    STATISTICS  883 

reported  upon  the  schedules  to  the  "result  slips"  or  "compilation  blanks," 
either  directly  or  through  the  means  of  cards. 

(4)  Tabulation  or  the  making  of  statistical  tables  in  the  form  in 
which  they  are  to  appear  in  the  printed  reports.  This  is  the  only  form 
in  which  statistics  ordinarily  are  seen  by  the  persons  who  make  use  of 
statistical  reports,  and  it  is  the  chief  object  of  working  statisticians  to 
make  such  tables  clear  and  unmistakable  in  their  form  and  as  compre- 
hensive as  possible  under  the  limitations  of  time,  cost,  and  space. 

(5)  Finally,  an  analysis,  more  or  less  detailed,  by  the  compiler  of 
the  statistics  may  be  of  value,  as  he  is  presumably  best  qualified  to  point 
out  their  purpose,  the  conditions,  and  qualifications  that  must  be  con- 
sidered in  using  them,  and  to  indicate  generally  to  the  reader  the  rela- 
tions between  them  and  similar  data  for  the  same  or  other  localities. 

Eevised  United  States  Standard  Certificate  of  Death. — The 
certificate  of  death  constitutes  the  basic  schedule  for  the  collection  of 
mortality  statistics,  and  upon  the  uniformity  and  precision  with  which 
the  several  items  are  filled  out  depends  largely  the  comparability  of 
the  resulting  data.  Prior  to  1902  there  was  the  greatest  diversity  in 
this  respect  among  the  various  registration  states  and  cities.  A  standard 
form  was  recommended  in  that  year  by  the  committee  of  the  American 
Public  Health  Association,  approved  by  the  United  States  Census,  which 
employed  it  for  all  transcripts  of  deaths  received  from  registration 
sources,  and  came  into  very  extensive  use  by  state  and  city  offices.  In 
1909  this  form  was  revised  at  the  meeting  of  the  American  Public 
Health  Association  at  Eichmond  and  the  blank  now  known  as  the 
Eevised  United  States  Standard  Certificate  of  Death  was  recommended 
for  general  adoption  beginning  January  1,  1910.  The  blank  as  now  in 
use,  together  with  the  standard  instructions,  which  may  be  supple- 
mented by  local  offices,  intended  to  secure  more  precise  returns  with 
respect  to  cause  of  death  and  occupation,  is  given  on  pages  885  and  886. 
As  reproduced,  it  is  somewhat  changed  in  size.  Copies  of  the  certificate 
can  be  obtained  by  request  from  the  Bureau  of  Census,  Washington,  D.  C. 

The  twenty  items  upon  the  revised  U.  S.  standard  certificate  of 
death  may  be  divided  into  two  classes:  (1)  the  personal  items,  and  (2) 
the  statistical  items.  The  latter  in  their  various  combinations  constitute 
the  material  out  of  which  the  mortality  statistics  are  created.  For  con- 
venience they  are  indicated  by  italics  in  the  following  list : 

(1)  Place  of  Death  (Locality). — This  includes  identification  of  the 
country,  state,  county,  city,  or  other  minor  subdivisions  of  a  state,  and 
the  wards,  sanitary  sections,  blocks,  or  other  subdivisions  of  a  city. 

(2)  Full  name. — For  purposes  of  identification  only. 

(3)  Sex. — This  is  a  primary  distinction  which  ought  to  be  carried 
out  with  respect  to  nearly  all  statistical  compilations. 

(4)  Color  or  Race. — This  is  of  fundamental  importance  when  the 


884  VITAL    STATISTICS 

proportion  of  colored  population  is  large  (as  much  as  10  per  cent.), 
and  demands  separate  tables  or  subdivisions  of  all  tables  with  respect 
to  color  when  it  reaches  a  higher  limit  (say  25  per  cent.). 

(5)  Conjugal  or  Civil  Condition. — Of  little  value  except  when 
taken  in  connection  with  age  distribution.  Unrelated  tables  of  deaths 
by  conjugal  condition  are  worthless. 

(6)  Date  of  Birth. — This  may  be  considered  as  confirmatory  of 
the  statement  of  age  and  contributing  to  the  accuracy  of  the  latter 
statement.  WTien  so  used  it  is  negligible  as  a  statistical  item.  It  may, 
however,  be  selected  as  the  basis  of  Life  Tables,  according  to  certain 
methods  of  their  construction,  in  which  case  it  becomes  a  statistical 
item  of  special  importance. 

(7)  Age. — Perhaps  the  most  important  statistical  item  after  speci- 
fication of  the  year  and  place  of  death.  Exact  statement  of  ages  of  very 
young  decedents  may  be  essential  for  the  separation  of  stillbirths  from 
deaths.  Valuable  tables  for  public  health  purposes  could  be  constructed 
for  an  area  at  a  given  time  if  the  ages  at  death  were  the  only  data 
afforded ;  and  all  comparisons  that  do  not  take  age  distribution  into 
consideration  are  liable  to  be  misleading. 

(8)  Occupation. — A  correct  statement,  both  of  the  particular  kind 
of  work  and  of  the  industry,  is  necessary  for  satisfactory  statistics  of 
occupational  mortality — the  most  important  and  the  most  difficult  to 
obtain  of  any  mortality  statistics. 

(9)  Birthplace  (nativity). — Of  special  interest  in  the  United 
States,  where  the  large  proportion  of  foreign-born  makes  the  analysis  of 
mortality  by  nationality,  or  at  least  by  general  nativity,  of  importance. 

(10)  Name  of  Father. — Of  personal  and  legal  importance  only. 

(11)  Birthplace  of  father  (nativity  of  father). 

(12)  Maiden  Xame  of  Mother. — A  personal  particular  of  special 
value  for  genealogical  purposes. 

(13)  Birthplace  of  mother  (nativity  of  mother). 

Items  11  and  13,  sometimes  in  combination  as  Birthplace  of  Parents, 
are  useful  in  studying  infant  and  child  mortality. 

(14)  Statement  of  Informant. — Valuable  only  as  attesting  the 
knowledge  of  the  person  filling  out  the  blank  as  to  the  personal  par- 
ticulars. 

(15)  Signature  of  Eegistrar  and  Date  of  Filing. — Of  administra- 
tive value  only;  in  this  respect  important  in  order  to  show  that  the 
law  requiring  permits  in  advance  of  disposition  of  the  body  has  been 
duly  complied  with. 

(16)  Date  of  Death. — Statistical  reports  are  usually  for  calendar 
years,  and  hence  the  statement  of  year  is  of  primary  importance.  For 
monthly  or  weekly  bulletins  of  vital  statistics  the  basis  of  compilation 
may  be  either  the  deaths  that  actually  occurred  in  the  period  included  or 


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COLLECTION    OF    VITAL    STATISTICS  887 

those  that  were  reported  therein ;  in  the  latter  case  the  fact  that  reported 
deaths  are  employed  should  be  stated  in  order  to  explain  any  possible 
discrepancy  between  the  figures  thus  given  and  thus  presented  in  the 
annual  reports  based  upon  the  deaths  that  occurred. 

(17)  Cause  of  Death. — The  most  important  item  from  a  sanitary 
standpoint  and  one  that  is  most  difficult  to  obtain  with  precision.  The 
subdivision  of  this  item  into  (a)  primary  and  (b)  secondary  intro- 
duces special  difficulties  into  the  interpretation  of  the  returns  prior  to 
the  process  of  "classification"  according  to  the  schedule  of  the  Interna- 
tional List  of  Causes  of  Death,  and  yet  is  very  necessary  in  order  to 
give  a  correct  idea  of  the  true  causation. 

(18)  Length  of  Eesidence. — Not  at  present  employed  as  a  basis  of 
segregating  deaths  of  non-residents  or  recent  residents.  It  is  desirable 
that  this  should  be  done,  to  a  certain  extent,  at  least  in  the  way  of  form- 
ing supplementary  statements  to  be  used  in  connection  with  the  regular 
tables  that  include  all  deaths  that  occur  in  the  given  area.  Precise  rules 
will  be  necessary  for  this  purpose,  and  as  deaths  of  residents  occurring 
in  other  localities  cannot,  as  a  rule,  be  added,  statistics  of  mortality 
based  solely  upon  deaths  of  residents  will  be  understatements. 

(19)  Place  and  date  of  burial. 

(20)  Name  and  address  of  undertaker. 

There  are  thus  eleven  separate  statistical  items  or  elements  to  be 
considered  with  reference  to  each  death,  or,  taking  the  parent  nativity 
in  conjunction  instead  of  that  of  each  parent  separately,  there  are  ten 
statistical  elements  to  be  considered  in  the  compilation  of  deaths.  For 
a  given  area  and  unit  of  time  the  facts  concerning  the  other  eight 
statistical  elements  might  be  shown  independently  according  to  appro- 
priate schedules  for  each.  The  schedule  for  sex  is  simply  the  statement 
of  males  and  females,  or,  in  some  cases,  of  unknown  sex.  That  of  color, 
for  the  United  States,  usually  includes  a  statement  of  white,  black  (or 
negro),  Chinese,  Japanese,  and  Indian.  The  schedule  for  civil  condi- 
tion relates  to  the  number  returned  as  single  or  never  married,  married, 
widowed,  divorced,  and  unknown.  The  schedule  for  occupations  might 
consist  of  a  simple  alphabetical  list  of  occupations  returned  or  a  com- 
plete "classification,"  which  may  embrace  occupations  or  kinds  of  work 
in  the  ordinary  sense  and  also  the  nature  of  the  industries.  The 
schedule  for  cause  of  death  is  a  most  complicated  and  difficult  subject, 
although  the  purpose  is  simple,  namely,  that  of  giving  a  list  of  definite 
diseases  or  other  causes  from  which  deaths  occur. 

It  is  evident  that  great  variety  and  complexity  may  occur  in  the 
construction  of  statistical  tables  relating  to  deaths,  and  examination  of 
current  registration  reports  will  indicate  many  practical  difficulties  in 
obtaining  comparable  figures.  There  is  now  a  movement  in  the  direc- 
tion  of    greater   uniformity   in   the   preparation    of   tables,   with   per- 


888  VITAL    STATISTICS 

haps  the  recommendation  of  certain  standard  tables  to  be  presented  in 
all  reports,  and  it  is  liopcd  that  the  result  will  be  greater  simplicity, 
precision,  and  consequently  greater  usefulness  of  the  statistical  compila- 
tions. 

Population.— Knowledge  of  population  is  back  of  all  intelligent  study 
of  vital  statistics.  Indeed,  the  study  of  vital  statistics  or  the  registration 
returns  of  births,  marriages,  and  deaths  is  very  important  for  the  light 
that  it  throws  ujion  the  movement  of  population.  The  related  subjects 
are  included  in  the  general  scope  of  Demography,  a  term  not  yet  in 
familiar  English  use. 

We  may  consider  population  as  it  exists  at  a  particular  time  or  as 
it  changes  according  to  the  observed  laws  of  growth.  The  first  point 
of  view  is  that  afforded  by  the  census.  This  is  taken  on  a  certain  day, 
or,  as  is  the  practice  in  the  United  States,  as  0/  a  certain  day,  and 
presents  a  cross-section  of  the  conditions  then  existing.  Comparisons 
of  the  data  of  censuses  taken  at  regular  intervals  may  give  a  correct  idea 
of  the  general  movement  of  population,  but  cannot  go  into  the  detailed 
changes  that  occur  from  year  to  year. 

Vital  statistics  alone,  that  is  to  say,  the  data  as  to  the  occurrence  of 
certain  numbers  of  births,  deaths,  and  marriages  in  a  given  country, 
state,  or  city  during  a  certain  time,  are  of  little  significance  unless  linked 
to  a  statement  of  the  size  and  character  of  the  population  from  which 
they  were  derived.  For  the  same  area  and  under  the  tacit  assumption 
that  the  population  has  remained  substantially  constant  for  a  short 
2:)eriod  of  time,  valuable  comparisons  may  be  made  of  the  absolute  num- 
bers of  the  returns  for  successive  weeks,  months,  or  for  a  few  years. 
TThen  the  period  is  extended,  however,  such  comparisons  cease  to  be 
of  value  and  it  is  necessary  to  introduce  the  basic  element  of  population. 
This  is  done  by  the  computation  of  vital  rates. 

Vital  Rates. — The  comparison  of  vital  eventst  or  of  persons  affected 
by  vital  events,  is  usually  made  with  the  living  population  by  means  of 
rates  based  upon  groups  containing  a  definite  number  of  individuals. 
As  an  example,  the  table  for  England  and  Wales  is  selected  from  the 
International  Tables  presented  in  a  recent  report  (1909)  of  the  Eeg- 
istrar-General  of  England: 


COLLECTION    OF    VITAL    STATISTICS 


889 


England  and  Wales- 


-POPULATION,  MaRKIAGES^  BiRTHS,  AND  DEATHS, 

1881-1909 


Niimbers 

Proportion  per  1,000  of 

Deaths 

the  Population 

of 

Children 

Under  1 

Year 

Estimated 
Population 

Persons 

Births 

Deaths 

Persons 

Year  to 
1,000 

in  the  Middle 

Married 

Exclusive 

of  Still- 

Married 

Births 

Deaths 

Birtha 

of  Each  Year 

born 

1881* 

26,046,142 

394,580 

883,642 

491,935 

15.1 

33.9 

18.9 

130 

1882 

26,334,942 

408,810 

889,014 

516,654 

15.5 

33.8 

19.6 

141 

1883 

26,626,949 

412,768 

890,722 

522,997 

15.5 

33.5 

19.6 

137 

1884 

26,922,192 

408,602 

906,750 

530,828 

15.1 

33.6 

19.7 

147 

1885 

27,220,706 

395,490 

894,270 

522,750 

14.5 

32.9 

19.2 

138 

1886 

27,522,532 

392,142 

903,760 

537,276 

14.2 

32.8 

19.5 

149 

1887 

27,827,706 

401,036 

886,331 

530,758 

14.4 

31.9 

19.1 

145 

1888 

28,136,258 

407,642 

879,868 

510,971 

14.4 

31.2 

18.1 

136 

1889 

28,448,239 

427,730 

885,944 

518,353 

15.0 

31.1 

18.2 

144 

1890 

28,763,673 

466,056 

869,937 

562,248 

15.5 

30.2 

19.5 

151 

1891* 

29,085,819 

453,052 

914,157 

587,925 

15.6 

31.4 

20.2 

149 

1892 

29,421.392 

454,270 

897,957 

559,684 

15.4 

30.4 

19.0 

148 

1893 

29,760,842 

437,378 

914,572 

569,958 

14.7 

30.7 

19.2 

159 

1894 

30,104,201 

452,898 

890,289 

498,827 

15.0 

29.6 

16.6 

137 

1895 

30,451,528 

456,408 

922,291 

568,997 

15.0 

30.3 

18.7 

161 

1896 

30,802,858 

485,528 

915,331 

526,727 

15.7 

29.6 

17.1 

148 

1897 

31,158,245 

498,290 

921,683 

541,487 

16.0 

29.6 

17.4 

156 

1898 

31,517,725 

510,758 

923,165 

552,141 

16.2 

29.3 

17.5 

160 

1899 

31,881,365 

524,668 

928,646 

581,799 

16.5 

29.1 

18.2 

163 

1900 

32,249,187 

514,960 

927,062 

587,830 

16.0 

28.7 

18.2 

154 

1901* 

32,621,263 

518,800 

929,807 

551,585 

15.9 

28.5 

16.9 

151 

1902 

32,997,626 

523,500 

940,509 

535,538 

15.9 

28.5 

16.2 

133 

1903 

33,378,338 

522,206 

948,271 

514,628 

15.6 

28.4 

15.4 

132 

1904 

33,763,434 

515,712 

945,389 

549,784 

15.2 

27.9 

16.2 

145 

1905 

34,152,977 

521,484 

929,293 

520,031 

15.3 

27.2 

15.2 

128 

1906 

34,547,016 

540,076 

935,081 

531,281 

15.6 

27.1 

15.4 

132 

1907 

34,945,600 

552,842 

918,042 

524,221 

15.8 

26.3 

15.0 

118 

1908 

35,348,780 

529,880 

940,383 

520,456 

14.9 

26.5 

14.7 

120 

1909 

35,756,615 

521,088 

914.472 

518,003 

14.6 

25.6 

14.5 

109 

*  Census  year. 

The  columns  headed  "Proportion  per  1,000  of  the  Population"  con- 
tain the  death  rates.  These  are  crude,  general,  or  gross  annual  rates. 
All  rates  are  taken  as  annual  unless  otherwise  specified,  that  is  to  say, 
they  relate  to  the  vital  events  in  the  given  unit  of  area  (e.  g.,  England 
and  Wales)  for  the  unit  of  time  (one  year).  If  the  events  are  for 
greater  or  less  periods  of  time  than  one  year  they  should  be  reduced 
to  the  form  of  annual  rates  for  comparison. 

The  rates  are  called  crude,  general,  or  gross  rates  because  they  are 
based  upon  the  population  as  a  whole,  without  making  allowance  for 
the  effect  of  differences  in  age  and  sex  distribution.  Such  rates  are 
the  ordinary  rates  presented  in  all  American  registration  reports,  and 
form  the  first  step  in  the  comparative  study  of  the  vital  statistics  of 
different  areas.  The  following  tables  show  the  crude  birth  rates,  death 
rates,  marriage  rates,  and  rates  of  natural  increase  of  population  for 
certain  foreign  countries  for  recent  years  and  periods  of  years : 


890 


VITAL    STATISTICS 


International  Vital  Statistics 
(From  the  Seventy-second  Annual  Report  of  the  Registrar-General  of  England,  1909) 


Quinquennial 

Period? 

Years 

Country 

1881- 
1885 

1880- 
1890 

1891- 
1895 

1896- 
1900 

1901- 
1905 

1906 

1907 

1908 

1909 

Persons  Married  per  1,000  Persons  Living 


Austria 

Belgium 

Bulgaria 

England  and  Wales . 

France 

Germany 

Holland 

Hungary 

Italy 

Japan 

New  South  Walea. . . 

New  Zealand 

Sweden 


15.8 
13.7 
17.9 
15.2 
15.0 
15.4 
14.3 
20.4 
16.1 


17.0 
13.6 
12.8 


15.5 
14.2 
17.4 
14.7 
14.4 
15.8 
14.0 
17.8 
15.5 
16.6 
14.9 
12.0 
12.2 


15.8 
15.1 
16.4 
15.1 
15.0 
15.9 
14.5 
18.0 
14.8 
17.0 
13.3 
12.2 
11.5 


16.2 
16.6 
10.6 
10.1 
15.1 
16,8 
14.9 
17.0 
14.3 
18.1 
13.9 
14.2 
12.2 


15.7 

16.1 

19.8 

15.6 

15. 

10. 


11.8 


15.8 
16.1 
19.1 
15.6 
15.6 
16.3 
14.9 
17.4 
15.5 
14.6 
15.3 
17.0 
12.3 


15.0 

15.3 

16.0 

15.6 

19.8 

17.7 

15.8 

14.9 

10.0 

16.1 

10.3 

15.9 

15.0 

14.4 

19.0 

18.2 

15.4 

16.6 

17.7 

18.7 

15.7 

15.9 

18.0 

18.0 

12.4 

12.2 

Crude  Birth  Rates  per  1,000  Persons  Living 


Austria 

Belgium 

Bulgaria 

England  and  AValcs . 

France 

Germany 

Holland 

Hungary 

Italy 

Japan 

New  South  Wales . . . 

New  Zealand 

Sweden  

United  States  i 


38.2 
30.7 
37.2 
33.5 
24.7 
37.0 
34.8 
44.6 
38.0 


37.7 
36.3 
29.4 


37.8 
29.3 
35.9 
31.4 
23.1 
36.5 
33.6 
43.7 
37.5 
28.5 
36.4 
31.2 
28.8 


37. 

28. 

37. 

30. 

22. 

36. 

32.9 

41.7 

36.0 

28.6 

32.9 

27.7 

27.4 


37.3 
28.9 
41.0 
29.3 
21.9 
36.0 
32.1 
39.4 
34.0 
31.1 
28.0 
25.7 
26.9 


35.6 
27.7 
40.6 
28.1 
21.2 
34.3 
31.5 
37.2 
32.6 
31.7 
26.7 
26.6 
26.1 


34.9 
25.7 
44.0 
27.1 
20.6 
33 . 1 
30.4 
36.0 
31.9 
28.9 
27.0 
27.1 
25.7 


33.8 
25.3 
43.6 
26.3 
19.7 
32.3 
30.0 
36.0 
31.5 
33.0 
27.1 
27.3 
25.5 


33.6 
24.9 
40.4 
26.5 
20.2 
32.1 
29.7 
36.3 
33.4 
33.9 
26.8 
27.4 
24.6 
25.7 


Crude  Death  Rates  per  1,000  Persons  Living 


Austria 

Belgium 

Bulgaria 

England  and  Wale.s 

France 

Germany 

Holland 

Hungary 

Italy 

Japan 

New  South  Whales 

New  Zealand 

Sweden 

United    States    (registration    area 
only) 


30.1 
20.6 
17.7 
19.4 
22  2 
25.3 
21.4 
33.1 
27.3 


15.7 
10.9 
17.5 


28.9 
20.2 
18,9 
18.9 
22.0 
24.4 
20.5 
32.1 
27.2 
20.6 
13.8 
9.9 
16.4 


27.9 
20.1 

27.8 
18.7 
22.3 
23.3 
19.6 
31.8 
25.5 
21.1 
12.8 
10.1 
16.6 


25.6 

18.1 
23.9 
17.7 
20.7 
21.2 
17.2 
27.9 
22.9 
20.7 
11.9 
9.6 
16.1 


24.2 
17.0 
22.5 
16.0 
19.6 
19.9 
16.0 
26.2 
21.9 
20.9 
11.2 
9.9 
15.5 

16.2 


22.4 
16.4 
22.3 
15.4 
19.9 
18.2 
14.8 
24.8 
20.8 
19.8 
9.9 
9.3 
14.4 


22.6 
15.7 
22.3 
15.0 
20.2 
18.0 
14.6 
25.2 
20.7 
20.9 
10.6 
10.9 
14.6 

16.0 


22.5 
16.5 
24.3 
14.7 
19.0 
18.1 
15.0 
24.8 
22 . 0 
21.0 
10.1 
9.5 
14.9 

14.8 


Natural  Increase  (Excess  of  Births  over  Deaths)  per  1,000  Persons  Living 


Austria 

Belgium 

Bulgaria 

England  and  Wales . 

France 

Germany 

Holland 

Hungary 

Italy 

Japan 

New  South  Wales. . . 

New  Zealand 

Sweden  


8.1 

8,9 

9.5 

11.7 

11.4 

12.5 

11.2 

11.2 

10.1 

9,1 

8.8 

10.8 

10.7 

9.3 

9.6 

8.4 

19.5 

17.0 

9.7 

17.1 

18.1 

21.7 

21.3 

16.1 

14.1 

12.5 

11.8 

11.6 

12.1 

11.7 

11.3 

11.8 

2.5 

1.1 

0.0 

1.2 

1.6 

0.7 

0.5 

1.2 

11.7 

12.1 

13.0 

14.8 

14.4 

14.9 

14.3 

14.0 

13.4 

13.1 

13.3 

14.9 

15.5 

15.6 

15.4 

14.4 

11.5 

11.6 

9.9 

11.5 

11.0 

11.2 

10.8 

11.5 

10.7 

10.3 

10.5 

11.1 

10.7 

11.1 

10.8 

10.8 

7.9 
22.6 

7.5 
20.1 

10.4 
16.1 

10.8 
15.5 

9.1 
17.1 

12.1 
16.5 

12.9 
16.7 

22.0 

25.4 

21.3 

17.6 

16.1 

16.7 

17.8 

16.4 

17.9 

11.9 

12.4 

10.8 

10.8 

10.6 

11.3 

10.9 

10.8 

1  For  provisional  registration  area  for  births  only;  this  was  established  for  the  first  time  for  1908 
and  is  much  smaller  than  the  registration  area  for  deaths. 

*  Including  77,283  deaths  in  the  earthquake  at  Messina  and  Roggio  (Dec.  28,  1908);  excluding 
these  deaths  the  death  rate  was  20.3. 


COLLECTION    OF    VITAL    STATISTICS  891 

The  data  for  the  United  States  have  been  added  to  the  rates  for  the 
conntries  given  in  the  International  Statistics,  and  relate  only  to  deaths 
in  the  registration  area  since  1900  and  to  births  in  the  provisional 
registration  area  established  for  1908,  The  latter  is  much  smaller  than 
the  death  registration  area,  the  returns  are  not  yet  fully  tested — it  is 
possible  that  certain  areas  included  do  not  really  record  as  high  a  pro- 
portion as  nine  out  of  every  ten  births  that  occur— and  hence  no  com- 
parison of  the  births  and  deaths  can  be  made  for  the  establishment  of 
the  rate  of  natural  increase  of  population  as  shown  for  the  other 
countries. 

To  proceed  with  the  examination  of  the  table  containing  the  vital 
statistics  of  England  and  Wales,  it  will  be  observed  that  the  careful 
qualification  is  made  for  both  births  and  deaths  that  the  statements  given 
are  "Exclusive  of  stillbirths."  This  follows  as  a  matter  of  course  in 
England,  where  stillbirths  are  not  registered,  exceist  under  local  pro- 
visions, but  in  many  countries,  and  especially  in  the  United  States,  it  is 
extremely  important  to  know,  in  examining  the  statistics  for  a  series 
of  years,  whether  stillbirths  were  or  were  not  counted  among  the  births 
and  among  the  deaths.  The  present  practice  is  to  exclude  them  from 
both,  so  that  the  term  "Births"  means  living  births  or  children  born 
alive,  and  "Deaths"  means  the  deaths  of  those  only  who  were  counted 
among  the  living  births.  Of  course  in  taking  the  difference  of  births  and 
deaths,  either  both  inclusive  or  both  exclusive  of  stillbirths,  the  amount 
of  natural  increase  is  not  affected. 

Persons  married,  or  twice  the  number  of  marriages,  is  usually  pre- 
ferred to  the  number  of  marriages  per  1,000,  although  the  latter  rate  is 
frequently  employed.  The  comparison  is  more  direct  with  the  persons 
forming  the  population. 

Lastly,  the  basis  of  all  the  rates  (except  the  rate  of  infantile  mor- 
tality in  the  last  column)  is  the  column  showing  the  estimated  popula- 
tion in  the  middle  of  each  year.  The  English  census  is  taken  about 
April  1  in  the  years  designated  by  an  asterisk  in  the  table.  Censuses  of 
various  countries  vary  greatly  in  the  precise  period  of  the  year  in 
which  they  are  taken,  hence  it  is  customary  to  prepare  midyear  esti- 
mates, even  for  census  years,  upon  which  to  base  the  vital  rates.  Of 
course,  all  intercensal  populations  must  be  estimated,  and  also  postcensal 
populations,  or  populations  of  years  following  the  year  of  the  last  census 
available.  The  years  1902-1909  are  postcensal  years,  but  as  soon  as 
the  census  of  1911  was  taken  new  estimates  of  population  can  be  in- 
terpolated for  the  years  between  1901  and  1911,  which  thus  become  in- 
tercensal years  as  considered  with  reference  to  the  last  enumeration 
of  population. 

The  computation  of  crude  vital  rates  is  very  simple,  the  practical  rule 
being  to  annex  three  ciphers  to  the  number  of  births  (exclusive  of  still- 


892  VITAL    STATISTICS 

births),  deaths  (exclusive  of  stillbirths),  stillbirths,  and  persons  married 
(twice  the  number  of  marriages),  and  divide  by  the  estimated  midyear 
population.  This  is  for  rates  per  1,000  of  mean  population,  and  rates 
per  1.000  are  the  generally  accepted  bases  of  comparison  and  usually  to 
be  understood  when  the  word  rate  is  used,  except  when  individual  causes 
are  referred  to.  It  is  unnecessary  to  carry  the  computation  beyond  two 
places  of  decimals  nor  to  express  the  result  further  than  to  tlie  first  deci- 
mal place,  although  it  is  not  unusual  to  express  the  second  decimal 
figure.  It  adds  nothing  to  precision  to  carry  the  quotient  out  at  great 
length.  The  death  rate  of  the  registration  area  of  the  United  States 
in  1910  was  15.0  per  1,000,  as  derived  from  a  midyear  population,  of 
53,843,890  persons  and  805,412  deaths.  This  is  Just  as  accurate  as  the 
statement  of  14.96  or  14.958  per  1,000.  It  is  customary  in  the  United 
States  to  express  death  rates  of  individual  causes  as  rates  per  100,000 
population,  chiefly  to  avoid  the  use  of  fractional  expressions.  Thus  a 
death  rate  from  typhoid  fever  of  41.9  per  100,000  seems  more  significant 
than  when  stated  as  a  rate  of  0.42  per  1,000.  Of  course,  the  two  ex- 
pressions are  quite  identical,  as  also  those  of  4.2  per  10,000,  and  419 
per  1,000,000. 

The  variety  of  ratios  employed  for  the  expression  of  mortality  rates 
is  needlessly  large,  and  it  would  be  desirable  to  limit  the  number.  As 
an  example  the  provisionally  estimated  population  of  England  and  Wales 
for  the  year  1909  was  35,756,615,  the  total  number  of  deaths  from  all 
causes  was  518,003,  and  the  number  of  deaths  from  diphtheria  was 
5,235.  The  relations  between  the  population  and  deaths  may  be  stated 
in  several  ways : 

Expressed  as                        All  Causes  Diphtheria 

Death  rate  per  million 14,487.  146. 

Death  rate  per  hundred  thousand ....     1,448.7  14.6 

Death  rate  per  ten  thousand 144.87  1.46 

Death  rate  per  thousand' 14.487  0.146 

Death  rate  per  hundred   (per  cent.)..            1.4487  0.0146 

Death  rate  per  ten  (never  used) 0.14487  0.00146 

Death  rate  per  unit 0.014487  0.000146 

If  the  rates  were  always  carried  out  as  above  it  would  be  easy  to 
convert  one  form  of  expression  into  any  other  by  shifting  the  position 
of  the  decimal  point  as  required.  The  death  rate  per  1,000  from  all 
causes  would  ordinarily  be  written  as  14.5  or  14.49.  The  Eegistrar- 
General's  reports  have  for  many  years  given  the  rates  for  individual 
causes  as  per  1,000,000,  without  fraction,  a  form  with  wliich  the  rate 
per  100,000,  with  fraction,  as  used  in  the  American  reports,  is  readily 
comparable  by  dropping  the  decimal.  Recently,  however,  some  English 
tables  have  employed  the  rate  per  1,000  for  individual  causes  (e.  g.,  diph- 
theria, 0.15),  a  method  which  has  the  advantage  of  bringing  the  rate 


COLLECTION^    OF    VITAL    STATISTICS  893 

for  each  disease  more  closely  into  touch  with  the  rate  for  all  causes.  It 
is  not  necessary  to  refer  to  the  reciprocal  expressions  obtained  by  dividing 
the  population  by  the  deaths,  since  the  use  of  these  is  practically  obsolete 
in  registration  reports.  They  have  the  disadvantage  that  changes  are 
not  readily  comparable  and  that  the  numbers  increase  as  the  mortality 
diminishes. 

All  rates  ordinarily  employed  in  registration  reports  are  central  death 
rates,  as  distinguished  by  the  actuary  from  rates  of  mortality  based 
upon  the  deaths  and  population  entering  upon  an  age  or  period,  except 
the  rate  of  infantile  mortality,  which  is  the  number  of  deaths  of  in- 
fants under  one  year  of  age  per  1,000  births,  not  per  1,000  population 
under  one  year  of  age. 

All  rates  are  also  customarily  stated  as  annual  rates,  although  for 
use  in  weekly  or  monthly  bulletins  they  may  be  computed  upon  returns 
that  include  only  a  portion  of  the  year.  The  assumption  is  made  that  if 
the  number  of  deaths  that  occurred  during  the  week  or  month  continued 
with  the  same  frequency  for  the  year  the  annual  rate  would  be  equal  to 
the  product  of  the  number  of  deaths  observed  in  the  period  into  the 
ratio  between  the  period  and  the  year,  divided  by  the  mean  population 
for  the  year.  Such  rates  are  ephemeral  and  usually  subject  to  the  limita- 
tions incident  to  the  use  of  small  numbers.  It  should  be  quite  sufficient 
to  multiply  the  deaths  in  a  week,  especially  if  the  reported  and  not  the 
actual  deaths,  by  52,  inasmuch  as  the  assumption  of  a  fixed  mean 
population  introduces  an  artificial  fiuctuation  into  the  series  of  weekly 
rates.  A  more  exact  relation  between  the  week  and  the  year  is  given  by 
the  multiplier  52.17747;  by  dividing  the  estimated  mean  population 
of  the  year  by  this  number  a  working  weekly  mean  population  is  ob- 
tained by  which  the  number  of  deaths  in  the  week  is  divided  directly 
to  give  the  weekly  rate  in  annual  form.  For  months  the  multipliers 
may  be  11.8,  12.2,  and  13  for  31-day,  30-day,  and  28-day  months, 
respectively.  Closer  approximations  may  be  used,  a  mean  monthly  popu- 
lation can  be  computed  for  each  month,  and  the  computation  of  rates  for 
individual  causes  may  be  facilitated  by  finding  the  rate  for  one  death 
and  multiplying  by  the  number  of  deaths  from  each  cause.  Too  much 
refinement  is  unnecessary,  as  the  monthly  rates  are  subject  to  a  con- 
siderable systematic  error  unless  graduated  monthly  estimates  of  popula- 
tion are  used  instead  of  the  estimated  population  in  the  middle  of  the 
year. 

Methods  of  Estimating  Population.— There  is  no  way  of  know- 
ing the  exact  population  of  a  country,  state,  or  city  except  by  actual 
enumeration,  and  this  can  be  done  only  for  the  year  of  the  census.  It 
is  understood,  of  course,  that  there  is  a  certain  margin  of  error  in  all 
census  enumerations,  no  matter  how  carefully  conducted.  This  is  not, 
as  a  rule,  sufficient  to  be  of  any  consequence,  but  in  the  statement  of 


894  VITAL    STATISTICS 

population  the  figures  below  thousands  have  no  significance  for  large 
areas  in  which  millions  of  population  are  involvecL  It  would  be  quite 
as  correct  to  take  the  mean  population  to  the  nearest  thousand  for  Eng- 
land and  AYales  in  1901  (32,621,000)  as  to  give  the  exact  number, 
based  upon  the  method  of  computation  applied  to  the  census  taken  on 
April  1,  1901  (32,527,843),  which  resulted  in  a  midyear  estimate  of 
32,621,263.  Indeed,  it  is  likely  that  even  the  thousands  are  uncertain, 
and  as  there  may  also  be  some  understatement  of  vital  events,  especially 
of  births  in  various  countries,  rates  are  not  always  entitled  to  absolute 
credence  to  the  ultimate  places  of  decimals  sometimes  employed.  All 
vital  rates  based  upon  estimated  populations  (and  practically  all  rates 
are  in  fact  so  based)  and  upon  registration  less  than  absolutely  com- 
plete are  to  be  considered  as  approximate  expressions,  and  not  as  per- 
fect statements  of  truth.  The  actual  errors,  as  a  rule,  are  probably 
slight,  counterbalancing  (as  in  the  slight  understatement,  both  of  popu- 
lation and  vital  events),  and  may  be  neglected  for  practical  purposes. 

Since  it  is  not  feasible  to  attempt  to  fix  exactly  the  population  for 
any  year  lying  between  two  censuses  or  following  the  latest  census,  the 
purpose  of  estimating  populations  for  non-census  years  is  to  afford  a 
reasonable  and  uniform  basis  whereby  the  vital  rates  of  a  country  and  its 
subdivisions  may  be  compared.  Laying  aside  the  method  of  keeping  an 
exact  account  of  the  excess  of  births  over  deaths  and  the  gain  or  loss 
from  migration,  which  is  not  generally  practicable,  the  chief  methods 
employed  for  this  purpose  are  those  known  as  the  (1)  geometrical  and 
the  (2)  arithmetical  methods. 

The  geometrical  method  assumes  a  constant  rate  of  increase  between 
census  years  or,  in  other  words,  that  the  amount  of  annual  increase  is 
in  proportion  to  the  population.  This  assumption  would  be  absolutely 
correct  for  a  population  dependent  entirely  upon  natural  increase  for 
its  growth  and  in  which  the  birth  rates  and  death  rates  remained  con- 
stant or  varied  in  the  same  direction  and  by  the  same  amount,  so  that 
their  difference  or  the  rate  of  natural  increase  for  each  year  was  the 
same.  Thus,  with  an  initial  population  of  100,000  persons,  an  initial 
birth  rate  of  30  per  1,000,  less  a  death  rate  of  20  per  1,000,  would  afford 
a  rate  of  natural  increase  of  10  per  1,000  (or  1  per  cent.)  per  annum. 
The  amount  of  increase  would  be  1,000  persons  and  the  population  of 
the  second  year  would  be  101,000.  With  the  same  rate  of  increase  the 
number  added  for  the  next  year  would  be  1,010,  not  1,000,  as  for  the 
year  before;  the  additional  10  persons  represent  the  rate  of  growth 
applied  to  the  increment  of  the  previous  year.  In  other  words,  it  is  a 
simple  application  of  the  principle  of  compound  interest  and,  the  rate 
of  growth  remaining  constant,  the  annual  increments  of  population  are 
a  little  larger  each  year. 

The  arithmetical  method  assumes  a  constant  amount  of  increase  be- 


COLLECTIO^T    OF    A^ITAL    STATISTICS  895 

tween  census  years.  The  total  increase  of  population  from  one  census  to 
the  next  is  divided  b}'  the  number  of  years  between  the  censuses,  and  the 
resulting  average  annual  increase  is  added  from  year  to  year  to  give  the 
estimated  populations.  For  example,  if  a  certain  pojDulation  increased 
from  100,000  persons  in  1900  to  110,000  persons  in  1910,  the  annual 
increment  of  population,  according  to  this  method,  would  be  1.000  and 
the  estimated  population  for  1901  would  be  101,000  persons;  for  1902 
it  would  be  102,000  persons,  and  so  on.  It  is  evident  that  as  the  same 
number  of  persons  is  added  each  year  to  a  constantly  increasing  basis  of 
population  the  annual  raie  of  increase  is  a  decreasing  one. 

The  choice  of  methods  for  a  given  area,  aside  from  considerations 
of  uniformity,  may  depend  upon  whether  the  population  is  in  fact  in- 
creasing at  a  uniform  rate  or  one  approximately  so.  If  the  annual  rates 
of  increase  are  uniform  the  decennial  rates  will  also  be  uniform  and 
the  geometrical  method  will  be  the  method  of  choice.  For  example, 
if  a  state  showed  an  increase  of  population  amounting  to  20  per  cent, 
from  1890  to  1900  and  a  like  increase  of  20  per  cent,  from  1900  to  1910 
it  is  reasonable  to  suppose  that  the  annual  rates  of  increase  are  the  same 
for  the  two  decades  ('^1.20  =  1.0181,  or  1.84  per  cent.).  With  an 
initial  population  of  100,000  in  1890  the  population  of  1900  would  be 
120,000,  and  that  of  1910  would  be  114,000.  Estimates  for  the  post- 
censal  years  following  1910  might  be  made  on  the  assumption  that  the 
rate  found  constant,  or  practically  so,  for  the  preceding  decades  would 
continue  as  the  rule  of  growth.  But  suppose  the  population  increased 
only  as  much  from  1900  to  1910  (20,000)  as  it  did  from  1890  to  1900. 
It  is  evident  that  the  rate  of  growth  has  decreased,  and  it  would  lead 
to  error  to  base  estimates  upon  the  hypothesis  of  a  constant  rate  when 
the  decennial  increments  plainly  indicate  a  diminishing  rate.  The  use 
of  equal  amounts  of  annual  increase  is  more  suitable  for  populations 
for  which  the  decennial  periods  do  not  show  fairly  constant  or  increasing 
percentages  of  growth. 

A  practical  illustration  of  the  method  of  computation  of  postcensal 
populations  according  to  each  method  may  be  made  for  England  and 
Wales  for  the  years  1902-1909.  The  estimates  are  based  on  the  popula- 
tions given  for  the  middle  of  the  preceding  census  3-ears  1891  and  1901,^ 
on  the  following  page. 

The  arithmetical  method  is  the  more  easily  applied.  The  difference 
between  the  populations  of  1891  and  1892  is  the  actual  increase  of 
population  during  the  decade,  and  one-tenth  of  the  difference  represents 
the  average  annual  increase  (353,544.4)  which  is  added  successively 
to  give  the  estimated  populations  of  the  postcensal  years.  The  fractional 
part  is  carried  only  for  convenience,  so  that  the  result  for  1911  will 
check  exactly  with  the  sum  of  the  population  of  1901  and  the  decennial 

^See  table  on  p.  896. 


896  VITAL    STATISTICS 

Geometrical  Arithmetical 

Year                                                 Method  Method 

Numhcr  Logarithm  Number 

1901 32,621 .263  7.5135008  32,261,263 

1891  29,085,819  7.4636813  29,085,819 

Difference 0.0498195  3,535,444 

One-tenth  of  dif- 
ference     0.0049819.5  353,544.4 

1901 (32,621,263)  7.5135008  32,621,263 

Add    0.0049819.5  353,544.4 

1902    (32,997,626)  7.5184827.5  32.974,807.4 

Add    0.0049819.5  353,544.4 

1903    (33,378,338)  7.5234647  33,328,351.8 

Add    0.0049819.5  353,544.4 

1904    (33,763,434)  7.5284466.5  33,681,896.2 

Add    0.0049819.5  353,544.4 

1905    (34,152,977)  7.5334286  34,035,440.6 

Add    0.0049819.5  353,544.4 

1906    (34,547,016)  7.5384105.5  34.388,985 

Add    0.0049819.5  353,544.4 

1907    (34,945,600)  7.5433925  34,742,529.4 

Add    0.0049819.5  353,544.4 

1908    (35,348,780)  7.5483744.5  35,096,073.8 

Add    0.0049819.5  353,544.4 

1909    (35,756,615)  7.5533564  35,449,618.2 

Add    0.0049819.5  353,544.4 

1910    (36,169,150)  7.5583383.5  35,803,162.6 

Add    0.0049819.5  353,544.4 

1911    (36,586,454)  7.5633203  36,156,707 

Check : 

1901    (32,621,263)  7.5135008  32,621,263 

Add    ( difference, 

1891-1901)....  0.0498195  3,535,444 

1911    7.5633203  36,156,707 

increase.  In  reading  the  estimated  population  for  each  year  the  fraction 
is  disregarded  if  less  than  0.4  and  added  as  an  additional  unit  if  0.5  or 
greater. 

The  geometrical  method  deals  with  the  logarithms,  and  not  with 

the  natural  numbers.     The  difference  is  the  logarithm  of  the  ratio  of 


COLLECTION    OF   VITAL    STATISTICS  897 

decennial  increase  of  population  from  1891  to  1901,  and  is  equivalent 
to  dividing  32,621,263  by  29,085,819,  or  1.1215,  which  may  be  otherwise 
stated  as  an  increase  of  12.15  per  cent,  during  the  decade.  One-tenth 
of  the  difference  of  the  logarithms  is  the  logarithm  of  the  rate  of  annual 
increase  which,  applied  year  by  year  in  the  manner  of  compound  in- 
terest, would  afford  the  ascertained  rate  of  decennial  increase.  It  is 
equivalent  to  extracting  the  tenth  root  of  the  ratio  of  decennial  increase, 
and  in  the  present  computation  amounts  to  1.0115,  or,  otherwise  stated, 
1.15  per  cent.  The  estimated  populations  (antilogarithms)  for  each 
year  are  taken  from  the  tables  of  logarithms  to  correspond  to  the  logar- 
ithms found  by  the  successive  addition  of  the  one-tenth  difference  to 
the  logarithm  of  the  population  of  the  last  census  year,  and  the  result 
is  checked  by  agreement  with  the  sum  of  this  logarithm  and  that  of  the 
difference  at  the  end  of  the  decade.  For  ordinary  purposes  and  for 
smaller  populations  it  is  not  necessary  to  use  seven-place  tables;  in 
fact,  four-place  tables  are  sufficiently  accurate  for  most  uses  of  vital 
statistics. 

The  final  test  of  a  series  of  estimated  populations  for  postcensal  years 
lies  in  its  agreement  with  the  results  of  the  following  census.  All  post- 
censal estimates  are  provisional  in  character,  and  should  be  revised  as 
soon  as  the  latest  census  gives  a  new  fixed  point  by  which  the  true 
nature  of  the  change  in  population  can  be  determined.  The  results  of 
the  English  census  of  1911  are  now  available  and  the  estimated  popula- 
tion for  the  middle  of  the  year  1911  as  given  in  the  Quarterly  Eeturn  of 
Marriages,  Births,  and  Deaths,  published  by  the  Eegistrar-General  for 
the  second  quarter  of  that  year,  was  36,168,750,  or  417,704  less  than 
the  population  estimated  according  to  the  rate  of  increase  between  1891 
and  1901.  The  excess  of  the  estimated  over  the  actual  population  was 
only  1.15  per  cent.,  a  proportion  so  small  when  we  consider  the  long 
period  between  the  censuses  that  it  confirms  the  general  value  of  the  rates 
computed  for  the  intercensal  years.  The  difference  between  the  actual 
and  the  arithmetically  estimated  population  was  even  less  ( — 12,043, 
or  — 0.33  per  cent.).  It  happens  that  the  arithmetical  method  would 
have  given  better  results  for  the  past  decade  in  this  particular  instance. 
The  geometiical  method  is  the  one  generally  employed  by  European  sta- 
tisticians, and  conformity  to  international  usage  is  an  important  point 
in  its  favor.  The  arithmetical  method  has  been  used  by  the  Bureau  of 
the  Census  for  the  registration  area  of  the  United  States  since  1900, 
after  a  comparative  study  which  showed  that  it  was  more  applicable  to 
the  observed  conditions  of  growth  of  American  populations.  The  re- 
sults of  the  last  census  indicate  some  areas,  however,  in  which  a  more 
uniform  rate  of  growth  from  decade  to  decade  suggests  that  the  geomet- 
rical rate  of  increase  is  becoming  more  consistent  with  conditions  of 
growth  in  the  United  States, 


898  VITAL    STATISTICS 

For  the  United  States  at  present  it  is  desirable  that  all  populations 
employed  in  state  and  city  registration  reports  and  bulletins  should  be 
estimated  according  to  the  arithmetical  method,  so  that  the  figures  will 
be  comparable  upon  a  uniform  basis  and  in  agreement  with  those  em- 
ployed by  the  Federal  census.  A  resolution  to  this  effect  was  adopted 
by  the  American  Public  Health  Association.  Where  the  geometrical 
method  is  preferred,  an  alternative  series  of  rates  should  be  presented. 
The  populations  estimated  by  the  latter  method  are  usually  greater  for 
post-censal  years,  so  that  a  very  considerable  reduction  in  the  apparent 
rates  may  occur  at  the  end  of  the  period.  For  intercensal  estimates,  on 
the  contrary,  the  populations  by  the  arithmetical  method  are  greater,  so 
that  the  rates  on  the  basis  of  the  geometrical  estimate  are  higher,  espe- 
cially for  the  middle  years  of  the  period.  The  arithmetical  method  has 
also  the  great  practical  advantage  that  estimates  made  for  the  sub- 
divisions and  the  whole  of  an  area  exactly  balance.  It  is  necessary  to 
use  it  even  when  the  general  principle  of  the  increase  in  geometrical 
progression  is  accepted.  Following  is  the  statement  of  the  method  actu- 
ally employed  in  the  Eegistrar-General's  reports : 

(1)  The  populations  of  the  whole  country  and  of  its  various  con- 
stituent portions  are  calculated  on  the  assumption  of  a  rate  of  increase 
in  arithmetical  progression  equal  in  each  case  to  that  obtaining  in  the 
previous  intercensal  period.  The  sum  of  the  populations  so  calculated 
for  parts  of  the  country  equals  that  of  the  whole.  [This  is  the  United 
States  Census  method.] 

(2)  The  population  of  the  whole  country  is  recalculated  on  the 
assumption  of  a  rate  of  increase  in  geometrical  progression  equal  to  that 
obtaining  in  the  preceding  intercensal  period. 

(3)  The  relation  between  the  arithmetical  and  geometrical  results 
so  obtained  for  the  whole  country  is  expressed  by  the  factor  resulting 
from  the  division  of  the  geometrical  progression  estimate  by  the  arith- 
metical. 

(4)  The  estimates  for  portions  of  the  country,  based  upon  the  as- 
sumption of  continued  increase  in  arithmetical  progression,  are  multi- 
plied by  the  above  factor.  The  sum  of  the  results  equals  the  estimate  for 
the  whole  country  by  geometrical  progression  obtained  in  stage  2. 

In  the  preceding  comparison  of  the  arithmetical  and  geometrical 
methods  of  estimating  population  as  applied,  to  England  and  Wales 
the  basic  populations  were  the  estimated  midyear  populations  of  1891 
and  1901.  These  midyear  populations  were  themselves  estimated  by  the 
geometric  method  from  the  census  figures  which  relate  to  a  date  about 
the  beginning  of  the  second  quarter  of  the  year.  In  the  United  States, 
as  the  dates  of  the  censuses  were  nearly  in  the  middle  of  the  year  (as 
of  June  1)  until  that  of  1910,  no  allowance  has  heretofore  been  made 
for  the  difference  between  the  date  of  enumeration  and  the  middle  of 


COLLECTION    OF    VITAL    STATISTICS 


899 


the  year.  Beginning  with  1910,  however,  such  an  allowance  has  been 
made  in  the  Census  mortality  statistics,  and  the  intercensal  populations 
for  the  preceding  intercensal  periods  have  been  recomputed  on  this 
basis,  without,  however,  -disturbing  established  rates  as  of  June  1  for 
census  years  prior  to  1910,  whether  state  or  federal.  The  method  em- 
ployed is  explained  in  the  Annual  Bulletin  on  Mortality  Statistics,  1909, 
the  example  taken  being  the  District  of  Columbia  (city  of  Washing- 
ton) : 


Year  and  Exact  Date  of  Census 
or  Estimate 

Method 

I 

Present 
Estimates 
Based  on 
Censuses 
of  June  1, 
1890,  and 

June  1, 
1900 

Method 
II 

Revised 
Estimates 
Based  on 
Census  of 

June  1, 
1900,  and 
Estimate 
for  June 

1,  1910 

Method 
III 

Revised 
Estimates 
Based  on 
Censuses 
of  June  1, 
1900,  and 
April  15, 
1910 

Method 
IV 

Revised 
Estimates 
Based  on 
Census  of 

June  1, 
1900,  and 
Estimate 

for  July 

1,  1910 

Method 
V 

Revised 
Estimates 
Based  on 
Estimates 

for  July 

1,   1900, 
and  July 

1,  1910 

1890  (June  1) 

*230,392 

235,225 
240,057 
244,890 
249,722 
254,555 
259,388 
264,220 
269,053 
273,885 
*278,718 

1891                        

1892    

1893                      

1894          

1895                     

1896        

1897                    

1898 

1899 

•278,718 

•278,718 

•278,718 

""  1  July  1,  estimated          

•279,160 

1901 

283,551 
288,383 
293,216 
298,048 
302,881 
307,714 
312,546 
317,379 
322,211 

284,019 
289,321 
294,622 
299,924 
305,225 
310,526 
315,828 
321,129 
326,431 

283,953 
289,188 
294,423 
299,658 
304,894 
310,129 
315,364 
320,599 
325,834 
•331,069 

284,064 
289,409 
294,755 
300,100 
305,446 
310,791 
316,137 
321,482 
326,828 

284,461 

1902 

289,763 

1903 

295,064 

1904 

300,365 

1905 

305,667 

1906 

310,968 

1907 

316,269 

1908 

321,570 

1909 

326,872 

•  (  April  15 

1910s  June  1,  estimated 

327,044 

•331,732 

•332,173 
337,519 
342,864 
348,210 
353,555 
358,901 
364,246 
369,592 
374,937 
380,283 

•332,173 

1911 

337,033 
342,335 
347,636 
352,938 
358,239 
363,540 
368,842 
374,143 
379,445 

336,304 
341,539 
346,774 
352,009 
357,245 
362,480 
367,715 
372,950 
378,185 
383,420 

337,474 

1912 

342,776 

1913 

348,077 

1914 

353,378 

1915 

358,680 

1916 

363,981 

1917 

369,282 

1918 

374,583 

1919 

379,885 

1920-<  June  1,  estimated 

375,370 

384,746 

385,628 

385,186 

"In  the  above  table  census  figures  are  printed  in  boldfaced  type  and 
the  average  annual  increase  in  each  column  is  taken  between  the  figures 
distinguished  by  asterisks  as  the  bases  for  the  estimated  populations. 

"Method  I  represents  the  method  of  estimating  population  used  up 
to  the  present  time.  The  enumerated  populations  for  the  census  years 
1890  and  1900,  both  taken  as  of  June  1,  are  used  as  the  bases.  The 
difference  between  these  populations,  divided  by  10,  represents  the 
average  annual  increase  from  June  1,   1890,  to  June   1,   1900.     This 


900  VITAL    STATISTICS 

difference,  added  successively  to  each  of  the  years  1891  to  1899,  gives 
the  estimated  population  for  each  year  of  the  intercensal  period,  and  the 
continued  addition  of  the  same  annual  average  to  the  years  1901  to 
1909  would  give  the  postcensal  estimates  on  the  same  basis,  that  for  the 
year  1910  (June  1)  being  327,044,  or  only  4,025  less  than  the  actual 
enumerated  population  (April  15),  331,069.  The  postcensal  estimates 
by  this  method  have  been  used  in  the  annual  reports  for  1901  to  1908, 
and  there  would  have  been  little  objection  to  using  the  estimate  for 
1909  in  this  individual  case,  but  for  some  areas  the  difference  might 
have  been  considerable  and  the  intercensal  estimate  for  1909,  based  upon 
the  census  of  1900  and  1910,  is  more  desirable. 

"Method  II  shows  how  the  estimates  as  of  June  1  might  be  supplied 
for  the  intercensal  period  1900  to  1910  and  continued  for  future  years 
by  estimating  the  population  as  of  June  1  from  the  enumeration  of 
April  15,  1910,  and  comparing  as  usual  with  the  former  census  of 
June  1,  1900. 

"Method  III  is  an  objectionable  one,  but  is  shown  because  registra- 
tion officials  may  attempt  perhaps  to  make  estimates  by  direct  compari- 
son of  the  population  as  enumerated  June  1,  1900,  and  April  15,  1910, 
without  regarding  the  differences  in  dates  of  enumeration.  While  it  is 
true  that  in  many  cities  population  resident  on  April  15  is  more  nearly 
the  correct  midyear  population  than  would  be  the  population  actually 
enumerated  as  of  July  1,  it  is  certain  that  for  the  country  as  a  whole 
considerable  growth  takes  place  between  April  15  and  the  middle  of 
the  year.  Consequently,  if  we  compare  an  enumeration  of  June  1, 
1900,  with  an  eniuneration  not  ten  years  later,  but  less  than  ten  years 
later  by  one  and  one-half  months,  it  is  evident  that  the  estimated 
population  on  this  basis  ten  years  subsequent,  or  for  1920,  would  be 
for  three  months  prior  to  June  1,  or  as  of  March  1. 

"Method  IV.  Another  method  would  be  to  obtain  the  midyear 
estimate  for  1910  and  compare  it  directly  with  the  enumeration  of 
June  1,  1900,  disregarding  the  differences  in  dates  for  the  intercensal 
period  1900  to  1910,  then  continuing  with  midyear  estimates.  This 
would  be  fairly  satisfactory,  although  it  would  seem  preferable  to  adopt 
the  plan  next  in  order. 

"Method  V,  which  has  been  adopted  by  the  Bureau  of  the  Census 
for  the  intercensal  estimates  from  1900,  or  from  the  date  of  the  latest 
state  census,  to  1910,  and  for  future  estimates  of  population  beginning 
with  1911,  is  the  midyear  estimate,  or  that  of  approximately  July  1. 
It  makes  necessary  a  slight  computation  before  using  the  actual  results 
of  enumeration  according  to  the  census  of  April  15,  1910,  but  the  esti- 
mated midyear  populations  for  1900  and  1910  once  having  been  ob- 
tained, the  subsequent  interpolations  or  extrapolations  are  very  simple. 
No  change  is  proposed  in  the  arithmetic  method,  or  that  of  the  average 


COLLECTION    OF    VITAL    STATISTICS  901 

annual  increase,  which  has  given  good  results  for  the  past  decade  and 
is  more  applicable  to  the  observed  method  of  growth  of  population  of 
this  country  than  the  geometric  method. 

"The  process  of  estimating  the  midyear  populations  for  1900  and 
1910  from  the  census  enumerations  as  of  June  1  and  April  15,  respec- 
tively, is  very  simj)le.  In  former  estimates,  when  each  census  was  of 
date  June  1,  the  interval  between  them  was  exactly  ten  years,  or  120 
months.  The  interval  between  the  census  of  June  1,  1900,  and  the 
census  of  April  15,  1910,  is  not  120  months,  but  only  118.5  months; 
dividing  the  observed  increase  of  population  for  a  given  area  by  118.5, 
the  average  monthly  increase  during  the  decade  is  obtained.  This 
monthly  increase  added  to  the  population  June  1,  1900,  gives  the  mid- 
year population  for  1900,  and  two  and  one-half  times  the  monthly  in- 
crease added  to  the  population  of  April  15,  1910,  gives  the  midyear 
population  for  1910.  One-tenth  of  the  difference  between -the  two  mid- 
year populations  is  then  added  successively  for  the  intercensal  years 
1900  to  1910  and  the  postcensal  years  beginning  with  1911.  Suitable 
allowance  must,  of  course,  be  made  for  changes  of  area." 

Specific  and  Corrected  Death.  Rates. — The  death  rates  heretofore 
considered  have  been  based  upon  the  comparison  of  total  deaths  or  the 
deaths  due  to  particular  causes  with  the  aggregate  population.  Each 
element  of  the  population  has  its  peculiar  relation  to  the  rate  of  mor- 
tality, and  therefore  for  exact  comparisons  the  constitution  of  the  popu- 
lation must  be  considered.  The  death  rate  of  males  per  1,000  male 
population  is  practically  always  higher  than  the  death  rate  of  females 
per  1,000  female  population;  for  England  and  Wales,  1909,  the  rates 
were  15.4  and  13.7,  respectively,  the  ratio  of  male  to  female  mortality 
being  112  per  cent.  Hence  a  state  or  country  with  a  relatively  greater 
proportion  of  female  population  than  another  will  normally  show  a  lower 
death  rate.  The  female  death  rate,  in  the  march  toward  lower  mortality 
which  has  been  the  characteristic  of  the  vital  statistics  of  the  past  few 
decades,  seems  to  lead  the  way  and  to  be  followed  after  an  interval  by 
the  male  death  rate. 

Color  or  race,  especially  in  the  United  States,  is  a  very  important 
element  of  population.  The  total  death  rate  of  the  registration  area  for 
the  census  yesiT  1900  being  17.8  per  1,000,  the  death  rate  of  the  white 
population  included  was  17.3,  and  that  of  the  colored  population  was 
29.6.  But  the  colored  population  was  entirely  urban,  so  that  the  com- 
parison is  somewhat  unfair,  because  the  death  rates  of  cities  are  usually 
found  to  be  higher  than  of  the  country.  Much  of  the  difference  between 
the  death  rates  of  the  white  and  colored  in  various  cities  may  be  due  to 
conditions  of  housing,  employment,  or  other  factors  not  dependent  at  all 
upon  essential  differences  in  the  race  relation  to  disease.  The  death  rates 
of  various  nationalities  vary  greatly.  The  death  rates  of  cities  having 
59 


902 


VITAL    STATISTICS 


large  proportions  of  foreign-born  population  living  under  insanitary  con- 
ditions, in  crowded  tenements,  or  otherwise  exposed  to  uni'avorahle  condi- 
tions, are  higher  than  those  of  cities  more  favorably  situated.  It  is 
unfair  to  compare  the  death  rates  of  the  white  population  alone  in  cer- 
tain cities  wnth  the  gross  death  rates  in  other  cities  without  considering 
that  the  colored  mortality  omitted  corresponds  to  the  mortality  of  a 
lal)oring  and  tenement  class  not  otherwise  re})resented.  It  is  desirable, 
however,  that  the  deaths  of  the  colored  should  ])e  segregated  from  those 
of  the  white,  with  distinction  as  to  whether  negro,  Indian,  Chinese,  or 
Japanese,  whenever  they  form  a  considerable  proportion  of  total  deaths, 
and  that  sej)arate  tables  by  sex  and  age  be  shown  therefor. 

One  of  the  most  important  factors  to  be  considered  in  comparing 
the  death  rates  of  various  areas  is  the  distribution  of  population  by  age. 
The  following  table  shows,  for  the  group  of  registration  states  as  consti- 
tuted in  1900,  the  percentages  of  population  and  deaths  at  each  decennial 
age  group  from  birth  to  the  end  of  life,  and  also  the  corresponding  data 
for  the  first  two  quinquennial  periods  of  age  and  for  the  first  year  of 
life,  with  the  specific  decdli  rates  for  each  age: 


Age 

Population 

Deaths 

Death   Rate 
per  1,000  Pop- 

Number 

Per  Cent. 

Number 

Per  Cent. 

ulation  of  the 
Same  Age 

All  ages 

19,960,742 

100.0 

343,217 

100.0 

17.2 

Under  1  year 

437,944 

2,072,797 

1,984,486 

4,057,643 

3,624,065 

3,745,605 

3,104,747 

2,261,283 

1,558,210 

977,227 

464,260 

118,651 

9,908 

39,143 

2.2 

10.4 

9.9 

20.3 

18.2 

18.8 

15.6 

11.3 

7.8 

4.9 

2.3 

0.6 

0.0 

0.2 

71,117 

103,529 

9,242 

112,771 

14,169 

27,546 

28,322 

27,152 

30,987 

37,556 

38,631 

21,471 

3,424 

1,188 

20,7 

30.2 

2.7 

32.9 

4.1 

8.0 

8.3 

7.9 

9.0 

10.9 

11.3 

6.3 

1.0 

0.3 

162.4 

Under  5  years 

49.9 

5  to  9  years 

4.7 

Under  10  years 

27.8 

10  to  19  years 

3.9 

20  to  29  years 

7.4 

30  to  39  years 

9.1 

40  to  49  years 

12.0 

50  to  59  vears  . . 

19.9 

60  to  69  years 

38.4 

70  to  79  years 

83.2 

80  to  89  years 

181.0 

90  years  and  over 

Unknown  age 

345.6 
30.4 

The  corrected  death  rate  known  as  the  "Index  of  mortality,"  which 
was  adopted  by  the  International  Statistical  Institute  in  1895  on  the 
basis  of  recommendations  made  by  Dr.  Josef  von  Korosi,  considers  only 
the  proportions  of  the  population  at  five  groups  of  ages,  and  a})plies  the 
specific  death  rates  at  these  ages  as  ascertained  for  each  country  or  state 
to  the  population  of  Sweden  at  the  census  of  1800.  the  distribution  of 
which  at  these  age  groups  per  1,000  is  known  as  the  "Standard  poi)ula- 
tion."    As  an  example,  the  computation  of  the  index  of  mortality  accord- 


COLLECTION    OF    VITAL    STATISTICS 


903 


ing  to  tMs  method  for  Xew  South  Wales  is  taken  from  the  Official  Year- 
Book  of  the  Commonwealth  of  Australia,  1911 : 


New  South  Wales 
Age  Groups 

Mean  Popu- 
lation, 1909, 
Distributed 
According 
to  Results 
of  Census 
of  1901 

Number 

of 

Deaths 

1909 

Number  of 
Deaths  per 

1,000  of 
Mean  Popu- 
lation, 1909, 

in  Each 
Age  Group 

Age  Distri- 
bution per 
1,000  of 
Standard 
Population 

Index 

of 

Mortality 

Persons  (all  ages) 

1,605,863 

15,810 

9.85 

1,000.0 

13.44 

Under  1  year 

1  to  19  j^ears 

20  to  39  years 

40,484 
704,050 
514,932 
256,586 

89,811 

3,234 
1,960 
2,251 
2,965 
5,400 

79.88 

2.78 

4.37 

11.56 

60.13 

25.5 
398.0 
269.6 
192.3 
114.6 

2.04 
1.11 
1  18 

40  to  59  years 

2.22 

60  3'ears  and  over 

6  89 

The  crude  death  rate  is  found  by  dividing  the  total  number  of  deaths 
in  the  year  (15,810)  by  the  estimated  midyear  population  (1,605,863), 
and  amounts  to  9.85  per  1,000.  "Wlien,  however,  the  deaths  at  the  five 
age-groups  are  divided  by  the  estimated  midyear  popidation  of  each  age- 
group  the  specific  death  rates  are  obtained  for  each  gxoup.  The  result 
of  such  specific  rates  for  a  population  having  the  constitution  of  New 
South  "Wales  is  indicated  b}^  the  crude  rate  already  obtained  (9.85), 
but  what  would  the  rate  have  been  if  applied  to  other  populations  of 
greater  or  less  favorable  age  constitution?  It  is  impracticable  to  com- 
pare New  South  Wales  with  every  other  country  or  state  individualh^, 
but  the  same  object  is  attained  by  reducing  New  South  Wales  and  any 
other  state  or  country  to  a  basis  of  comparison  by  means  of  a  selected 
population,  which  happened  to  be  that  of  Sweden  at  the  last  census 
prior  to  the  date  of  the  establishment  of  the  system.  So  a  t3qDical  thou- 
sand by  age  is  taken,  out  of  which  25.5  were  infants  under  one  year  of 
age.  The  ratio  to  total  population  is  small,  but  the  death  rate  (not 
infant  mortality)  of  this  group  is  high  (79.88  per  1,000  =  nearly  8  per 
cent.)  ;  consider  it  as  applied  to  a  population  of  only  25.5  persons  and 
as  a  result  or  contribution  to  the  mortality  of  the  typical  thousand  2.04 
deaths  would  occur  at  this  age.  (It  is  unfortunate  to  liave  to  speak 
of  fractional  deaths  in  this  connection,  but  we  are  considering  a  thousand 
typical  of  a  much  larger  actual  population.)  The  next  group,  1  to  19 
years,  has  the  lowest  death  rate,  but  the  largest  proportion  of  the 
standard  population.  Three  hundred  and  ninety-eight  persons,  with  a 
death  rate  of  only  2.78  per  1,000,  would  afford  only  1.11  deaths  to  the 
mortality  of  the  typical  thousand.  And  so  on,  noting  that  tlie  high  death 
rate  at  sixty  years  and  over  (60.13),  affecting  over  11  per  cent.  (111.6  per 
1,000)  of  the  standard  group,  contributes  over  half  of  the  total  deaths 
(6.89).     For  the  total  deaths  of  the  standard  thousand  are  of  course 


904  VITAL    STATISTICS 

obtained  by  adding  together  the  deaths  that  would  have  occurred  at 
each  age  period  if  the  several  specific  death  rates  at  those  periods  had 
been  such  as  actually  occurred  in  Xew  South  Wales  during  the  year 
1909.  This  corrected  death  rate  or  mortality  index  (13.44)  exceeds  the 
crude  rate  by  3.59  per  1,000,  or  nearly  four  points  of  mortality,  and 
shows  that  the  age  distribution  of  Xew  South  Wales  was  favorable  to 
that  extent  as  compared  to  the  age  distribution  of  the  population  of 
Sweden  in  1890.  And  so  the  rates  of  the  other  states  and  the  Common- 
wealth of  Australia  would  l)e  raised,  for  the  same  year  and  under  the 
^aiiie  assumption  of  identical  age  distributions  in  1909  and  1901,  as 
follows:  Victoria,  crude  rate  11.24.  corrected  rate  13.74;  Queensland, 
9.79  to  13.80;  South  Australia,  9.37  to  12.57;  Western  Australia,  9.93 
to  15.07;  Tasmania.  10.00  to  13.14;  and  the  Commonwealth  as  a  whole 
from  10.22  to  13.56.  Comparisons  with  other  countries  are  not  given 
in  the  report  and  do  not  seem  to  have  been  made  very  generally  accord- 
ing to  this  system. 

Any  other  country,  the  average  of  a  group  of  countries,  or  even  an 
arliitrary  age  distribution,  might  have  been  selected  as  a  basis  of  com- 
parison. In  point  of  fact  the  most  valuable  corrections  of  mortality 
data  for  both  age  and  sex.  together  with  the  most  extensive  list  of  inter- 
national comparisons,  have  been  made  in  the  annual  reports  of  the 
Eegistrar-General  of  England,  in  which  for  some  years  past  death  rat(.s 
corrected  according  to  the  age  and  sex  distribution  of  England  and 
Wales  in  1901  have  been  presented  for  the  leading  countries  of  the 
world,  together  with  tables  of  specific  death  rates  and  of  the  distribution 
of  the  population  of  each  country  by  sex  and  age  at  recent  censuses. 
The  results  for  tlie  aggregate  of  both  sexes,  together  with  corresponding 
crude  and  corrected  rates  for  the  registration  states  of  1900,  are  shown 
in  the  table  on  page  905. 

It  will  be  observed  that  for  the  group  of  registration  states  as 
constituted  in  1900  the  change  from  the  crude  to  the  corrected  figure 
is  but  a  slight  one.  and  the  actual  rate  is  practically  the  same  as  that  of 
England  and  Wales.  Some  of  the  states,  as,  for  example.  Maine,  have 
a  less  favorable  age  and  sex  constitution  of  the  population  than  that 
of  the  average,  as  a  result  of  which  the  rate  obtained  by  applying  the 
specific  death  rates  to  the  standard  population  is  considerably  less  than 
the  crude  rate.  The  death  rate  of  Sweden  corrected  on  the  English 
standard  population  shows  a  decrease  from  16.78  to  13.88,  or  nearly 
3  per  1,000.  The  death  rate  of  Xew  South  Wales  corrected  on  the 
English  standard  rose  from  11.72  to  13.10,  a  difference  of  1.38,  while 
the  correction  for  the  year  1909  upon  the  Swedish  population  of  1890 
as  a  standard  shows  an  increase  from  9.85  to  13.44,  or  3.59.  On  the 
whole  the  English  standard  would  seem  most  convenient  for  use  in 
the  United  States,  as  involving  less  change  in  the  size  of  the  rates,  but 


COLLECTIOX    OF    VITAL    STATISTICS 


905 


Mean  Annual  Crude  and  Corrected  Death  Rates  ^  per  1,000  Living  in  Eng- 
land   AND    Wales    and    in    Certain    European    Countries    and    British 
Colonies. 


Countries  (Arranged  in  Order  of  Their  Corrected 
Death  Rates — Persons) 


Deaths  to  1,000  Living 


Persons 

Corrected 

Crude 

Death  Rates 

Death  Rates 

28.61 

32.80 

26.53 

27.63 

24.87 

26.34 

23.12 

24.83 

20.92 

23.26 

20.23 

22.72 

19.70 

21.08 

19.52 

20.84 

19.12 

20.54 

17.61 

17.91 

17.50 

20.80 

17.16 

17.16 

16.86 

18.22 

16.78 

18.53 

16.59 

18.27 

15.83 

13.72 

15.40 

17.32 

13.88 

16.78 

13.63 

15.80 

13.29 

11.89 

13.10 

11.72 

13.08 

13.12 

11.73 

11.02 

11.44 

10.88 

10.80 

10.01 

17.04 

17.19 

17.37 

18.02 

24.36 

22.25 

14.37 

14.19 

14.85 

17.11 

18.13 

18.25 

13.90 

14.03 

16.31 

18.55 

18.20 

17.75 

18.26 

18.21 

20.87 

20.45 

13.80 

16.56 

Russia  (European)  (1896-8) 

Spain  (1900-02) 

Hungary  (1899-01) 

Austria  (1899-01) 

Bulgaria  (1899-01) 

Italy  (1900-02) 

Prussia  (1899-01) 

German  Empire  (1901) 

Finland  (1899-01) 

Scotland  (1900-02) 

France  (1900-02) 

England  and  Wales  (1900-02) 

Switzerland  (1899-01) 

Belgium  (1899-01) 

Ireland  (1900-02) 

Western  Australia  (1900-02) 

The  Netherlands  (1898-1900) 

Sweden  (1899-01) 

Denmark  (1900-02) 

Queensland  (1900-02) 

New  South  Wales  (1900-02) 

Victoria  (1900-02) 

South  Australia  (1900-02) 

Tasmania  (1900-02) 

New  Zealand  (1900-02) 

United  States  (registration  states,   1900) 

Connecticut 

District  of  Columbia 

Indiana 

Maine 

Massachusetts 

Michigan 

New  Hampshire 

New  Jersey 

New  York 

Rhode  Island 

Vermont 


1  The  corrected  death  rates  are  the  death  rates  at  all  ages  that  would  have  resulted  from  the  rates 
prevailing  at  the  various  age  groups  if  the  sex  and  age  constitution  of  the  populations  in  the  several 
countries  had  been  identical  with  that  of  the  population  of  England  and  Wales  as  enumerated  at  the 
Census  of  1901. 

2  Data  for  the  United  States  added  to  the  original  table. 

some  method  of  correction  should  be  emplo^-ed,  especially  for  the  com- 
parison of  the  death  rates  of  cities  with  widely  different  age  constitu- 
tion of  population,  as  otherwise  the  most  misleading  inferences  as  to 
comparative  healthfulness  may  be  drawn. 

Classification  of  Causes  of  Death.- — A  large  part  of  the  work  of  a 
registration  oiUce  consists  of  the  tabulation  of  the  causes  of  death,  and 
it  is  necessary,  for  the  sake  of  uniformity  and  comparability  of  the  re- 


906 


VITAL    STATISTICS 


suiting  statistics,  that  tliis  shall  be  done  according  to  certain  recognized 
methods.  The  selection  of  a  uniform  classification  is  the  first  essential, 
and  it  is  fortunate  that  we  arc  now  in  possession  of  a  system  which 
is  in  practical  use  in  a  large  numl)cr  of  countries.  The  International 
Classification  of  Causes  of  Death,  sometimes  known  as  the  "Bertillon 
System,"  from  the  name  of  the  distinguished  demographer,  Dr.  Jacques 
Bertillon,  who  rc])orted  it  to  the  International  Statistical  Institute  at 
Chicago  in  1893,  has  been  employed  by  the  U.  S.  Bureau  of  the  Census 
since  1900,  is  used  by  all  the  registration  states,  and  has  been  adopted 
by  Great  Britain  beginning  with  1911.  The  complete  list  of  countries 
using  it  may  be  found  in  the  report  of  the  International  Commission 
of  Eevision,  which  meets  every  ten  years  for  the  purpose  of  revising  it 
so  that  it  may  be  abreast  of  medical  progress.  The  last  revision  was 
made  in  Paris  in  1909.  A  Manual  of  the  International  List  has  been 
published  by  the  Census  Office  and  also  a  Physicians'  Pocket  Eeference, 
which  has  been  distributed  to  all  the  physicians  of  the  United  States 
so  that  they  may  aid  in  the  precise  statement  of  causes  of  death  and  so 
improve  the  quality  of  the  mortality  statistics  in  this  respect.  The  Belle- 
vue  Hospital  Xomenclature  of  Diseases  and  Conditions  has  also  been 
arranged  in  the  order  of  the  International  List,  so  that  it  is  now  avail- 
able for  use  by  hospitals  for  recording  and  statistical  purposes. 

The  use  of  a  classification,  or  statistical  list,  as  it  is  preferably  called, 
is  a  process  of  condensation  of  the  multitudinous  terms  employed  by  phy- 
sicians upon  certificates  of  death  to  a  uniform  list  of  fairly  precise  titles. 
It  is  unnecessary  to  present  the  International  List  in  full  in  this  work 
because  it  is  readily  available  in  the  official  statistical  reports  and  other 
publications  issued  by  the  Federal  and  state  authorities  and  by  England 
(after  1911)  and  other  countries.  As  an  example  the  "inclusions"  for 
typhoid  fever,  the  first  title  of  the  tabular  list,  may  be  shown  as  pre- 
sented in  the  Census  Manual  (1911)  : 

I— GENERAL  DISEASES. 

1.     Typhoid  Fever 


This   title  includes. 

Abdominal  fever 

typhoid 
typhus 

Abortive  typhoid 

Ambulant  typhoid 

Cerebral  typhoid 
typhus 

Continued  fever 

Enteric  fever 

Enterica 

Gastroenteric  fever 


Hemorrhagic  typhoid  fever 
Ileotyphus 

Intermittent  typhoid  fever 
Malignant  typhoid  fever 
Mountain  fever 
Paratyphoid  fever 
Paratyphus 
Posttyphoid  abscess 
Rheumatic  typhoid  fever 
Typhobilious  fever 
Typhoenteritis 
Typhogastric  fever 


COLLECTION   OF   VITAL  STATISTICS  907 

L    Typhoid  Fever  Continued 


This  title  includes: 
Typhoid  fever 

malaria 
meningitis 
stupor 
ulcer 


Typhomalaria 
Typhomalarial  fever 
Typhoperitonitis 
Typhus  (unqualified)^ 
abdominalis 


It  is  unfortunate  that  physicians,  in  reporting  causes  of  death,  should 
not  write  "t}^hoid  fever"  invariably,  and  no  other  expression,  when 
typhoid  fever  is  in  fact  the  cause  of  death.  The  difficulty  is  even  greater 
with  respect  to  many  other  causes,  as,  for  example,  acute  anterior  polio- 
myelitis and  cerebrospinal  fever  (epidemic  cerebrospinal  meningitis). 
The  Physicians'  Pocket  Eeference  contains  a  list  of  indefinite  and  un- 
desirable terms,  framed  by  the  Committee  on  jSTomenclature  of  the 
American  Medical  Association  in  conjunction  with  the  Government 
services  concerned,  and  there  is  a  prospect  of  a  further  reform  in  prac- 
tical medical  nomenclature.  The  selection  of  the  cause  of  death  for 
statistical  tabulation  when  two  or  more  causes  are  returned  upon  the 
certificates  is  important.  Variations  in  this  respect  may  affect  the  result- 
ing statistics  to  an  appreciable  degree.  Some  of  the  principles  em- 
ployed are  indicated  in  the  following  suggestions  for  the  preference  of 
jointly  returned  causes  of  death  as  given  in  the  Manual  of  the  Inter- 
national List  of  Causes  of  Death: 

"For  returns  upon  the  Standard  Certificate  of  Death,  and  especially 
for  those  returns  in  which  the  instructions  have  been  regarded  by  the 
reporting  physicians,  the  following  suggestions  for  classifying  may  be 
helpful : 

"1.  Select  the  primary  cause,  that  is,  the  real  or  underlying  cause  of 
death.     This  is  usually: 

"(a)    The  cause  first  in  order. 

"(b)  The  cause  of  longer  duration.  If  the  physician  writes  the  cause 
of  shorter  duration  first,  inquiry  may  be  made  whether  it  is  not  a  mere 
symptom,  complication,  or  terminal  condition. 

"(c)  The  cause  of  which  the  contributory  (secondary)  cause  is  a 
frequent  complication.  See  lists  of  'Frequent  complications'  under  the 
various  titles  of  the  Tabular  List. 

"(d)  The  physician  may  indicate  the  relation  of  the  causes  by 
words,  although  this  is  a  departure  from  the  way  in  which  the  blank  was 
intended  to  be  filled  out.     For  example,  'Bronchopneumonia  following 

^The  majority  of  deaths  returned  in  the  United  States  from  "typhus"  or 
"typhus  fever"  are  in  reality  from  typhoid  fever.  Deaths  properly  chargeable 
to  International  Title  No.  2  (Typhus  fever)  are  so  infrequent  in  this  country 
that  the  Bureau  of  the  Census  invariably  makes  an  effort  to  identify  each  as  a 
case  of  true  esanthematic  typhus.  If  no  additional  information  can  be  obtained, 
"typhus"  is  compiled  under    (1)    and  "typhus  fever"  under   (2). 


908  VITAL    STATISTICS 

measles'  (primary  cause  last)  or  'Measles  followed  hy  bronchopneu- 
monia' (primary  cause  first). 

"2.  If  the  relation  of  primary  and  secondary  is  not  clear,  prefer 
general  diseases,  and  especially  dangerous  infective  or  epidemic  diseases, 
to  local  diseases. 

"3.     Prefer  severe  or  usually  fatal  diseases  to  mild  diseases. 

"4.  Disregard  ill-defined  causes  (Class  XIV),  and  also  indefinite 
and  ill-defined  terms  (e.  g.,  'debility,'  'atrophy')  in  Classes  XI  and  XII 
that  are  referred,  for  certain  ages,  to  Class  XIV,  as  compared  with  defi- 
nite causes.  Neglect  mere  modes  of  death  (failure  of  heart  or  respira- 
tion) and  terminal  symptoms  or  conditions  (e.  g.,  hypostatic  congestion 
of  lungs). 

"5.  Select  homicide  and  suicide  in  preference  to  any  consequences, 
and  severe  accidental  injuries,  sufficient  in  themselves  to  cause  death, 
to  all  ordinary  consequences.  Tetanus  is  preferred  to  any  accidental 
injury,  and  erysipelas,  septicemia,  pyemia,  peritonitis,  etc.,  are  pre- 
ferred to  less  serious  accidental  injuries.  Prefer  definite  means  of  acci- 
dental injury  (e.g.,  railway  accident,  explosion  in  coal  mine,  etc.)  to 
vague  statements  or  statement  of  the  nature  of  the  injury  only  (e.  g., 
accident,  fracture  of  skull). 

"6.  Physical  diseases  (e.  g.,  tuberculosis  of  lungs,  dial)etes)  are  ])re- 
f erred  to  mental  diseases  as  causes  of  death  (e.  g.,  manic  depressive  psy- 
chosis), but  general  paralysis  of  the  insane  is  a  preferred  term. 

"7.  Prefer  puerperal  causes  except  when  a  serious  disease  (e.  g.,  can- 
cer, chronic  Bright's  disease)  was  the  independent  cause. 

"8.  Disregard  indefinite  terms  and  titles  generally  in  favor  of  definite 
terms  and  titles." 

References  to  Sources  and  General  Precautions  in  Use  of  Statistical 
Data. — All  figures  are  not  statistics  and,  as  a  rule,  for  serious  statistical 
studies  reference  should  be  made  to  the  original  sources  of  the  data 
as  found  usually  in  the  official  reports.  Every  sanitary  and  registration 
official,  as  well  as  all  students  of  comparative  statistics,  should  have 
access  to  the  annual  reports  of  the  Eegistrar-General  of  England  on 
births,  deaths,  and  marriages.  Besides  affording  examples  of  the  ex- 
tensive use  of  corrected  death  rates  for  a  population  with  vital  statistics 
very  similar  to  those  of  the  United  States  and  probably  more  generally 
comparable  to  those  of  this  country — if  we  possessed  them  in  as  full 
detail — than  those  of  any  other  nation,  the  Eegistrar-General's  reports 
present  each  year  valuable  tables  of  international  vital  statistics  pre- 
pared through  the  cooperation  of  the  official  registrars  of  practically  all 
countries  with  adequate  registration.  The  United  States  appeared  in 
this  collection  for  the  first  time  in  1909,  with  tables,  of  course,  relating 
only  to  the  registration  area  and  for  deaths  alone.  Another  publication 
of  the  Pegistrar-General,  the  "Annual  Summary  of  Marriages,  Births, 


GENERAL    PEECAUTIONS  909 

and  Deaths  in  England  and  Wales,  and  in  London,"  gives  death  rates 
of  many  cities  of  the  world  from  certain  important  diseases,  the  rates  of 
infantile  mortality,  etc. 

For  a  general  view  of  the  vital  statistics  of  the  world  the  Statistique 
Internationale  du  Mouvement  de  la  Population,  1905,  published  by  the 
French  Government  in  1907  under  the  direction  of  M.  Lucien  March, 
Director  of  the  General  Statistical  Bureau  of  France,  is  the  most  con- 
venient and  reliable  source  of  reference.  Even  though  the  extremely 
interesting  text  should  not  be  fully  available  to  English-speaking  per- 
sons, the  figTires  themselves,  most  carefully  verified  and  reduced  from 
official  reports,  are  in  that  universal  language  independent  of  the  limits 
of  nationality  that  constitutes  the  body  of  statistics.  Uniformly  esti- 
mated populations  afford  the  bases  of  vital  rates,  which  may  be  traced 
from  their  beginnings  in  Sweden  (1749)  and  Finland  (1750)  until 
the  present  time,  when  practically  all  civilized  countries  save  the  LTnited 
States  are  represented.  The  data  are  brought  down,  as  far  as  possible, 
to  1905,  so  that  rates  for  the  first  quinquennial  period  of  the  century 
(1901-1905)  are  available,  and  presumably  will  be  continued  as  soon 
as  the  official  reports  for  the  following  quinquennium  are  at  hand.  In 
this  connection  a  word  may  be  said  relative  to  the  foolish  preference 
sometimes  expressed  for  the  "latest  data."  Vital  statistics  carefully  re- 
corded and  tabulated  are  an  imperishable  possession,  and  for  many  pur- 
poses observations  made  several  years  before  the  date  of  use  are  just  as 
cogent  as  the  results  of  the  latest  year.  It  is  not  necessary  that  statistics 
should  be  "news"  to  be  useful;  and,  in  fact,  the  careful  preparation  of 
certain  kinds  of  vital  statistics  requires  that  the  reports  should  be  de- 
ferred until  the  material  has  been  carefully  digested.  For  example,  the 
Supplement  to  the  Sixty-fifth  Annual  Eeport  of  the  Eegistrar-General 
of  England  (1902),  containing  Life  Tables  and  statistics  of  occupational 
mortality  based  upon  the  returns  of  deaths  for  1891-1900,  was  not 
published  until  1907-08;  the  magnificent  German  Life  Tables  (Kaiser- 
lichen  Statistischen  Amte)  for  the  same  period  appeared  in  1910.  Of 
course,  annual  reports  may  be  issued  within  a  reasonable  time  after 
the  year  to  which  they  relate,  but  even  for  these,  as  a  rule,  more  time 
in  preparation  and  condensation  rather  than  hasty  publication  of  crude 
and  inaccurate  data  would  be  desirable.  For  immediate  use  monthly  and 
weekly  bulletins  may  give  all  essential  information  required. 

An  especially  valuable  compilation  for  city  registration  officials  is 
the  Statistique  Demographique  des  Grandes  Yilles  du  Monde,  1880-1909, 
published  for  the  Thirteenth  Session  of  the  International  Statistical 
Institute  at  The  Hague,  1911,  by  the  Municipal  Bureau  of  Statistics  of 
Amsterdam.  The  first  part  contains  data  for  European  cities,  and  is 
to  be  followed  by  a  volume  containing  data  for  other  great  cities  of 
the  world.    The  tables  relate  to  the  movement  of  population,  with  rates 


910  VITAL    STATISTICS 

for  persons  married,  births,  deaths,  and  natural  increase  of  population 
based  upon  populations  estimated  to  the  middle  of  each  year,  births  and 
stillbirths  by  legitimacy  and  sex,  deaths  of  infants  under  one  year  per 
100  live  births  of  the  year  preceding,  deaths  under  one  year  (in- 
cluding stillbirths)  per  100  total  births  (including  stillbirths)  of  the 
same  year,  and  deaths  and  death  rates  per  100,000  population  from 
scarlet  fever,  diphtheria  (including  croup),  whooping-cough,  typhoid 
fever,  pulmonary  phthisis,  and  cancer. 

For  the  mortality  statistics  of  the  United  States  recourse  will  first 
be  had  to  the  annual  reports  published  by  the  Bureau  of  the  Census. 
That  for  1909  presented  revised  rates  for  all  causes  and  individual 
causes  of  death  for  all  areas  (registration  states,  including  cities  of 
10,000  population  and  over,  rural  population  of  counties  exclusive  of 
such  cities,  and  registration  cities  in  non-registration  states)  for  each 
year  of  the  decennial  period  1900-1909.  Annual  reports  are  also  pub- 
lished by  various  states  and  cities,  and  in  some  of  these  are  presented 
standard  tables  containing  estimated  populations  and  rates  for  preceding 
years.  It  is  always  well  to  examine  the  series  of  estimates  for  assurance 
that  they  have  been  made  in  some  regular  and  systematic  manner,  which 
should  always  be  mentioned  in  connection  with  the  table,  as  rates  based 
upon  mere  guesses  or  reckless  estimates,  and  not  revised  and  corrected 
after  the  following  census  has  proved  them  to  be  incorrect,  may  be  found 
in  certain  reports.  In  general,  for  the  United  States  any  reports  or 
bulletins  that  present  rates  based  upon  less  than  the  total  number  of 
deaths  that  occurred  in  the  area  for  the  time  covered  should  be  discarded. 
Some  otfices  exclude  deaths  of  non-residents  according  to  the  arbitrary 
interpretation  of  this  term  by  the  local  official,  and  without  including 
deaths  of  residents  that  may  occur  elsewhere,  deaths  from  violence, 
deaths  of  infants  under  one  day  or  under  one  week  old,  etc.,  and  yet 
venture  to  compare  their  vitiated  rates  with  those  regularly  computed 
by  the  majority  of  American  offices  in  accordance  with  the  Eules  of 
Statistical  Practice  adopted  by  the  American  Public  Health  Association. 
The  reckless  haste  to  produce  a  low  death  rate  (in  mere  figures,  not 
facts)  has  led  to  all  sorts  of  unjustifiable  tampering  with  statistical 
returns. 


SECTION  X 
INDUSTRIAL  HYGIENE  AND  DISEASES  OF  OCCUPATION 

Industrial  hygiene  is  one  of  the  most  important  topics  in  pre- 
ventive medicine,  as  it  deals  with  the  health,  the  welfare,  and  the 
human  rights  of  the  vast  majority  of  the  population.  Industrial  hygiene 
is  a  subject  in  which  the  medical,  economic,  and  sociologic  aspects  are 
closely  interwoven,  and  it  requires  a  broad  grasp  and  intimate  knowl- 
edge of  the  conditions  to  avoid  the  dangers  and  correct  the  injustices  to 
which  workpeople  are  subjected.  The  questions  of  industrial  hygiene 
strike  at  the  very  root  of  our  social  fabric;  they  include  the  relation  of 
capital  and  labor,  and  the  relation  of  man  to  his  fellow  men.  The  man 
of  means  may,  to  a  large  extent,  select  not  only  the  place,  but  even 
the  character  of  his  employment.  He  can  choose  his  own  hours  of  work 
and  can  largely  control  his  environment  while  at  work,  so  far  as  it 
affects  his  health  and  comfort ;  he  can  purchase  fresh  air,  sunshine,  good 
food,  rest,  recreation,  and  other  conditions  that  make  for  health, 
longevity,  and  happiness.  The  employee  must  largely  accept  the  condi- 
tions as  he  finds  them  and  is  frequently  denied  many  advantages,  even 
necessities.  As  the  power  of  the  employee  is  limited,  he  needs  the 
assistance  of  the  state  to  correct  the  unreasonable  demands  which  capital 
has  ever  exacted  of  labor.  Legislators  should  champion  the  rights  of 
work-people,  especially  in  the  realm  of  industrial  hygiene.  Our  country 
has  been  negligent  in  this  regard  and  has  fallen  far  behind  England  and 
continental  countries.  The  situation  has  received  some  assistance  through 
organized  labor,  which  has  exerted  a  good  influence  in  limiting  the 
avarice  of  the  employer,  in  shortening  the  hours  of  work,  in  obtaining 
a  more  just  share  of  the  profits,  in  improving  sanitary  conditions,  and 
in  exacting  a  modicum  of  human  consideration.  Thus  when  the  stone 
masons  came  to  build  the  Hygienic  Laboratory  in  Washington  they 
refused  to  work  until  a  proper  shelter  and  other  reasonable  conveniences 
were  provided;  as  required  by  their  labor  union. 

Modern  conditions  have  brought  entirely  new  problems  into  industrial 
hygiene.  These  have  come  about  largely  through  the  development  of 
new  industries  and  the  invention  of  new  processes,  through  improved 
and  changed  methods  of  transportation,  and  through  specialization  and 

911 


912  INDUSTRIAL    HYGIENE 

crowding  in  cities  and  work  places,  tlirough  artificial  light,  through 
changing  relations  between  capital  and  labor,  and  the  intensive  and 
unrelenting  pressure  of  the  times.  Some  of  the  conditions  which  oppress 
the  workmen  are  brought  about  bv  the  greed  of  capital  and  disregard 
of  the  human  machine,  but  indifference,  carelessness,  and  ignorance  of 
the  workman  himself  are  responsible  for  many  avoidable  accidents  and 
preventable  maladies.  In  Eastman's  study  of  work  accidents  in  Pitts- 
burgh it  appeared  that,  out  of  410  fatal  accidents,  the  victim  or  his 
fellow  workers  were  responsible  in  188  cases  and  the  employer  in  147 
cases.  Despite  the  improvements  in  labor-saving  devices  the  human 
machine  will  ever  remain  the  most  vital  and  indispensable  machine  in 
the  production  of  wealth — at  the  same  time  it  is  the  most  delicate  and 
sensitive  machine.  Both  from  the  standpoint  of  humanity  and  the 
standpoint  of  economy  the  human  machine  deserves  greater  care  and 
consideration  than  any  other  mechanism  engaged  in  the  production  of 
wealth. 

There  are  especial  dangers  to  health  incident  to  certain  industries, 
such  as  liability  to  lead  poisoning  in  the  manufacture  of  white  lead; 
of  phossy  jaw  in  the  manufacture  of  matches  made  with  white  phos- 
phorus; of  caisson  disease  in  divers  and  those  who  work  in  compressed 
air ;  there  are  extra  hazards  to  life  and  limb  in  railroading,  mining,  and 
among  those  who  work  with  explosives;  there  is  a  particular  danger  to 
those  who  are  compelled  to  work  in  a  dusty  atmosphere,  more  so  if 
the  dust  is  of  an  irritating  or  poisonous  nature;  and  there  is  danger 
to  those  who  are  compelled  to  breathe  poisonous  fumes  such  as  carbon 
monoxid,  hydrogen,  sulphid,  mercury,  etc.  These  special  instances  repre- 
sent the  true  diseases  of  occupation.  There  are  many  other  influences, 
not  specifically  inherent  to  industry,  to  which  the  workman  is  often 
subjected  which  seriously  influence  health,  such  as  poor  ventilation,  lack 
of  cleanliness,  overcrowding,  excessive  hours,  improper  light,  fatigue, 
and  a  hundred  and  one  conditions  which  affect  the  health  and  the  effi- 
ciency of  the  workman.  These  examples  are  usually  considered  under 
industrial  hygiene.  Work  should  be  ennobling,  and  anything  whicli 
tends  to  degrade  it  is  morally  wrong. 

The  statistics  of  morbidity  and  mortality  in  relation  to  diseases  of 
occupation  need  careful  scrutiny,  especially  when  used  for  comparison. 
The  factors  which  enter  into  such  statistics  are  so  numerous  and  the 
conditions  so  variable  that  misleading  conclusions  are  common.  The 
workmen  come  and  go,  they  vary  very  much  in  physical  vigor  to  start 
with,  are  of  all  ages,  both  sexes,  many  nationalities,  arid  are  greatly 
influenced  l)y  home  conditions  and  by  the  character  of  their  recreation. 
Many  industries,  while  not  in  themselves  particularly  hazardous,  are 
rendered  so  through  intemperance  or  dissipation.  The  statistician  must 
be  careful  to  take  all  factors  into  account  that  bear  upon  the  subject. 


GENERAL    CONSIDEEATIONS 


913 


Some  industries  are  blamed  for  conditions  affecting  health  that  really 
are  due  to  the  insanitary  home"  conditions  and  bad  habits  of  the  in- 
dividual. 

In  recording  the  nature  of  a  man's  work  it  is  not  sufficient  simply  to 
state  that  he  is  a  laborer,  mechanic,  machinist,  mill  operator,  and  the 
like.  Such  information  is  frequently  of  no  more  value  to  the  student 
of  the  diseases  of  occupation  than  the  name  of  the  person  himself.  If 
the  person  is  a  blacksmith  or  works  with  heavy  metals  it  is  plain  that 


1-J 

1 

F 

Li 

-.,- 

Fig.  132. — Red  Oxid  of  Lead  and  Litharge  Being  Mixed  in  the  Manuf.^cture  of 
Storage  Batteries.  The  workman  is  wearing  a  respirator,  but  should  also  protect 
himself  with  long-wristed  gloves. 

he  works  under  a  severe  physical  strain.  If  he  is  a  sailor  upon  a  sailing 
ship  we  know  that  he  is  exposed  to  rough  weather  and  unusually  severe 
conditions,  whereas  if  he  is  a  sailor  upon  a  modern  passenger  steamship 
the  conditions  of  his  work  may  be  no  more  severe  than  those  of  the 
janitors  and  charmen  in  a  large  office  building.  If  he  is  in  finance  we 
may  be  sure  that  he  is  subject  to  severe  nervous  strain.  It  is  therefore 
not  sufficient  simply  to  give  the  name  of  the  trade,  but  detailed  inquiry 
should  be  made  into  the  nature  of  the  work  and  the  particular  condi- 
tions under  which  he  works. 


914  INDUSTRIAL    HYGIENE 

With  the  exception  of  phosphorus,  lead,  and  mercury  poisoninfj,  little, 
if  any,  investigations  of  value  have  been  made  in  this  country  into  the 
vast  question  of  industrial  poisoning.  That  careful  study  carried  out 
by  competent  authorities  is  urgently  needed  can  be  seen  from  the  follow- 
ing list  of  poisons  that  are  in  every-day  use  in  our  industries :  methyl 
alcohol,  ammonia,  anilin,  antimony,  arsenic,  arsenuretted  hydrogen  gas, 
benzol,  carbon  bisulphid,  carbon  monoxid,  chlorid  of  lime,  chlorin,  chro- 
mium, di-nitro-benzol,  formaldehyd.  mineral  acids,  manganese,  nitro- 
benzin,  nitrous  oxids,  picric  acid,  prussic  acid,  pyridin,  sulphuretted 
hydrogen,  and  many  more. 

Our  country  has  long  nursed  the  delusion  that  the  conditions  under 
which  our  workmen  operate  are  better  than  corresponding  conditions 
abroad.  Recent  investigations  have  shown  the  contrary  to  be  the  fact. 
Thus,  Dr.  Alice  Hamilton  discovered  25  cases  of  lead  poisoning  during 
one  year  in  a  "model"  Illinois  factory  employing  200  hands,  while  large 
English  white  lead  works  under  careful  supervision  frequently  show  not 
a  case  of  lead  poisoning  for  several  successive  years.  We  are  just  wak- 
ing up  to  the  seriousness  of  the  situation — 'the  first  American  Con- 
gress-on  Industrial  Diseases  met  in  June,  1910.^ 

Andrews  estimates  that  in  the  United  States  30,000  wage  earners 
are  killed  by  industrial  accidents  every  year,  and  that  at  least  500,000 
more  are  seriously  injured.  A  memorial  on  industrial  injuries  prepared 
by  a  committee  of  inspectors,  appointed  by  the  President  of  the  Asso- 
ciation for  Labor  Legislation,  states  that  there  are  probably  not  less  than 
13,000.000  cases  of  sickness  each  year  among  those  engaged  in  industrial 
employments.  The  money  lost  each  year  (for  those  who  find  dollars 
more  expressive  than  lives)  is  conservatively  calculated  at  nearly  three- 
fourths  of  a  billion  dollars.  At  least  one-fourth  of  this  painful  in- 
capacity for  work  and  consequent  economic  loss  can  be  prevented. 

The  diseases  of  occupation  refer  only  to  those  diseases  which  are 
contracted  because  of  the  occupation  and  which  would  not  have  been 
contracted  if  the  individual  had  not  engaged  in  that  particular  occupa- 
tion. i\Iost  of  the  diseases  of  occupation  are  due  to  poisonous  and  irri- 
tating gases,  vapors,  or  dust  to  which  work-people  are  exposed.  Special 
affections  are  sometimes  caused  by  exposure  to  high  temperatures,  ab- 
normal atmospheric  pressures,  and  other  unusual  conditions  peculiar  to 
some  occupations.  These  are  the  true  occupational  diseases.  In  addi- 
tion to  these  there  are  a  large  number  of  affections  caused  by  insanitary 
factory  or  office  surroundings,  such  as  overcrowding,  bad  air,  imperfect 
light,   lack   of  cleanliness,  improper  washing  or   toilet    facilities,   etc. 

^  The  Massachusetts  legislature  of  1904  took  the  first  step  in  this  country 
to  obtain  definite  scientific  data  on  the  subject  of  the  occupational  diseases. 
The  State  Board  of  Health  of  Massachusetts  made  an  investigation  into  the 
scientific  condition  of  factories,  workshops,  and  mercantile  establishments,  and 
published  its  first  report  on  the  subject  in  1907. 


FUNDAMENTAL    CONSIDEEATIONS  915 

When  disease  is  contracted  or  health  undermined  through  such  insanitary 
conditions  it  cannot  be  regarded  as  an  inherent  or  special  danger  of  a 
particular  occupation.  If  a  person  contracts  typhoid  fever  or  diphtheria 
through  the  use  of  a  common  drinking  cup  or  a  roller  towel  in  a  fac- 
tory, workshop,  or  oflEice  these  evidently  cannot  be  considered  occupa- 
tional diseases.  On  the  other  hand,  if  a  person  contracts  lead  poisoning 
because  he  is  required  to  carry  lead  bars  this  is  evidently  a  danger  in- 
herent to  his  occupation,  and  thus  becomes  a  true  disease  of  occupation. 
The  general  sanitary  and  hygienic  conditions  under  which  work  is  done 
are  comprised  under  the  term  "industrial  hygiene,"  while  the  maladies 
caused  by  exposure  to  poisonous  fumes,  dust,  or  other  special  dangers 
during  a  manufacturing  process  comprise  the  true  diseases  of  occupation. 
Industrial  hygiene,  from  the  standpoint  of  the  sanitarian,  is  simply  a 
special  application  of  our  general  knowledge  bearing  upon  the  health 
and  welfare  of  mankind.  Industrial  diseases,  on  the  other  hand,  re- 
quire a  special  study  as  to  their  causes,  symptoms,  and  modes  of  pre- 
vention. 

An  industry  may  be  a  nuisance  or  disturbance  to  the  community  as 
well  as  to  those  engaged  in  its  various  processes.  Thus  the  noise  of  a 
tack  factory  or  boiler  shop,  the  smells  from  glue  or  fertilizing  factories, 
or  the  fumes  from  smelting  or  chemical  works,  or  the  smoke  from  chim- 
neys or  locomotives,  wastes  from  tanneries,  paper  mills,  and  mines  do 
not  come  directly  in  the  chapter  of  industrial  hygiene  or  the  diseases  of 
occupation,  however  closely  related. 


SOME  FUNDAMENTAL  CONSIDERATIONS  IN  PREVENTION 

In  order  to  improve  the  hygienic  conditions  under  which  people 
work,  and  in  order  to  prevent  the  diseases  of  occupation,  five  funda- 
mental conditions  are  essential:  (1)  investigations;  (2)  laws;  (3)  fac- 
tory inspection;  (4)  penalties;  (5)  education.  It  is  self-evident  that 
before  anything  may  be  accomplished  a  careful  study  must  be  made  of 
the  facts.  These  investigations  must  include  not  only  scientific  studies, 
but  also  economic  and  sociological  factors.  Suitable  laws  are  necessary, 
for  it  has  been  found  in  practice  that  the  conditions  cannot  be  cor- 
rected by  an  appeal  to  voluntary  reform.  To  be  effective  the  laws 
must  provide  ample  ways  and  means  for  their  energetic  enforcement. 
A  systematic  factory  inspection  is  necessary  in  order  not  only  to  protect 
workpeople  against  the  preventable  diseases  of  occupation  and  to  cor- 
rect sanitary  defects,  but  also  to  enforce  the  laws  concerning  hours  of 
occupation,  child  labor  laws,  and  related  subjects.  These  laws  have 
little  force  unless  they  provide  a  penalty  both  against  the  employer  and 
the  employees.     Either   party  to  the   contract  should   be   held   legally 


91G  INDUSTRIAL    HYGIENE 

responsible  in  case  of  violation.  Finally,  education  directed  to  the 
emploj'er,  the  employee,  and  also  to  the  })ublic  at  large  is  necessary  to 
obtain  the  laws  and  maintain  the  standards. 

Hours  of  Work. — No  general  rule  can  be  laid  down  for  the  hours  of 
work,  which  may  vary  with  the  character  of  the  employment.  Thus 
the  hours  of  active  work  are  limited  by  a  smith  or  glass-blower,  a 
worker  in  a  caisson  or  mine,  a  locomotive  engineer,  and  other  occupa- 
tions necessitating  great  muscular  effort  or  intensive  concentration,  or 
exposure  to  unnatural  conditions.  Formerly  men  worked  at  the  quieter 
occupations  all  the  time  not  given  to  sleep;  now  the  day  is  better 
divided  into  eight  hours  of  work,  eight  hours  of  "re-creation,"  and 
eight  hours  of  sleep.  Hygienically,  it  is  important  to  have  one  full 
day's  rest  each  week.  It  cannot  be  maintained  from  the  medical  side 
that  working  longer  than  eight  hours  a  day  is  harmful  to  health,  but 
it  is  held  that  no  employer  has  the  right  to  utilize  the  greater  part  of  a 
man's  day  and  thus  deprive  him  of  the  leisure  to  which  he,  as  a  human 
being,  is  entitled.  Since  his  whole  nature  has  to  be  developed,  time 
must  be  given  for  the  intellectual,  moral,  and  physical  welfare  of  man, 
which  cannot  take  place  if  the  hours  of  employment  are  too  long,  the 
work  too  hard,  or  of  a  grinding  nature.  The  hours  of  work  depend 
somewhat  upon  the  physical  exertion  required  and  also  upon  the 
nervous  tension.  The  Saturday  half  holidays,  especially  during  the 
heated  term;  a  vacation  period,  and  a  tendency  to  increase  the  number 
of  holidays  are  all  signs  of  social  improvement  which  make  for  health 
and  happiness. 

Fatigue. — Economic  engineers  find  that  it  pays  to  give  employees 
a  rest  at  stated  intervals  and  to  guard  the  conditions,  surrounding 
workers,  so  that  they  are  neither  molested  nor  interrupted,  that  the 
light  and  other  factors  are  agreeable,  and  the  sanitary  surroundings 
good.  Work  and  rest  must  be  judiciously  alternated.  Efficiency  ceases 
when  fatigue  begins.  The  danger  to  the  workman  himself,  as  well  as 
to  others,  is  now  recognized  from  a  tired  brain,  tired  nerves,  and  tired 
muscles.  Accidents  are  especially  prone  to  happen  to  workmen  who 
are  tired.  Thus  most  accidents  in  factories  happen  as  the  day  wears  on. 
The  effect  of  fatigue  on  the  occurrence  of  accidents  is  graphically  shown 
by  French  and  Belgian  statistics.  The  number  of  accidents  increases 
progressively  during  the  morning  hours,  drops  after  the  noon  inter- 
mission, and  then  rises  from  hour  to  hour  until  the  end  of  the  working 
day,  affording  a  practical  illustration  of  Helmholtz's  experiments  in 
attention  fatigue.  Fatigue  is  not  only  dangerous  to  the  workman  him- 
self, but  sometimes  to  others-;  thus  the  overwrought  and  tired-out  train 
dispatcher  may  send  trains  into  collision.  Further,  fatigue  of  certain 
nerves  and  muscles  may  result  in  definite  symptoms  such  as  writers' 
cramp,    or   more   general   manifestations   such    as   nervous  prostration. 


FUNDAMENTAL  CONSIDEEATIONS 


917 


Typewriters,  telegraph  operators,  and  others  suffer  from  these  occupa- 
tional neuroses. 

Next  to  fatigue,  nervous  tension  and  worry  are  very  wearing,  and 
when  combined  become  especially  harmful.  Diabetes  prevails  among 
engine  drivers  to  a  considerable  extent.  Worry,  hurry,  and  a  high 
nervous  tension  are  recognized  as  a  frequent  predisposing  cause  of  ill 
health  or  breakdown  in  all  walks  of  life,  including  the  so-called  higher 
professions. 


FiQ.  133. 


-An  Effective  Dust-removing  System  in  the  Boot-and-Shoe  Industry. 
Edge  trimming.      (Mass.  State  Board  of  Health.) 


Children. — The  first  factory  act  in  this  country  was  passed  by  the 
state  of  New  York  in  1886.  By  this  act  no  child  under  13  years  of  age 
was  allowed  to  work  in  factories.  Since  then  the  minimum  has  been 
raised  to  14.  The  injustice  to  the  child  and  the  consequence  upon  its 
health  and  development  of  subjecting  it  to  the  monotony  and  grind 
of  factory  life  are  too  evident  to  need  emphasis.  Eecently  it  has  been 
claimed  that  in  certain  districts,  as,  for  example,  the  mill  district  of  our 
southland,  the  children  are  better  off  in  a  good  textile  mill  of  modern 
construction  than  they  are  living  under  the  insanitary  conditions  of  their 
homes.  It  would  be  just  as  logical  to  state  that  they  would  improve  in 
60 


918  INDUSTRIAL    HYGIENE 

healtli  if  removed  to  a  prison  or  almshouse.  The  child  of  to-day  is  the 
citizen  of  to-morrow  and  his  liealth  and  development  are  the  most  im- 
portant assets  of  the  state.  In  Germany  children  under  12  are  not  al- 
lowed to  work  in  factories ;  between  12  and  14  they  are  not  allowed  more 
than  6  hours  per  day,  and  between  14  and  16  not  more  than  10  hours 
per  day.  Further,  they  are  not  allowed  to  begin  work  eariier  than  5.30 
a.  m.  nor  work  later  than  8.30  p.  m.,  and  one  hour  is  required  for  dinner. 
Children  are  not  allowed  at  all  in  certain  dangerous  trades,  as  coal 
mines,  etc.  In  this  country  child  labor  is  legally  prohibited  in  factories, 
upon  the  stage,  and  other  undesirable  places  in  many  of  the  states :  the 
question  with  us  is  somewhat  complicated  on  account  of  the  industrial 
competition  between  the  states.  The  regulation  of  child  labor  and  com- 
pulsory education  are  too  important  for  longer  delay.  There  are  cer- 
tain occupations  in  which  minors  under  no  circumstance  sliould  be  per- 
mitted to  engage.  This  includes  the  dangerous  trades  in  which  there  is 
liability  to  accident  and  the  trades  in  which  there  is  danger  to  health  on 
account  of  irritating  dust  or  poisonous  fumes.  There  are  also  certain 
occupations,  such  as  messenger  boys  at  night,  which  should  be  entirely 
prohibited  by  law  on  account  of  the  exposure  to  temptation. 

Women. — Women  are  physiologically  not  capable  of  doing  the  same 
work  as  men,  especially  during  the  period  of  maternity.  Further,  several 
days  each  month  women  are  more  or  less  incapacitated  for  most  kinds  of 
work  on  account  of  menstruation.  Pregnant  women  should  not  work 
for  several  weeks  before  labor,  and  after  labor  not  until  the  uterus  has 
undergone  involution,  which  is  a  matter  of  another  month.  In  Switzer- 
land the  law  requires  a  total  of  8  weeks  before  and  after  labor.  This  is 
a  wise  law  which  all  enlightened  countries  should  accept.  Justice  de- 
mands that  women  should  be  given  full  pay  during  this  time,  which  is 
of  such  great  moment  to  her  own  health  and  that  of  her  offspring.  Mr. 
Brandeis  successfully  defended  the  constitutionality  of  the  ten-hour 
law  for  women  in  Oregon.  The  brief  submitted  by  this  eminent  jurist 
in  a  similar  action  before  the  Illinois  Supreme  Court  ^  should  be  read  by 
those  interested  in  this  subject.  The  primary  object  of  this  brief  is  to 
show  that  the  demands  of  public  health  require  legal  restrictions  in  the 
work  of  women  because  of  the  peculiar  importance  to  the  community  of 
the  health  of  mothers.  The  effect  of  overwork  on  the  different  organs 
is  reviewed,  also  the  effect  of  night  work,  of  prolonged  standing  on  the 
feet,  of  foot-power  machinery,  and  of  the  speeding  up  required  by  the 
"piece-work  system."  The  general  literature  upon  fatigue  and  overwork 
is  reviewed. 

The  effect  of  overwork  upon  fecundity  and  upon  infant  mortality  is 

*  Brandeis.  Louis  D.,  assisted  by  Goldmark,  Josephine :  Brief  and  Argument 
for  Appellants.  In  the  Supreme  Court  of  the  State  of  Illinois,  December  term, 
1909. 


FUNDAMENTAL    CONSIDERATIONS  919 

impressive.  Broggi  states  that  of  172,365  Italian  women  between  the 
ages  of  fifteen  and  fifty-four  years  who  were  employed  in  industrial  oc- 
cupations the  average  child-bearing  coefficient  was  only  about  one-third 
of  the  general  fertility  of  Italian  women. 

It  is  now  a  well-established  fact  that  infant  mortality  is  shockingly 
high  among  the  babies  of  women  who  work  in  factories  and  mills.  It 
has  been  shown  in  Germany  and  England  that  infant  mortality  increases 
progressively  according  to  the  increase  in  the  proportion  of  women 
obliged  to  work  outside  of  their  homes,  and  this  is  true  even  if  the 
mother's  work  results  in  higher  standards  of  comfort  in  the  home.  The 
two -classical  demonstrations  of  this  rule  are  the  great  Lancashire  cotton 
famine  and  the  Siege  of  Paris,  during  both  of  which  crises  there  were 
loss  of  employment  and  great  privation.  In  spite  of  the  starvation  and 
the  increased  general  death-rate,  the  infants'  death  rate  fell  in  Paris 
actually  to  40  per  cent,  simply  because  the  women,  being  out  of  work, 
were  obliged  themselves  to  nurse  and  care  for  their  children.  The  infant 
mortality  in  industrial  centers  such  as  Fall  Eiver,  Lowell,  and  Lawrence, 
in  Massachusetts,  which  are  mill  towns,  is  twice  as  high  as  similar 
towns  without  many  factories  and  no  overcrowding. 

It  is  plainly  the  duty  of  the  nation  to  restrict  the  hours  of  work  of 
women  and  also  prohibit  their  employment  in  certain  industries  known 
to  be  particularly  hazardous  to  the  sex.  Saleswomen  should  be  provided 
with  seats  in  shops  so  as  to  avoid  the  ill  effects  of  prolonged  standing, 
they  should  have  one  or  two  days  each  month  for  rest  during  the 
menstrual  period,  and  should  be  protected  against  undue  strain  and 
fatigue,  \\1iile  women's  work  may  be  regulated  in  the  industries  and 
the  hours  of  employment  may  be  limited  by  law,  there  can  be  no  law  to 
regulate  women's  work  in  the  household  which  is  "never  done."  Men 
have  still  to  learn  the  lesson  that  nervous  breakdown  and  the  results  of 
fatigue  are  as  harmful  in  women  who  overwork  in  the  home  as  in  those 
who  work  in  shops  and  factories.  The  long  hours  and  confining  work 
of  house  servants  sometimes  lead  to  anemia  and  other  troubles.  Cooks 
are  exposed  to  the  effects  of  excessive  heat  and  to  sudden  changes  of 
temperature.  Domestic  "servants"  as  a  class  supply  a  large  contingent  of 
patients  in  hospitals  and  out-clinics.  The  long  hours  and  insufficient 
sleeping  accommodations,  as  well  as  the  nature  of  the  work,  lead  to  ill 
health  which  may  in  part  account  for  the  disinclination  of  women  to 
accept  this  kind  of  service. 

Factory  Inspection. — There  is  no  longer  doubt  but  that  factory  in- 
spection is  necessary  as  a  protection  to  the  workman.  An  efficient  sys- 
tem requires  a  good  comprehensive  basic  law  and  a  capable  corps  of  in- 
spectors. The  inspectors  should  be  thoroughly  familiar  with  the  law  and 
with  the  processes  of  manufacture  and  also  with  the  problems  of  pre- 
ventive  medicine.      Factory    inspectors    should   be   capable    of   making 


920  INDUSTRIAL    HYGIENE 

recommendations  outside  of  the  strict  regulations  under  which  they 
operate  so  as  to  improve  conditions  and  meet  the  needs  of  an  ever  chang- 
ing situation.  Factory  inspection  really  falls  into  two  categories,  one 
of  which  deals  mainly  with  the  medical  side  and  the  other  with  the  legal 
and  economic  side.  Both  inspectors  should  take  into  account  the  social 
and  humanitarian  side.  Some  of  the  factors  wliich  should  engage  the 
attention  of  a  factory  inspector  are:  ventilation,  dust,  gases,  vapors, 
odors,  temperature,  moisture,  light,  cleanliness,  over-crowding,  excessive 
heat,  dampness,  drinking-water,  children,  women,  washing  facilities, 
water-closets,  cloakrooms,  receptacles  for  expectoration,  defective  sani- 
tary arrangements,  hours  of  work  and  rest,  the  age  of  the  employee?, 
their  physical  condition,  etc.  Hanson  points  out  that  medical  men, 
through  their  training  and  attitude,  make  the  hest  factory  inspectors, 
for  they  alone  are  in  a  ])osition  to  make  the  best  use  of  facts,  and  learn 
something  of  the  sanitary  conditions  of  premises  where  men  and  women 
work,  to  study  the  possible  injurious  effects  of  certain  processes,  to  in- 
spect devices  designed  to  protect  the  employees  against  injury  or  against 
dangerous  fumes  and  dust,  and  to  judge  the  effects  on  the  health  of  op- 
eratives of  such  substances,  as  well  as  to  detect  the  symptoms  of  certain 
poisons  incident  to  such  occupations,  to  detect  and  protect  the  employees 
and  others  from  infectious  diseases,  to  make  physical  examinations  of 
minors,  and  to  collect  and  make  proper  use  of  all  facts  and  data,  includ- 
ing morbidity  and  mortality  statistics,  pertaining  to  occupational  hygiene. 
The  medical  inspector  is  also  able  to  correlate  the  injurious  influences 
in  the  factory,  in  the  home,  and  in  the  habits  of  the  individual. 

Preventable  Accidents. — The  most  obvious  and  striking  of  the  pre- 
ventable accidents  occur  on  railroads,  in  mines,  arid  in  factories.  About 
10,000  persons  are  killed  and  100.000  more  or  less  seriously  injured  on 
the  railroads  of  the  United  States  every  year.  Some  3,000  fatal  acci- 
dents occur  annually  in  the  course  of  mining  operations,  and  probably 
5,000  deaths  result  from  accidents,  in  the  operation  of  machinery  in 
factory  and  workshop.  Much  of  this  is  preventable,  in  fact,  prevented 
in  other  countries.  Winslow  points  out  that  fatalities  are  four  times  as 
common  among  our  railroad  employees  as  among  those  of  England,  and 
other  accidents  seven  times  as  frequent.  Coal  mining  was  nearly  as 
fatal  in  Belgium  between  1830  and  1840  as  it  is  in  the  United  States 
to-day,  but  the  Belgians  have  cut  their  death  rate  down  to  less  than  one- 
third  of  what  it  was. 

A  system  of  workmen's  compensation,  by  which  the  victim  of  in- 
dustrial accidents,  except  when  caused  by  his  own  neglect,  is  entitled  ])y 
right,  and  without  legal  proceedings,  to  a  proper  money  equivalent  for 
the  injury  received,  is  simple  justice  which  has  been  long  delayed  in  this 
country.  Workmen's  compensation  laws  have  been  in  successful  opera- 
tion  in   all   the   principal    European   countries.      Many   of   our    larger 


DISEASES    OF    OCCUPATION"  921 

corporations  voluntarily  and  automatically  compensate  employees  in  case 
of  accidents.  In  1910  New  York,  Montana,  and  Maryland  passed  laws 
making  such  an  arrangement  optional  or  compulsory  for  certain  classes 
of  occupations.  In  New  York  the  law  was  declared  unconstitutional. 
In  1911,  10  different  states,  California,  Illinois,  Kansas,  Massachusetts, 
Nevada,  New  Hampshire,  New  Jersey,  Ohio,  Washington,  and  Wiscon- 
sin, enacted  laws  bearing  on  this  subject. 


Fig.  134. — System  of  Hoods  and  Ventilators  to  Caery  off  the  Fumes  from  the 
Furnaces  in  a  Foundry.     (Mass.  State  Board  of  Health.) 

Sedentary  Occupations. — Sedentary  occupations  in  themselves  may 
lead  to  harm,  especially  in  the  cases  of  those  who  bend  forward  while  at 
work,  causing  contraction  of  the  chest  and  pressure  upon  vital  organs 
which  interferes  with  important  physiological  functions.  The  circula- 
tion is  impeded,  respirations  are  shallow,  the  ultilization  of  food  is 
diminished  and  the  appetite  fails,  constipation  and  hemorrhoids  are  com- 
mon, and  there  is  a  predisposition  to  common  colds  and  diseases  of  the 
lungs. 

DISEASES   OF  OCCUPATION 

Classification  of  the  Occupational  Diseases.' — Oliver  divides  the  occu- 
pational diseases  into  five  general  classes : 


922  INDUSTRIAL    HYGIENE 

(1)  Diseases  due  to  gases,  vapors,  and  high  temperatures. 

(2)  Diseases  due  to  conditions  of  atmospheric  pressure. 

(3)  Diseases  due  to  metallic  poisons,  dusts,  and  fumes. 

(4)  Diseases  due  to  organic  or  inorganic  dust  and  heated  atmos- 
pheres. 

(5)  Diseases  due  to  fatigue. 

Many  other  classifications  have  been  attempted,  but  it  is  evident  that 
no  general  system  can  be  entirely  satisfactory.  Each  occupation  requires 
individual  study  and  separate  consideration.  In  many  occupations  a 
combination  of  varying  factors,  such  as  dust  fumes,  poisons,  fatigue,  etc., 
operate  coincidently.  In  the  following  pages  only  the  well-known  and 
better  studied  diseases  of  occupation  and  the  conditions  which  render 
them  hazardous,  as  well  as  methods  of  prevention,  are  considered.  The 
number  of  occupational  diseases  is  rapidly  growing  as  the  subject  is 
receiving  more  careful  attention.  Thus  recently  it  has  been  shown  that 
workers  with  heated  tallow  and  other  animal  grease  are  subject  to  gastro- 
intestinal disturbances,  apparently  due  to  the  volatile  fatty  acids  that 
are  given  off  and  that  the  workers  ingest  and  inhale.  Strumpf  and 
Zable  ^  describe  chronic  antimony  poisoning  among  type-setters.  Skin 
diseases  are  frequently  found  among  workers  in  the  following:  galvan- 
izing, cutters  of  glass  and  pearl  shell,  workers  with  tar,  paraffin,  arsenic, 
cement,  dyes,  printer's  ink,  chromium,  potassium  permanganate,  and 
among  polishers. 

LEAD 

Lead  poisoning  is  one  of  the  most  frequent,  most  serious,  and  most 
insidious  of  all  the  occupational  intoxications.  If  'a  pound  of  lead  drops 
on  a  workman's  head  the  catastrophe  is  more  obvious  than  if  minute 
quantities  of  lead  salts  are  taken  into  the  system  day  by  day,  but  the 
poisoning  may  be  as  fatal  as  the  accident.  The  population  at  large  is 
also  frequently  poisoned  with  lead  from  a  variety  of  sources.  Thus  the 
lead  may  be  in  the  drinking-water  as  a  result  of  contact  with  lead  pipes, 
in  canned  goods  from  the  solder,  in  foods  cooked  in  lead-enameled 
utensils,  and  from  handling  lead  or  objects  containing  lead. 

Lead  is  a  typical  cumulative  poison.  A  large  amount  may  be  taken 
at  one  time  without  noticeable  effect,  but  small  quantities  ingested  daily 
are  absorbed,  stored  in  the  body,  resulting  in  chronic  poisoning  and  even 
death.  Lead  is  excreted  both  by  the  kidneys  and  the  liver,  and  also  the 
skin.  It  probably  does  not  appear  in  the  urine  except  with  albumin,  that 
is,  lead  can  only  pass  a  damaged  kidney.  The  lead  excreted  by  the  liver 
passes  into  the  intestines  with  the  bile  and  may  be  found  in  the  feces. 
The  elimination  of  the  lead,  however,  is  slow  and  uncertain.  As  much 
as  one  ounce  of  the  acetate  of  lead  has  been  taken  at  one  time  without 

^  Zeitschr.  f.  experimentelle  Path,  und  Pharmakologie,  1910,  LXIII,  p.  242. 


DISEASES    OF    OCCUPATION"  923 

^  injury.  Older  physicians  frequently  prescribed  the  acetate  of  lead  as  an 
astringent  in  doses  of  10,  20,  or  30  grains.  The  same  amount  of  lead 
distributed  in  minute  doses  and  taken  daily  would,  in  all  likelihood, 
result  in  serious  poisoning.  The  reason  for  this  is  that  when  one  large 
dose  is  taken  only  a  small  quantity  is  absorbed ;  the  rest  is  swept  through 
the  intestines,  but  when  small  quantities  are  taken  at  frequent  intervals 
practically  all  is  absorbed  and  the  metal  accumulates  in  the  tissues, 
poisoning  especially  the  delicate  nervous  structures. 

The  susceptibility  to  lead  poisoning  varies  greatly.  Of  a  number  of 
persons  exposed  to  the  same  conditions  some  are  fatally  poisoned,  others 
suffer  with  mild  plumbism,  and  still  others  escape  entirely.  Young  per- 
sons are  much  more  susceptible  than  old.  Young  adults  suffer  most. 
Women  are  more  susceptible  than  men.  Eecognizing  this  fact,  in  1898 
England  abolished  female  labor  in  the  dangerous  processes  of  white  lead 
manufacture.  The  reasons  for  this  varying  susceptibility  are  only  partly 
understood.  Hyperacidity  of  the  gastric  juice  is  a  predisposing  factor, 
because  the  lead  in  such  persons  is  readily  converted  to  the  soluble 
chlorid  in  the  stomach.  Personal  cleanliness  is  another  important  fac- 
tor, and  workers  in  lead  who  do  not  give  scrupulous  attention  to  cleanli- 
ness of  person  and  clothing  suffer  most.  Persons  who  are  not  particu- 
larly careful  about  cleaning  their  hands  before  eating,  or  who  frequently 
carry  their  fingers  to  their  mouth  and  nose,  run  especial  risks.  Oliver 
has  shown  by  experiments  on  animals  that  alcohol  precipitates  attacks 
of  plumbism,  a  fact  which,  in  the  human  subject,  clinical  experience  has 
again  and  again  confirmed.  There  is  not  the  least  doubt  that  alcoholic 
intemperance  predisposes  to  lead  poisoning. 

Practically  all  forms  of  lead  are  poisonous,  even  the  metal  itself. 
The  carbonate,  the  oxid,  and  the  chromate  are  the  most  serious  because 
these  are  most  employed  in  the  industries.  The  soluble  salts  are  more 
readily  absorbed  than  insoluble  salts. 

In  the  majority  of  cases  of  lead  poisoning  in  the  industries  the  lead 
comes  through  the  air  to  the  victim  as  dust,  sometimes  as  fumes.  Pre- 
ventive measures  must,  therefore,  be  directed  toward  keeping  the  air 
about  the  workmen  free  from  lead.  A  lead  trade  is  dangerous  in  propor- 
tion to  its  dustiness.  Lead  is  usually  taken  into  the  system  from  the 
digestive  tract,  although  absorption  from  the  respiratory  tract  and  even 
through  the  skin  may  occur.  For  many  years  it  was  a  disputed  point 
whether  the  lead  entered  through  the  skin  or  the  intestinal  tract,  but  it  is 
now  conceded  that  the  intestinal  mucosa,  also  that  of  the  mouth,  is 
the  usual  portal  of  entry.  Much  of  the  lead  dust  that  is  a  source  of  lead 
poisoning  is,  in  fact,  swallowed. 

The  water-soluble  salts  of  lead  such  as  acetate,  chlorid,  and  nitrate 
may  be  absorbed  through  the  skin,  but  this  is  slow  and  requires  long 
exposure.     It  is  possible  that  the  non-soluble  salts  may  be  changed  by 


924  INDUSTRIAL    HYGIENE 

contact  with  the  fatty  acids  on  the  skin  into  soluble  compounds.  Lead 
poisoning  may  be  caused  by  absorption  through  the  skin  from  cosmetics 
containing  lead.  Edsall  thinks  skin  absorption  relatively  unimportant. 
In  this  he  is  in  accord  with  Weyl.  Legge,  Oliver,  and  Sommerfeld. 

The  symptoms  of  lead  poisoning  are :  a  blue  line  on  the  gums  (sulphid 
of  lead),  a  diminution  in  the  secretion  of  saliva  and  a  sweetish  taste  in 
the  mouth,  colic,  constipation,  weakness,  slowing  of  the  pulse,  increase 
in  blood  pressure,  and  anemia.  The  corpuscles  may  fall  below  50  per 
cent,  and  many  of  the  red  cells  show  a  granular  basophilic  degeneration 
when  stained  with  one  of  the  polychrome  methylene  blue  dyes.  Lead 
palsy  is  very  common.  It  is  a  peripheral  toxic  neuritis  and  usually 
affects  a  localized  group  of  muscles  such  as  the  extensor  muscles  of  the 
forearm — painter's  wrist  drop.  The  common  symptoms  are  colic,  con- 
stipation, and  paralysis.  Edsall  calls  attention  to  the  fact  that  encephali- 
tis, which  expresses  itself  as  an  acute  insanity,  is  a  frequent  manifesta- 
tion of  lead  poisoning. 

The  character  of  certain  occupations  has  an  influence  on  the  type  of 
lead-poisoning  which  develops.  Thus  Teleky  finds  that,  while  composi- 
tors in  Vienna  seldom  suffer  from  colic  or  from  the  severer  types  of  lead 
poisoning,  they  are  subject  to  an  unusual  extent  to  diseases  of  the  lungs 
and  kidneys.  The  relation  between  tuberculosis  and  chronic  plumbism 
is  shown  in  Hahn's  diagrams  based  on  the  records  of  typographical  trades 
in  Vienna  and  Berlin,  the  curves  of  the  two  diseases  showing  a  remark- 
able parallelism.  Colic  is  said  by  Legge  to  be  most  frequent  among 
workers  in  white  lead,  red  lead,  enameling,  storage-batteries,  coach-paint- 
ing (which  involves  sandpapering),  while  the  severer  form  with  paralysis 
is  found  in  brass-workers,  plumbers,  printers,  file-cutters,  and  tinsmiths. 
The  former  are  very  dusty  trades;  poisoning  occurs  rapidly  and  enceph- 
alopathy is  more  frequent  than  paralysis. 

The  manner  in  which  lead  is  handled  makes  a  vast  difference  so  far 
as  the  liability  to  plumbism  is  concerned.  Thus  Stiiler  found  in  Vienna 
that  carriage  painters  are  ten  to  twenty  times  more  subject  to  lead  poison- 
ing than  house  painters.  This  has  been  confirmed  by  Edsall  in  this 
country.  The  reason  for  this  is  that  carriage  painters  apply  a  large 
number  of  coats  of  paint  and  varnish,  polishing  between  each  coat,  and 
thereby  enveloping  themselves  in  dust  which  contains  much  lead; 
furthermore,  carriage  painters  are  required  to  work  indoors. 

Red  Lead  (Litharge,  Massicot,  or  Lead  Oxid) . — In  the  manufacture 
of  red  lead  the  metal  is  simply  roasted  in  a  reverberatory  furnace  and 
raked  from  time  to  time.  A  considerable  amount  of  fujnes  escape  from 
the  mouth  of  the  furnace  and  unless  this  is  hooded  and  a  strong  draft 
provided  to  carry  it  away  the  workmen  may  become  poisoned.  The  red 
lead  is  removed  in  large  pieces  and  then  ground,  during  which  process 
quantities  of  fine  dust  are  raised  which  may  also  poison  the  workmen. 


DISEASES    OF    OCCUPATION" 


925 


White  Lead. — Most  of  the  white  lead  is  still  made  by  the  old  Dutch 
method,  which  consists  in  the  transformation  of  metallic  lead  into  the 
white  carbonate  by  a  slow  and  double  process  of  conversion.  Numerous 
earthenware  pots  containing  3  per  cent,  of  acetic  acid  are  placed  on  tan 
in  a  large  three-walled  chamber,  and  uj)on  these  pots  are  laid  thin  strips 
of  metallic  lead  and  subsequently  planks  of  wood.  Tier  after  tier  of 
pots  resting  on  bark  and  covered  with  metallic  lead  and  wood  are  thus 
superimposed  until  the  chamber,  25  or  30  feet  in  height,  is  filled  to 
within  6  feet  from  the  top.    This  chamber,  known  as  the  '^blue"  bed,  is 


Fig.  135. — A  Worker  with  i.hAn  oxid,  Showing  Respirator  to  Protect  Himself 
AGAINST  THE  PoisoNOus  DusT.     (Mass.  State  Board  of  Health.) 

kept  closed  for  14  weeks  or  longer.  Fermentation  causes  a  rise  in  tem- 
perature and  a  production  of  carbonic  acid.  The  acetic  acid  acts  upon 
the  lead  and  converts  it  into  acetate  of  lead,  while  the  COo  evolved  from 
the  bark  changes  the  acetate  into  carbonate  or  the  well-known  white  lead 
of  commerce.  The  danger  of  plumbism  occurs  during  the  emptying  or 
stripping  of  what  is  now  called  the  "white"  bed.  If  sufficient  time  has 
not  been  given  for  the  very  soluble  acetate  to  have  become  changed  into 
the  carbonate  the  danger  is  thereby  greater.  During  the  stripping  of 
the  "white"  bed  there  is  a  considerable  quantity  of  dust  raised,  a  large 
part  of  which  is  white  lead,  and  unless  spraying  with  water  is  effectively 
carried  out  the  workmen  cannot  avoid  inhaling  the  dust. 


926  INDUSTRIAL    HYGIENE 

Dr.  T.  Morison  Legge  found  that  of  1,463  persons  employed  off  and 
on  in  white  lead  works  the  incidence  of  lead  poisoning  was  6  per  cent, 
of  the  average  number  regularly  employed,  and  in  those  casually  em- 
ployed 39  per  cent.  This  shows  the  great  risk  of  exposing  unskilled 
labor  in  a  dangerous  occupation. 

In  some  progressive  plants  the  white  lead  is  transferred  mechanically 
from  the  white  beds  to  the  mixing  department,  where  it  is  ground, 
washed  with  water,  and  subsequently  mixed  with  oil,  and  thus  converted 
straightway  into  paint  without  even  being  handled  at  all.  This  greatly 
diminishes  the  danger. 

White  paint  contains  75  per  cent,  of  lead  carbonate  and  25  per  cent, 
of  oil.  The  men  who  mix  the  paint  do  not  suffer  to  any  extent  from 
plunibism.  as  little  dust  i?  raised  during  this  process. 

The  Manufacture  of  Pottery  and  Earthenware. — Next  to  the  white 
and  red  lead  industries  the  glazing  of  pottery  and  earthenware  furnishes 
the  largest  numbers  of  victims  of  lead  poisoning.  The  lead  is  contained 
in  the  glaze  with  which  such  ware  is  coated  and  the  danger  occurs  in 
cleaning  and  polishing  the  "biscuit,"  during  which  process  a  considerable 
amount  of  dust  containing  lead  is  raised. 

The  article  to  be  made  is  shaped  and  molded  from  the  clay  or  kaolin 
and  then  placed  in  an  oven  and  fired.  Some  pottery,  such  as  terra  cotta 
and  stoneware,  requires  only  one  firing,  but  all  others  have  to  be  fired 
twice.  After  the  first  firing  the  ware  is  known  as  '^Discuit."  The  biscuit 
is  dipped  into  a  liquid  glaze  and  then  fired  again,  which  produces  the 
hard,  smooth,  vitrified  surface. 

A  "non-fritted"  glaze  contains  raw  lead,  that  is,  the  carbonate.  The 
ware  is  dipped  into  the  mixture,  then  dried,  and  each  piece  is  smoothed 
and  cleaned.  During  the  cleaning  of  the  biscuit,  especially  when  pre- 
pared with  a  non-fritted  glaze,  considerable  dust  containing  lead  car- 
bonate is  raised. 

A  "fritted  glaze"  is  a  compound  of  raw  lead  (carbonate),  silica,  boric 
acid,  etc.,  fused  together  at  a  high  temperature.  This  produces  a  glass- 
like substance  in  wliich  the  lead  is  rendered  more  insoluble.  When 
ground  and  mixed  with  fine  clay  and  water  it  forms  a  white  chalky 
liquid  into  which  the  biscuit  is  dipped.  This  fritted  glaze  is  safer  for 
the  workmen  than  the  non-fritted  glaze  containing  raw  lead. 

The  use  of  leadless  glazes  has  been  opposed  by  many  manufacturers, 
but  it  has  been  shown  by  Thorpe  and  Oliver  that  the  largest  proportion 
of  earthenware  can  be  made  without  lead  in  the  glaze.  The  advantages 
of  lead  in  the  glaze  are  that  it  melts  at  a  low  temperature  and  gives  a 
deep  gloss  with  a  delicate  bluish  tint  which  is  generally  admired.  In 
Justice  to  the  manufacturers  it  should  be  stated  that  they  have  not  found 
the  leadless  glazes  to  prove  satisfactory. 

In  the  manufacture  of  pottery  the  workmen  are  liable  to  lung  dis- 


DISEASES    OF    OCCUPATION  927 

eases  on  one  hand,  and  lead  poisoning  on  the  other.  This  places  pottery 
manufacture  high  on  the  list  of  dangerous  trades.  "Potter's  rot"  and 
"potter's  asthma"  are  familiar  terms.  The  dangers  may  largely  be 
avoided  by  the  introduction  of  fans  and  strong  drafts  to  carry  away  the 
dust  from  the  faces  of  the  workers  and  the  use  of  a  fritted  or,  better,  a 
leadless  glaze. 

Besides  the  glazing,  exposure  to  lead  occurs  in  the  decorating  of  pot- 
tery, in  putting  on  dry  colors,  and  in  so-called  erographing,  in  which 
the  lead  colors  are  sprayed  on  the  surface  of  the  pottery. 

Another  danger  in  the  manufacture  of  pottery  is  the  irritating  dust 
which  rises  from  the  finely  ground  flint  in  which  the  biscuit  is  packed 
when  fired. 

File  Cutting.  — The  better  grades  of  files  are  cut  by  hand  in  the  fol- 
lowing manner :  The  workman  sits  astride  on  a  "stock."  In  front  of 
him  is  a  stone  block,  in  the  center  of  which  a  piece  of  steel  bar  called  a 
"stiddy"  is  inserted,  and  in  this  stiddy  is  placed  a  piece  of  metallic  lead 
which  is  called  the  "bed."  The  lines  are  made  by  striking  with  a  ham- 
mer and  chisel,  each  line  upon  the  file  representing  a  blow  from  the 
hammer.  There  is  a  considerable  quantity  of  dust  given  off  when  the 
file  is  rubbed  with  charcoal  before  it  is  turned.  This  dust  contains  a 
large  proportion  of  lead.  The  lead  is  also  taken  into  the  mouth  from  the 
hands  through  uncleanly  habits  of  the  workmen.  File  cutters  frequently 
suffer  from  lead  palsy. 

Miscellaneous  Industries. — Layet  computed  that  in  France  111  in- 
dustrial processes  involve  the  use  of  lead.  Hamilton  ^  found  70  such 
processes  in  Illinois  in  which  lead  or  its  salts  are  handled  and  which 
have  caused  lead  poisoning  in  recent  times. 

Some  of  the  industries  in  which  lead  poisoning  may  occur  are :  mak- 
ing and  selling  wall  paper,  polishing  brass,  polishing  nickel,  finishing 
cut  glass,  holding  lead-covered  nails  in  the  mouth  while  shingling  a  roof, 
working  with  aluminium  foil  (7  per  cent,  lead),  in  lithography,  zinc 
smelting,  making  ornamental  tiles  with  a  non-fritted  lead  glaze,  wrap- 
ping cigars  in  "tin"  foil,  enameling  bath-tubs,  laying  electric  cables, 
stopping  the  inequalities  of  wood  with  white  lead  in  making  automo- 
biles, assembling  and  recharging  old  storage-battery  plates,  polishing 
handles  of  coffins,  etc.  Lead  jDoisoning  may  also  be  contracted  from 
diamond  cutting,  the  setting  and  polishing  of  precious  stones,  from 
enameling  iron  plates  and  hollow  ware,  from  electric  accumulator  works, 
from  printing,  type-founding,  type-setting,  and  linotyping,  from  dye 
works  where  yellow  colors  are  got  from  chromate  of  lead,  from  house, 
coach  and  ship  painting,  etc. 

V.  A.  M.  A.,  Vol.  LVI,  No.  17,  April  29,  1911,  1240-1245. 


928  INDUSTRIAL    HYGIENE 

PEEVENTION 

The  prevention  of  lead  poisoning  rests,  in  the  main,  upon  the  fact 
that  the  h'ad  comes  to  tlie  workman  usually  as  dust,  sometimes  as  fumes 
through  the  air,  but  it  must  he  remembered  that  lead  is  also  carried  to 
the  mouth  by  dejjosits  on  the  hands  and  other  objects.  Whether  the  lead 
enters  the  body  by  inhalation,  by  ingestion,  or  through  the  skin  becomes 
more  of  an  academic  than  a  practical  question  so  far  as  prevention  is 
concerned. 

The  first  essential  then  is  to  keep  the  air  which  the  workman  breathes 
and  which  surrounds  him  free  of  lead.  Most  cases  of  lead  poisoning 
could  be  averted  by  a  pro])er  system  of  ventilation.  Certain  processes 
should  be  carried  on  under  hoods  with  a  strong  draft,  or  in  cabinets,  or 
special  rooms  with  an  air  current  so  arranged  that  the  lead  is  kept  away 
from  the  mouth,  nose,  hands,  and  clothes  of  those  wlio  are  exposed. 

On  the  part  of  the  workman  the  prevention  of  lead  j)oisoning  con- 
sists in  cleanliness  of  the  hands  and  of  the  finger  nails,  frequent  bathing, 
and  the  use  of  special  clothing  while  at  work.  Care  must  l)e  taken  not 
to  carry  the  fingers,  which  may  be  contaminated  with  lead,  to  the  mouth 
and  nose,  and  to  thoroughly  wash  the  hands  before  eating.  Workmen 
should  never  take  their  lunch  in  the  rooms  where  there  is  a  suspicion  of 
lead  in  the  air.  In  the  few  instances  where  the  above  precautions  are 
not  practical  respirators  should  be  worn. 

Cleanliness  is  one  of  the  all-essential  requirements.  A  special  room 
for  the  clothes  of  the  workmen  and  special  overalls  should  be  provided 
for  those  who  are  exposed  to  lead.  It  is  ignorance  of  the  danger  and  the 
want  of  personal  cleanliness  that  make  casual  labor  in  lead  works  espe- 
cially dangerous.  Even  the  women  who  wash  the  clothes  of  the  workmen 
employed  in  lead  factories  may  sometimes  suffer  from  lead  poisoning. 
Lavatories  should  be  provided  at  the  factory  and  the  hands  should  be 
washed  with  water  containing  a  small  quantity  of  acetic  acid  followed  by 
a  liberal  allowance  of  soap. 

Workmen  should  alternate  employment  and  not  remain  too  long  in 
the  dangerous  departments.  Supplanting  hand  labor  by  machinery 
diminishes  the  number  exposed  to  the  risk.  A  medical  inspection  is  an 
important  preventive  guard  in  educating  the  workmen  and  in  detecting 
mild  and  beginning  cases. 

A  radical  measure  would  be  the  substitution  of  zinc-white  for  lead 
paints.  Zinc  may  be  used  as  a  substitute  for  lead,  especially  in  indoor 
work ;  in  fact  this  has  been  required  by  law  in  France.  White  lead  ap- 
pears to  be  superior  to  zinc  for  outdoor  work. 

Keeping  down  the  hyperacidity  of  the  gastric  juice  is  believed  to  be 
a  good  preventive  measure.  This  may  be  accomplished  in  part  by  taking 
a  bland  oil  or  drinking  milk  rich  in  cream  at  intervals  during  work. 


DISEASES    OF    OCCUPATION 


929 


The  Massachusetts  State  Board  of  Health  issues  the  following  pro- 
tective measures  against  lead  poisoning : 

The  poison  gains  entrance  into  the  system : 

(1)  By  swallowing  minute  particles  of  lead. 

(2)  By  inhaling  lead  dust  or  the  fumes  of  lead  in  a  molten  state, 
or  the  vapor  of  lead  in  a  fused  state. 

(3)  By  absorption  from  the  skin  in  handling  lead. 


Fig.  136. — The  Stone  Industry.  The  workman  is  using  a  surfacing  machine  operated 
with  compressed  air.  The  strong  blast  of  air  keeps  the  granite  clean,  but  gives  rise  to 
a  great  amount  of  dust.  Of  the  mineral  dusts  granite  is  generally  considered  as  most 
irritating.     (Mass.  State  Board  of  Health.) 


Advice  to  Employees 


(1)  General  personal  cleanliness  is  of  the  first  importance. 

(2)  Thoroughly  clean  your  hands  before  touching  food  and  before 
leaving  the  workroom. 

(3)  Thoroughly  rinse  your  mouth  before  eating. 

(4)  Take  good,  nutritious  food  and  plenty  of  milk. 

(5)  Take  a  substantial  breakfast;  an  empty  stomach  is  more  sus- 
ceptible to  the  poisonous  effects  of  lead. 

(6)  Never  eat  at  your  work.  Eat  your  luncheon  outside  of  the 
workroom  if  possible ;  if  not,  in  a  part  of  the  room  away  from  the  lead. 
Never  smoke  or  use  tobacco  in  any  form  while  at  work. 

(7)  Avoid  all  excesses;  alcoholic  beverages  are  especially  injurious. 


930  INDUSTRIAL   HYGIENE 

(8)  Wear  overalls  or  a  long  coat  at  your  work;  also  a  cap  or  some 
head  covering.  Whenever  practicable  wear  gloves  when  lead  is  to  be 
handled. 

(9)  Persons  working  in  white  lead  or  other  powdered  compounds 
of  lead  should  alwa3's  wear  a  respirator  while  at  work.  Cause  as  little 
dust  as  possible. 

(10)   Consult  a  physician  at  the  first  sign  of  ill  health. 

Advice  to  Employers 

(1)  Provide  washing  facilities,  lockers,  and  a  place  for  the  em- 
ployees to  eat  luncheons  away  from  lead. 

(2)  Provide  respirators  for  all  the  workers  who  have  to  handle  white 
lead  or  other  powdered  compounds  of  lead. 

(3)  The  floors  of  the  workrooms  and  benches  at  which  men  work 
should  be  cleaned  daily  after  thoroughly  moistening  them. 

(4:)  These  regulations  should  be  posted  in  a  conspicuous  place  in 
the  workroom. 

PHOSPHORUS 

There  are  two  kinds  of  phosphorus:  (1)  the  white  or  yellow,  discov- 
ered by  Brandt  of  Hamburg  in  1669,  (2)  the  red  or  amorphous,  discov- 
ered by  Schroter  of  Vienna  in  1845.  The  amorphous  phosphorus  is 
obtained  from  the  white  phosphorus  by  exposing  it  in  a  closed  vessel 
for  some  time  to  a  temperature  of  250°  C.  The  white  or  yellow  phos- 
phorus is  poisonous  and  has  been  the  cause  of  much  suffering  in  the 
match  industry.  The  red  or  amorphous  phosphorus  is  practically  not 
poisonous. 

Three  kinds  of  matches  are  made:  (1)  the  safety  match,  which  con- 
tains no  phosphorus  and  is  harmless.  The  match  heads  contain  potas- 
sium chlorate  or  chromate  and  other  compounds  rich  in  oxygen  from 
which  the  oxygen  required  to  induce  conflagration  is  evolved.  The  paste 
applied  to  the  side  of  the  match-box  contains  antimony  sulphid  and  red 
phosphorus:  (2)  the  strike-anywhere  match  contains  the  poisonous  white 
phosphorus  in  the  head,  and  in  addition  glue,  chlorate  of  potassium, 
powdered  glass,  and  magenta  or  some  other  coloring  agent.  The  paste, 
or  composition,  contains  on  an  average  5  per  cent,  of  phosphorus.  It  is 
in  mixing  this  paste,  especially  when  done  by  hand  in  open  vessels,  and 
also  in  dipping  the  wooden  splints,  that  the  work-people  are  exposed  to 
fumes  that  become  a  menace  to  health:  (3)  the  strike-anywhere  match 
made  with  the  non-poisonous  sesquisulphid  of  phosphorus.  The  paste 
from  which  these  non-poisonous  matches  are  made  is  as  follows : 


DISEASES    OF    OCCUPATION  931 

Sesquisulphid  of  phosphorus 6  parts 

Chlorate  of  potassium    24 

Oxid  of  zinc   6 

Eed  ochre 6 

Powdered  glass 6 

Glue 18 

Water 34 

Sometimes  these  matches  also  contain  from  3  to  4  per  cent,  of  red- 
phosphorus  which  prevents  the  formation  of  unstable  subsulphids.  These 
matches  have  been  used  exclusively  for  the  last  13  years  in  France.  In 
our  country  the  strike-anywhere  match  made  with  poisonous  white  phos- 
phorus constitutes  the  principal  output. 

When  pure,  phosphorus  is  colorless  and  transparent,  but  when  exposed 
to  the  light  it  becomes  yellowish.  The  white  and  yellow  forms  are  ex- 
tremely poisonous;  the  red  or  amorphous  phosphorus  can  be  handled 
with  impunity.  Eed  phosphorus  does  not  take  fire  when  rubbed  on  a 
rough  surface.  It  is  non-volatile  and  when  swallowed  is,  comparatively 
speaking,  non-poisonous.  One  to  3  grains  of  white  phosphorus  will 
cause  death.  The  fumes  from  white  or  yellow  phosphorus  are  rich  in 
phosphorus  oxids  and  these  are  absorbed  in  various  ways.  Professor 
Thorpe  exposed  decayed  human  teeth  to  the  fumes  of  phosphorus  for  13 
hours  and  he  found  that  they  lost  0.37  per  cent,  of  their  weight  and  that 
carious  teeth,  when  exposed  to  a  dilute  solution  of  phosphoric  acid  (1 
per  cent.),  lost  8.9  per  cent,  of  their  original  weight.  The  atmosphere 
of  an  ill-ventilated  match  factory  in  which  the  white  or  yellow  phos- 
phorus is  used  reeks  with  the  garlicky  odor  characteristic  of  phosphorus. 
The  fumes  become  dissolved  in  the  saliva  of  the  mouth  and  exercise  a 
solvent  action  upon  the  teeth  of  persons  inhaling  this  poisonous  atmos- 
phere several  hours  of  each  working  day.  The  poison  also  clings  to  the 
fingers  and  hands  of  the  work-people.  Thus  Oliver  found  the  hands  of  a 
boxer  to  be  deeply  stained  by  the  dye  given  off  by  the  heads  of  the 
matches,  to  emit  a  characteristic  garlicky  odor  and  glow  in  the  dark. 
The  phosphorus  is  also  absorbed  by  the  drinking-water  if  exposed. 

The  principal  and  characteristic  disease  produced  by  white  or  yellow 
phosphorus  is  necrosis  of  the  jaw,  known  as  "phossy  jaw."  This 
is  a  localized  inflammatory  infection  of  the  jaw-bone  extremely  painful 
in  the  early  stages,  which  runs  a  chronic  course  and  invariably  ends  in 
the  localized  death  of  the  bone.  The  gums  become  swollen  and  the  jaw- 
bone painful;  sooner  or  later  pus  forms  and  although  the  teeth  are  ex- 
tracted the  pain  continues.  The  inflammation  gradually  extends  to  the 
bone. 

It  is  probable  that  the  phosphorus  fumes  and  the  phosphoric  acid 
acting  through  decayed  teeth  set  up  inflammation,  thereby  allowing 
microorganisms,  always  present  in  the  mouth,  to  carry  the  morbid  process 


932  INDUSTRIAL    HYGIENE 

deeper.  Lewin  of  Berlin  does  not  believe  that  it  is  primarily  necessary 
for  a  lucifer  match-maker  to  have  decayed  teeth,  for  the  phosphorus 
fumes,  in  his  opinion,  inflame  the  gums  in  the  first  instance,  and  as  a 
consequence  there  is  induced  a  septic  gingivitis,  which  is  followed  by 
disease  of  the  bone.  Other  effects  of  phosphorus,  though  less  frequent, 
are  phosphorism,  whicli  is  a  general  cachectic  condition  met  with  prin- 
cipally in  female  workers,  and  characterized  by  anemia,  dyspepsia,  al- 
buminuria, and  a  tendency  to  bronchitis.  Fragiliias  ossium  is  another 
condition  met  with  in  phosphorus  workers.  According  to  Dearden,  the 
bones  of  match-dippers  contain  an  excess  of  phosplioric  acid  which  com- 
bines with  the  preexisting  neutral  phosphate  of  lime  to  form  a  slightly 
acid  salt  and  thereby  causing  excessive  brittleness  of  the  bones. 

The  prevalence  of  phossy  jaw  may  be  gleaned  from  the  fact  that  in 
Great  Britain  somewhat  less  than  1  i;er  cent,  of  the  match-makers  have 
suffered  from  it.  In  Switzerland  the  incidence  was  formerly  l.G  to  3 
per  cent.,  and  in  France  2  to  3  per  cent.  In  this  country  the  subject 
was  investigated  by  the  Bureau  of  Labor,  who  found  that  there  are  about 
3,500  emplo3-ees  in  15  of  the  17  match  factories  in  the  L^nited  States; 
of  3,383  whose  occupation  was  specified  65  per  cent,  were  exposed  to 
phosphorus  fumes.  It  was  also  found  that  95  per  cent,  of  1,395  so  ex- 
posed are  women.  An  intensive  study  of  three  factories  was  made  and 
82  cases  of  necrosis  were  discovered. 

Several  years  ago  the  Belgian  government  offered  a  prize  of  50,000 
francs  to  any  person  who  would  invent  a  safety  strike-anywhere  match 
free  from  white  phosphorus.  The  problem  was  solved  by  Sevene  and 
Cahan  of  France,  who  demonstrated  that  the  sesquisulphid  of  phosphorus 
would  accomplish  all  that  white  phosphorus  does  without  causing  poison- 
ing. The  sesquisulphid  is  an  almost  inodorous  powder  and  is,  practically 
speaking,  nonpoisonous.  It  contains  a  trace  of  red  or  amorphous  phos- 
phorus. Since  the  introduction  into  France  of  the  manufacture  of  the 
sesquisulphid  match  there  has  not  been  in  the  factories  of  that  country, 
where  the  manufacture  of  matches  is  a  state  monopoly,  one  case  of  phos- 
phorus poisoning,  nor  has  there  been  any  explosion  or  fire  in  any  of  the 
match  works.  It  has  been  found  that  the  sesquisulphid  of  phosphorus 
acts,  in  some  instances,  as  an  irritant,  causing  conjunctivitis  and  edema 
of  the  eyelids,  also  eczema  of  the  skin.  This  may  be  obviated  by  bathing 
the  eyes  and  douching  the  nostrils  twice  a  day  before  leaving  the  factory 
with  an  alkaline  solution  of  bicarbonate  of  soda. 

PEEVENTION 

The  prevention  of  phosphorus  necrosis  consists  in  the  substitution  of 
the  sesquisulphid  for  the  poisonous  white  and  yellow  forms.  Even 
stringent  regulations  will  not  protect  those  who  have  to  work  with  the 


DISEASES    OF    OCCUPATION 


933 


white  or  yellow  phosphorus.  The  experience  of  Great  Britain  is  espe- 
cially noteworthy.  In  1888  Great  Britain^  after  a  thorough  investigation 
'of  the  conditions,  made  stringent  regulations  coupled  with  an  efficient 
inspection,  but  phossy  jaw  was  not  prevented,  and  in  1908  the  use  of 
white  phosphorus  was  prohibited.  White  phosphorus  was  prohibited  by 
Finland  in  1872  and  in  Denmark  2  years  later,  since  which  time  no  case 
of  phosphorus  necrosis  has  occurred  in  these  countries.  France  pro- 
hibited its  use  in  1897,  Switzerland  in  1898,  the  ISTetherlands  in  1901,  and 
in  1905  the  International  Association  for  Labor  Legislation  secured  a 


- 

1                i  ^:           Mi»--'^M 

'^ 

Tig.  137. — Workmen  Exposed  to  Zinc  Fumes  in  Brass  Casting,  Causing  a  Condi- 
tion Known  as  "Brass-founder's  Ague." 

treaty  providing  for  the  prohibition  of  the  making  and  selling  of  matches 
made  of  white  phosphorus,  which  treaty  was  signed  by  France,  Denmark, 
Germany,  Italy,  Switzerland,  the  JSTetherlands,  and  Great  Britain.  This 
country  has  grossly  neglected  to  protect  its  workmen  and  has  yet  taken 
no  action  despite  the  serious  conditions  demonstrated  by  John  B.  An- 
drews, Secretary  of  the  American  Association  for  Labor  Legislation.^ 
Phosphorus  poisoning  may  in  part  be  prevented  by  a  medical  ex- 
amination, special  attention  being  paid  to  the  state  of  the  teeth.  The 
services  of  a  dentist  are  essential.  Personal  cleanliness  and  the  use  of 
mouth  washes  are  helpful.     The  workroom  should  be  well  ventilated  and 

^Congress   passed   a   prohibitive   tax   on   poisonous   phosphorus,   April,    1912; 
effective  June,   1913. 
61 


934  INDUSTRIAL   HYGIENE 

fans  should  be  kept  running  to  withdraw  all  fumes  away  from  the  faces 
of  the  workers.  Washing  accommodations  should  be  ample,  hot  and  cold 
water  should  be  provided,  along  with  plenty  of  soap  and  towels. 

Persons  sometimes  commit  suicide  by  dissolving  the  white  or  yellow 
phosphorus  from  match  heads  and  drinking  the  solution.  This  is  not 
possible  in  the  case  of  matches  made  with  the  red  or  amorphous  phos- 
phorus or  the  sesquisulphid. 

ARSENIC 

Arsenic  acts  as  an  irritant  to  the  skin  and  mucous  membranes,  setting 
up  conjunctivitis,  eczema,  and  ulcerations;  it  also  produces  general  pois- 
oning, causing  anemia  and  neuritis.  Arsenical  neuritis  is  particularly 
severe  and  often  serious.  In  the  industries  arsenical  poisoning  is  found 
among  workers  in  the  manufacture  of  Scheelc's  green,  in  the  manufac- 
ture and  use  of  wall  papers  and  artificial  flowers  containing  arsenical 
coloring  agents,  during  the  packing  of  white  arsenic,  and  in  reduction 
works  of  arsenic  mines. 

Workers  in  arsenic  suffer  from  painful  redness  of  the  eyes  and  from 
eczema  of  the  eyelids.  Men  employed  in  the  manufacture  of  Scheele's 
green  (arsenite  of  copper)  frequently  have  painful  ulcers  on  their 
fingers  or  other  portions  of  the  body  where  the  dust  collects.  Smelters 
sometimes  suffer  from  "arsenic  pock,"  an  irritation  of  the  skin  due  to 
the  action  of  the  very  fine  dust  upon  the  perspiring  skin.  The  bronchitis 
from  which  workers  about  smelting  works  suffer  has  been  attributed 
partly  to  the  fumes  given  off  by  the  raw  material  and  partly  to  the  rather 
large  amounts  of  sulphur  contained  in  the  fumes.  Men  employed  in 
removing  vitriol  solution  from  the  depositing  tanks  in  copper  works  oc- 
casionally suffer  in  consequence  of  the  inhalation  of  arsenuretted  hy- 
drogen gas. 

Arsenic  is  also  used  in  curing  furs.  The  Massachusetts  law  forbids 
arsenic  to  exceed  1  grain  per  square  yard,  but  analyses  reveal  that  it 
often  reaches  170  grains.  Out  of  48  samples  of  fur  recently  examined 
in  America  11  were  found  heavily  loaded  with  arsenic.  The  presence 
of  such  large  quantities  of  arsenic  in  furs  that  are  worn  or  in  rugs  for 
rooms  must  be  a  source  of  danger. 

From  wall  paper  the  arsenic  may  be  absorbed  either  as  solid  particles 
detached  from  the  paper  or  as  a  volatile  gas  formed  from  arsenical  or- 
ganic matter  by  the  action  of  several  moulds,  notably  Penicillium  hrevi- 
caule,  Mucor  mecedo,  etc.  (Gosio.)  For  the  liberation  of  the  volatile 
arsenical  compounds  moisture  and  a  certain  amount  of  heat  (60  to  95° 
F.)  are  necessary.  The  volatile  compound,  according  to  Sanger,  is  prob- 
ably an  organic  derivative  of  arsenic  pentoxid.  Arsenic,  as  well  as  other 
irritants,  is  believed  to  predispose  the  tissues  to  growths  of  a  cancerous 
nature. 


DISEASES    OF    OCCUPATION"  935 

MERCURY 

Mercurial  poisoning  may  be  contracted  by  workmen  employed  in  ex- 
tracting mercury  from  cinnabar  (sulphid  of  mercury),  in  which  it  is 
usually  found  in  nature.  The  ore  is  simply  roasted  and  the  mercury 
volatilizes  and  readily  condenses  in  metallic  form.  Mercury  volatilizes 
at  a  low  temperature  and  it  is  this  circumstance  which  creates  much  of 
the  danger  to  those  who  work  with  this  substance,  especially  men  who 
work  in  a  closed  and  heated  atmosphere  containing  the  vapor  given  off 
by  the  metal.  Mercury  is  absorbed  by  the  digestive  system,  the  respira- 
tory tract,  and  also  through  the  skin.  As  an  instance  of  the  absorption 
of  mercury  through  the  skin  Edsall  cites  two  cases  in  dentists  who  were 
poisoned  as  a  result  of  the  custom  found  in  many  dentists  of  working 
up  their  amalgam  in  the  palms  of  their  hands. 

The  occupations  in  which  mercury  is  used  and  in  which  mercrfrial 
poisoning  occurs  are :  the  separation  of  gold  and  silver  from  their  re- 
spective ores,  which  is  done  by  means  of  an  amalgam ;  the  manufacture 
of  incandescent  lamps,  in  which  mercury  pumps  are  used  to  create  a 
vacuum;  in  barometer  and  thermometer  making;  in  felt-hat  and  fur 
dressing,  in  which  mercuric  nitrate  is  used;  in  water-gilding,  where  an 
amalgam  of  gold  or  silver,  after  having  been  applied  to  an  object,  is 
heated  and  the  mercury  driven  off;  and  other  industries. 

The  New  York  and  ISTew  Jersey  section  of  the  National  Civic  Federa- 
tion in  three  months'  time  found  60  cases  of  mercurial  poisoning,  a 
nervous  disease  called  in  the  trade  "the  shakes,"  among  the  hat  makers 
of  Brooklyn,  Newark,  and  Orange  as  a  result  of  the  mercury  salts  used 
in  preparing  felt. 

The  symptoms  of  mercurial  poisoning  are :  anemia,  headache,  dizzi- 
ness, tremor  of  the  muscles,  especially  the  tongue  and  limbs,  fetid  breath, 
soft,  swollen,  and  ulcerated  gums,  and  loosening  of  the  teeth.  The  sub- 
maxillary and  other  glands  of  the  neck  become  painful  and  the  secretion 
of  saliva  excessive.  Erethism  and  apprehensiveness  are  common;  in 
severe  cases  depression  and  melancholia.  A  persistent  and  apparently 
causeless  diarrhea  is  frequently  a  symptom  of  mercurial  poisoning. 

PEEVENTION 

The  prevention  of  mercury  poisoning  is  almost  a  direct  counterpart 
of  the  prevention  of  lead  poisoning.  The  air  must  be  kept  free  of  mer- 
cury, and  this  can  be  accomplished  by  proper  systems  of  ventilation,  by 
the  use  of  hoods  with  forced  draft  and  other  devices  to  keep  the  mercury 
fumes  away  from  the  workmen.  Eubber  gloves  may  be  worn  to  prevent 
absorption  through  the  skin  and  also  to  prevent  the  carrying  of  the  mer- 
cury to  the  mouth.    Here  again  scrupulous  cleanliness  in  and  after  leav- 


936  INDUSTRIAL   HYGIENE 

ing  the  workroom,  a  change  of  clothing,  and  washing  the  hands  before 
eating  are  essential.  . 

CARBON  MONOXID 

Carbon  monoxid  is  a  colorless,  inodorous,  and  highly  poisonous  gas. 
It  burns  with  a  pale  blue  flame.  It  is  one  of  the  products  of  the  incom- 
plete combustion  of  illuminating  gas,  also  of  coal  and  explosives.  It  is 
met  with  in  coal  mines  and  other  subterranean  galleries  where  blasting 
has  been  effected  by  dynamite  and  gun-powder.  It  forms  7  to  10  per 
cent,  of  ordinary  illuminating  gas  (coal  gas)  and  30  per  cent,  of  water 
gas.  It  is  the  source  of  the  blue  flame  seen  on  the  surface  of  an  ordinary 
coal  fire.  The  gas  is  given  off  in  quantities  from  coke  ovens ;  it  is  evolved 
from  blasting  furnaces  in  the  smelting  of  iron,  especially  during  the 
charging  of  furnaces  and  their  tapping.  Carbon  monoxid  frequently 
remains  in  the  furnace,  and  workmen  who  enter  such  a  furnace  in  order 
to  clean  it  may  be  overcome.  In  England  the  law  requires  two  workmen 
to  clean  furnaces ;  one  stands  by  in  case  of  accident.  Carbon  monoxid  is 
also  evolved  from  hot-water  heaters;  in  the  Leblanc  process  of  soda 
manufacture ;  in  cement  and  brick  works,  etc. 

The  poisonous  properties  of  carbon  monoxid  are,  according  to  Hal- 
dane,  due  to  the  great  affinity  it  has  for  the  hemoglobin  of  the  red 
corpuscles.  It  has  from  140  to  250  times  greater  chemical  affinity  for 
hemoglobin  than  oxygen.  It  forms  carbon  monoxid  hemoglobin,  a  more 
stable  compound  than  oxyhemoglobin,  and  therefore  prevents  the  oxygen 
being  given  to  the  tissues.  When  the  percentage  of  carbon  monoxid  rises 
to  0.-4  the  atmosphere  becomes  dangerous  to  animal  life.     (See  page  635.) 

The  inhalation  of  carbon  monoxid  causes  headache  and  a  sense  of 
loss  of  power  in  the  lower  extremities.  It  is  this  circumstance  which 
explains  many  of  the  cases  of  fatal  poisoning  in  confined  spaces.  There 
are  also  dizziness,  throbbing  of  the  temples,  ringing  in  the  ears,  a  sense 
of  lassitude,  and,  in  severe  cases,  convulsions  and  loss  of  consciousness. 
The  inhalation  of  small  quantities  also  leads  to  delusions  and  other 
mental  s}Tnptoms.  If  the  gas  enters  a  bedroom  and  is  inhaled  by  persons 
who  are  asleep  the  sleep  only  becomes  deeper  and  profound  narcosis  is 
developed  from  which  there  may  be  no  awakening. 

Oliver  gives  the  following  illustration  of  the  subtle  poisoning  by 
carbon  monoxid  at  Pelton  Fell,  a  mining  village  in  Durham  County. 
Some  shale  which  had  been  tipped  at  the  edge  of  a  ravine  caught  fire. 
The  carbon  monoxid  gas  given  off  during  the  combustion  traveled 
through  the  soil  and  entered  two  houses  in  different  streets,  full  30 
feet  away,  causing  the  death  of  two  elderly  people.  It  is  to  the  breath- 
ing of  this  gas  during  sleep  that  the  death  of  tramps,  drawn  to  the  coke 
ovens  1)V  their  inviting  warmth  on  a  winter's  night,  is  attributed.     I 


DISEASES    OF    OCCUPATION  937 

have  already  instanced  the  case  of  death  from  carbon  monoxid  resulting 
from  the  imperfect  operation  of  a  gas  water-heater.     (See  page  636.) 

EYDBOGEN   SULPHID 

Hydrogen  sulphid  is  an  extremely  poisonous  gas  causing  death  in- 
stantaneously if  inhaled  in  large  quantities.  In  smaller  amounts  the 
symptoms  caused  are  nausea,  vertigo,  headache,  general  malaise,  all  of 
which  soon  disappear  if  the  workman  goes  into  the  open  air.  There  are 
only  a  few  industrial  undertakings  in  which  hydrogen  sulphid  is  met 
with,  such  as  chemical  and  gas  works;  the  black  bronzing  of  metals  by 
means  of  sulphid  of  arsenic ;  the  cleaning  of  boilers ;  in  certain  processes 
of  soap  making  where  large  quantities  of  fat  are  decomposed;  in  the 
preparation  of  Prussian  blue;  during  the  decomposition  of  ferrocyanid 
of  potassium  by  sulphate  of  iron.  In  nature  hydrogen  sulphid  is  one 
of  the  products  formed  during  the  putrefaction  of  organic  matter  con- 
taining sulphur.  The  gas  may  therefore  be  found  about  privies,  the 
mud  of  marshes,  and  collections  of  filth  and  manure,  but  in  quantities 
top  small  to  seriously  influence  health. 

DUSTY  TRADES 

Dust  is  the  great  enemy  of  the  workman.  Much  ill  health  is  caused 
by  the  inhalation  of  dust,  some  of  which  is  also  injurious  when  ingested 
and  some  of  which  is  irritating  to  the  skin.  Dust  of  all  kinds,  both 
organic  and  inorganic,  is  met  with  in  the  various  industries.  Organic 
dust  is  usually  less  irritating  and  dangerous  than  inorganic  dust,  which 
becomes  harmful  particularly  when  the  particles  are  sharp  and  therefore 
irritating.  The  principal  trades  and  occupations  in  which  excessive 
amounts  of  dust  are  found  are :  all  forms  of  grinding  and  many  processes 
of  polishing  and  cleaning;  the  textile  industries;  in  the  lead,  copper, 
and  iron  trades  irritating  and  poisonous  dusts  are  raised ;  also  in  pottery 
works  and  masonry,  and  in  the  handling  of  leather,  skins,  feathers, 
wool,  cotton,  wood,  paper,  tobacco,  etc.  The  amount  of  dust  may  be 
very  great;  thus  Hesse  found  in  one  cubic  meter  of  air  the  following 
amounts  of  dust  in  the  occupations  named: 

Felt  hat  factory 175  milligTams 

An  old  flour  mill 48  " 

A  new  flour  mill 4  " 

Mechanical  knittmg   3  " 

Sculpturing 9  " 

A  paper  factory 4-25  " 

Iron  works   72-100  " 

A  coal  mine 14  " 

A  living  room 0  " 


938 


INDUSTRIAL    HYGIENE 


The  kinds  of  dust  vary  greatly  in  their  hygienic  significance.  Some 
are  poisonous,  some  act  as  mechanical  irritants.  The  principal  poisonous 
dusts  found  in  the  industries  are  lead,  mercury,  arsenic,  phosphorus, 
and  zinc;  less  often  substances  from  tobacco,  wood,  dyes,  and  chem- 
ical works.  The  dust  particles  which  act  by  mechanical  irritation  are 
especially  the  hard,  irregular  particles  with  sharp  edges  from  iron,  steel, 
and  other  metals;  from  granite,  basalt,  or  marble;  while  those  from 
coal,  chalk,  and  plaster  of  paris  are  less  irritating. 

According  to  Sommerfeld  the  following  proportion  of  persons  per 


PlIiCKS  Ui"  Bkuu.M  ColiN. 


Nails  \Vhich  Combs  out  the  Small 

(.Masd.  State  Board  of  Health.) 


thousand  in  the  various  dusty  occupations  mentioned  die  of  pulmonary 
tuberculosis : 

Occupation  without  dust  production 2.39 

With  dust  production 5.42 

With  porcelain  dust 14.0 

With  iron  dust 5.55 

With  lead  dust 7.79 

With  stone  dust 34.9 

With  porcelain  dust 14 

With  stone  workers 4.3 

With  wood  and  paper  dust 5.96 

With  tobacco  dust 8.47 


DISEASES    OF    OCCUPATION  939 

Persons  exposed  to  excessive  amounts  of  dust  for  long  periods  of 
time  suffer  from  a  general  condition  known  as  pneumonolconiosis ;  when 
due  to  coal  dust  the  condition  is  known  as  anthracosis ;  when  due  to 
stone  dust,  siderosis  or  chalicosis;  when  due  to  vegetable  fibers  such  as 
cotton,  hyssinosis.  The  dust  may,  in  part,  be  free  in  the  alveoli  of  the 
lungs  and  in  part  is  inclosed  in  the  cells.  The  epithelial  cells  lining  the 
alveoli  act  as  phagocytes.  At  times  some  of  the  alveoli  may  be  plugged 
with  dust  particles.  Sometimes  the  dust  remains  in  the  lungs  without 
any  apparent  reaction  on  the  part  of  the  tissues.  Usually  round  cells 
appear  in  the  interalveolar  spaces,  and  other  indications  of  irritation  and 
inflammatory  reaction  take  place,  leading  to  connective  tissue  formation 
between  the  alveoli  and  thickening  of  the  alveolar  wall  itself.  This  may 
progress  to  an  indurative  bronchitis ;  that  is,  several  alveoli  become  drawn 
together  by  the  contracting  connective  tissue  into  a  nodule.  Other  forms 
of  inflammation,  such  as  nodular  peribronchitis  or  nodular  perivasculitis, 
may  take  place.  The  dust  particles  axe  also  carried  by  the  phagocytes 
to  the  regional  lymphatics,  where  they  lodge.  These  irritative  processes 
cause  a  low  grade  inflammatory  reaction  which  only  awaits  the  coming 
of  bacteria  to  start  specific  or  destructive  processes. 

Some  dust  is  especially  irritating  to  the  conjunctiva,  as  wood  dust 
or  arsenic.  Certain  kinds  of  dust  are  prone  to  cause  chronic  catarrhal 
inflammation  of  the  upper  respiratory  passages,  while  dust  containing 
specific  microorganisms  such  as  anthrax  may  lead  to  acute  pneumonia 
(wool  sorter's  pneumonia). 

General  Principles  of  Prevention. — Much  of  tiie  dust  raised  in  in- 
dustrial processes  may  be  limited  by  improvements  in  machinery  or  pre- 
ventive devices.  Sometimes  the  dust  may  be  kept  down  by  moisture, 
sprays,  or  even  conducting  the  work  under  water  when  practicable. 
Thus  wet  grinding  may  be  substituted  for  dry.  Certain  dusty  operations 
should  be  conducted  in  inclosed  hoods  or  special  cabinets  so  as  to  con- 
fine the  dust  and  thus  protect  the  workpeople,  or  the  dust  may  be  re- 
moved by  suction  fan  devices.  Good  ventilation  diminishes  the  danger 
very  much.  When  workmen  are  compelled  to  stay  in  dusty  atmospheres 
they  should  wear  respiratory  masks,  and  the  number  of  persons  thus 
exposed  should  be  reduced  to  a  minimum.  Some  exceedingly  dusty  proc- 
esses, such  as  cleaning  castings  with  a  sand  blast,  demand  the  wearing 
of  a  protective  headgear.  Many  workmen  prefer  taking  chances  to  wear- 
ing uncomfortable  respirators. 

THE  TEXTILE  INDUSTRIES 

The  manufacture  of  cotton,  linens,  silk,  and  jnte  has  received  an 
unenviable  reputation  as  dangerous  occupations,  despite  the  fact  that 
these  industries  need  not  in  themselves  be  particularly  unhealthy  occupa- 


940  INDUSTRIAL    HYGIENE 

tions.  The  textile  industries  illustrate  several  points  in  the  diseases  of 
occupation.  One  is  that  an  entire  industry  should  not  be  condemned 
because  one  of  its  processes  is  attended  with  a  certain  amount  of  danger. 
The  other  is  that  the  risks  to  health  may  be  prevented  or  greatly 
ameliorated.  General  improvement  in  the  sanitary  conditions  of  textile 
mills  is  one  of  the  promising  signs  of  material  advancement  in  industrial 
hj'giene. 

The  principal  conditions  which  affect  health  in  the  textile  industries 
are :  The  working  in  a  dusty  atmosphere  which  is  often  kept  very  moist 
and  usually  very  warm  in  order  to  keep  the  fiber  pliable  and  workable. 
The  humidity  and  temperature  may  be  regulated,  and  by  efficient  systems 
of  ventilation  their  ill  effects  may  be  minimized  or  even  neutralized. 
The  dust  may  also  be  lessened,  and  in  the  processes  in  which  it  is 
excessive  the  workmen  may  protect  themselves  with  respirators. 

Much  dust  is  raised  during  the  opening  and  empt3'ing  of  the  bales 
of  the  raw  material.  This  is  avoided  in  the  better  mills  by  the  use  of 
machinery.  Most  of  the  dust  is  raised  during  the  process  of  "carding"; 
some  during  "roving,"  "spinning"  the  yarn,  and  "winding"  it ;  and  also 
considerable  during  "weaving."  In  linen  factories  the  "hecklers,"  that 
is,  the  men  who  dress  and  sort  the  rough  flax  (converted  into  tow 
by  having  been  passed  through  a  machine),  are  exposed  to  consider- 
able amounts  of  dust  and  suffer  from  dryness  of  the  throat  and  bron- 
chitis, attended  by  cough  and  shortness  of  breath.  In  the  manufacture 
of  sacks,  twine,  and  carpets  from  jute  the  processes  that  are  extremely 
dusty  are  the  preparing  and  spinning.  The  dust  given  off  by  jute  is 
irritating. 

Working  in  an  atmosphere  which  is  excessively  moist  and  frequently 
very  warm,  and,  further,  containing  an  excessive  amount  of  organic 
dust,  subjects  the  workmen  to  artificial  and  unnatural  conditions  which 
cannot  be  conducive  to  health.  Presumably  the  heat  and  moisture  pre- 
dispose to  rheumatic  states  and  inflammatory  conditions  of  the  res- 
piratory tract  which  are  aggravated  by  the  irritation  of  the  fibrous  dust. 
It  is  believed  that  workmen  so  exposed  are  more  prone  to  contract 
common  colds,  bronchitis,  tuberculosis,  and  other  inflammatory  diseases 
of  the  respiratory  tract. 

In  Massachusetts  there  is  a  law  regulating  the  amount  of  humidity 
and  temperature  in  the  textile  mills  which  is  based  upon  the  English 
schedule  contained  in  the  Weaver's  act  of  1870.  The  conditions  in 
Massachusetts,  however,  are  so  different  from  those  found  in  England, 
especially  in  the  summer  time,  that  the  schedule  has  not  been  found 
practical.  Much  of  the  ill  effects  in  the  textile  industries  may  be  neu- 
tralized by  good  ventilation,  abundant  air  space,  cleanliness,  sufficient 
light,  and  the  use  of  improved  machinery.  Special  rooms  should  be 
provided   for  the  clothes,  in  order  that  the  moist  garments  may  be 


DISEASES    OF    OCCUPATION"  941 

changed  for  dry  ones  before  the  workpeople  go  into  the  open  air,  thus 
avoiding  the  chilling  effects  of  damp  garments. 

WOOD   DUST 

It  is  well  known  that  workers  in  wood  are  subject  to  the  mechanical 
effects  of  ordinary  sawdust,  which  is  moderately  irritating.  Workers 
with  boxwood,  teak,  and  sequoia  (redwood)  are  subject  also  to  the  gen- 
eral poisonous  effects  of  alkaloids  and  other  substances  contained  in 
these  woods  which  may  have  more  marked  general  effects,  especially  on 
the  circulation  and,  still  more  frequently,  marked  local  effect  on  the 
mucous  membranes  and  the  skin.  In  1902  Young  observed  that  men 
working  with  Maracaibo  boxwood  complained  of  dryness  of  the  throat 
and  inflammation  of  the  eyes  which  lasted  two  or  three  days.  This 
wood  is  used  in  the  making  of  rulers.  Oliver  notes  that  joiners  that 
saw  and  chip  sequoia  wood  suffer  with  symptoms  resembling  a  bad  cold 
in  the  head  and  chest;  a  tolerance  seems  to  be  established  except  by 
men  who  are  liable  to  bronchitis  and  asthma.  Wounds  caused  by  splin- 
ters of  the  wood  invariably  suppurate  and  do  not  heal  readily.  Oliver 
found  that  rats  were  also  susceptible  to  sequoia  sawdust.  They  suffer 
from  a  running  at  the  nostrils. 

Certain  kinds  of  wood  have  a  bad  reputation  among  joiners.  Some 
sawdusts  are  more  irritating  than  others,  probably  from  the  large  amount 
of  inorganic  matter  they  contain.  A  West  African  boxwood  from  which 
shuttles  are  made  causes  headache,  coryza,  excessive  secretion  of  tears, 
and  attacks  of  asthma.  These  woods  contain  alkaloids,  glucosides,  and 
other  extractives.  Workers  in  teakwood  occasionally  suffer  from  der- 
matitis. 

MINING 

Coal  mining  is  one  of  the  dangerous  and  unhealthy  occupations. 
The  dust,  the  unnatural  conditions  under  which  the  miner  is  com- 
pelled to  work  underground,  the  poor  air,  and  sometimes  exposure  to 
poisonous  fumes  all  conspire  to  make  this  occupation  one  attended  with 
unusual  risks.  The  unsatisfactory  methods  for  disposal  of  feces  often 
found  in  mines  favor  the  spread  of  hookworm  and  other  parasites.  To 
this  must  be  added  the  danger  of  accidents  and  explosions. 

The  conditions  of  mines  have  been  greatly  improved,  especially 
through  better  systems  of  ventilation,  through  the  use  of  safety  lamps, 
through  reduction  of  the  amount  of  dust,  the  regulation  of  the  hours 
of  occupation,  and  devices  to  detect  poisonous  and  explosive  gases.  The 
sanitation  and  cleanliness  of  mines  have  also  shown  development.  As 
an  illustration  of  some  of  the  complications  and  difficulties  of  this  sub- 
ject, reference  is  made  to  the  fact  that  moisture  will  prevent  explosion 


942  INDUSTEIAL    HYGTEXE 

in  mines.  Moisture  was.  therefore,  introduced  into  some  of  the  German 
mines  with  good  results,  so  far  as  explosions  a^e  concerned,  but  the 
moisture  favored  the  development  of  the  hookworm  larvae  and  hence 
caused  such  a  great  increase  in  the  amount  of  hookworm  infection  that 
it  became  necessary  to  seek  other  methods. 

The  mortality  from  accidents  and  diseases  of  the  lungs  is  high. 
Coal  miners'  phthisis,  or  anthracosis,  is  a  well-known  disease.  Although 
coal  is  a  vegetable  product  the  result  largely  of  microbial  action,  fresh 
coal  is  free  from  microorganisms.  Oliver  points  out  that  in  some  of  the 
mining  centers  colliers  not  onl}'^  suffer  less  from  pulmonary  tuberculosis 
than  persons  in  other  occupations,  but  that  they  also  suffer  unequally 
in  different  mining  centers,  ^^^ly  this  is  so  it  is  difficult  to  say.  While 
the  death  rate  from  pulmonary  tuberculosis  in  miners  is  in  some  places 
low,  that  due  to  non-tuberculous  affections  of  the  lungs  is,  comparatively 
speaking,  high. 

DeCrocq  speaks  of  the  rarity  of  phthisis  among  Belgian  coal  miners. 
Arnold  reports  that  in  Germany  tuberculous  diseases  are  rare  among 
coal  miners  and  that  there  is  a  prevailing  opinion  that  anthracosis  is 
antagonistic  to  tuberculosis.  Goldman  attributed  the  freedom  of  the 
coal  miner  from  pubiionary  tuberculosis  to  an  antiseptic  action  of  the 
coal  dust. 

Other  diseases  to  which  coal  miners  are  subject  are  ''beat  hand,"'  as  a 
consequence  of  using  the  pick  and  friction  of  the  handle.  The  skin 
of  the  palm  over  the  bases  of  the  fingers  of  both  hands,  also  the 
skin  over  the  fleshy  ball  of  the  thumb  and  that  of  the  other  side  of 
the  hand,  becomes  extremely  hard  and  horny.  In  addition  to  the 
enormous  thickening  of  the  epithelial  layers  of  the  skin  there  is  in- 
flammation of  the  subcutaneous  connective  tissue.  Occasionally  suppura- 
tion takes  place  in  the  deeper  layers  of  the  hard  skin.  The  suppuratory 
areas  are  called  "keens"  by  the  miners.  Beat  hand  is  a  painful  affec- 
tion and  unfits  the  individual  for  work  for  some  time.  A  similar 
condition  sometimes  occurs  on  the  knees  and  elbows,  hence  the  term 
"beat-knee"  and  "beat-elbow."  Miners  also  frequently  complain  of  back- 
ache, largely  the  result  of  the  peculiar  mode  of  sitting  while  at  work. 
Dyspepsia,  miner's  nystagmus,  and  ankylostomiasis  are  other  conditions 
to  which  miners  are  prone. 

EFFECTS   OF  HEAT 

In  many  trades  workmen,  more  particularly  firemen,  stokers,  workers 
in  foundries  and  steel  mills,  are  exposed  to  high  degrees  of  heat.  Ed- 
salP  has  recently  called  attention  to  the  ill  effects  of  exposure  to  unusual 
degrees  of  heat.     The  symptoms  are  acute  and  violent  muscle  spasms. 

•  Jour.  Amer.  Med.  Assn.,  LI,  Dec.  5,  1908,  p.  1969. 


DISEASES    OF    OCCUPATION  943 

The  acute  effect  may  be  heat-stroke  and  heat  prostration ;  there  may  be 
nervous  lesicns  such  as  focal  meningitis,  as  well  as  more  or  less 
serious  circulatory  weakness,  anemia,  acute  and  chronic  disturbances  of 
digestion,  acute  and  chronic  nephritis.  Eespiratory  diseases  and  skin 
lesions  appear  to  be  unduly  frequent  in  persons  exposed  to  high  de- 
grees of  heat.  There  is  more  than  a  suspicion  that  cataracts,  retinal 
and  choroidal  changes,  or  chronic  conjunctival  lesions  are  brought  on 
in  glass-blowers  and  perhaps  also  in  iron  puddlers  and  other  persons 
whose  eyes  are  exposed  to  very  intense  heat  and  light.  De  Schweinitz 
states  that  he  can  often  tell  whether  men  working  at  puddling  furnaces 
are  right-handed  or  left-handed  by  studying  the  effects  of  this  exposure 
on  their  eye  grounds.  Eopke  ^  states  that  Quint  described  to  him  cases 
of  right-sided  cataract  in  right-handed  iron  workers  and  left-sided  in 
those  who  were  left-handed. 

PARASITES 

There  are  several  species  of  parasites  to  which  workmen  in  certain 
industries  are  specially  subjected.  Of  these  the  best  known  are :  anthrax, 
or  wool-sorter's  disease,  and  hookworm  disease,  or  miner's  anemia. 

Wool-sorter's  disease  is  an  infection  with  the  Bacillus  antliracis. 
The  spores  cling  to  the  hides  of  animals  that  have  died  from  the  disease 
or  have  been  slaughtered  on  account  of  it.  Spores  also  remain  attached 
to  wool  and  horsehair  and  to  pig's  bristles  used  in  brush-making.  The 
infection  may  be  taken  in  through  the  slightest  scratch  or  any  open 
Avound  or  through  inhalation  of  dust  containing  the  spores,  or  may  be 
ingested  in  the  food.  "Wool-sorter's  disease  most  often  appears  in  the 
wool-sorting,  wool-combing,  and  sj^inning  industries,  in  the  manipula- 
tion of  horsehair  for  stuffing  chairs  and  mattresses,  and  the  prepara- 
tion of  bristles  for  brush-making.  Anthrax  has  also  been  met  with  in 
persons  employed  in  tanyards  and  in  warehouses  that  connect  with 
docks.     The  subject  is  fully  discussed  by  Legge  in  his  Milroy  lectures.' 

The  prevention  of  anthrax  is  first  and  foremost  a  problem  in  animal 
husbandry  which,  in  this  country,  comes  under  the  purview  of  the  Bureau 
of  Animal  Industry.  Animals  having  anthrax  should  be  killed  and  all 
anthrax  carcasses  should  be  buried,  incinerated,  or  tanked  in  such  a 
manner  as  to  destroy  the  infection  and  prevent  its  dissemination.  This 
is  one  of  the  questions  for  international  sanitary  agreement,  for  the  wool 
from  Prussia,  the  hair  and  mohair  from  Asiatic  Turkey,  the  horse- 
hair from  China,  the  bristles  from  Siberia,  and  the  hides  from  India 
may  carry  the  anthrax  spores  from  these  far-off  lands  and  cause  in- 
fection among  our  workmen.      It   is  exceedingly   difficult  to   disinfect 

^Weyl's   "Hanclbuch   der  Arbeiterkrankheiten, "   1908. 
^Lancet.   March   18,   1905. 


944  INUUSTKIAL    HYGIENE 

hides  so  as  to  kill  the  antlirax  spores.  Horsehair,  eowliair,  goat's  hair, 
pig's  bristles,  and  wool  before  they  arc  manipulated  should  be  disin- 
fected either:  (1)  by  steam  at  17  pounds  pressure,  eijuivalcnt  to  220° 
F.,  for  at  least  half  an  hour;  (2)  by  boiling  for  at  least  a  (juarter  of 
an  hour  in  a  2  per  cent,  solution  of  i)otassium  })erinanganatc,  and  sub- 
sequent bleaching  in  a  3  to  4  per  cent,  solution  of  sulphurous  acid;  (3) 
by  boiling  in  water  for  at^least  two  hours.  In  Germany  the  government 
regulations  require  the  disinfection  of  wool  and  hair  from  foreign 
parts  and  provide  public  disinfection  stations  for  this  })urpose.  For  a 
discussion  of  antlirax  see  ])age  285. 

Hookworm  Disease. — Miners  are  specially  suljject  to  hookworm  dis- 
ease. The  parasite  enters  through  the  skin  from  the  polluted  soil  of 
the  mines.  The  outbreak  which  called  attention  to  this  danger  was 
the  eijidemic  which  occurred  among  the  workmen  on  St.  Gothard's 
tunnel  in  1892.  Since  then  the  disease  has  been  called  "miner's  ane- 
mia." Gunn^  found  that  from  50  to  80  per  cent,  of  those  working  in 
the  mines  of  California  and  the  neighboring  state  of  Nevada  were  in- 
fected with  hookworms.  For  a  full  discussion  of  hookworm  disease  see 
page  114. 

Other  occupations  in  which  there  is  a  special  exposure  to  the  risk 
of  infection  are:  physicians,  nurses,  ward-tenders,  pathologists,  experi- 
mental investigators,  etc. 

THE    CAISSON   DISEASE 

The  effects  of  compressed  air  and  the  effects  of  rarefied  air  are 
discussed  on  pages  598  and  GOO. 

REFERENCES 

Oliver,  Thomas :  "Diseases  of  Occupation,  from  the  Legislative,  So- 
cial, and  Medical  Points  of  View."    New  York,  1909. 

Weyl,  Theodor :  "Handbuch  der  Hygiene."  Gewerbehyg.,  Vol.  VIII, 
Jena,  1897. 

Various  authors:  "Eisks  in  Modern  Industry."  Published  by  the 
American  Academy  of  Political  and  Social  Science,  Phila.,  Pa.,  1912. 

Goldmark,  Josephine,  and  Brandeis,  L.  D. :  "Fatigue  and  Efficiency." 
Charities  Publication  Committee,  105  E.  22d  St.,  New  York,  1912. 

V.  A.  M.  A.,  Jan.  28,  1911,  Vol.  LVI,  No.  4,  p.  259. 


SECTION  XI 
SCHOOLS 

It  took  a  long  time  to  realize  that  the  whole  child  goes  to  school — 
his  boclr,  mind,  and  soul;  that  education  of  the  mind  alone  is  one- 
sided and  may  be  hurtful;  finally,  that  the  hygiene  of  the  child  and  his 
teacher,  as  well  as  the  sanitation  of  school  buildings  and  their  equip- 
ment, is  of  fundamental  importance.  The  combination  of  compulsory 
education  and  schools,  having  an  unbalanced  curriculum  or  impure 
water  or  vitiated  air  or  improper  sanitation,  is  nothing  short  of  a 
crime  by  the  state  against  the  state.  The  child  profits  directly  from 
attendance  upon  a  school  which  has  due  regard  for  the  child's  physical 
well  being  and  the  development  of  his  character;  the  state  profits  in- 
directly from  the  lessons  in  sanitation  and  hvgiene  which  are  carried 
into  the  child's  home,  and  are  applied  as  a  matter  of  course  in  the 
home  of  the  future  citizen.  Thus  the  principles  of  personal  hj'giene  and 
sanitation  become  second  nature,  and  in  this  way  the  conquest  of  the 
preventable  diseases  may  be  materially  hastened.  It  is  an  economic  waste 
to  educate  children  and  then  permit  them  to  die  of  some  prevental^le  in- 
fection before  they  have  reached  the  period  of  maturity  and  productivity. 

The  school  furnishes  abundant  material  for  the  physiologist  and  the 
psychologist  to  study  growth  and  development.  The  effect  of  the  nature 
and  order  of  the  studies  for  each  school  year;  the  hours  of  work,  rest, 
and  play;  the  direction  of  physical  exercise  should  all  be  regulated  ac- 
cording to  the  average  recjuirements  and  cajDacities  of  each  school 
period,  and  should  be  based  upon  accurate  observations  extending  over 
long  periods  of  time.  Both  the  immediate  effects  and  the  remote  in- 
fluences upon  adult  life  should  be  taken  into  consideration.  Youth  is 
the  time  of  unrest  and  activity,  and  it  is  part  of  the  school  work  to 
direct  these  energies  so  as  to  obtain  the  best  development;  youth  also 
requires  generous  nourishment  and  sufficient  sleep.  A  child  who  comes 
to  school  tired  and  worn  from  disturbed  slumber  cannot  profit  in  body 
or  mind.  The  child  who  comes  to  school  hungry  or  who  does  not  have 
a  judicious  luncheon  at  the  recess  j^eriod  is  seriously  handicapped  physi- 
cally and  mentally.  The  Cjuality  of  the  food  offered  for  sale  at  recess 
should  be  under  close  scrutiny.     The  hot  lunches  and  nutritious  food 

945 


94G  SCHOOLS 

furniphed  some  of  the  school  chiklren  in  Boston  and  other  cities  at  a 
reasonal)le  price  is  a  practical  and  wise  movement. 

One  of  the  dutirs  of  the  scliool  is  to  teach  and  to  recpiire  at  all 
times  cleanliness  of  person  and  clothing.  The  example  of  clean  school- 
rooms, corridors,  lockers,  toilets,  hasement,  and  grounds  will,  in  time, 
influence  the  yonng  citizen.  Floors  especially  should  he  ke])t  clean  and 
the  child  he  required  to  use  the  door  mats  before  entering  the  building. 
Dust  must  be  discouraged  in  all  ways.  In  some  schools  in  poor  districts 
it  is  a  good  j)lan  to  have  shower  baths  for  those  pupils  who  do  not 
enjoy  good  bathing  facilities  at  home.  A  toothbrush  drill  is  the  means 
of  teaching  many  a  child  the  first  principles  in  dental  prophylaxis.  The 
teacher  should  be  constantly  on  the  lookout  to  imjiress  upon  the  pu})ils 
the  elementary  facts  in  hygiene,  such  as  turning  aside  the  head  and 
holding  the  handkerchief  before  the  mouth  and  nose  when  coughing  or 
sneezing.  The  teacher  should  discourage  the  hal)it  children  have  of 
carrying  their  fingers  to  their  mouths  and  noses.  The  anti-spitting  rules 
should  be  reiterated  and  strictly  enforced.  The  danger  of  mouthing 
toys  and  pencils  and  the  habit  generally  of  placing  things  in  the  mouth 
should  be  discouraged;  "swapping"  partly  eaten  articles  of  food  should 
be  prohibited,  and  the  reasons  explained.  Cleanliness  is  not  instinctive 
in  children ;  it  must  be  learned.  The  significance  of  modern  biological 
cleanliness  can  come  only  through  education  and  example.  Progress 
in  these  matters  cannot  be  made  without  an  intelligent  understanding 
on  the  i)art  of  the  teacher.  It  is  therefore  important  to  teach  the 
teacher. 

Fatigue,  prolonged  and  oft  repeated,  may  injure  the  development 
and  health  of  the  child.  Fatigue  is  favored  by  poor  ventilation,  com- 
pulsory sitting  upon  hard  and  ill  fitting  seats  at  im])roperly  constructed 
desks,  prolonged  tension  of  a  strict  discipline,  studies  that  are  too  in- 
tensive, and  insufficient  relaxation  or  inconsiderate  treatment  of  the 
little  ones.  Discipline,  obedience,  and.  regard,  for  the  human  rights  of 
others  are  among  the  most  important  things  learned  at  school.  Many 
a  child  is  unjustly  disciplined  and  his  little  soul  harassed  through  no 
fault  of  his  own.  but  perhaps  on  account  of  defective  eyesight  or  hear- 
ing, or  other  physical  handicap,  or  some  mental  deficiency. 

The  question  of  home  work  should  be  carefully  regulated  in 
accordance  with  the  capacity  and  age  of  the  child.  Children  should 
not  be  kept  busy  at  prescribed  work  most  of  the  hours  of  the  day. 
Some  time  should  be  left  for  quiet  play  and  the  encouragement  of 
personal  inclinations  during  which  time  the  best  development  uncon- 
sciously occurs.  Initiative,  self-reliance,  and  self-help  are  submerged  by 
lack  of  free  time.  The  amount  and  nature  of  the  work,  both  in  and 
out  of  school,  must  be  judiciously  considered  and  should  be  based  upon 
long  years  of  careful  study  and  observation.     The  immediate  as  well  as 


SCHOOL    BUILDING  947 

the  remote  effects  should  be  taken  into  consideration.  Many  an  ill- 
tempered  child  is  simply  overwrought  and  chronically  tired  out  through 
excessive  application  of  a  conscientious  and  studious  nature  to  tasks 
beyond  the  physiological  capacity  of  his  little  brain  and  body. 

The  child  should  not  be  sent  to  school  too  young.  Children  must 
first  learn  to  walk,  run,  talk,  and  coordinate  muscles  before  they  under- 
take reading,  writing,  and  arithmetic.  Pupils  should  not  be  graded  ac- 
cording to  their  ages,  but  according  to  their  capacity  and  physical  de- 
velopment. 

For  the  elementary  schools  one  short  morning  session  is  enough. 
The  general  tendency  is  to  reduce  the  hours  of  compulsory  school  at- 
tendance and  increase  the  optional  time  through  elective  systems  which 
encourage  and  foster  native  talents. 

Primary  pupils  should  not  spend  more  than  one-third  of  their  school 
time  in  their  seats.  Exercises  of  various  kinds  that  call  into  play  mus- 
cular activity  are  most  important  at  this  age,  not  only  for  mental 
growth,  but  for  physical  growth,  as  well  as  for  relief  from  the  fatigue 
occasioned  by  sitting  at  desks. 

The  child  on  beginning  school  life  enters  an  environment  radically 
different  from  the  free  and  active  life  which  was  his  before  school  days 
began.  The  effect  may  be  seen  by  the  fact  that  children  usually  lose 
weight  and  the  nervous  system  becomes  affected  during  the  first  weeks 
of  school. 

Ungraded  or  special  schools  should  be  provided  for  backward  and 
defective  children  and  for  those  having  favus,  ring-worm,  rachitis,  or 
other  conditions  requiring  either  special  pedagogical  methods  or  par- 
ticular medical  treatment.  Open-air,  or  fresh-air,  schools  for  children 
who  have  or  are  threatened  with  tuberculosis  serve  a  very  useful  purpose. 

Finally,  the  whole  school  program  should  remember  that  the  object 
is  not  to  teach  the  child  to  be  a  child,  but  to  direct  his  development 
so  as  to  become  a  useful  man  or  woman.  The  school  system  should  there- 
fore be  carried  out  with  due  regard  for  future  events  and  should  be 
correlated  with  the  adult  life  of  the  child. 

School  Building. — The  school  must  be  centrally  located,  so  as  to  be 
convenient  especially  for  the  primary  and  grammar  grades,  and  the 
school  building  should  be  modern,  artistic,  clean,  and  sanitary  in  all  its 
appointments.  Every  school  building  should  have  playgrounds  con- 
nected with  it.  Playgrounds  should  be  level;  about  30  square  feet  for 
each  pupil  is  necessary  to  meet  the  demands  of  play.  Thus  1,000  pupils 
require  300  x  100  square,  feet  for  playgrounds  alone.  In  cities,  roofs 
may  be  utilized  for  play.  School -houses  should  be  built  in  places  that 
are  quiet  and  free  from  nuisances,  dangers  of  various  kinds,  and  on 
ground  that  is  either  naturally  dry  or  made  so  by  subsoil  drainage.  The 
building  should  be  solidly  constructed  and  should  stand  apart,  so  that 


948  SCHOOLS 

sun  and  air  may  reach  it  from  all  sides.  A  substantial  and  artistic 
structure  well  placed  has  an  important  influence  ui)on  the  yomij;  mind 
and  character.  _  Trees  and  judicious  landscape  gardening  should  pro- 
vide shelter  and  shade  and  add  to  the  attractiveness.  The  foliage,  how- 
ever, must  not  interfere  with  the  light  and  ventilation  of  the  school- 
rooms. If  the  building  faces  north,  with  corridors  and  stairs  on  this 
side,  all  the  rooms  will  have  sunlight  at  some  time  during  the  day. 
The  best  general  arrangement  of  tlie  ])lan  of  the  building  is  tbat  in 
which  the  school-rooms  are  all  placed  on  one  side  of  tlie  building,  with 
the  corridors,  halls,  stairways,  and  wardrobes  on  the  other.  Built  in 
the  old  way,  with  rooms  around  a  central  well,  school-bouses  have  dark 
central  balls  and  staircases,  and  favorable  ligliting  cannot  l)c  bad  in  some 
of  the  school-rooms. 

Buildings  three  or  four  stories  high  in  schools  which  re(Hiire  tbe 
pupils  to  pass  from  the  lower  to  the  upper  floors  several  times  a  day 
impose  a  stress  in  climbing  so  many  flights  of  stairs  tbat  may  be  in- 
jurious to  the  pupils,  cs])ecially  to  girls.  Such  buildings  may  be  pro- 
vided with  elevators,  or  at  least  with  inclines  instead  of  stairs. 

The  basement  should  be  under  the  Avhole  building  and  carefnlly 
protected  against  dampness.  Further,  the  basement  should  be  well 
lighted  and  sunny. 

School  buildings  should  have  at  least  two  entrances,  with  doors 
opening  outward;  the  halls  and  corridors  should  be  generous  and  well 
lighted,  and  the  stairs  have  easy  risers  and  treads  for  children.  The 
risers  sbould  lie  nl  out  6  inches  and  the  treads  no  greater  than  l'^  inches. 
The  School-room. — The  school-room  is  the  unit  in  ])lanning  a  school 
building;  that  is.  the  building  should  be  a  number  of  school-rooms 
properly  disposed,  and  not  a  building  cut  into  school-rooms  whose  size 
and  arrangements  are  dependent  upon  the  size  and  shape  of  the  building. 
Some  of  the  important  considerations  in  the  school-room  are  the 
number  of  pupils  to  be  accommodated,  its  size  and  shape,  the  amount 
and  direction  of  the  light,  the  ventilation  and  heating. 

The  minimum  floor  space  for  each  pupil  should  be  15  square  feet. 
If  18  square  feet  are  allowed  all  exercises  are  made  easier  both  for 
pupil  and  teacher.  Two  hundred  cubic  feet  of  air  space  is  the  minimum 
commonly  allowed ;  therefore  a  standard  school-room  designed  to  accom- 
modate 30  pupils  should  be  20  feet  wide  by  24  feet  long,  with  a  ceiling 
13  feet  high.  The  best  shape  for  a  school-room  is  that  of  an  oblong, 
the  width  being  to  the  length  about  as  3  to  4.  No  teacher  should  be  re- 
quired to  have  classes  exceeding  30  pupils.  The  rooms,  floor  space,  and 
air  space  should  be  at  least  as  capacious  for  the  primary  as  for  the 
grammar  grades. 

The  color  of  the  walls  should  be  such  as  to  absorb  the  least  light 
and  prove  least  taxing  to  the  eyes.    A  light  green-gray  is  favored.     The 


SCHOOL    FUENITURE 


949 


surface  should  not  be  glossy  and  should  either  Le  coated  with  an  oil 
paint,  so  that  the  walls  may  be  washed,  or,  better,  calcimined  with  a 
water  paint  that  may  be  readily  renewed.  The  ceiling  should  be  white, 
so  as  to  reflect  the  light. 

The  School  Furniture. — ^The  most  important  articles  of  school  fur- 
niture, considered  from  the  view  of  hygiene,  are  desks  and  desk  chairs, 
for  the  reason  that  the  pupil  spends  during  school  hours  so  much  time  at 
work  at  his  desk.  Unless,  therefore,  desks  and  chairs  are  constructed 
with  full  regard  for  certain  well-known  laws  of  hygiene  they  produce 
defects  of  eyesight,  injurious  effects  as  to  posture,  and  wrong  habits 
of  carriage  which  are  borne  through  life  and,  sadly  enough,  become 
more  pronounced  as  the  years  increase.^ 

Professor  Bowditch  of  Harvard  University  carefully  measured  and 
weighed  25,000  school  boys  and  girls  of  Boston  and  found  surprising 
variations.  Taking  ages  on  their  last  birthdays  Professor  Bowditch 
found  the  following:  variations  in  height : 


Boys 

Girls 

6  years  of  age 

47.132 
40.66 

47.36 

40.57 

Difference 

6.47 

6.79 

11  years  of  age 

57.50 
49.47 

57.96 

49.33 

Difference 

8.03 

8.63 

15  years  of  age 

67.90 
56.55 

65.00 

57.39 

Difference 

11.35 

7.61 

'  All  figures  are  inches. 

Besides  the  variations  in  height  there  is  also  variation  in  growth,  and 
provision  for  this  difference  must  therefore  be  made  in  the  construction 
and  adjustment  of  the  desk  and  seat.  The  growth  of  girls  is  more 
rapid  from  12  to  14  years  of  age,  while  boys  grow  most  rapidly  from 
14  to  16  years  of  age.  The  annual  growth  during  the  maximum  period 
is  often  an  inch  more  than  the  annual  growth  at  other  periods.  Fur- 
ther, there  exist  certain  anatomical  differences  of  proportion  between 
boys  and  girls.  The  sitting  height  of  girls  is  greater  proportionately 
than  their  standing  height  in  comparison  with  boys. 

The  Desk  and  Seat. — The  desk  and  seat  must  therefore  be  ad- 
justed so  as  to  provide  for  differences  of  height  and  differences  of  growth. 
The  desk  must  not  be  a  prison  stall,  but  should  be  comfortable   and 

^Shaw,  Edward  E.:   "School  Hygiene."     The  Macmillan  Co.,  N.  Y.,  1902. 
62 


950  SCHOOLS 

roomy.  It  must  not  favor  the  development  of  myopia  and  must  not 
force  a  pupil  into  wrong  postures.  The  matter  is  of  greater  importance 
than  school  men  generally  recognize. 

The  chair  and  seat  should  be  of  such  a  height  that  the  thigh  of  the 
pupil  when  seated  will  be  perfectly  level,  the  lower  leg  being  in  an 
exactly  vertical  position,  with  the  foot  resting  wholly  upon  the  floor; 
that  is,  the  thigh  and  the  lower  leg  will,  when  the  chair  is  of  a  proper 
height,  form  a  right  angle  with  each  other.  The  seat  must  therefore 
be  adjusted  accordingly.    The  seat  itself  should  not  be  flat,  but  somewhat 


FiQ.   139. — Faulty  Posture.     (Shaw's  "  School  Hygiene, "  Macmillan  Co.) 

concave,  the  lowest  part  of  the  concavity  being  where  the  tuberosities 
of  the  ischium  rest.  The  concavity  has  the  additional  advantage  of 
counteracting  the  tendency  to  slide  forward  on  the  seat  when  the 
pupil  leans  back.  The  seat  should  have  a  back  rest  that  will  sup- 
port the  small  of  the  back  properly  without  leaning  back  excessively. 
Whether  or  not  it  supports  the  rest  of  the  back  is  of  small  consequence. 
Support  of  the  back  carried  to  the  level  of  the  shoulder  blades  is  likely 
to  do  more  harm  than  good. 

The  distance  between  the  seat  and  the  desk  should  be  such  that  the 
scholar  may  read  at  the  desk  and  write  on  it  without  leaning  forward 
more  than  a  little  and  without  entirely  losing  the  support  of  the  back 


SCHOOL   FtJRmTURE  951 

rest.  The  desk  should  not  be  so  close  as  to  press  against  the  abdomen, 
nor  near  enough  to  interfere  with  easy  rising  from  the  seat.  This 
means  a  distance  of  10%  to  1-1%  inches  from  the  edge  of  the  desk  to 
the  seat  back.  It  also  means  that  the  seat  must  not  project  under  the 
desk  more  than  an  inch  at  most.  The  desk  should  be  high  enough 
for  the  arm  to  rest  comfortably  without  much  resting  of  the  elbow; 
not,  however,  so  low  that  the  scholar  must  bend  down  to  write  on  it. 


Fig.  140. — The  Heusinger  Desk.     (Shaw's  "  School  Hygiene, "  Macmillan  Co.) 

If  the  desk  top  is  made  to  slide  backward  and  forward  it  will 
give  the  pupil  more  freedom  of  movement  wliile  at  the  desk  and  will 
also  permit  him  to  sit  down  at  the  desk  and  rise  from  it  with  greater 
ease.  One  of  the  important  considerations  of  a  school  desk  is  the  proper 
slope  of  the  top.  It  is  well  known  that  the  line  of  sight  which  least 
taxes  the  eyes  should  fall  upon  the  printed  page  perpendicularly  to  its 


952 


SCHOOLS 


plane.  To  accomplish  this  some  writers  recommend  a  slope  of  45°  for 
the  desk  top;  others  30'^.  These  angles,  however,  are  not  practicable. 
The  Vienna  Expert  School  Desk  Commission  recommends  an 
angle  of  15°  for  the  desk  top,  which  is  also  approved  by  the 
experiments  of  Shaw.  Such  a  slope  pennits  a  perfect  pos- 
ture in  vertical  writing. 

A  foot  rest  is  sometimes  attached  to  desks.  The  weight  of  opinion 
is  now  against  foot  rests,  as  they  restrict  the  free  movement  of  the 
pupil's  feet  while  at  the  desk  and  interfere  with  opportunity  to  shift 
his  feet  and  legs  for  relief  from  inactivity,  and  further  interfere  with 
the  thorough  cleansing  of  the  floor  under  the  desk.  Shaw  recommends 
the  Heusinger  desk,  Fig.  140,  and  also  the  Ideal  desk.     The  desk  and 

scat  shown  in  the  accompanying 
photograph,  Fig.  141,  are  known  as 
the  Boston  school  desk  and  chair. 
There  are  now  many  thousands  in 
use  in  the  Boston  schools,  and  they 
are  being  adopted  elsewhere. 

The  seat  and  chair  should  be  ad- 
justed for  each  pupil  when  he  enters 
school  or  is  transferred  to  another 
room.  Desks  and  seats  sliould  be 
adjusted  at  least  twice  a  year:  at 
the  opening  of  school  in  September 
and  again  in  February  or  March. 

The  Blackboard. — The  black- 
board should  be  placed  upon  the  wall 
opposite  the  principal  liglit.  The 
board  should  not  have  a  shiny,  re- 
flecting surface,  and  should  never  be 
placed  between  windows  or  near 
them. 

The  best  blackboards  are  made  of  slate,  as  they  can  be  washed,  which 
lessens  the  dust  nuisance.  The  best  slate  for  this  purpose  is  a  greenish 
or  strong  black  color,  which  is  to  be  preferred  to  the  grays  and  brownish- 
blacks.  Colored  crayons  made  with  arsenic  or  sulphid  of  mercury  carry 
danger  and  should  be  prohibited. 

Posture. — Every  condition  must  be  eliminated  and  every  care  exer- 
cised to  prevent  the  acquiring  of  physical  defects  in  school,  as  well  as 
to  prevent  the  accentuation  of  those  physical  defects  which  the  chill 
may  have  possessed  before  entering  school.  Posture  during  sitting  is 
of  greater  consequence  than  posture  during  standing,  on  account  of 
the  longer  time  the  child  sits  and  the  muscular  fatigue  caused  by  the 
inactivity  of  a  great  number  of  muscles  of  the  body  for  a  long  period. 


Fig. 


141. — Boston  School  Desk  and 
Chaik. 


LIGHTING  953 

Stooping  over  the  desk  leads  to  myopia;  it  also  contracts  the  chest  and 
interferes  with  free  respiration,  and  puts  additional  labor  on  the 
heart;  it  results  in  round  shoulders  and  curving  of  the  spine  backward 
and  a  carriage  in  which  the  head  is  pitched  forward;  it  also  tends  to 
displacement  of  the  internal  organs,  both  of  the  abdomen  and  pelvis. 

In  order  that  the  pupil  may  be  in  a  proper  physical  condition  to 
maintain  an  erect  posture  while  in  hie  seat,  and  thus  form  correct 
habits  which  he  will  carry  through  life,  he  must  be  given  periods  of 
relief  from  sitting  at  the  desk  and  corrective  exercises  at  different  times 
during  the  day.  In  the  first  year  the  child  should  not  be  confined  at  his 
desk  more  than  one-third  of  the  time.  In  the  succeeding  years  the  total 
amount  of  time  occupied  at  the  desk  may  be  gradually  lengthened.  In 
addition  to  the  regular  recesses  there  should  be  frequent  short  inter- 
vals of  respite  from  sitting  at  the  desk  devoted  mostly  to  some  form 
of  physical  exercise. 

A  recess  of  not  less  than  20  minutes  during  the  morning  session 
and  again  during  the  afternoon  session,  when  all  pupils,  if  the  weather 
and  climate  permit,  go  out  of  doors  and  engage  in  some  form  of  active 
play,  is  of  incalculable  value  in  its  results  upon  physical  health  and 
mental  development.  In  addition  there  should  be  given  to  each  grade 
every  school  day  at  least  two  short  periods  of  systematic  physical  drills 
with  the  windows  open. 

Lighting. — The  light  must  be  of  proper  intensity,  equally  diffused, 
and  come  from  the  proper  direction.  So  far  as  intensity  is  concerned 
the  light  must  be  neither  too  dim  nor  too  strong,  both  extremes  being 
harmful.  The  general  rule  is  that  the  amount  of  transparent  glass  sur- 
face admitting  light  should  be  from  one-sixth  to  one-fourth  of  the  floor 
space.  The  correct  amount  of  window  space  will  depend  on  the  loca- 
tion of  the  building,  direction  from  which  the  light  is  admitted,  size 
and  shape  of  the  room,  and  the  proximity  of  other  buildings  or  objects 
which  might  obstruct  the  light. 

The  amount  of  transparent  glass  surface  required  for  proper  illu- 
mination must  be  great  enough  to  afford  sufficient  light  on  rainy,  over- 
cast, and  cloudy  days.  Excessive  window  space  is  scarcely  possible,  for 
the  excess  illumination  on  bright  days  may  be  regulated  and  softened 
with  shades  and  awnings. 

The  amount  of  illumination  is  measured  by  candle  meters  or  candle 
feet;  that  is,  the  illumination  afforded  by  a  standard  candle  at  a 
distance  of  one  meter  or  one  foot.  Shaw^  believes  that  the  illumination 
should  provide  at  least  50  candle  meters  in  the  most  unfavorable  part  of 
the  room. 

Factory-ribbed  glass  or  Luxfer  prisms,  which  refract  the  light  into 
the  parts  of  the  room  where  the  light  is  needed,  are  a  very  decided  ad- 

^Shaw,  Edward  R.:   "School  Hygiene."     The  Macmillan  Co.,  N,  Y.,  1902. 


954  SCHOOLS 

vantage,  especially  where  schools  have  a  small  amount  of  free  space 
in  crowded  city  districts. 

The  principal  light  should  come  from  the  scholar's  left,  so  as  not  to 
throw  annoying  shadows  while  writing.  Windows  may  also  be  placed 
in  the  rear  of  the  scholars.  When  practicable  a  skylight  furnishes  the 
best  direction  for  illumination.  Windows  may  also  be  placed  at  the 
right  for  ventilating  purposes  or  for  admitting  direct  sunlight  while 
the  scholars  are  not  engaged  in  study.  The  window  sash  should  be 
3I/2  to  4  feet  from  the  floor  and  should  reach  as  near  the  ceiling  as  the 
construction  of  the  building  will  permit,  for  the  higher  the  windows 
reach  the  deeper  the  light  penetrates  into  the  room.  Light  should 
never  enter  from  the  front  and  shine  in  the  pupils'  eyes.  Window 
curtains  should  be  "opaque"  and  of  a  greenish  cast.  The  upper  fourth 
of  the  window  furnishes  one-third  of  the  light,  also  the  best  light,  hence 
it  is  obvious  that  curtains  should  not  be  hnng  from  the  top,  but  from 
the  bottom,  and  should  roll  upward.  Artists  have  long  learned  the 
lesson  that  light  from  above  follows  the  direction  of  nature  and  is  most 
agreeable  and  best. 

Ventilation  and  Heating. — Ventilation  of  the  school-room  is  of 
paramount  importance.  There  is  a  great  waste  of  time  and  energy 
of  both  the  teacher  and  pupil  working  in  a  vitiated  atmosphere,  for 
pure  air  properly  conditioned  is  necessary  for  mental  work.  Bad  air 
means  sluggishness,  headache,  listlessness,  inattention,  lack  of  energy, 
and  a  depression  of  mental  vigor;  further,  bad  air  lowers  resistance  to 
certain  diseases.  In  cold  climates  ventilation  and  heating  go  hand  in 
hand. 

In  favorable  climates  and  during  mild  weather  the  windows  should 
be  kept  open.  Even  during  cold  weather  the  windows  should  be  opened 
periodically  and  the  room  thoroughly  flushed  out  with  fresh  air.  The 
windows  should  always  be  thrown  open  at  recess  and  also  during  calis- 
thenic  drills  and  physical  exercises.  The  experience  of  the  open-air 
and  fresh-air  schools  teaches  that  cold  is  a  fine  tonic  for  mind  and 
body. 

Direct  radiation  from  stoves  or  steam  coils  or  hot-water  pipes  is 
inadvisable  for  school-rooms.  The  hot-air  furnace  may  be  used,  pro- 
vided the  air  is  sui^ciently  moistened,  but  the  direct-indirect  system 
with  steam  or  hot-water  pipes  is  to  be  preferred.  Two  thousand  cubic 
feet  of  air  should  be  provided  for  each  scholar  hourly.  The  Massa- 
chusetts law  requires  30  cubic  feet  of  pure  air  every  minute  per  pupil 
(1,800  cubic  feet  per  hour).  The  fresh-air  inlet  should  be  capacious 
and  separate  outlets  for  the  foul  air  should  be  provided.  The  cross- 
section  of  inlets  and  outlets  should  equal  from  16  to  20  square  inches 
for  each  scholar.  Ordinarily  it  is  preferable  to  place  both  inlets  and 
outlets  on  the  same  side  of  the  room,  viz.,  upon  the  inner  wall  or  warm 


CLOAK-EOOMS  955 

side.  When  so  placed  the  warm  air  should  be  admitted  about  7  feet 
above  the  floor  and  the  foul  air  should"  pass  out  close  to  the  floor. 

Special  attention  should  be  given  to  the  question  of  humidity,  so 
that  the  warmed  fresh  air  shall  not  be  excessively  dry. 

The  temperature  commonly  accepted  as  proper  for  a  school-room  is 
between  60°  and  68°  F.  The  children  would  probably  work  to  better 
advantage  if  the  temperature  were  kept  a  few  degrees  lower  and  the 
humidity  kept  so  that  the  wet  bulb  never  goes  above  70°  F.  (see  page 
613.  A  thermometer  should  hang  at  about  the  breathing  line  in 
every  school-room  and  the  teacher  should  take  hourly  readings  and  keep 
a  record.  The  temperature  of  school-rooms  is  usually  too  high,  and 
those  heated  with  the  hot-air  furnace  are  usually  also  too  dry.  Both 
extremes  are  prejudicial.  If  the  air  of  the  neighborhood  is  smoky  and 
dusty  it  may  readily  be  flltered  before  it  is  pumped  into  the  school-room. 
The  combination  of  the  plenum  and  vacuum  systems,  the  air  being  driven 
by  rotary  fans,  is  one  of  the  best  methods  of  artificially  ventilating 
school-rooms.     (See  chapter  on  Ventilation.) 

Water-closets  and  Urinals. — Separate  accommodations  must  be  pro- 
vided for  the  sexes;  privies  in  country  districts  should  be  in  entirely 
separate  buildings.  The  urinals  should  be  constantly  and  automatically 
flushed  and  water-closets  and  urinals  should  be  made  to  allow  complete 
inspection  and  use  of  the  scrubbing  brush.  Thorough  ventilation  of 
the  toilet-rooms  should  be  planned  for  and  they  should  be  kept  clean 
and  sweet  at  all  times. 

The  water-closets  may  be  in  the  basement  if  properly  constructed 
and  independently  ventilated.  The  floors  should  be  asphalted  to  facili- 
taite  cleaning  and  flushing,  and  should  be  scrubbed  at  least  once  a  week. 
The  toilet-room  should  be  well  lighted.  Deodorizers  should  not  be  used, 
for  if  toilet-rooms  are  kept  clean  and  water-closets  well  flushed  they 
will  not  be  necessary.  Urinals  should  be  made  of  slate  or  hard  asphalt 
or  other  non-absorptive  material,  and  one  urinal  should  be  provided 
for  each  fifteen  boys.  The  outhouses  in  country  schools  should  be 
properly  constructed  and  under  supervision.  In  fact,  a  matron  should 
be  in  attendance  to  assist  the  little  tots  in  the  kindergarten  and  lower 
elementary  grades,  and  a  watchful  eye  on  the  part  of  the  master  of 
the  school  and  those  he  delegates  for  this  duty  should  be  kept  to  prevent 
misbehavior  in  toilet-rooms. 

Cloak-rooms. — There  should  be  one  cloak-room  for  each  class-room, 
and  it  should  connect  both  with  the  hall  and  the  class-room.  Cloak- 
rooms should  be  lighted  from  the  outside,  heated,  and  thoroughly  ven- 
tilated to  carry  ofE  odors  and  to  dry  tlie  clothing.  Hanging  the  clothing 
in  the  halls  is  undesirable,  for  obvious  reasons.  Each  j^upil  should  have 
a  shelf  on  which  to  lay  hats  and  small  articles,  hooks  upon  which  to 
hang  overcoats,  and  a  space  for  rubber  shoes  and  umbrella. 


956  SCHOOLS 

Teachers  should  see  to  it  that  the  pupils  do  not  sit  in  wet  shoes  and 
stockings  or  in  wot  clothes.  Each  school  should  have  some  provision 
for  drying  wearing  apparel,  such  as  a  drying  chamber  which  may  be 
in  charge  of  the  janitor,  to  dry  the  wet  clothing  during  school  hours. 

Dressing-rooms  should  also  be  provided  for  the  teachers.  All  such 
rooms  and  lockers  should  be  kept  scrupulously  clean. 

Cleanliness. — Schools  should  be  kept  scrupulously  clean  and  every 
precaution  taken  to  prevent  dust.  Cleanliness  of  person  and  surround- 
ings should  be  one  of  the  important  lessons  which  the  pupil  learns  at 
school.  Through  example  and  discipline  pupils  should  be  taught  to  love 
order  and  neatness  and  to  abhor  untidiness  and  slovenliness.  Cleanliness 
is  the  keynote  of  all  sanitation. 

Some  of  these  requirements  for  schools  are:  clean  drinking  water; 
bubbling  fountains  and  the  abolition  of  the  common  drinking  cup;  dis- 
continuance of  the  roller  towel,  cake  of  soap,  brush,  eomb,  or  other 
toilet  articles  used  in  common;  cleanliness  of  floors,  desks,  corridors, 
cloak-rooms,  toilet-rooms,  basement,  and  grounds;  the  prohibition  of 
dry  sweeping  or  dusting.  Blackboards  should  be  washed  frequently  to 
avoid  the  dust  nuisance,  and  the  floors  may  be  treated  with  one  of 
the  dustless  floor  oils.  The  windows  should  be  kept  clean,  and  each 
child  should  have  his  individual  books,  pencils,  and  other  accessories. 

Medical  Inspection  of  Schools. — The  medical  inspection  of  schools 
is  no  longer  an  experiment,  but  a  pressing  necessity.  It  is  founded  on 
a  recognition  of  the  close  connection  which  exists  between  the  physical 
and  mental  condition  of  children  in  the  whole  process  of  education. 
It  seeks  to  secure  ultimately  for  every  child,  normal  or  defective,  con- 
ditions of  life  compatible  with  that  full  and  effective  development  of  its 
organic  functions,  its  special  senses,  and  its  mental  and  spiritual  powers 
which  constitute  a  true  education. 

The  object  of  a  medical  inspection  of  schools  is  not  primarily  the 
treatment  of  diseases,  but  rather  their  prevention.  One  of  the  principal 
objects  is  the  early  recognition  of  physical  defects  such  as  errors  of  re- 
fraction, imperfect  hearing,  malformations  of  the  body  from  abnormal 
positions,  adenoids,  enlarged  tonsils,  and  other  ol)structions  of  breath- 
ing, and  sources  of  inflammation,  etc.  An  important  object  of  the  med- 
ical inspection  of  school  children  is  to  determine  their  fitness  to  enter 
school  and  to  recognize  mental  and  nervous  disorders;  also  the  early 
recognition  of  the  communicable  diseases  and  measures  to  prevent  their 
spread ;  the  supervision  of  vaccination,  and  disinfection ;  the  teaching  of 
personal  hygiene  to  pupils  and  teachers,  and  the  sanitation  and  clean- 
liness of  the  school  building  and  its  surroundings;  the  adjustment  of 
the  seat  and  desk,  and  the  medical  supervision  of  the  mental  and  physical 
work  of  the  child. 

Medical  inspection  of  schools  is  making  slow  progress.    A  systematic 


MEDICAL    IXSPECTIOX  957 

school  inspection  was  started  in  Brussels  in  1874  and  in  Paris  in  1884:, 
since  which  time  the  movement  has  become  world-wide.  In  America 
the  first  systematic  inspection  of  school  children  was  begun  in  1894, 
after  four  years'  effort  by  Dr.  Samuel  H.  Durgin,  Commissioner  of 
Health  of  Boston,  who  is  regarded  as  the  father  of  the  system  through- 
out America.  The  first  scientific  and  extensive  examination  of  school 
children  was  made  by  Dr.  Henry  P.  Bowditch,^  whose  essay  upon  "The 
Growth  of  Children  Studied  by  Galton's  Method  of  Percentile  Grades" 
has  become  a  classic  in  the  subject.  In  1908  there  were  only  seventy 
cities  outside  of  Massachusetts  having  medical  inspection  of  schools. 
Massachusetts  has  a  compulsory  medical  inspection  law ;  New  Jersey  has 
a  permissive  one;  Averment  has  a  law  requiring  an  annual  testing  of 
the  vision  and  hearing  of  all  school  children,  and  Connecticut  one  pro- 
viding for  such  tests  triennially. 

Physical  defects  are  not  equally  significant  either  from  the  medical 
or  from  the  pedagogical  standpoint.  Each  kind  of  defect  should  be 
separately  studied,  and  classifications  should  not  include  pediculosis 
with  defective  vision;  club-foot  with  defective  hearing;  adenoids  with 
ringworm. 

The  objects  of  the  medical  inspection  of  schools  may  be  greatly  as- 
sisted by  teaching  the  teachers  the  elementary  facts  concerned. 

Medical  inspection  of  schools  was  organized  in  this  country  for  the 
purpose  of  controlling  the  communicable  diseases  of  childhood.  It 
must  at  once  be  admitted  that  it  has  been  a  failure  so  far  as  this  ob- 
ject is  concerned,  for  it  has  had  very  slight  influence  upon  the  prevalence 
of  measles,  scarlet  fever,  diphtheria,  whooping-cough,  mumps,  etc.  Theo- 
retically we  would  expect  a  good  system  of  medical  inspection  of  school 
children  to  check  the  prevalence  of  these  diseases.  Perhaps  it  does 
so  to  a  limited  extent.  With  improvements  in  the  system  and  enthusi- 
asm in  the   cause  much  may  still  be  accomphshed  along  these  lines. 

There  has  been  much  discussion  concerning  who  shall  conduct  the 
medical  inspection.  It  is  plain  that  in  any  system  the  teacher  must  be  the 
"ultimate  inspector,  and  teachers  are  quite  competent  to  carry  out  simple 
tests  for  determining  the  acuteness  of  vision  and  hearing.  In  one 
sense  the  teacher  is  the  foster  mother  of  the  child  and  frequently  knows 
the  child  better  than  its  own  mother.  The  teacher  should  report  to 
the  medical  inspector  children  who  show  any  of  the  following  symptoms : 
loss  of  weight,  pallor,  puifiness  of  the  face,  shortness  of  breath,  swellings 
in  the  neck,  general  lassitude,  growing  pains,  rheumatism,  flushing  of 
the  face,  eruptions  of  any  sort,  cold  in  the  head,  especially  running  eyes, 
irritating  discharge  from  the  nose,  evidence  of  sore  throat,  cough,  vomit- 
ing, or  frequent  requests  to  go  to  the  toilet. 

^  Twenty-second  Annual  Eeport,  State  Board  of  Health  of  Mass.,  1890,  pp. 
479-522. 


958  SCHOOLS 

The  next  most  important  link  in  the  chain  of  a  good  system  of 
medical  inspection  is  the  nurse.  She  is  ahle  to  detect  the  beginning 
symptoms  of  disease  and  can  be  trusted  to  treat  sim])le  troubles.  The 
chief  value  of  the  school  nurse,  perhaps,  is  in  establishing  communica- 
tion with  the  home  and  securing  friendly  cooperation  with  the  parents. 
Parental  neglect  is  rarely  due  to  the  lack  of  parental  affection,  but  to 
ignorance.  The  nurse  is  frequently  able  to  gain  the  confidence  of  both 
child  and  parent  when  the  medical  inspector  fails.  The  nurse,  further, 
will  assist  the  medical  staff  in  carrying  out  treatment.  One  of  the 
chief  duties  of  the  school  nurse  is  a  sort  of  social  service. 

It  is  the  duty  of  the  medical  inspector  to  detect  defects,  not  to  treat 
them.  Who  shall  treat  the  child  is  a  matter  for  the  parents  or  guardian 
to  decide.  It  is  not  suflficient  merely  to  notify  parents  that  the  child 
needs  treatment,  for  frequently  no  attention  is  paid  to  the  notices.  The 
child  may  be  referred  to  or  taken  by  the  school  nurse  to  the  hospital  or 
outclinic.  In  some  districts  school  clinics  have  been  instituted  with 
success. 

Duties  of  the  Medical  Inspectors. — An  ideal  system  of  medical 
inspection  of  schools  would  consist  of  a  corps  of  trained  and  competent 
physicians  and  sanitarians  who  would  devote  their  entire  time  to  this 
special  work.  The  staff  should  have  the  assistance  of  experts  in  ven- 
tilation and  heating,  experts  in  sanitary  architecture,  experts  in  sanitary 
engineering,  and  experts  in  the  various  medical  specialties. 

Specialists  should  visit  all  school  buildings  no  less  than  three  times 
each  year  in  order  to  investigate  all  matters  of  heating,  lighting,  and 
ventilation,  cleanliness,  gymnasiums,  bath,  and  toilets,  and  the  seat- 
ing arrangements  with  reference  to  the  size  of  the  pupils ;  the  purity  of 
the  drinking  water,  the  quality  of  the  food  purchased  by  the  children  at 
the  recess  period,  and  the  general  conditions  of  the  neighborhood  that 
may  affect  the  health  of  the  pupils.  Furthermore,  cooperation  between 
the  medical  and  pedagogical  departments  should  be  helpful  in  solving 
the  many  difficult  problems  concerning  the  curriculum. 

In  addition  to  these  general  inspections  all  children  entering  school 
should  be  examined  individually  three  times  during  the  first  year.  The 
first  examination  is  for  the  purpose  of  establishing  whether  the  child 
is  fit  for  school  and  can  do  the  work  without  injury  either  to  its  mental 
or  physical  well-being.  The  second  should  be  a  physical  examination, 
which  may  be  made  more  thorough  if  the  child  is  required  to  strip. 
This,  however,  should  not  be  done  unless  the  parents  of  the  child  are 
present  or  give  their  consent.  The  third  examination  consists  of  special 
tests  of  the  eyes,  ears,  nose,  throat,  and  teeth. 

Aside  from  these  regular  examinations  the  school  physician  must 
respond  to  every  call  when  a  pupil  comes  to  school  having  an  eruption, 
fever,  or  other  symptoms  indicating  a  communicable  disease.    The  med- 


COMMUNICABLE    DISEASES    OF    CHILDHOOD 


959 


ical  inspectors  should  also  oversee  disinfection,  vaccination,  and  certify 
the  return  to  school  of  any  child  who  has  been  out  of  school  by  reason 
of  a  communicable  disease. 

The  Communicable  Diseases  of  Childhood. — Parents  naturally  come 
to  regard  the  school  as  a  veritable  pesthouse  for  the  spread  of  the  com- 
municable diseases  of  childhood — especially  measles,  whooping-cough, 
mumps,  diphtheria,  scarlet  fever,  chicken-pox,  common  colds,  etc.  Many 
of  these  diseases  prevail  in  epidemic  form  during  the  summer  time, 
when  school  is  closed,  and  under  other  circumstances  which  show  that 
epidemics  may  be  independent  of  school  attendance.  It  is  difficult  to 
determine  just  what  part  is  played  by  the  commingling  of  the  pupils 
in  school  in  the  spread  of  such  diseases  and  what  part  is  due  to  other 
factors.  Some  diseases  take  a  sudden  jump  in  the  autumn  with  the 
opening  of  school.  Further,  these  diseases  are  not  contracted  by  the 
school  children  alone,  but  are  carried  home  to  the  other  members  of 
the  household,  and  thereby  create  secondary  foci.  This  problem  of  the 
communicable  diseases  and  the  schools  is  far  from  solution;  the  spread 
of  these  diseases  has  not  been  conquered  by  medical  inspection,  and  their 
relation  to  school  attendance  is  one  that  needs  careful  observation  and 
study. 

THE  PERIOD  OF  EXCLUSION  FROM  SCHOOL  FOR  THE  COMMON  COMMUNICABLE 

DISEASES 


Scarlet  fever 

6  weeks,  or  longer  if  redness  of  the  throat,  nasal 
discharge  or  other  sequelae  persist 

Measles 

2  weeks  from  date  of  appearance  of  eruption 

German  measles 

1  week  from  date  of  appearance  of  eruption 

Chicken-pox 

Until  aU  scabs  are  gone 

Diphtheria 

1  week  after  second  negative  culture  from  nose 
and  throat 

Whooping-cough 

8  weeks  from  appearance  of  characteristic  cough 

Mumps 

3  weeks  or  longer  if  swelling  persists 

Pediculosis 

Until  aU  parasites  and  nits  are  gone 

Ringworm 

Scabies 
Impetigo 

Until  examination  reveals  successful  treatment 

The  question  of  closing  the  schools  when  some  one  of  these  diseases 
breaks  out  is  often  a  difficult  one  to  decide.  If  the  children  commingle 
out  of  school,  upon  the  streets  and  playgronnds,  no  useful  purpose  is 
accomplished  by  closing  the  schools.  At  the  beginning  of  an  outbreak 
of  measles  or  scarlet  fever  the  schools  may  be  closed  for  two  weeks  and 
then  opened,  but  careful  guard  must  be  exercised  to  discover  new  cases 


960  SCHOOLS 

and  a  watch  kept  over  the  return  of  convalescents.  Under  these  cir- 
cumstances a  daily  inspection  should  he  conducted  before,  and  not  after, 
the  children  enter  school.  If  closinfr  the  schools  for  two  weeks  is  not 
effective  probably  nothing  will  be  gained  by  prolonging  the  period. 

The  diseases  for  which  children  should  be  excluded  from  school  are: 
smallpox,  scarlet  fever,  measles,  German  measles,  chicken-pox,  diph- 
theria, tonsillitis,  whooping-cough,  pediculosis,  mumps,  scabies,  tra- 
choma, ringworm,  impetigo  contagiosa,  venereal  disease,  pulmonary  tu- 
berculosis, influenza. 

.The  Eyes.  — Errors  of  refraction  are  exceedingly  common,  and  if  not 
corrected  are  the  cause  of  headache,  nervousness,  reflex  pains,  and  a 
great  variety  of  symptoms.  They  are  also  a  great  handicap  to  the 
mental  and  physical  development  of  the  child.  The  vision  of  all  chil- 
dren should  be  examined  annually,  and  at  least  once  for  color-blindness. 
It  has  been  shown  that  the  unnatural  strain  of  accommodating  the  eyes 
to  close  work  (for  which  they  were  not  intended)  leads  to  myopia  in  a 
large  proportion  of  growing  children.  Thus  the  percentage  of  myopia  in- 
creases markedly  from  the  primary  classes  through  the  grammar  grades, 
and  is  highest  in  the  high-schools.  The  eyes  should  therefore  be  tested 
and  errors  of  refraction  corrected  at  least  once  a  year.  There  are 
certain  children  who  show  normal  vision  by  the  ordinary  tests  (Snellen 
test  type),  yet  whose  eyes  should  be  examined  by  an  export  if  they 
habitually  hold  the  head  too  near  the  book  (less  than  12  to  14  inches) ; 
or  if  they  frequently  complain  of  headache,  especially  in  the  latter  por- 
tion of  school  hours;  or  if  one  eye  deviates  even  temporarily  from  the 
normal  position.  The  following  symptoms  also  indicate  trouble  with 
the  eyes,  viz.,  scowling  and  wrinkling  of  the  forehead  when  reading  or 
writing,  twitching  of  the  face,  inattention,  and  slowness  in  book  studies 
in  a  child  otherwise  bright. 

The  conditions  which  are  especially  hard  upon  the  eyes  are  dim  light, 
improper  angle  of  vision,  small  print,  and  prolonged  focusing  at  close 
range.    Type  for  books  should  not  be  smaller  than  the  following: 


First  year 

Second  and  third  years . 

Fourth  year 

Above  this  grade 


Type 


2.6  mm. 
2.0  mm. 
1 .8  mm. 
1 .6  mm. 


Width  of  Leading 


4.5  mm. 
4 . 0  mm. 

3.6  mm. 
3.0  mm. 


In  addition  to  the  size  the  characters  should  be  sim])le,  the  ink 
black,  and  printed  upon  paper  with  a  mat,  unreflecting  surface  tliat  is 
free  from  gloss.  Paper  of  a  grayish  tone  is  to  be  avoided  and  the  paper 
should  be  thick  enough  or  of  such  quality  that  the  print  does  not  show 


NOSE    AND    THEOAT  961 

through  from  the  back.  Pupils  should  be  taught  that  it  is  advisable 
while  reading  or  during  other  close  focusing  of  the  eyes  occasionally  to 
look  away  and  accommodate  for  distance  to  relieve  the  tension  and  coun- 
teract the  tendency  to  myopia. 

The  Ears. — It  has  been  found  that  approximately  20  per  cent,  of 
school  children  possess  some  defect  of  hearing  either  in  one  or  both 
ears.  Defective  hearing  is  frequently  mistaken  for  inattention  upon  the 
part  of  the  pupil,  for  which  he  may  be  unjustly '  punished.  Practical 
tests  to  determine  the  acuteness  of  hearing  should  be  made  separately 
with  each  ear  by  the  use  of  a  watch  or  by  the  whisper  voice.  Dis- 
charges from  the  ears,  known  as  abscesses  in  the  ears,  or  earache  should 
at  once  be  reported  to  the  proper  medical  attendant. 

The  Teeth. — The  proper  use  of  the  toothbrush  and  silk  floss  to  keep 
the  surfaces  and  spaces  between  the  teeth  clean  should  be  impressed 
upon  every  pupil.  For  young  children  silk  floss  is  not  advisable  if 
the  space  between  the  teeth  is  filled  with  soft  tissue.  The  teeth  should 
be  examined  by  a  competent  dentist  at  least  once,  and  preferably  twice, 
a  year.  In  the  light  of  our  present  knowledge  it  is  an  outrage  to  allow 
caries  of  the  teeth  to  develop  into  toothache  before  children  are  taken 
to  a  dentist.  Irregularities  of  the  teeth,  especially  those  which  make  it 
impossible  to  close  the  mouth  properly,  lead  to  faulty  digestion,  to  mouth 
breathing,  and  other  defects.  The  first  permanent  molars  are  perhaps 
the  most  important  teeth  in  the  mouth,  and  are  the  most  frequently 
neglected  because  they  are  so  often  mistaken  for  temporary  teeth.  It 
should  be  known  that  decay  of  the  teeth  is  caused  primarily  by  the 
fermentation  of  starchy  foods  and  sugars,  so  that  the  greatest  factor 
in  preventing  dental  caries  is  the  removal  of  food  particles  by  frequent 
brushing  and  the  use  of  the  silk  floss.  Children  should  be  discouraged 
from  eating  crackers  and  candy  between  meals  and  the  teeth  should  be 
cleaned  after  each  meal. 

To  provide  expert  dental  attention  for  all  carious  teeth,  including 
the  temporary  set,  would  overtax  the  facilities  of  any  community.  Den- 
tal clinics  should  be  provided  in  which  caries  of  the  temporary  teeth 
should  have  at  least  temporary  treatment.  It  should  be  remembered  that 
one  infected  tooth  is  like  a  rotten  apple  in  a  barrel  in  that  it  is  apt  to 
involve  the  others. 

Nose  and  Throat. — The  noses  and  throats  of  all  pupils  should  be 
examined  for  any  cause  of  obstruction  to  respiration,  particularly  ade- 
noids, polypi,  deviation  of  the  septum,  etc.  Nosebleed  should  always  be 
reported  and  inquiry  should  be  made  as  to  mouth-breathing  during 
sleep.  In  all  cases  of  acute  illness  the  throat  and  mouth  should  be 
examined  for  indications  of  scarlet  fever  or  measles  and  for  the  signs 
of  tonsillitis  or  diphtheria,  and  a  culture  should  be  taken  in  any  sus- 
pected case  of  diphtheria.     The  presence  of  a  discharge  froni  the  nose 


962  SCHOOLS 

should  be  noted,  and  if  it  is  thick  and  creamy  a  culture  should  always 
be  taken.  If  the  discharge  from  the  nose  is  only  from  one  nostril  a 
foreign  body  or  local  cause  should  be  looked  for.  Adenoids  may  be  in- 
ferred from  mouth-breathing,  snoring,  chronic  post-nasal  catarrh,  or 
recurring  ear  trouble.  Pupils  with  obviously  large  tonsils,  recurring 
tonsillitis,  and  enlargement  of  the  glands  of  the  neck  should  be  referred 
to  a  physician  for  treatment. 

Diseases  of  the  Skin. — Apart  from  the  exanthemata  the  diseases  of 
the  skin  which  are  of  importance  because  communicable  are :  scabies, 
pediculosis,  ringworm,  and  impetigo. 

Scabies. — All  children  who  are  scratching  or  have  an  irritation  on 
the  skin  should  be  examined  for  scabies  (the  itchmite).  It  is  important 
that  all  infected  members  of  the  family  be  treated  until  cured,  else  the 
disease  is  passed  back  and  forth  from  one  to  another.  It  is  also  im- 
portant that  all  clothing,  bedding,  towels,  etc.,  and  similar  things  that 
come  in  contact  with  the  body  be  boiled  each  time  they  are  washed.  All 
cases  of  scabies  should  be  excluded  from  school  until  cured.  Sulphur 
ointment  is  usually  efficacious. 

Pediculi  Capitis. — Pediculi  capitis  (head  lice)  are  extremely  com- 
mon among  children,  and  are  communicated  directly  and  also  by  wearing 
each  other's  hats  or  hanging  them  on  each  other's  pegs,  or  from  combs 
and  brushes.  No  person  should  be  blamed  for  having  lice,  only  for 
keeping  them.  The  condition  may  be  suspected  by  the  teacher  in  chil- 
dren who  show  indications  of  irritation  of  the  scalp,  and  the  condition 
is  easily  detected  by  looking  for  the  eggs  (nits),  which  are  small  white 
objects  adhering  to  the  hair.  Head  lice  are  best  treated  by  killing  the 
living  parasites  with  crude  petroleum  and  then  getting  rid  of  the  nits. 
With  boys  this  is  easy;  a  close  haircut  is  all  that  is  needed.  With  girls 
a  fine-tooth  comb  wet  in  alcohol  or  vinegar,  which  dissolves  the  attach- 
ment of  the  eggs  to  the  hair,  may  be  used.  All  combs  and  brushes  used 
should  be  carefully  washed  and  disinfected.  Children  with  pediculi 
should  be  excluded  from  school  until  their  heads  are  clean. 

EiNGWOKM. — Eingworm  of  the  skin  yields  readily  to  treatment, 
but  upon  the  scalp  is  extremely  chronic.  When  the  disease  attacks  the 
scalp  the  hair  falls  off  or  breaks  off  near  the  scalp,  leaving  areas  the 
size  of  a  dime  or  dollar  nearly  bald.  The  scalp  in  these  areas  is  usually 
dry  and  somewhat  scaly,  but  may  be  swollen  and  crusted.  The 
disease  spreads  at  the  circumference  of  the  area  and  new  areas  arise 
from  scratching,  etc.  The  diagnosis  is  made  by  looking  for  the 
fungus. 

Favus. — Favus  is  a  disease  somewhat  allied  to  ringworm,  more  com- 
mon in  Europe  than  in  America.  In  this  disease  quite  abundant  crusts 
of  a  yellowish  color  are  present  when  the  process  is  active.  The  roots 
of  the  hair  are  killed  by  the  Achorion  schdnleinii,  so  that  loss  of  hair 


NERVOUS    DISEASES  963 

from  this  disease  is  permanent,  a  scar  remaining  when  the  condition  is 
cured. 

Children  with  ringworm  or  favus  should  not  be  allowed  to  attend 
school.  Children  should  be  taught  to  use  their  own  brushes  and  combs 
and  not  to  wear  each  other's  hats,  caps,  etc.  In  some  districts  special 
schools  are  maintained  for  favus  and  for  ringworm  of  the  scalp,  where 
the  pupils  receive  treatment. 

Impetigo. — Impetigo  is  a  disease  characterized  by  pustules  which 
appear  on  the  face,  neck,  and  hands,  less  often  upon  the  body  and  scalp. 
The  size  of  the  pustules  varies  very  much  and  they  often  run  together  to 
form  on  the  face  large  superficial  sores  covered  with  thick,  dirty,  yellow- 
ish, or  brownish  crusts.  The  disease  is  contagious  and  spreads  by 
scratching  as  well  as  by  using  common  towels  and  other  things.  Chil- 
dren having  impetigo  should  not  be  allowed  to  attend  school  until  all 
the  sores  are  healed  and  the  skin  smooth. 

Nervous  Diseases  and  Mental  Defects. — A  sharp  lookout  for  indica- 
tions of  diseases  of  the  nerves  and  of  mental  defects  should  be  kept  and 
especial  notice  taken  of  suggestive  symptoms  in  a  child  who  did  not 
formerly  show  them.  The  teacher  should  be  taught  to  report  instances 
of  restlessness  or  inability  to  stand  or  sit  quietly  in  a  previously  quiet 
child,  especially  if  to  this  are  added  irritability  of  temper  and  loss  of 
self-control,  such  as  crying  for  trifles  or  inability  to  keep  the  attention 
fixed. 

Chorea. — Twitching  of  the  muscles,  the  result  of  disease,  may  cause 
the  child  to  drop  things,  render  his  work  awkward,  or  interfere  with 
writing  or  drawing.  Such  children  are  too  often  scolded  for  being  in- 
attentive or  careless.  The  indications  of  chorea  (St.  Vitus's  dance) 
should  not  be  confounded  with  habit-spasms  such  as  blinking  of  the 
eyelids  or  the  slower  twitching  movements  of  the  face  or  shoulders  or 
other  parts  of  the  body,  which  may  be  due  to  defects  of  vision,  adenoid 
growths,  or  other  reflex  causes.  Cases  of  chorea  should  be  removed 
from  school  at  once,  both  for  the  child's  sake  and  to  prevent  an  epidemic 
of  imitative  movements  such  as  sometimes  occurs.  Children  with  habit- 
spasms  need  not  be  withdrawn  from  school  work,  although  these  condi- 
tions often  require  treatment. 

Epilepsy. — Mild  epileptic  attacks  (petit  mal)  are  frequently  over- 
looked or  misunderstood  by  the  teacher.  They  may  be  mistaken  for 
fainting.  Usually  these  attacks  are  only  momentary,  in  which  the  child 
stares  fixedly  and  does  not  reply  to  questions  or  in  which  he  suddenly 
stops  speaking  or  whatever  he  is  doing  and  is  unaware  of  what  is 
going  on  about  him.  The  lapse  of  consciousness  is  one  of  the  charac- 
teristic features  of  epilepsy.  The  attack  may  be  accompanied  by  rolling 
up  of  the  eyes,  drooling,  or  unusual  movements  of  the  lips ;  an  epileptic 
fit  often  appears  like  a  choking  attack.     Teachers  very  frequently  mis- 


964  SCHOOLS 

understand  epileptic  attacks  and  cannot  be  expected  to  dii^tinguish  them 
from  hysterical  convulsions  and  other  diseases.  It  does  not  necessarily- 
follow  that  eases  of  epilepsy  should  he  withdrawn  from  the  school,  but 
medical  advice  should  always  be  had. 

Neurasthenia. — Neurasthenia  or  nerve  fatigue  may  be  shown  by 
irritability  or  sleeplessness  and  other  indications  tlireatening  a  nervous 
breakdown.  This  may  be  due  to  irregular  habits,  want  of  proper  sleep, 
lack  of  suitable  food,  poor  hygienic  conditions,  or  simply  from  the  child 
being  pushed  in  school  beyond  his  physical  or  mental  capacity.  Exces- 
sive fear  or  morbid  ideas,  bashfulness,  undue  sensitiveness,  causeless  fits 
of  crying,  morbid  introspection,  and  self-consciousness  may  also  be 
symptoms  of  a  neurasthenic  condition,  and  call  for  investigation  and 
for  the  teacher's  sympathy  and  winning  of  the  child's  confidence  to 
prevent  developments  of  a  more  serious  nature. 

The  teacher  should  know  that  forgetfulness,  loss  of  interest  in  work 
and  play,  desire  for  solitude,  untidiness  in  dress  or  person,  and  like 
changes  of  character  are  sometimes  incidental  to  the  period  of  puberty. 

Defectives. — Mentally  defective  children  in  the  public  schools 
exhibit  certain  common  characteristics  which  soon  become  evident.  The 
typical  incorrigible  child  of  the  primary  grades  often  is  a  mentally 
defective  child  of  the  excitable  type.  They  are  destructive,  cruel  to 
smaller  children,  and  often  precocious  sexually.  Certain  cases  show 
marked  moral  deficiency.  Mentally  defective  children  must  be  distin- 
guished from  those  who  are  only  temporarily  backward  as  a  result  of 
some  removable  cause  such  as  defective  vision,  impaired  hearing,  ade- 
noid growths,  or  as  the  result  of  unhappy  home  conditions,  irregular 
habits,  want  of  proper  sleep,  lack  of  suitable  food,  bad  hygienic  condi- 
tions, etc.  Teachers  should  refer  to  the  medical  inspectors  for  examina- 
tion children  who,  without  obvious  cause,  such  as  absence  or  ill  health, 
show  themselves  unable  to  keep  up  in  their  school  work,  who  are  unable 
to  fix  their  attention,  or  are  incorrigible. 

A  careful  lookout  should  be  kept  for  children  showing  sexual  per- 
version, for  one  sexual  pervert  may  demoralize  a  whole  school. 

Vaccination. — Vaccination  should  be  required  of  all  children  be- 
fore they  are  permitted  to  attend  school.  The  evidence  of  a  successful 
vaccination  usually  accepted  is  a  physician's  certificate  or  a  characteris- 
tic scar.  For  the  indices  of  a  successful  take  see  page  11.  School 
children  should  be  vaccinated  before  entering  school  and  again  before 
entering  high  school. 

REFERENCES 

The  following  references  have  been  used  in  the  preparation  of  this 
chapter,  especially  the  books  of  Shaw  and  Hogarth. 


EEFERENCES  965 

Shaw,  Edward  R. :  "School  Hygiene."  The  Macmillan  Co.,  N.  Y., 
1902. 

Hogarth,  A.  H. :  "Medical  Inspection  of  Schools."  Oxford  Medical 
Publications,  London,  1909. 

Gulick,  L.  H.,  and  Ayres,  L.  P. :  "Medical  Inspection  of  Schools." 
New  York  Charities  Publication  Committee,  MCMVIII. 

Stevens,  E.  M. :  "Medical  Supervision  in  Schools."  Bailliere,  Tin- 
dall,  and  Cox,  London,  1910. 

Baginscky,  Adolf:  "Handbuch  der  Schulhygiene."  Bd.  I,  1898; 
Bd.  II,  1900.     Ferdinand  Enke,  Stuttgart. 

Transactions  of  the  International  Congress  on  School  Hygiene. 

Zeitschrift  f.   Schulgesundheitspflege. 

Bowditch,  H.  P.:  "'The  Growth  of  Children  Studied  by  Galton's 
Method  of  Percentile  Grades."  Twenty-second  Annual  Report  of  the 
State  Board  of  Health  of  Mass.,  1890,  pp.  479-522. 

Weyl,  Theodor:  "Handbuch  der  Hygiene."  Vol.  VII,  Erste  Abt, 
Schulhygiene^  Jena,  1895. 


SECTION  XII 
DISINFECTION 

CHAPTER  I 
GENERAL    CONSIDERATIONS 

Definitions. — Disinfection  means  the  destruction  of  the  agents  caus- 
ing infection.  An  object  is  said  to  be  infected  when  contaminated  with 
pathogenic  microorganisms.  It  is  disinfected  by  destroying  these  or- 
ganisms, whether  they  are  in  the  substance  or  on  the  surface  of  that 
object.  Disinfection,  then,  deals  only  with  destroying  the  vitality  of 
those  minute  forms  of  life  which  cause  disease.  It  does  not  mean  the 
destruction  of  all  the  lower  forms  of  animal  and  vegetable  life  that  may 
be  in  or  upon  an  object — this  is  sterilization. 

Sterilization. — All  processes  which  sterilize  necessarily  disinfect, 
but  all  disinfecting  processes  by  no  means  sterilize.  The  distinction 
between  disinfection  and  sterilization  arises  principally  from  the  fact 
that  spores  have  a  much  greater  resistance  to  all  influences  which  de- 
stroy the  vegetative  cells.  Fortunately,  none  of  the  pestilential  diseases 
of  man  which  occur  in  widespread  epidemics,  so  far  as  known,  are  caused 
by  microorganisms  with  resistant  spores;  therefore  the  usual  processes 
of  disinfection  may  be  thoroughly  efficient,  yet  leave  many  harmless  and 
hardy  forms  of  microscopic  life  alive.  In  other  words,  sterilization  is 
rarely  necessar\'  in  public  health  work,  except  in  the  case  of  anthrax, 
tetanus  and  other  spore-bearing  infections. 

Antiseptics. — Antiseptic  substances  prevent  decomposition  and  de- 
cay. Such  substances  retard  or  prevent  the  growth  and  activity  of  micro- 
organisms, but  do  not  necessarily  destroy  them ;  that  is,  antiseptics  delay 
or  prevent  fermentation  and  putrefaction  without  destroying  the  micro- 
organisms which  cause  these  processes.  There  is  a  great  difference  be- 
tween the  antiseptic  and  the  disinfecting  power  of  most  substances.  For 
instance,  a  solution  of  formalin  will  restrain  the  development  of  most 
bacteria  in  the  proportion  of  1  to  50.000,  but  it  requires  a  3  to  5  per  cent, 
solution  of  this  liquid  to  kill  the  bacteria  in  a  reasonably  short  time.  As 
weak  a  solution  of  bichlorid  of  mercury  as  1  to  300,000  will  sometimes 
966 


NATURE'S    DISINFECTING    AGENCIES  967 

prevent  the  germination  of  anthrax  spores,  whereas  it  requires  a  1  to 
1,000  solution  to  destroy  them.  Saturated  solutions  of  salt  or  sugar 
will  preserve  meat,  vegetables,  and  other  organic  substances ;  that  is,  they 
are  antiseptic  in  their  action  but  not  germicidal,  as  they  have  small 
powers  of  destroying  microorganisms. 

Asepsis. — Asepsis  means  freedom  from  or  absence  of  living  micro- 
organisms and  is  practically  equivalent  to  sterilization. 

Germicide. — A  germicide  is  a  substance  or  agent  which  destroys 
germs.  Germicides  and  disinfectants  are  interchangeable  terms,  as 
both  are  used  to  indicate  the  destruction  of  microorganisms.  Most 
germicides  used  in  public  health  work  are  potent  enough  to  sterilize 
objects  with  which  they  come  in  contact. 

Deodorant. — A  deodorant  is  a  substance  which  has  the  power  to 
destroy  or  to  neutralize  the  unpleasant  odors  arising  from  organic  mat- 
ter undergoing  fermentation  or  putrefaction.  Such  substances  must  be 
distinguished  carefully  from  disinfectants.  Deodorants  destroy  smells; 
disinfectants  destroy  germs.  Many  of  the  disinfecting  agents  are  also 
deodorants,  but  all  deodorizing  substances  are  by  no  means  disinfectants. 
For  example,  charcoal  will  absorb  the  malodorous  gases  arising  from 
putrefying  and  fermenting  materials,  but  it  is  inert  so  far  as  its  power 
to  destroy  the  cause  of  these  processes  is  concerned.  Formalin,  on  the 
other  hand,  is  a  true  deodorant  and  disinfectant,  as  it  combines  with 
the  organic  matter  to  form  new  compounds  which  are  both  odorless 
and  sterile.  Bichlorid  of  mercury,  while  a  very  potent  germicide,  has 
practically  no  immediate  effect  upon  odors.  The  volatile  oils  and  other 
substances  having  a  pungent  odor  are  not  deodorants ;  they  simply  cover 
up  one  smell  with  another. 

Nature's  Disinfecting  Agencies. — In  nature  many  forces  are  con- 
stantly at  work  to  destroy  infection  and  thereby  limit  the  spread  of 
the  communicable  diseases.  It  is  the  duty  of  the  sanitarian  to  encourage 
the  use  of  these  natural  disinfecting  agencies;  they  are  dilution,  sun- 
light, dryness,  and  symbiosis.  Sunlight  is  a  great  destroyer  of  germ  life. 
Few  microbes,  especially  the  pathogenic  ones,  can  live  in  the  direct  bright 
sunlight  many  hours.  Dryness  is  another  natural  condition  that  is 
destructive  to  many  of  the  minute  forms  of  life  with  which  we  have 
to  contend.  The  combination  of  dryness  and  sunlight  is  quite  as  good, 
if  not  better,  than  the  ordinary  fumigating  processes  which  are  com- 
monly used  in  practical  disinfection  against  surface  contamination. 
Dryness,  sunlight,  and  cleanliness  are  the  keynotes  of  sanitation  in 
the  modern  acceptation  of  the  term. 

We  now  know  that  most  of  the  pathogenic  microorganisms  do  not 
grow  and  multiply  in  our  environment.  For  the  most  part  they  die 
when  wafted  into  the  air  or  carried  into  water  or  deposited  in  the 
soil.     It   is  only  occasionally  that  they  find  conditions   favorable  for 


968  GENEEAL    CONSIDERATIONS 

development  in  foods  such  as  milk  and  meat,  and  exceptionally  in 
water.  Further,  it  is  to  be  noted  that  ordinarily  it  requires  a  certain 
number  of  microorganisms  to  produce  infection.  It  is  quite  conceivable 
that  a  single  typhoid  bacillus  or  a  single  tetanus  spore  may  "kindle  a 
conflagration."  Experimental  evidence  with  the  infections  upon  labora- 
tory animals  teaches  the  lesson  that  ordinarily  an  animal  is  capable  of 
taking  care  of  minute  and  dilute  amounts  of  infection.  Dilution,  attenu- 
ation, and  the  conditions  of  our  environment,  unfavorable  to  most  germs 
harmful  to  man,  therefore  protect  us  in  no  small  measure  against  the 
communicable  diseases. 

Cleanliness. — Cleanliness  is  a  very  important  adjunct  to  the  work 
of  disinfection.  In  fact,  cleanliness  lies  at  the  base  of  all  our  sanitary 
measures.  The  mere  act  of  cleaning  removes  some  of  the  adherent  mi- 
crobes from  the  surface  and  the  ordinary  scrubbing  and  washing  result 
in  the  final  destruction  of  many  more.  Dry  dusting  and  sweeping  serve 
only  to  stir  up  dust  and  infection,  which  settle  down  again  upon  the 
same  or  other  surfaces.  Cleanliness  serves  another  important  purpose, 
so  far  as  infection  is  concerned ;  it  removes  the  organic  matter  on  which 
and  in  which  bacteria  may  find  favorable  conditions  for  prolonging  life 
and  virulence.  The  modern  conception  of  cleanliness  has  expanded  with 
the  growth  of  the  sanitary  sciences.  We  now  aim  at  biological  cleanli- 
ness as  well  as  esthetic  cleanliness.  This  includes  not  only  the  removal 
of  organic  matter,  but  the  destruction  of  insects  and  vermin,  and  their 
feeding  and  breeding  places.  So  far  as  personal  cleanliness  is  con- 
cerned, the  two  important  acts  to  prevent  infection  are:  (1)  Washing 
the  hands  before  eating  and  (2)  keeping  the  fingers  away  from  the 
mouth  and  nose. 

In  the  wholesale  disinfection  which  must  be  practiced  to  check  wide- 
spread epidemic  diseases  due  to  bacterial  infection  we  are  largely  limited 
to  the  use  of  the  agents  which  nature  has  constantly  at  work  to  destroy 
such  infection.  Against  a  single  case  of  communicable  disease  or  against 
a  limited  infected  area  we  may  employ  aggressive  measures  such  as 
steam  and  strong  chemicals;  but  when  a  disease,  due  to  bacterial  in- 
fection, has  spread  over  an  extensive  district  these  methods  must  be 
supplemented  by  all  the  resources  of  nature.  The  people  must  be  edu- 
cated so  as  individuall}^  to  employ  intelligent  measures  to  avoid  the 
infection.  Cleanliness  must  be  more  scrupulously  practiced  than  ever, 
sunlight  and  dryness  must  be  given  their  fullest  opportunity  to  operate 
even  at  the  expense  of  a  few  faded  carpets  or  colors. 

Symbiosis. — Many  pathogenic  microorganisms  are  destroyed  in  the 
process  of  putrefaction  and  fermentation.  They  die  in  the  fierce  strug- 
gle for  existence  going  on  in  these  processes  of  decomposition.  For  the 
most  part  the  hardier  saprophytic  forms  of  life  overpower  and  kill  the 
disease-producing  microorganisms   having  comparatively   feeble  powers 


COXTEOLS  969 

of  resistance.  The  fact  that  infected  carcasses,  sewage,  and  putrid  or- 
ganic matter  generally  purify  themselves  by  the  ver}^  processes  that  de- 
stroy them  is  a  fortunate  provision  of  nature. 

When  and  Where  to  Disinfect. — It  naturally  suggests  itself  that  it 
is  much  better  to  prevent  infection  than  to  be  compelled  to  destroy  it 
after  it  has  become  disseminated  through  ignorance,  carelessness,  or  neg- 
ligence. It  is  the  duty  of  the  disinfector  to  destroy  infection  whenever 
it  is  found;  it  is  the  ideal  of  the  sanitarian  to  prevent  the  spread  of 
infection  so  as  to  render  broadcast  disinfection  unnecessary. 

The  best  place  to  apply  disinfection  is  at  the  seat  of  origin  of  the 
infection.  Man  is  the  fountain-head  of  most  of  the  infections  to  which 
he  is  heir;  hence  the  most  effective  place  to  apply  disinfectants  is  at 
the  bedside,  and  to  the  excretions,  especially  those  from  the  mouth,  nose, 
and  bowels.  When  proper  precautionary  measures  have  been  taken  at 
the  bedside  with  a  ease  of  cholera,  typhoid  fever,  or  plague  there  is  little 
need  of  subsequently  disinfecting  the  sickroom,  but  when  a  diffusion 
of  the  infection  results  then  a  general  disinfection  becomes  neces- 
sary. 

Qualifications  of  the  Disinfector. — The  disinfection  of  any  given 
place  is  a  complex  operation,  and  should  not  be  attempted  by  anyone  not 
familiar  with  the  pecidiarities  of  the  particular  infection  with  which 
he  has  to  deal  and  a  thorough  knowledge  of  the  disinfecting  agents  em- 
ployed. In  other  words,  it  is  quite  as  important  to  know  what  to  disin- 
fect as  how  to  disinfect  and  when  to  disinfect.  A  thorough  understand- 
ing of  the  causes  and  modes  of  transmission  of  the  communicable  dis- 
eases is  the  most  useful  weapon  the  disinfector  has  in  his  fight  against 
the  spread  of  infection. 

The  success  of  the  disinfector  lies  in  personal  attention  to  minute 
details.  Germs  are  little  things,  and  it  is  little  things  that  count  in  this 
kind  of  work.  The  disinfector  who  is  satisfied  to  leave  the  process  in 
the  hands  of  an  inexperienced  person  with  a  few  words  of  instruction 
cannot  expect  to  obtain  trustworthy  results.  The  disinfector  must  give 
personal  surveillance  to  the  whole  process — ^the  materials,  the  strength  of 
solutions,  modes  of  application — and  must  be  present  to  guide  and  direct 
every  step  of  the  operation  with  the  same  conscientiousness  and  thor- 
oughness with  which  the  surgeon  assures  himself  of  every  detail  of 
asepsis  in  his  operating-room. 

Controls. — Every  disinfecting  process  should  be  controlled  by  ex- 
posing cultures  upon  preparation  slips  or  threads  as  a  guide  and  check 
to  the  thoroughness  of  the  process.  This  may  perhaps  best  be  done  by 
saturating  threads  with  an  active  culture  of  B.  prodigiosiis.  These 
threads  are  attached  to  little  slips  of  paper  which  are  then  exposed 
in  various  portions  of  the  room  to  be  disinfected.  After  the  completion 
of  the   operation  the   threads  are  inoculated  into  Dunham's   peptone 


970  GENERAL    CONSIDERATIONS 

medium.  If  the  B.  prodigiosus  has  survived  the  characteristic  red  color 
appears  in  the  culture  medium. 

Disinfection  Must  Be  in  Excess  of  Requirements. — The  disinfection 
of  rooms,  bedding,  ships,  and  objects  that  have  been  exposed  to  in- 
fection must  of  necessity  be  greatly  in  excess  of  the  actual  requirements. 
This  is  one  of  the  difficulties  met  with  in  attacking  an  invisible  foe. 
A  sickroom  might  readily  be  disinfected  and  rendered  safe  by  applying 
a  few  gills  of  one  of  the  germicidal  solutions  to  a  small  spot  or  a  limited 
area.  But,  as  we  cannot  see  the  germs,  it  is  necessary  to  apply  our 
disinfecting  agents  to  every  inch  of  surface  of  the  room  and  all  its 
contents  in  order  not  to  miss  that  particular  spot.  At  first  disinfec- 
tion was  directed  by  a  shotgun  process  in  a  general  sort  of  blunderbuss 
way  against  everything,  but  now  that  we  know  more  about  the  habits 
and  habitat  of  each  one  of  the  particular  microorganisms  we  can  con- 
centrate our  efforts  with  some  exactness  upon  the  particular  object  liable 
to  transmit  infection,  and  with  greater  assurance  of  eradicating  danger. 

The  Ideal  Disinfectant. — The  ideal  disinfectant  must  first  and  fore- 
most possess  a  high  germicidal  power.  It  must  not  be  handicapped  by 
the  presence  of  organic  matter;  it  must  be  reasonably  stable,  so  as  not 
to  deteriorate  under  ordinary  conditions;  it  must  be  soluble  or  readily 
miscible  in  water;  if  it  forms  an  emulsion  the  emulsion  should  be  per- 
manent ;  it  should  be  harmless  to  man  and  the  higher  animals ;  it  should 
have  the  power  of  penetration;  it  should  not  corrode  metals,  bleach  pig- 
ments, or  rot  fabrics,  and,  finally,  it  should  be  reasonable  in  price. 

The  stress  of  modern  activities  demands  disinfecting  processes  that 
are  instantaneous  in  their  action,  all-pervading  in  their  effects,  cheap, 
harmless,  and  free  from  unpleasant  odors  that  might  be  offensive  to 
the  fastidious.  Such  perfect  disinfectors  are  not  known.  It  requires 
money  and  the  expenditure  of  well-directed  and  intelligent  energy  to 
accomplish  satisfactory  disinfection.  No  one  substance  is  applicable  to 
all  diseases  or  to  all  substances,  or  even  to  the  same  disease  or  the 
same  sul)stance  under  different  conditions. 

Terminal  Disinfection. — Terminal  disinfection  during  recent  years 
has  been  disparaged  as  a  public  health  measure  because  it  has  little 
effect  upon  the  control  of  the  communicable  diseases  and  the  cost  of  such 
disinfection  appears  to  be  disproportionately  large  to  the  benefits.  The 
evident  limitations  of  terminal  disinfection  have  cast  doubt  in  the 
minds  of  some  health  officers  upon  the  value  of  disinfection  in  general. 
This  is  an  unfortunate  attitude.  No  one  can  question  the  great  value 
of  disinfection  properly  applied.  It  is,  of  course,  much  more  important 
to  destroy  the  infection  in  the  discharges  throughout  the  course  of  a 
case  of  typhoid  fever  than  to  trust  to  one  final  disinfection  of  the  sick- 
room and  its  contents.  The  same  holds  with  about  equal  force  for  most 
of  the  communicable  diseases.    We  now  know  that  fomites  play  a  com- 


STANDAEDIZATION    OF    DISINFECTANTS  971 

paratively  minor  role  in  the  transmission  of  disease.  The  disinfection 
of  rooms  and  objects  does  not  now,  therefore,  hold  the  importance  in 
the  minds  of  sanitarians  that  it  once  did.  However,  if  terminal  disin- 
fection prevents  the  occurrence  of  only  a  small  number  of  cases  it  would 
still  seem  to  be  worth  while.  Moreover,  what  health  officer  would  will- 
ingly allow  his  child  to  occupy  the  bed  or  handle  the  objects  in  a  room 
soon  after  a  case  of  typhoid,  scarlet  fever,  tuberculosis,  or  diphtheria 
without  first  applying  some  effective  method  of  purification  ?  The  greater 
the  care  and  cleanliness  exercised  during  the  progress  of  the  disease 
the  less  the  need  of  terminal  disinfection.  So  long  as  we  possess  such 
a  reasonably  efficient  and  satisfactory  substance  as  formaldehyd,  ter- 
minal disinfection  should  be  practiced  after  all  diseases  in  which  the 
environment  may  become  infected,  even  though  the  danger  be  slight. 

The  Standardization  of  Disinfectants. — There  is  no  accurate  stand- 
ard by  which  the  power  of  disinfecting  agents  may  be  measured.  There 
are  conditions  influencing  the  life  of  the  bacterial  cell  which  we  are 
unable  to  control.  It  is  for  this  reason  that  the  strengths  of  solutions 
necessary  to  disinfect  are  variously  stated  by  different  authorities,  and 
the  time  of  exposure  is  for  the  same  reason  not  always  definitely  de- 
cided. The  difficulty  in  this  connection  is  to  determine  the  minimum 
conditions  which  will  furnish  trustworthy  results  and  still  provide  a 
coefficient  of  safety  necessary  for  general  practice. 

While  the  results  of  scientific  work  in  the  laboratory  must  be  our 
guide  as  to  the  value  and  efficiency  of  any  disinfecting  process  we  cannot 
ignore  the  results  of  experience  gained  in  actual  practice  in  combating 
the  communicable  diseases.  This  is  especially  true  of  disinfectants  used 
against  a  disease  the  cause  of  which  is  only  surmised  or  the  mode  of 
transmission  not  definitely  known.  We  have  had  a  lesson  on  this  point 
in  the  case  of  sulphur.  This  substance  had  long  been  used  as  a  disin- 
fectant for  yellow  fever,  and  practical  experience  had  justified  the  con- 
fidence placed  in  sulphur  fumigation  to  check  the  spread  of  this  disease, 
but  when  the  scientific  tests  made  in  the  laboratory  showed  that  sulphur 
dioxid  is  a  very  poor  germicide  discredit  was  thrown  upon  it;  now  that 
we  know  that  sulphur  dioxid  is  one  of  the  best  insecticides  confidence 
has  been  restored  both  as  to  the  scientific  and  practical  value  of  this 
substance. 

On  the  other  hand,  laboratory  experiments  have  established  with 
great  accuracy  the  value  and  reliability  of  certain  disinfectants  which 
otherwise  would  have  gone  begging.  Some  substances,  such  as  zinc 
chlorid  and  sulphate  of  iron,  have  been  robbed  of  the  high  value  in 
which  they  were  formerly  held  and  placed  near  the  bottom  of  the  list 
of  disinfectants.  Even  carbolic  acid  has  been  shown  to  have  less  germi- 
cidal power  than  was  supposed. 

Methods. — No  satisfactor}^  method  of  estimating  the  comparative 


973  GENERAL    COXSTDERATIONS 

germicidal  value  of  disinfectants  under  the  varying  conditions  met  with 
in  actual  practice  has  yet  been  devised.  Some  of  the  principal  factors  to 
be  reckoned  with  are  the  character  of  the  microorganisms  to  be  de- 
stroyed, the  nature  of  the  medium  in  which  they  exist,  the  temperature 
at  which  the  disinfecting  process  is  carried  on,  the  time  during  which 
the  disinfectant  is  allowed  to  act,  its  chemical  nature,  power  of  penetra- 
tion, etc.,  etc. 

Koch^  in  1881  used  cultures  of  B.  prodigiosus,  B.  pyocyaneus,  and 
B.  antliracis,  both  with  and  without  spores.  He  soaked  threads  in  a 
culture  of  the  test  organism  and  afterward  dried  them  for  various 
periods  and  then  exposed  these  infected  threads  to  the  action  of  the 
disinfectant  to  be  tested.  The  threads  were  then  washed  and  laid  on 
the  surface  of  a  solid  nutrient  medium  and  inculiatcd  for  growth.  This 
method,  although  characterized  by  greater  scientific  accuracy  than  the 
methods  previously  used,  lacked  perhaps  those  broader  features  of  the 
older,  rougher  experiments;  that  is,  the  method  did  not  approximate 
the  conditions  met  with  in  practical  disinfection  closely  enough. 

G.  Simms  Woodhead  ^  in  1887  used  silk  threads  which,  after  being 
thoroughly  dried,  were  soaked  in  a  culture  or  emulsion  of  the  micro- 
organism. These  threads  were  placed  in  the  disinfectant  to  be  tested, 
then  thoroughly  washed  in  distilled  water,  and  transferred  to  fluid 
nutrient  medium.  Similar  methods  were  used  by  Fraenkel,"  Behring,* 
and  many  others. 

Stenberg  ^  in  1888  described  a  method  which  he  used  as  early  as 
1880.  He  mixed  5  c.  c.  of  a  young  culture  with  equal  quantities  of  the 
solution  of  the  germicidal  agent.  Thus  5  c.  c.  of  a  1  to  200  solution  of 
carbolic  acid  would  be  added  to  5  c.  c.  of  a  recent  culture  of  typhoid, 
and  after  stated  intervals  1  or  2  loopfuls  would  be  transferred  to 
a  nutrient  medium.  This  was  evidently  the  predecessor  of  the  drop 
method. 

The  next  modification  was  to  add  a  small  quantity  of  the  bacterial 
emulsion  to  a  large  quantity  of  the  disinfectant,  thus  reducing  to  a 
minimum  the  amount  of  foreign  matter  in  the  mixture. 

Kronig  ®  and  Paul  in  1897  adopted  an  entirely  original  plan.  They 
coated  small  garnets  of  uniform  size  with  an  emulsion  containing  sporu- 
lating  anthrax  bacilli.     These  were  dried  and  then  dropped  into  the 

^Mitteilungen  aus  dem  laiserlichen  Gesundheitsamte,  I,  1881,  abstracted  by 
Whitelegge,  in  "Eecent  Essays,"  New  Sydenham  Society,  London,  1886,  Vol. 
CXV,  p.  493. 

■Proceed,  of  the  Boy.  Phtjsical  Soc.,  Edinburgh,  1887,  Vol.  IX,  p.  386. 

*"Die  Desinficerenden  Eigenschaften  der  Kresole,"  Zeit.  f.  Byg.,  Leipzic, 
3890,  Vol.  VI,  S.  521. 

*"Ueber  Desinfektion,  mittel  und-methoden, "  Zeit.  f.  Eyg.,  Leipzic,  1890, 
Vol.  IX,  S.  395. 

'^"A  Manual  of  Bacteriology,"  New  York,  1893,  p.  186. 

""Die  chemischen  Grundlagen  der  Lehre  von  der  Gif twirkung, "  Zeit.  f. 
Byg..  Leipzic,  1807,  Vol.  XXV,  S.  1. 


STANDARDIZATION^    OF    DISINFECTANTS 


973 


disinfecting  solution.  After  exposure  for  stated  intervals  the  garnets 
were  removed,  rinsed,  and  the  organisms  washed  ofE  in  sterile  water, 
plated,  and  counted. 

Eideal   and  Walker  in   1903   introduced   a  method  by   which  they 


Fig.  142. — Device  for  Determining  Carbolic  Coefficients.  Consists  of  a  wooden 
box  14"  long  by  14"  wide  by  15"  high,  containing  a  metal  pail  (A)  10"  in  diameter, 
and  834"  deep.  A  shelf  made  of  wire  mesh  (B)  is  inserted  2"  from  the  top  of  the  pail, 
which  is  filled  with  water.  A  pipe  with  a  faucet  (C)  from  the  bottom  of  the  pail  will 
be  found  very  convenient  to  draw  off  the  water  and  regulate  its  temperature.  Asbes- 
tos packing  (E)  completely  surrounds  the  pail  in  order  to  insulate  it.  The  hd  of  the 
box  (F) ,  which  is  raised  in  the  drawing,  contains  openings  for  the  five  test-tubes,  and 
three  other  openings  for  cultures  and  thermometer.  When  the  lid  is  in  place  the  test- 
tubes  rest  upon  the  shelf  (B).  A  drawer  (D)  in  the  bottom  of  the  box  is  convenient 
to  keep  test-tubes,  inoculating  needles,  thermometer,  and  other  parts  of  the  apparatus. 


proposed  to  determine  and  state  in  definite  numerical  terms  the  value  of 
any  disinfectant.  This  they  called  the  "carbolic-coefficient,"  for  the 
reason  that  carbolic  acid  is  taken  as  the  unit  or  measurement  against 
which  the  germicidal  power  of  all  other  substances  is  compared. 


974  GEXEEAL    CONSIDERATIONS 

The  Carbolic  Coefficiknt. — This  test,  sometimes  known  as  the 
Rideal-Walker  method  of  standardizing  disinfectants,  lias  been  variously 
nioditied  and  improved,^  It  is  at  present  the  best  method  we  have  for 
comparing  the  strengths  of  germicidal  substances  in  solution.  The 
method,  however,  has  distinct  limitations,  as  it  only  gives  information 
concerning  the  relative  value  of  germicides  upon  the  naked  germ  cells 
under  favorable  conditions  of  ax:-tion. 

In  order  to  obtain  results  that  may  have  comparative  value  and  to 
avoid  discrepancies  it  is  of  the  greatest  importance  to  keep  all  the 
factors  of  the  test  uniform  and  to  give  attention  to  every  detail.  The 
following  are  the  more  important  factors  and  principles  upon  which  this 
test  is  based : 

Time. — The  time  is  taken  as  the  constant  and  the  strength  of  the 
disinfectant  as  the  variant.  It  is  easy  to  demonstrate  that,  if  reversed, 
totally  erroneous  results  will  be  obtained. 

Test  Organism. — The  culture  recommended  is  a  2-i-hour-old  B.  typho- 
sus grown  in  bouillon.  It  is  important  always  to  use  the  same  strain 
of  typhoid,  as  different  races  vary  in  resistance.  Further,  the  culture 
should  be  carried  over  every  twenty-four  hours  on  at  least  three  succes- 
sive days  before  using  it  in  a  test.  It  is  sometimes  advisable  to  filter 
the  culture  through  filter-paper  in  order  to  remove  clumps  just  before 
beginning  a  test.  The  culture  should  always  be  grown  under  the  same 
conditions,  upon  the  same  medium,  so  as  to  insure  uniformity. 

Medium. — The  standard  beef-extract  broth  (reaction  +  1.5)  recom- 
mended by  the  Committee  on  Standards  of  the  American  Public  Health 
Association  for  Water  Analysis,  is  used  both  to  grow  the  test  typhoid 
organism  and  also  for  the  sub-cultures  made  after  exposure  to  the  dis- 
infectant. Ten  c.  c.  of  this  broth  are  placed  in  each  test-tube  for  the 
sub-cultures,  as  this  amount  is  sufficient  to  avoid  any  antiseptic  activity 
of  the  disinfectant  carried  over. 

Temperature  of  Exposure. — This  is  one  of  the  most  important 
factors.  The  germicidal  activity  of  substances  increases  with  the  tem- 
perature. In  this  respect  germicidal  reactions  resemble  chemical  reac- 
tions. It  is  therefore  of  the  utmost  importance  that  the  solutions  tested 
should  be  always  at  the  same  temperature,  and  for  this  purpose  20°  C. 
has  been  selected.  The  solutions  to  be  tested,  and  the  typhoid  culture 
itself  must  be  brought  to  this  temperature  before  they  are  mixed,  and 
then  maintained  at  this  temperature  in  a  water-bath. 

Proportion  of  Culture  to  Disinfectant. — Eideal  and  Walker  first  pro- 
posed to  use  one  drop  of  the  t}-phoid  culture  to  each  cubic  centimeter  of 

*  Eideal,  S.,  and  Walker.  J.  S.  A.:  Jour.  Hoy.  San.  In^t..  London,  1903,  Vol. 
XXIV,  p.  424.  ' '  The  Standardization  of  Disinfectants, ' '  The  Lancet  Commission, 
Vol.  CLXXVII,  Nos.  4498,  4499,  and  4500.  Anderson  and  MacClintic :  Jour. 
Infect.  Bis.,  Vol.  VIII,  No.  1,  Jan.,  1911,  pp.  1-26, 


STANDARDIZATION    OF    DISINFECTANTS 


975 


germicidal  solution.  It  is  more  accurate  to  use  a  measured  amount,  say 
0.1  c.  c.  of  the  24-liour-old  bouillon  culture  of  typhoid  to  5  c.  c.  of 
solution.  These  are  convenient  amounts  easily  and  accurately  measured 
with  standardized  delivery  pipettes.  It  should  be  kept  in  mind  that  the 
addition  of  the  bouillon  culture  dilutes  the  germicidal  solutions,  but  as 
this  is  a  constant  factor  it  does  not  affect  the  comparative  values  as  ex- 
pressed by  the  carbolic  coefficient,  but  may  be  taken  into  consideration 
in  judging  the  germicidal  values  for  practical  work. 

Inoculation  Loops. — Precisely  the  same  quantity  of  fluid  from  the 
mixture  should  be  removed  each  time  for  the  transplants.  This  is  done 
most  readily  with  platinum  loops  made  of  23  U.  S.  standard  gage  wire 
and  a  loop  4  millimeters  in  diameter.  Several  of  these  loops  should  be 
on  hand.  They  are  sterilized  and  placed  upon  a  rack.  As  one  is  used 
it  is  flamed  and  returned  to  the  rack,  so  that  it  will  be  cool  when  taken 
in  its  turn. 

The  following  method  is  the  one  used  in  my  laboratory  for  carrying 
out  the  carbolic  coefficient : 

A  solution  of  5  per  cent,  phenol  c.  p.  is  made  and  standardized 
chemically.^  The  usual  dilutions  of  1  to  90,  1  to  100,  and  1  to  110, 
etc.,  are  made  from  this  stock  solution  as  desired. 

The  solutions  of  the  germicidal  substances  to  be  tested  must  be  made 
accurately,  according  to  volumetric  or  gravimetric  methods. 


ARRANGEMENT  OF  THE  TUBES  IN  THE  WATER-BATH  AND  THEIR  CONTENTS 
0  minute  J^  minute  1  minute  IJ^  minutes  2  minutes 


cz:? 


c:::^ 


o? 


6  c.c.  phenol  1:90      5  c.c.  phenol  1: 100 

and  and 

0.1  c.c.  culture  0.1  c.c.  culture 


5  c.c.  solution  x 

0.5  c.c.  solution  x 

0.5  c.c.  solution 

1:900 

1:1000 

1:1200 

and 

and 

and 

0.1  c.c.  culture 

0.1  c.c.  culture 

0.1  c.c.  culture 

The  tests  are  carried  out  in  test-tubes  one  inch  in  diameter  and  three 
inches  long.  These  are  placed  in  a  row  in  a  water-bath.  The  test-tubes 
rest  upon  a  bed  of  sand  and  are  held  in  place  by  a  wire  rack  or  simply 
by  a  board  perforated  with  holes  of  suitable  size.  If  the  water-bath  is 
sufficiently  large  and  the  water  brought  to  Just  20°  C.  it  may  be  main- 
tained at  this  temperature  with  but  slight  attention. 

Each  test-tube  receives  5  c.  c.  of  the  solution  to  be  tested.     Time  is 


^  By   bromiu   titration, 

sis.") 


(See   description   in   Sutton's   "Volumetric    Analy- 


976 


GENEKAL    CONSIDERATIONS 


allowed  for  the  solutions  to  reach  the  temperature  of  20°  C,  then  the 
culture  wliich  has  previously  been  brouglit  to  20°  C.  is  added  and  mixed 
with  the  solution  in  each  test-tube  in  turn.  The  culture  is  added  to 
each  tube  at  intervals  of  just  30  seconds.  With  a  row  of  five  tubes  this 
will  make  a  2i/2-'Tiinute  interval  for  each  particular  test-tube. 

Two  and  one-half  minutes  after  the  phenol  and  the  culture  have 
been  mixed  together  in  tube  No.  1  a  loopful  of  tlie  mixture  is  re- 
moved and  planted  in  broth;  30  seconds  later  a  loopful  of  the  mixture 
is  taken  from  tube  No.  2,  and  so  on  throughout  the  series  at  intervals 
of  30  seconds.  The  entire  procedure  of  removing  the  loopful  of  mix- 
ture and  planting  it  into  one  of  the  test-tubes  containing  the  beef- 
extract  broth  requires  only  about  15  seconds,  allowing  plenty  of  time 
to  flame  the  loop,  replace  it  in  the  rack,  and  pick  up  another  loop  which 
had  previously  been  flamed  and  has  cooled  sufficiently  for  the  next  opera- 
tion. The  test-tubes  holding  the  mixture  of  germicidal  solution  and 
culture  need  not  be  removed  from  the  water-bath,  and  it  is  not  necessary 
to  keep  them  plugged  with  cotton.  The  loop  should  always  be  plunged 
to  the  bottom  and  care  taken  not  to  touch  the  sides  of  the  test-tube 
and  always  to  carry  away  a  loopful  of  the  fluid  to  be  transplanted.  The 
test-tubes  holding  the  beef-extract  media  for  the  transplants  are  con- 
veniently placed  in  wooden  racks  and  are  incubated  at  37°  C.  for  forty- 
eight  hours,  when  the  readings  as  to  growth  (  +  )  or  no  gro\\i;h  ( — )  are 
tabulated. 

An  example  of  a  carbolic  coefficient  test  follows : 


2y2 

5 

7H 

10 

Minutes 

Minutes 

Minutes 

Minutes 

-1- 

+ 
+ 
+ 

-f- 

— 

— 

+ 

— 

— 

+ 

+ 

+ 

+ 

12H 
Minutes 


Phenol  1  :  90 .  .  . 
Phenol  1  :  100 .  . 
Solution  XI  :  900 .  . 
Solution  X  1  :  1,000 
Solution  X  1  :  1,200 


+ 


The  carboUc  coefficient  of  solution  X  is  therefore  Vo"o^  =10. 

Anderson  and  McClintic^  have  modified  the  procedure  employed  by 
the  Lancet  Commission  to  determine  the  coefficient  to  be  the  mean 
between  the  strength  and  the  time  coefficient;  that  is,  the  figure  repre- 
senting the  degree  of  dilution  of  the  weakest  strength  of  the  disinfectant 
that  kills  within  2^/2  minutes  is  divided  by  the  figure  representing  the 
degree  of  dilution  of  the  weakest  strength  of  the  phenol  control  that 
kills  within  the  same  time.  The  same  calculation  is  done  for  the  weakest 
strength  that  kills  in  15  minutes.    The  mean  of  the  two  is  the  coefficient. 

Kendall  and  Edwards  -  have  devised  an  ingenious  method  to  deter- 

'  Hygienic  Laboratory  Bulletin.  U.  S.  P.  H.  and  M.  H.  S.,  No.  82,  1912. 
-Jonr.  Infect.  Dis.,  Vol.  VIII,  No.  2,  March,  1911,  pp.  250-257. 


STANDARDIZATION    OF    DISINFECTANTS  977 

mine  the  penetrating  power  of  germicides  in  the  presence  and  absence 
of  organic  matter.  The  method  consists  essentially  of  cylindrical  moulds 
of  agar  impregnated  with  the  test  organism.  Sections  of  these  cylin- 
drical moulds  or  artificial  feces  are  exposed  to  the  germicide  solutions 
and  plants  made  after  proper  intervals  of  time  from  a  core  taken  from 
the  center  of  the  cylinder. 

IxTERPRETATiON  OF  Eesults. — A  low  carbolic  coefficient  means  a 
useless  disinfectant ;  on  the  other  hand  it  should  be  remembered  that  be- 
cause a  germicide  has  a  high  carbolic  coefficient  is  no  true  indication 
that  it  is  a  favorable  agent  in  practical  work.  There  are  many  factors 
still  to  be  considered.  Thus  a  useful  disinfectant  should  not  be  very 
poisonous  to  higher  animals;  should  not  corrode  metals  or  rot  fabrics; 
should  not  stain  or  bleach ;  should  not  have  an  unpleasant  smell ;  should 
be  reasonably  cheap;  should  be  readily  miscible  with  water  and  not  de- 
posit from  solution  or  suspension;  should  be  reasonably  stable;  should 
act  both  in  alkaline  and  acid  media ;  should  not  be  greatly  influenced  by 
the  presence  of  organic  matter,  and  should  possess  a  fair  power  of  pene- 
tration. It  must  at  once  be  evident  that  no  one  test  can  determine  all 
of  these  factors,  so  that  a  thorough  and  comprehensive  study  of  the  sub- 
stance to  be  used  should  be  made  upon  many  different  parasites  under 
many  difi^erent  conditions  before  we  can  have  a  satisfactory  knowledge  of 
its  power  and  limitations.  This  is  one  of  the  reasons  that  makes  us  con- 
servative about  taking  up  new  germicidal  substances  until  thoroughly 
tested  under  different  conditions,  and  inclines  us  to  adhere  to  well- 
known  chemicals  such  as  bichlorid  of  mercury,  carbolic  acid,  the  coal-tar 
creosotes,  lime,  the  hypochlorites,  and  formalin,  the  advantages  and 
limitations  of  which  have  been  thoroughly  established. 


978 


GENERAL   CONSIDERATIONS 


The  Phenol  Coefficient  of  Some  Commercial  Germicides 
Determined  by  Thomas  B.  McClintic  ^ 


Bactcrol 

Bonetol 

Cabot's  Sulpho-Napthol 

Carbolene 

Carbolozone 

Car-Sul 

Chloro-Naptholeum 

Cremoline 

Creo-Carboline 

Creolin-Pearson 

Crescleum 

Crude  Carbolic  Acid 

Dusenberry's  Liquid  Creoleum . 
Germol . 


Without  Or- 
ganic Matter 


1.58 
1.23 
3.87 
1.36 
1.48 
2.00 
6.06 
1.26 
4.03 
3.25 
2.90 
2.75 
1.00 
2. 12 

Hycol '       12^30 

Hygeno  A 

Kreosota 

Kreotas 

Kreso 

Kresolig 

Lincoln  Disinfectant  . 

Liquor  cresolis  compositus  (U.  S.  P.) 

Lysol 

Napthalene 

Phenoco 

Phenol  liquid  (U.  S.  P.,  1890) 

Phenosote 

Phinotas 

R.  R.  Rogers  Disinfectant 

Rudisch's  Creolol 

Saponified  Cresol 

Tarola 

Trikresol 

Zenoleum 

Zodone •• 

Zonol 

Antozone  * 

Creola  Disinfectant 

Dioxj'gen 

Electrozone 

Formacone  Liquid 

Killitol : . 

Kretol 

Listerine 

Phenol  Disinfectant  and  Cleansing  Liquid 

Phenol  Sodique 

Pino-ljTDtol 

Piatt's  Chlorides 

Public  Health  Liquid  Disinfectant 

Sanitas 

The  Twentieth  Century  Disinfectant 

Veroform  Oennicide 

Worrell's  Insect  Exterminator  and  Disinfectant .... 

Zodane  No.  3 


2.50 
15.00 

1.77 
3.43 
1.37 
3.03 

1.24 

1.03 
3.12 
2.62 
2.25 
1.62 
2.37 

nU 
0.52 
weak 
0.90 
weak 
weak 
0.92 
weak 
0.61 
weak 
0.27 
weak 
0.48 
0.30 
0.13 
0.43 
weak 
weak 


With  Organic 
Matter 


1.34 

0.92 

2.33 

0.65 

0.48 

1.75 

3.21 

0.69 

2.26 

2.52 

1.75 

2.63 

0.40 

1.79 

9.37 

1.81 

0.65 

0.30 

2.32 

48 

10 

87 

57 

36 

86 

76 

31 


0.53 
2.05 
0.75 
0.57 
1.93 
2.50 
1.64 
0.51 
1.57 


>  Hyg.  Lab.  Butt.  No.  8S,  U.  S.  P.  H.  &  M.  H.  S. 
'  The  following  disinfectants  have  a  coefficient  of  less  than  1. 
was  impracticable  to  determine  the  coefficient. 


Most  of  them  are  so  weak  that  it 


CHAPTEE  II 
PHYSICAL    AGENTS    OF    DISINFECTION 

Sunlight. — Sunlight  is  an  active  germicide.  It  destroys  spores  as 
well  as  bacteria.  Unfortunately,  the  sunlight  is  so  uncertain  and  the 
force  of  the  sun's  rays  so  variable  and  their  disinfecting  powers  so 
superficial  that  it  cannot  be  depended  upon  as  an  aggressive  measure 
in  attacking  infection.  In  rooms,  ships,  and  confined  spaces  sunshine 
comes  more  under  the  purview  of  the  sanitarian  than  under  that  of  the 
disinfector,  but  the  latter  can  always  use  it  to  advantage  in  supplement- 
ing his  other  methods.  Boom  and  objects  may  always  be  sunned  and 
aired  with  advantage  after  disinfection. 

The  different  rays  of  light  have  very  different  effects  upon  germ 
life.  The  blue-violet  and  ultra-violets,  that  is,  the  more  refragible 
chemical  rays  of  short  wave  length,  are  the  only  ones  possessing  germi- 
cidal power.  The  red  and  yellow  rays  are  practically  inert  in  this 
regard.  The  source  of  light  seems  to  have  little  influence  upon  the 
result;  it  is  more  a  cjuestion  of  intensity  and  nature  of  the  rays.  Even 
diffused  light  retards  gro\\i;h  and  development  of  microorganisms,  and 
if  strong  enough  will  finally  kill  them.  Electric  light  containing  the 
proper  rays  is  efficient.  The  Eontgen  rays  have  no  bactericidal  proper- 
ties. 

The  time  required  for  light  to  destroy  bacteria  varies  with  its  bright- 
ness and  with  conditions  such  as  moisture,  temperature,  transparency, 
and  composition  of  the  media,  which  aid  or  hinder  the  effect  of  the 
raj'S.  The  time  also  varies  with  the  different  microorganisms;  plague 
bacilli  and  cholera  vibrio  usually  die  more  quickly  than  tubercle  bacilli. 
Spores  are  much  more  resistant  to  the  influence  of  the  chemical  rays 
than  the  bacterial  cells  themselves.  Thus  it  usually  requires  about  30 
hours'  sunning  to  kill  an  anthrax  spore,  while  the  anthrax  bacillus  is 
killed  in  one  or  two  hours  under  the  same  conditions. 

Ultra-violet  Rays. — Ultra-violet  rays  obtained  from  the  Cooper 
Hewitt  mercury  vapor  lamp  and  other  similar  devices  have  an  exceed- 
ingly powerful  germicidal  action,  killing  spores  as  well  as  bacterial 
cells.  Glass  is  opaque  to  these  rays  of  short  wave  lengths  and  it  is 
therefore  necessary  to   use   quartz   globes.      This  method   has   recently 

979 


980  PHYSICAL   AGENTS    OF    DISINFECTION" 

coine  into  use  for  the  sterilization  of  water  and  other  substances.  (See 
page  801. 

Electricity. — It  appears  that  electric  currents  have  little  germi- 
cidal action  in  themselves  and  tliat  the  apparent  effects  noted  by  some 
investigators  are  due  either  to  the  heat  generated  by  the  current  or 
to  electrolytic  action.  Electricity  has  very  little  use  in  practice  as  a 
disinfectant.  Hermite  used  the  products  of  electrolysis  for  the  steriliza- 
tion of  sewage.  He  added  sea-water  to  the  sewage  and  the  electrolytic 
action  caused  the  formation  of  hypochlorite,  which  has  well-known 
germicidal  action.  The  effect  of  electrical  currents  upon  bacteria 
seems  to  be  a  purely  chemical  one  in  the  case  of  antiseptic  substances, 
being  formed  by  electrolytic  decomposition;  or  a  thermal  one  in  the 
case  of  the  production  of  heat,  which  so  frequently  attends  the  dis- 
charge of  electric  currents. 

Burning. — Fire  is  the  great  purifier.  Burning  has,  however,  a  very 
limited  range  of  usefulness  in  practical  disinfection.  The  disinfector 
is  seldom  justified  in  burning  an  article  against  the  wish  of  its  owner, 
for  we  now  possess  methods  by  which  any  object  may  be  rendered  safe 
so  far  as  its  power  of  conveying  disease  is  concerned.  In  actual  prac- 
tice, however,  the  disinfector  often  comes  across  a  great  amount  of 
rubbish  and  articles  of  little  value  that  he  will  find  safer  and  cheaper 
to  burn  than  to  disinfect.  The  burning  of  garbage  and  refuse  is  the 
safest  means  of  disposing  of  such  organic  substances  from  a  sanitary 
standpoint,  especially  in  districts  where  pestilential  disease  prevails. 
From  the  same  standpoint  the  cremation  of  all  bodies  dead  of  a  com- 
municable' disease  is  the  safest  method  of  preventing  possible 
spread  of  infection  from  this  source.  Burning  is  the  more  satisfactory 
method  of  disinfecting  and  disposing  of  small  amounts  of  sputum  and 
other  infected  discharges.  Burning  of  the  surface  of  the  ground  by 
means  of  gasoline  torches  and  petroleum  is  sometimes  used  to  destroy 
animal  parasites  and  other  infections  which  find  lodgment  on  the  soil. 
The  gasoline  torch  is  also  used  to  fight  insect  pests  of  trees  and  plants. 

Dry  Heat. — A  temperature  of  150°  C.  continued  for  one  hour  will 
destroy  all  forms  of  life,  even  the  most  resistant  spores.  It  is  easy 
to  maintain  this  temperature  in  an  apparatus  of  special  construction 
known  as  a  hot-air  or  dry-wall  sterilizer.  Glassware  and  many  objects 
that  will  stand  this  degree  of  heat  are  sterilized  in  an  oven  of  this  kind 
in  bacteriological  laboratories  and  in  surgical  clinics.  Dry  heat  is  not 
as  satisfactory  a  disinfectant  as  moist  heat,  as  it  lacks  the  power  of 
penetration  and  is  injurious  to  fabrics.  Most  materials  will  bear  a 
temperature  of  110°  C.  without  much  injury,  but  when  this  tempera- 
ture is  exceeded  signs  of  damage  soon  begin  to  show.  Scorching  occurs 
sooner  with  woolen  materials,  such  as  flannels  and  blankets,  than  with 
cotton  and  linen.     Over-drying  renders  most  fabrics   very  brittle,  but 


BOILING 


981 


this  injury  may  be  lessened  by  allowing  the  materials  which  have  been 
subject  to  dry  heat  to  remain  in  the  air  long  enough  to  regain  their 
natural  degree  of  moisture  and  pliability  before  manipulating  them. 


Fig.  143. — Hot  Aib  Sterilizer. 


The  ordinary  household  cooking  oven  is  as  good  as  any  specially 
contrived  apparatus  for  the  disinfection  of  small  objects  by  dry  heat. 
In  the  absence  of  a  thermometer  it  is  usual  to  heat  the  oven  to  a 
point  necessary  to  brown  cotton  and  expose  the  objects  no  less  than 
one  hour. 

Boiling. — Boiling  is  such  a  commonplace,  every-day  procedure  that 
it  is  often  neglected  in  practical  disinfection  despite  the  fact  that 
it  is  one  of  the  readiest  and  most  effective  methods  of  destroying  in- 
fections of  all  kinds.  An  exposure  to  boiling  water  at  100°  C.  con- 
tinued for  an  hour  will  destroy  the  living  principles  of  practically  all 
the  infectious  diseases  with  which  we  have  to  deal  in  public  health 
work.  To  be  sure,  there  are  a  few  spores  that  have  shown  a  remark- 
able resistance  to  boiling  water  and  streaming  steam  in  laboratory  ex- 
periments. Boiling,  therefore,  cannot  be  entirely  depended  upon  where 
tetanus,  anthrax,  or  resisting  spores  are  in  question.  As  a  matter  of 
fact,  a  degree  of  moist  heat  much  lower  than  the  boiling  point  of 
water  is  effective  against  the  great  majority  of  the  known  viruses.  Thus 
a  temperature  of  60°  C.  for  20  minutes  will  destroy  the  microorganisms 
of  cholera,  typhoid,  dysentery,  diphtheria,  plague,  tuberculosis,  pneu- 
monia, erysipelas,  and  practically  all  non-spore-bearing  bacteria.  Boil- 
ing kills  them  at  once. 
64 


982  PHYSICAL   AGENTS    OF   DISINFECTION 

Boiling  is  especially  applicable  for  the  disinfection  of  bedding, 
body  linen,  towels,  and  fabrics  of  many  kinds;  also  kitchen  and  table- 
ware, cuspidors,  urinals,  and  a  great  variety  of  objects.  Surfaces,  such 
as  floors,  walls,  beds,  metal  work,  etc.,  may  be  effectively  disinfected 
by  mechanically  cleansing  them  with  boiling  water.  The  efficacy  of 
boiling  water,  especially  when  used  in  such  circumstances,  is  greatly 
increased  by  the  addition  of  corrosive  sublimate,  carbolic  acid,  or  one 
of  the  alkaline  coal-tar  creosotes.  The  addition  of  lye,  borax,  or  a 
strong  alkaline  soap  also  increases  the  penetrating  and  detergent  power 
of  boiling  water  when  applied  to  surfaces  soiled  with  organic  or  oily 
matters. 

In  using  boiling  water  for  the  disinfection  of  bright  steel  objects 
or  cutting  instruments  the  addition  of  1  per  cent,  of  an  alkaline  sub- 
stance such  as  carbonate  of  soda  will  prevent  rusting  and  injury  to 
the  cutting  edge. 

Steam. — Steam  is  one  of  the  most  satisfactory  disinfecting  agents 
we  possess.  It  is  reliable,  quick,  and  may  be  depended  upon  to  penetrate 
deeply.  Further,  it  does  more  than  disinfect;  it  sterilizes.  Vegetating 
bacteria  are  killed  instantly  and  most  spores  in  a  few  minutes.  It  may 
therefore  be  used  to  destroy  the  infection  of  any  one  of  the  communicable 
diseases. 

Either  streaming  steam  or  steam  under  pressure  is  used  in  practical 
disinfection. 

Streaming  steam  has  the  same  disinfecting  power  as  boiling  water, 
and  an  exposure  of  half  an  hour  to  an  hour  is  sufficient.  Steam  under 
pressure  is  a  more  powerful  germicide  than  streaming  steam.  At  a 
pressure  of  15  pounds  to  the'  square  inch  steam  has  a  temperature  of 
approximately  120°  C.  and  may  be  depended  upon  to  sterilize  in  20 
minutes.  At  20  pounds  pressure  it  has  a  temperature  of  approximately 
125°  C.  and  will  sterilize  in  15  minutes. 

Steam  is  applicable  to  the  disinfection  of  bedding,  clothing,  fabrics 
of  all  kinds,  and  a  great  variety  of  other  objects,  provided  certain  pre- 
cautions are  taken  to  prevent  shrinking,  staining,  running  of  colors, 
etc.  Steam  shrinks  woolens  and  injures  silk  fabrics;  it  ruins  leather, 
fur,  skins  of  all  kinds,  rubber  shoes,  oilcloth,  and  articles  made  of 
impure  rubber  or  containing  glue,  varnish,  or  wood. 

It  is  important  in  disinfecting  with  steam,  whether  with  stream- 
ing steam  or  steam  under  pressure,  to  expel  the  air  from  the  apparatus. 
The  air,  being  a  poor  conductor  of  heat,  forms  dead  spaces  and 
prevents  the  steam's  coming  in  direct  contact  with  the  articles  to  be 
disinfected,  thereby  defeating  the  object  to  be  attained.  As  steam  is 
lighter  than  air  the  latter  can  best  be  expelled  from  the  apparatus  by 
admitting  the  steam  from  above,  in  which  case  the  descending  column 
of  steam  forces  the  air  out  at  the  bottom.     If  the  steam  is  admitted  at 


STEAM 


983 


the  bottom  it  swirls  up,  making  a  nearly  uniform  mixture  with  the 
air,  and  while  the  temperature  quickly  rises  in  the  apparatus  the  air 
escapes  mixed  with  the  steam,  so  that  it  takes  a  long  time  and  an 
unnecessary  waste  of  steam  to  drive  out  the  contained  air. 

Disinfection  with  streaming  steam  may  be  accomplished  in  many 
ways  without  the  use  of  special  apparatus.  For  rough  and  ready  work 
on  the  railroad  the  objects  to  be  disinfected  may  be  hung  in  a  freight- 
car  and  the  steam  brought  from  the  locomotive.  On  board  a  vessel  one 
of  the  compartments  above  the  water-line  may  be  filled  with  steam 
from  the  boiler.  Objects  may  be  steamed  in  any  rough  structure  wher- 
ever a  boiler  is  found  to  furnish  the 
steam.  Such  a  structure  need  not  be 
tight,  for  the  streaming  steam  escaping 
from  the  cracks  produces  a  circulation 
and  favors  penetration. 

In  the  laboratory  small  objects  are 

disinfected  in  streaming  steam  in  the 

Arnold   steam   sterilizer   or   the   Koch 

steamer. 

On  account  of  the  great  certainty 

with  which  steam  under  pressure  acts 
it  is  the  favorite  method  in  practical 
disinfection,  especially  where  steriliza- 
tion is  required,  and  devices  for  apply- 
ing this  process  on  a  large  scale  have 
reached  a  high  degree  of  perfection. 
The  smaller  forms  of  steam  sterilizers 
under  pressure  are  known  as  digestors 
or  autoclaves  and  the  larger  ones  as 
steam  disinfecting  chambers. 

The   Autoclave. — The   autoclave, 

digestor,  or  steam  sterilizer  consists  of   ^^<^-  144.— Section  through  Aknold 

-,        „  Steam  Stebilizbe. 

a  closed  kettle  usually  made  of  copper 

and  sufficiently  strong  to  withstand  the  pressure.  Water  is  placed  in 
the  kettle  and  the  heat  is  applied  to  the  bottom,  usually  by  means  of 
several  Bunsen  gas  jets.  The  apparatus  is  surrounded  as  high  as  the 
shoulder,  where  the  lid  is  attached,  with  a  metal  jacket  which  serves  the 
purpose  of  bringing  the  heat  of  the  flame  in  contact  with  the  entire  sur- 
face of  the  kettle.  The  lid  is  made  to  fit  tightly  by  means  of  screw  bolts 
and  a  rubber  gasket.  A  thermometer,  pressure  gage,  safety  valve  and  a 
small  opening  with  a  stop-cock  for  the  purpose  of  allowing  the  escape 
of  the  air  are  provided.  If  all  the  air  is  not  expelled  from  the  apparatus 
the  dead  spaces  will  have  a  much  lower  temperature  than  that  registered 
on  the  thermometer.    For  instance,  the  steam  itself  may  register  a  tem- 


984 


PHYSICAL   AGENTS    OF    DISINFECTION 


Fig. 


145. — Section  thkough  Auto- 
clave. 


perature  of  130°   C,  while  test  fluids  exposed  may  only  reach  70°  to 
80°  C.     Therefore,  in  using  this  form  of  sterilizer  it  is  customary  to 

allow  the  steam  to  escape  in  full  force 
for  several  minutes  before  permitting 
the  pressure  to  rise. 

In  the  sterilization  of  liquids,  for 
wliich  this  apparatus  is  frequently  used, 
it  is  important,  at  the  conclusion  of  the 
process,  not  to  take  off  the  lid  or  open 
the  valves,  or  in  any  other  way  release 
the  pressure  until  the  apparatus  has 
cooled;  otherwise  the  condensed  steam 
causes  a  diminished  pressure,  in  which 
the  heated  liquids  will  boil  energeti- 
cally, resulting  in  a  bubbling  over,  a 
blowing  out  of  stoppers,  or  a  bursting 
of  the  flasks.  It  is  therefore  necessary 
to  wait  until  the  pressure  is  zero,  as 
registered  on  the  gage ;  or,  better,  until 
the  condensing  steam  produces  a  partial 
vacuum  and  the  air  is  automatically  sucked 
in  through  the  vacuum  valve,  which  is  some- 
times fitted  in  the  lid  of  the  apparatus  for 
this  very  purpose. 

The  Steam  Chamber. — The  steam  dis- 
infecting chamber  has  reached  a  high  degree 
of  usefulness  through  the  gradual  perfection 
of  the  details  of  its  working  parts.  These 
chambers  are  somewhat  complicated  and 
their  mechanical  construction  must  be  mas- 
tered in  order  to  insure  reliable  results. 
Steam  disinfecting  chambers  may  be  used 
with  streaming  steam  or  with  steam  under 
pressure;  with  formaldehyd  gas  alone,  or 
with  this  gas  in  combination  with  dry  heat; 
and,  finally,  with  various  combinations  of 
these  methods  with  or  without  a  vacuum. 
The  disinfecting  chamber  itself  may  be 
rectangular  or  cylindrical  in  shape,  the  for- 
mer giving  more  effective  space,  the  latter 
being  a  stronger  and  cheaper  method  of  con- 
struction.   The  chamber  is  built  of  an  inner 

and  outer  shell  forming  a  steam  jacket,  as  shown  in  Fig.   147.     The 
steam  jacket  serves  several  purposes.    By  heating  the  contents  of  the  dis- 


FlG. 


146. — Bramwell-Deane 
Steam  Sterilizer. 


STEAM 


985 


infecting  cylinder  before  the  steam  is  turned  in  it  avoids  condensation. 
During  the  process  of  disinfection  it  lielps  keep  the  steam  in  the  chamber 
"live/'  thereby  preventing  the  wetting  of  the  objects  exposed.  After  the 
disinfection  is  finished  and  the  chamber  opened  the  heat  from  the  steam 
in  the  jacket  may  be  used  to  dry  the  objects  which  have  just  been  steamed. 
Therefore,  in  using  this  apparatus  for  disinfecting  with  steam,  either  with 
or  without  pressure,  the  steam  is  kept  circulating  in  the  jacket  from  the 
beginning  to  the  end  of  the  process. 


Fig.  147. — Cross  Section  through  Steam  Disinfecting  Chamber. 

In  the  jacket  the  steam  has  a  perfectly  free  circulation,  so  that  the 
entire  disinfecting  cylinder,  with  the  exception  of  the  doors,  is  sur- 
rounded by  live  steam.  The  outer  shell  of  the  jacket  is  insulated  with 
a  covering  of  sectional  magnesia,  asbestos,  or  some  other  non-conduct- 
ing substance. 

The  steam  from  the  boiler  passes  through  the  main  steam  pipe  A 
(Fig.  149)  to  the  pressure-reducing  valve  (2),  and  thence  to  the  bot- 
tom of  the  jacket  at  B,  B. 

Into  the  disinfecting  chamber  itself  the  steam  can  be  admitted 
only  from  the  jacket,  through  the  circulating  pipes.  A,  C,  B  (Fig. 
147,  and  after  circulating  through  the   disinfecting  chamber  in  the 


986 


PHYSICAL    AGENTS    OF    DISINFECTION 


direction  as  shown  by  the  arrows  is  allowed  to  pass  out  with  the 
drip  through  the  drain  D  (Fig.  148).  Upon  the  completion  of  the 
process   the   steam   may   bo    blown   off   through   the   vacuum   pipe    F, 


but  this  outlet  should  not  be  used  during  the  steaming  because  the  de- 
sired circulation  would  not  be  obtained. 

It  will  be  noticed  that  the  steam  is  admitted  to  the  bottom  of  the 
jacket,  but  to  the  top  of  the  disinfecting  chamber,  which  is  designed 


STEAM  987 

to  favor  the  expulsion  of  the  air  through  its  outlet  at  the  bottom  by 
means  of  the  descending  column  of  steam.  Therefore,  in  order  to  expel 
all  the  air  and  fill  the  chamber  with  steam  it  is  essential  to  open  the 
drain  D  (Fig.  148)  while  the  steam  is  entering  through  B,  B,  and 
this  outlet,  D,  should  not  be  closed  until  steam  escapes  freely.  In  using 
the  vacuum  attachment  to  expel  the  air  contained  in  the  apparatus 
the  modus  operandi  is  somewhat  different. 

A  partial  vacuum  may  be  obtained  in  steam  chambers  of  this  type 
with  the  ejector  (4,  Fig.  149).  The  object  of  the  vacuum  is  to 
facilitate  the  penetration  of  the  steam,  which  rushes  into  all  the  inter- 
stices of  fabrics  and  inaccessible  places,  to  take  the  place  of  the  air 
which  has  been  withdrawn.  The  ejector  works  upon  the  familiar  prin- 
ciple of  the  water  vacuum  pump,  the  air  being  drawn  or  sucked  along 
with  the  current.  With  a  pressure  of  80  pounds  in  the  boiler  and  the 
valve  J  (Fig.  149)  wide  open  the  ejector  will  produce  a  partial  vacuum 
of  15  inches  in  one  of  the  largest  sized  chambers  in  one  minute,  which 
is  very  much  quicker  than  can  be  accomplished  with  the  ordinary  forms 
of  piston  pumps. 

Any  steam  disinfecting  chamber  may  have  attached  to  it  an  appa- 
ratus for  generating  formaldehyd  gas,  so  that  objects  that  are  injured 
by  exposure  to  steam  may  be  disinfected  with  formaldehyd,  plus  dry 
heat.  Before  the  formaldehyd  is  admitted  into  the  chamber  a  partial 
vacuum  may  be  established  by  means  of  the  ejector.  In  this  way  the 
penetration  of  the  gas  is  very  much  facilitated. 

In  the  best  patterns  the  steam  disinfecting  cylinders  are  open  at 
both  ends,  so  that  the  infected  objects  may  be  introduced  from  one  side 
and  taken  out  from  the  other,  which  diminishes  the  risk  of  reinfecting 
them.  The  joint  between  the  door  and  the  chamber  is  made  tight  by 
means  of  a  heavy  rubber  gasket.  The  door  should  not  be  pressed 
against  this  gasket  more  firmly  than  is  found  necessary  to  retain 
the  steam,  otherwise  the  rubber  will  soon  be  rendered  useless.  When 
not  in  use  the  door  should  be  kept  open,  otherwise  on  cooling  the  metal 
will  adhere  to  the  rubber  gasket.  This  may  be  prevented  to  a  certain 
extent  by  keeping  the  rubber  gasket  covered  with  graphite. 

In  addition  to  the  above-mentioned  attachments  the  disinfecting 
chambers  are  also  supplied  with  a  thermometer  (7,  Fig.  149),  the 
stem  of  which  is  turned  at  right  angles  and  protrudes  so  as  to  indicate 
the  temperature  of  the  interior  of  the  disinfecting  chamber.  The  ther- 
mometer, however,  is  so  close  to  the  jacket  that  it  is  influenced  by  the 
heat  in  the  jacket,  which  is  usually  higher  than  the  temperature  of 
the  interior  of  the  chamber.  The  thermometer  should  be  in  the  door, 
or  differently  arranged,  to  give  trustworthy  results.  In  disinfecting 
with  steam  under  pressure  the  pressure,  as  indicated  by  the  gage,  is  a 
more  reliable  guide  than  the  temperature  registered  by  the  thermometer. 


988 


PHYSICAL   AGENTS    OF    DISINFECTION 


There  are  forms  of  mercurial  and  metallic  thermometers  that  make  an 
electric  contact  when  a  certain  temperature  is  reached,  and  which  may 
be  connected  to  ring  a  bell.  They  have  a  decided  advantage  in  that 
they  may  be  placed  anywhere  within  the  chamber,  even  in  the  center 


of  bundles,  etc.,  and  are  more  trustworthy  than  any  form  of  mercurial 
instrument  fastened  through  the  heavy  metallic  walls  of  the  apparatus. 
An  ingenious  form  of  thermometer,  made  to  register  when  the 
temperature  reaches  100°  C,  has  been  designed  by  Merk,  and  is 
shown  in  the  accompanying  illustration  (Fig.  150).  A  small  stick  of 
the  metallic  substance  which  is  supplied  with  the  instrument  and  which 


STEAM  989 

melts  at  exactly  100°  C,  fastened  at  A,  keeps  the  electrodes  at  B  and 
C  apart.  The  entire  thermometer  D  is  then  placed  in  the  box  E  for 
protection,  and  this  is  placed  in  the  chamber  or  in  the  inside  of  bun- 
dles to  be  disinfected.  The  insulated  wires  from  F  and  G-  are  con- 
nected with  a  battery  and  bell.  As  soon  as  the  temperature  reaches 
100°  C.  the  little  metal  stick  melts,  the 
contact  is  made  between  B  and  C,  and  the 
bell  rings.  This  form  of  thermometer  is 
more  accurate  than  the  pyrometers,  which 
depend  upon  the  contact  being  made  by 
the  unequal  expansion  of  a  compound 
metal  bar,  for  the  reason  that  moisture 
collects  upon  the  electrodes  and  an  elec- 
tric contact  is  sometimes  made  before  the 

,1  ,  in,        1     J.1        1         •    •         Fig.    150. — ^Axjtomatic   Thermom- 

metal  parts  actually  touch,  thereby  giving  ^.^er. 

false  readings. 

Steam  chambers  must  always  be  provided  with  galvanized  or  copper 
hoods  to  prevent  rust-stained  drip  from  soiling  the  clothing  and  other 
objects  exposed  to  the  steam;  gages  to  indicate  both  vacuum  and  steam 
pressure,  and  a  safety  valve  to  prevent  over-pressure  in  the  chamber. 
The  amount  of  pressure  from  the  boiler  is  regulated  by  a  reducing  valve 
in  the  main  steam  pipe. 

For  convenience  in  handling  the  goods  cars  are  provided,  of  light 
wrought-iron  construction,  with  movable  trays  made  of  galvanized 
screens;  also  bronze  hooks  at  the  top  of  the  car,  permitting  the  articles 
to  be  laid  upon  the  trays  or  to  be  hung  up  on  the  hooks. 

In  the  accompanying  diagram  (Fig.  151)  the  method  of  installing 
the  steam  chambers  in  the  disinfecting  shed  of  a  quarantine  station  is 
shown.  It  will  be  noted  that  the  cylinders  open  on  both  ends,  and  that 
a  dividing  wall  running  across  the  building  separates  the  receiving  end, 
where  the  infected  objects  arrive  and  are  prepared  for  disinfection, 
from  the  discharging  end,  where  the  contents  of  the  chamber  are  aired, 
dried,  and  repacked  after  disinfection. 

This  separation  is  essential  where  a  large  amount  of  disinfection 
is  done  for  a  variety  of  diseases,  as,  for  example,  in  a  municipal  disin- 
fecting establishment  or  at  the  quarantine  station  of  a  busy  port.  It 
is  true  that  the  infection  of  certain  diseases  is  not  apt  to  contaminate 
the  surroundings,  and  in  such  cases  there  would  be  little  risk  in  taking 
the  disinfected  articles  out  of  the  same  end  of  the  chamber  from 
which  they  are  put  in,  especially  if  the  exposed  surfaces  are  mopped 
with  a  disinfectant  in  the  interim.  But  this  is  a  risk  that  need 
not  be  taken;  in  fact,  all  well-regulated  disinfecting  plants  maintain 
a  rigid  separation  between  the  two  sides,  never  allowing  both  doors 
of  the  chamber  to  be  open  at  the  same  time,  and  providing  two  sets 


990 


PHYSICAL   AGENTS    OF    DISINFECTION 


of   workmen,    one    for   the   "infected"    and    one    for   tlie    "disinfected" 
side. 

The  chaiiiljers  must  be  hjiuk'd  witli  care  in  order  to  ol)tain  reliable 

results  and  to  avoid  injuring  the 
articles  exposed  to  the  process. 
The  packages  must  not  be  too 
large  or  crowded  too  closely,  for, 
although  the  vacuum  facilitates 
the  penetration  of  the  steam, 
there  is  a  limit  in  this  regard; 
it  takes  so  much  longer  for  dis- 
infecting agents  to  penetrate 
dense  packages  and  bundles  that 
there  is  little  saving  of  time  and 
a  distinct  loss  in  trustworthi- 
ness. Steam  cannot  jjcnetrate 
compressed  bundles  of  rags, 
bales  of  cotton,  feathers,  hair, 
or  other  packages  of  merchan- 
dise which  are  often  presented 
for  disinfection.  Fortunately, 
it  is  seldom  necessary  to  disin- 
fect such  packages.  Wlien,  how- 
ever, this  is  called  for  it  is  es- 
sential to  open  and  properly  ex- 
pose such  objects  to  the  action 
of  the  disinfecting  agent. 

In  the  municipal  disinfecting 
stations  of  Paris  the  process  of 
applying  steam  under  pressure 
is  as  follows :  The  pressure  is 
brought  up  to  15  pounds  in  the 
chamber  and  held  there  five  min- 
utes; then  released.  The  pres- 
sure is  again  brought  up  to  15 
pounds,  held  there  five  minutes, 
and  again  released.  This  is  re- 
peated three  times,  when  the 
disinfection  is  completed.  The 
cylinders  are  fitted  with  an  in- 
genious arrangement  for  the  automatic  registration  of  the  process.  Each 
chamber  is  connected  by  a  small  copper  tube  to  a  register  with  a 
moving  pen  and  revolving  drum  carrying  a  chart.  The  horizontal  lines 
1  to  10  on  the  chart  each  represent  a  pressure  of  one-tenth  of  an  atmos- 


STEAM 


991 


phere,  and  the  vertical  lines  represent  five  minutes  in  the  revolution 
of  the  drum.     Each  steaming  is  represented  thus: 


Fig.  152. 


These  charts,  which  can  be  removed  only  by  the  chief  of  the  sta- 
tion, are  sent  each  day  to  the  Inspector-General,  and  give  a  perfect 
guarantee  that  each  steaming  has  been  done  as  directed. 


CHAPTER    III 
CHEJVnCAL   AGENTS    OF   DISINFECTION 

GASEOUS    DISINFECTANTS 

A  gas  is  an  ideal  weapon  for  destroying  such  invisible  foes  as  we 
have  to  deal  with  in  public  health  work,  especially  for  terminal  disin- 
fection. By  reaching  all  portions  of  a  room  or  confined  space  a  gas 
lessens  the  rigk  of  overlooking  any  surface  upon  which  the  infective  agent 
may  be  lodged,  but  the  ideal  gas  for  this  purpose  is  still  to  be  discovered. 

There  is  practically  only  one  gas  suitable  for  general  application, 
viz.,  formaldehyd.  This  substance  comes  nearer  being  an  ideal  disin- 
fectant than  any  of  the  gases  in  general  use.  It  is  not  poisonous, 
does  not  injure  fabrics,  colors,  metals,  or  objects  of  art  and  value. 
Formaldehyd,  however,  has  distinct  limitations,  which  are  dealt  with 
more  in  detail  under  the  description  of  the  gas. 

Sulphur  dioxid  is  too  destructive  for  fabrics,  colors,  and  metals 
for  general  use.  It  is  a  better  insecticide  than  germicide.  It  is  very 
poisonous  to  all  forms  of  animal  life,  which  makes  it  valuable  in 
disinfection  against  insect  and  animal-borne  diseases.  It  has  no  equal 
for  the  fumigation  of  the  holds  of  ships,  cellars,  sewers,  stables,  and 
other  rough  structures  infested  with  vermin. 

The  very  poisonous  and  destructive  nature  of  chlorin  gas  contracts 
its  usefulness  to  narrow  limits. 

Hydrocyanic  acid  gas  is  too  poisonous  to  use  in  the  household,  and 
is  limited  in  practice  to  the  destruction  of  infection  and  vermin  on 
board  ships,  in  warehouses,  greenhouses,  granaries,  railroad  cars,  and 
other  uninhabited  or  isolated  structures. 

None  of  the  gaseous  agents  can  be  depended  upon  for  more  than 
a  surface  disinfection.     They  all  lack  the  power  of  penetration. 

Preparation  of  the  Room. — The  preparation  of  a  room  or  space  to 
be  disinfected  with  a  gas  is  a  matter  of  some  importance.  A  larger 
amount  of  gas  than  is  thought  possible  is  lost  through  leaks  by  diffusion 
and  absorption  and  in  other  ways;  therefore  the  room  should  be  made 
tight,  all  cracks  and  crevices  should  be  well  closed  by  pasting  paper 
over  them  or  by  caulking  with  suitable  material  of  some  kind.  Do  not 
993 


GASEOUS    DISINFECTANTS  993 

forget  to  close  the  registers,  flues,  hearths,  and  ventilators,  and  look  care- 
fully for  openings  in  out-of-the-way  places.  Then  expose  the  objects  in 
the  room  so  that  the  gas  may  have  ready  access  to  all  the  surfaces.  Hang 
clothing,  bedding,  and  fabrics  upon  lines  strung  across  the  room;  move 
bureaus,  beds,  and  furniture  away  from  the  walls,  open  doors  of  clos- 
ets, drawers  of  bureaus,  lids  of  boxes,  and  the  like  so  that  the  gas  may 
freely  enter  and  diffuse  to  all  corners. 

While  the  articles  in  the  room  must  be  arranged  so  that  the  gas 
may  freely  gain  access  to  all  surfaces  possible,  the  mistake  must  not 
be  made  of  going  to  the  opposite  extreme  of  disarranging  the  contents 
of  the  room  too  much,  for  the  same  surfaces  should  be  exposed  to  the 
gas  that  were  exposed  to  the  infection. 

The  strength  of  the  gas  and  time  of  the  exposure  necessary  to  insure 
disinfection  have  been  determined  by  exact  laboratory  experiments, 
but  the  conditions  found  in  actual  practice  are  so  variable  that  we  must 
allow  for  a  liberal  excess  to  make  up  for  inevitable  wastage.  Wind 
pressure  also  seriously  influences  the  efficiency  of  gaseous  disinfectants 
in  a  confined  space.  Much  more  air  than  is  commonly  thought  possible 
forces  its  way  through  cracks  and  through  the  walls  themselves.  The 
wind  pressure  may  thus  drive  the  fumigating  gas  entirely  away  from 
one  side  of  the  room.  It  is  only  necessary  to  stand  upon  the  leeward 
side  of  a  structure  being  disinfected  with  sulphur  dioxid  or  formalde- 
hyd  to  realize  the  great  quantity  of  gas  blown  from  the  enclosure. 

Formaldehyd  Gas. — Formaldehyd  ^  is  the  most  generally  useful  and 
one  of  the  best  disinfecting  gases  that  we  possess.  Its  superiority  de- 
pends upon  its  high  value  as  a  germicide,  its  non-poisonous  nature,  and 
upon  the  fact  that  it  is  not  destructive.  The  secret  of  successful  disin- 
fection with  this  substance  is  to  obtain  a  large  volume  of  the  gas  in  a 
short  time. 

Formaldehyd  (HCHO)  exists  in  at  least  three  well-recognized  iso- 
meric states: 

(1)  Formaldehyd  (formic  aldehyd)  is  a  gas  at  ordinary  tempera- 
tures, colorless,  and  possessing  slight  odor,  but  having  an  extremely  irri- 
tating effect  upon  the  mucous  membranes.  At  a  temperature  of  about 
—  20°  C.  the  gas  polymerizes  into  paraformaldehyd,  known  commer- 
cially as  paraform. 

(2)  Paraform  is  a  white  substance,  unctuous  to  the  touch,  soluble 
in  both  water  and  alcohol.  It  consists  chemically  of  two  molecules 
of  formaldehyd.  It  is  this  substance  which  is  supposed  to  compose 
the  commercial  solutions  of  formaldehyd  known  as  formalin,  formol, 
etc. 

(3)  Trioxymethylene  is  formed  by  the  union  of  three  molecules  of 

^  Formaldehyd  is  the  gas,  formalin  is  the  aqueous  solution  of  the  gas. 


994  CHEMICAL    AGENTS    OF    DISINFECTION 

formal dehyd.     It  is  a  white  powder  giving  off  a  strong  odor  of  the 
ga<:.     It  is  but  slightly  soluble  in  alcohol  and  water. 

Fonnaldehyd  gas  possesses  about  the  same  specific  gravity  as  air; 
it  diffuses  slowly,  although  somewhat  better  than  sulphur  dioxid.  For- 
maldehyd  combines  with  nitrogenous  organic  matter,  A  few  drops 
added  to  the  white  of  an  egg  will  prevent  its  coagulation  by  heat.  The 
formaldehyd  unites  with  the  albumin  to  form  a  totally  new  compound. 
Combined  with  gelatin  it  keeps  that  substance  from  liquefying.  It 
is  from  this  property  of  combining  directly  with  the  albumins  form- 
ing the  protoplasm  of  the  microorganisms  that  formaldehyd  is  sup- 
posed to  derive  its  power  as  a  germicide.  It  is  perfectly  plain,  there- 
fore, why  there  must  be  direct  contact  between  the  gas  and  the  germ 
in  order  to  accomplish   disinfection. 

Formaldehyd  also  unites  readily  with  the  nitrogenous  products  of 
fermentation  and  decomposition,  forming  new  chemical  compounds 
which  are  both  odorless  and  sterile.  It  is  thus  a  true  deodorizer  in 
that  it  does  not  mask  one  odor  by  aiiother  still  more  powerful,  but 
forms  new  chemical  bodies  which  possess  no  odor. 

Formaldehyd  apparently  has  no  detrimental  effects  upon  silks, 
woolens,  cotton,  and  linen.  It  does  not  change  colors,  with  the  excep- 
tion possibly  of  a  slight  effect  upon  some  of  the  delicate  anilin  laven- 
ders. An  oil  painting  is  not  perceptibly  altered  after  prolonged  ex- 
posure to  the  gas.  The  metals  are  not  attacked.  It  is  this  non-de- 
structive property  of  the  gas  that  renders  it  generally  applicable.  It  is 
practically  the  only  gaseous  germicide  which  can  be  iised  in  the  richest 
apartments,  containing  objects  of  art  and  value,  without  fear  of  dam- 
age. 

The  commercial  solutions  known  as  formalin  are  said  to  contain 
40  per  cent,  of  formaldehyd  gas.  They  are  not  always  up  to  standard 
(average  36  per  cent.),  and,  being  volatile,  there  is  a  certain  loss  if 
not  well  kept.  In  winter  there  is  a  decided  deterioration,  owing  to 
the  polymerization  and  precipitation  of  trioxymethylene.  This  sub- 
stance is  often  found  in  abundance  at  the  bottom  of  the  bottle  or  car- 
boy as  a  white  precipitate.  For  these  reasons  it  is  well  to  use  an  excess 
of  the  liquid  in  practical  work  if  the  exact  strength  of  the  formalin 
has  not  recently  been  determined. 

Formalin  solutions  of  commerce  are  almost  all  acid  in  reaction, 
due  in  part  to  formic  acid.  Some  of  the  commercial  solutions  also 
contain  a  certain  amount  of  wood  alcohol  (about  10  per  cent.)  which 
is  added  to  increase  their  solubility  and  stability. 

A  certain  amount  of  heat  and  moisture  is  necessary  to  obtain 
successful  disinfection  with  formaldehyd  gas.  The  exact  amount  of 
moisture  necessary  depends  somewhat  upon  the  temperature.  As  a 
general  working  rule  it  may  be  stated  that  if  the  temperature  is  below 


GASEOUS    DISINFECTANTS  995 

65°  F.  or  if  the  relative  humidity  is  below  60  per  cent,  the  results  be- 
come irregular;  much  below  these  figures  the  results  are  unreliable. 
Formaldehj^d  polymerizes  at  low  temperatures,  therefore  in  cold  weather 
it  may  be  necessary  to  artificially  warm  the  room  to  be  disinfected.  In 
dry  weather  moisture  should  be  added  to  the  room. 

Formaldehyd  gas  cannot  be  depended  upon  to  accomplish  more 
than  a  surface  disinfection.  Under  ordinary  circumstances  it  possesses 
small  powers  of  penetration.  It  takes  a  large  volume  and  a  long 
exposure  to  penetrate  several  layers  of  thin  fabrics.  The  gas  polymerizes 
in  the  meshes  of  the  fabric  and  is  deposited  as  paraform  upon  surfaces. 
Large  quantities  of  the  formaldehyd  are  lost  by  uniting  chemically  with 
the  organic  matter  of  fabrics^  especially  woolens^  which  further  hinders 
its  penetration.  Therefore,  formaldehyd  gas  cannot  be  relied  upon  to 
disinfect  fabrics,  especially  quilted  goods  and  materials  requiring  deep 
penetration. 

Formaldehyd  gas  has  the  power  of  killing  spores,  although  not  with 
sufficient  certainty  to  render  it  a  trustworthy  agent  for  infections 
such  as  anthrax  and  tetanus.  It  has  the  great  advantage  of  killing  dry 
microorganisms,  although  not  quite  so  readily  as  when  they  are  moist. 

Bacteria  exposed  directly  to  the  action  of  a  concentrated  volume 
of  formaldehyd  gas  are  killed  almost  instantly.  Under  similar  condi- 
tions spores  are  killed  within  an  hour,  but  in  practical  work  it  is 
necessary  to  prolong  the  time  of  exposure,  as  it  takes  considerable  time 
for  it  to  permeate  to  all  the  corners  and  dead  spaces  of  a  room.  Bac- 
teria are  not  always  directly  exposed  upon  the  surface  of  objects,  as 
they  are  in  laboratory  experiments,  and,  furthermore,  they  are  fre- 
quently imbedded  in  albuminous  matter  or  in  dust,  both  of  which  retard 
the  action  of  the  gas. 

Formaldehyd  gas  is  not  toxic  to  the  higher  forms  of  animal  life, 
although  it  stands  at  the  head  of  the  list  of  germicides.  Long  exposure 
to  weak  atmospheres  of  the  gas  sufficient  to  kill  germs  has  but  slight 
effect  upon  animals.  Guinea-pigs,  rats,  mice,  and  rabbits  exposed  to 
concentrated  atmospheres  obtainable  by  any  of  the  methods  for  evolving 
it  are  not  killed  after  half  an  hour's  exposure.  The  only  effect  produced 
is  a  violent  irritation  of  the  mucous  membranes  of  the  respiratory  tract, 
from  which  the  animals  may  subsequently  die.  Microorganisms  exposed 
to  this  same  concentration  of  the  gas  are  killed  almost  instantly. 

Formaldehyd  is  not  an  insecticide.  In  the  strongest  volumes  of 
the  gas  obtainable  it  seems  to  have  practically  no  effect  upon  roaches, 
bedbugs,  and  insects  having  strong  chitinous  coverings.  It  may  kill 
the  frailer  insects,  but  its  action  is  uncertain;  thus  mosquitoes  may  live 
in  a  weak  atmosphere  of  the  gas  over  night. 

Upon  the  completion  of  the  time  required  to  disinfect  a  room  it 
is  best  to  open  all  the  doors  and  windows  and  let  the  gas  blow  away. 


996 


CHEMICAL   AGENTS    OF    DISINFECTION 


(1) 
(2) 
(3) 
(^) 
(5) 
(6) 
(7) 
(8) 


This  may  bo  a  troublesome  procedure.  If  the  windows  can  be  reached 
from  the  outside  it  is  easy  enougli.  but  if  the  room  must  be  entered 
it  is  advisable  for  the  operator  to  cover  his  mouth  and  nose  with  a 
moist  towel  and  act  quickly.  It  was  formerly  the  custom  to  neutralize 
the  gas  with  ammonia,  but  this  is  little  practiced  now.  The  ammonia 
neutralizes  the  formaldehyd  by  the  production  of  hexametliylene-tetra- 
mine. 

The  following  methods  are  used  for  disinfection  with  formaldehyd 
gas: 

Autoclave  under  pressure. 
Retort  without  pressure. 
Generator  or  lamp. 

Fornuildehyd  and  dry  heat  in  partial  vacuum. 
Spraying. 

Heating  para  form. 

Potassium  permanganate  and  formalin. 
Formalin,  lime,  and  aluminium  sulj^hate. 
The  most  generally  useful  of  these  methods  are  the  last  two.     They 
have  the  great  advantage  of  simplicity,  of  dispensing  with  all  apparatus, 
and  of  evolving  a  large  amount  of  the  gas  in  a  short  time. 

The    Pee:n[axgaxate-Formalix    Method. — Use    500   c.  c.    of   for- 
malin and  250  grams  of  potassium  permanganate  for  each   thousand 

cul)ic  feet  of  air  space.  The  peruum- 
ganate  is  first  placed  in  a  bucket 
or  basin  and  the  formalin  poured 
upon  it.  An  active  effervescence 
takes  place  and  considerable  heat  is 
evolved;  therefore  a  pail  of  sufficient 
capacity,  and  especially  of  sufficient 
height,  should  be  used  to  prevent 
splashing  or  boiling  over.  In  Board 
of  Health  work  it  is  advisable  to 
have  galvanized  iron  pails  made  for 
this  purpose  with  a  flaring  top.  The 
floor  should  be  protected  against  the 
heat  by  placing  the  bucket  upon  a 
brick,  board,  or  other  suitable  device. 

When  the  permanganate  of  potas- 
FiG.    153. — Flahini}    Top     Tin    Bucket      .  t     »  ,.  ,  i  ,     . 

FOR  Generating  Formaldehyd  by  smm  and  formalm  are  brought  in 
THE  Permanganate  Method.  Height  contact  \eT\  active  oxidation  takes 
15  inches,  diameter  10  inches  at  base,       ,  ■<!    ",i  t      j  •  p   p 

15  inches  at  top  of  flare.  place.  With  the  production  of  formic 

acid  and  heat.  It  is  the  heat  that 
liberates  the  formaldehyd  gas.  Chemically,  therefore,  the  method  is  a 
wasteful  one,  but  practically  a  very  serviceable  one.     It  was  first  de- 


GASEOUS    DISINFECTANTS  997 

scribed  by  Johnson  of  Sioux  City,  Iowa,  in  1904.  In  the  same  year 
Evans  and  Eussell  of  Augusta,  Maine,  used  the  method. 

The  Formalin'-Lime  and  Aluminium-Sulphate  Method. — 
This  method  was  first  described  by  Walker  of  the  Department  of 
Health,  Brooklyn,  N.  Y.  It  is  somewhat  slower  than  the  potassium 
permanganate  method,  but  otherwise  appears  to  be  just  as  efficient. 

The  proportions  for  each  1,000  cubic  feet  are  as  follows : 

Sol.  A. — Aluminium  sulphate 150  grams 

Dissolved  in  hot  water 300  c.  c. 

Sol.  5.— Formalin   (40  per  cent.  CHOH) ...     600  c.  c. 

Lime. — Unslaked  lime 2,000  grams 

Mix  solutions  A  and  B  and  pour  upon  the  lime. 

In  practical  work  20  to  25  pounds  of  the  commercial  aluminium 
sulphate  is  dissolved  in  5  .gallons  of  hot  water.  This  is  sufficient  to 
mix  with  15  gallons  of  a  40  per  cent,  formaldehyd  solution  and  then 
used  in  the  proportions  as  stated  above.  The  lime  should  be  freshly 
burned,  broken  into  small  particles,  and  should  slake  rapidly  in  cold 
water.  The  lime  is  placed  in  a  large  bucket.  The  formalin  and  alu- 
minium sulphate  solutions  should  be  mixed  and  poured  over  the  lime. 
In  a  few  minutes  the  lime  begins  to  slake  and  the  heat  evolved  drives 
off  the  formaldehyd  gas. 

The  Spraying  Method. — Spraying  formalin  is  a  satisfactory  and 
simple  method  of  disinfecting  small  inclosures,  such  as  wardrobes, 
closets,  and  cabinets.  It  is  not  practical  for  larger  rooms.  If  the  for- 
malin is  sprayed  directly  upon  the  objects  to  be  disinfected  they  enjoy  the 
direct  germicidal  action  of  the  substance  in  solution  and,  further,  are 
bathed  in  the  gas  which  is  slowly  evolved.  The  method  is  particularly 
serviceable  for  the  disinfection  of  bureau  drawers,  closets,  and  small 
spaces.  When  used  to  disinfect  small  rooms  suspend  a  bed  sheet  from  a 
line  stretched  across  the  middle  of  the  room.  An  ordinary  bed  sheet 
presenting  a  surface  of  about  2  by  2i/^  yards  is  required  for  every 
1,000  cubic  feet  of  space  of  the  room.  Properly  sprinkled  this  will 
carry,  without  dripping,  8  ounces  of  formalin.  The  ordinary  sprink- 
ling pot  used  by  florists  can  be  used  to  spray  the  sheets.  The  room 
should  remain  closed  not  less  than  8  hours. 

The  other  methods  for  disinfecting  with  formaldehyd  gas  are  not 
described  because  some  of  them  are  unreliable,  and  none  of  them  are 
as  serviceable  in  practical  work  as  the  formalin-permanganate  method 
or  the  formalin-lime  method. 

Sulphur  Dioxid. — Sulphur  dioxid  (SO2)  is  not  a  very  efficient  germi- 
cide, but  is  exceedingly  poisonous  to  mammalian  and  insect  life.  It 
is  this  property  which  makes  it  of  especial  value  as  a  fumigant  against 
65 


998  CHEMICAL    AGENTS    OF    DISINFECTION 

diseases   spread  by   rats,   mice,   flies,    fleas,   mosquitoes,   etc.      For  this 
purpose  it  has  no  superior. 

The  action  of  sulphur  dioxid  as  a  germicide  depends  upon  the 
presence  of  moisture.  The  dry  gas  is  practically  inert  against  bacteria. 
Sulphur  dioxid  cannot  be  depended  upon  where  penetration  is  required. 
Its  action  is  merely  upon  the  surface.    It  does  not  kill  spores. 

Sulphur  dioxid  possesses  the  advantage  of  being  cheap  and  readily 
procurable.  There  is  hardly  a  crossroad  store  in  the  country  where  a 
reasonable  quantity  of  sulphur,  either  in  the  form  of  flowers  or  in 
rolls  or  sticks  under  the  name  of  brimstone,  cannot  be  obtained.  Sul- 
phur dioxid  is  especially  applicable  to  the  holds  of  ships,  freight-cars, 
granaries,  stables,  out-houses,  and  similar  rough  structures — particu- 
larly if  infested  with  vermin. 

The  disadvantages  of  sulphur  dioxid  as  a  disinfecting  agent  are 
such  as  to  contract  its  application  to  rather  narrow  limits.  It  bleaches 
all  coloring  matter  of  vegetable  origin  and  .many  anilin  dyes.  It  at- 
tacks almost  all  metals;  it  acts  upon  cotton  and  linen  fabrics  so  as  to 
seriously  weaken  their  tensile  strength,  especially  if  starched. 

Sulphur  dioxid  is  a  heavy,  colorless,  irrespirable  gas  with  a  peculiar 
suffocating  odor  and  irritating  properties.  It  has  a  density  of  2.4.  On 
account  of  the  heavy  specific  gravity  as  compared  to  air  it  diffuses 
slowly  and  then  settles  toward  the  bottom  of  the  compartment. 

Cold  water  takes  up  more  than  30  times  its  volume  of  sulphur  dioxid. 
The  solution  contains  sulphurous  acid  (H2SO3),  and  it  is  in  reality 
this  acid  that  is  the  disinfecting  agent.  The  dry  gas  is  therefore 
inert  and  moisture  is  essential  in  order  to  obtain  any  germicidal  effect! 
It  is  also  this  acid  and  some  sulphuric  acid  which  has  such  a  de- 
structive effect  upon  fibers,  colors,  and  metals.  The  corrosive  action 
of  these  acids  upon  fabrics  takes  place  slowly,  and  the  damage  may 
largely  be  obviated  if  they  are  washed  at  once.  Metal  work  may  be 
protected  by  coating  it  with  a  thin  layer  of  vaselin  or  heavy-bodied  oil. 

Sulphur  dioxid  may  readily  be  condensed  into  a  clear  liquid  by 
either  cold  or  pressure  or  a  combination  of  both.  At  ordinary  atmos- 
pheric pressure  it  condenses  if  the  temperature  is  reduced  to  — 18°  C, 
which  is  about  the  temperature  of  a  mixture  of  ice  and  salt.  At  ordinary 
temperatures  it  liquefies  if  the  pressure  is  raised  to  about  four  atmos- 
pheres, that  is,  60  pounds.  This  liquid  is  a  stable  substance  when 
kept  well  sealed  and  protected  from  the  action  of  the  air.  It  rapidly 
volatilizes  when  poured  into  an  open  vessel.  It  is  now  found  in  com- 
merce and  is  one  of  the  methods  used  for  producing  the  gas  for  fumi- 
gating purposes. 

The  complete  combustion  of  1  pound  of  the  sulphur  in  a  space 
1,000  cubic  feet  will  produce  1.115  per  cent,  of  sulphur  dioxid.  but 
this  amount  cannot  be  obtained  in  practice  because  the  sulphur  of  com- 


GASEOUS    DISINFECTANTS  999 

merce  contains  impurities  such  as  sulphate  of  lime  and  sand,  and  a 
portion  of  the  burning  sulphur  is  always  oxidized  to  the  formation  of  ill- 
defined  compounds.  Therefore  one  pound  ma}'  be  considered  as  pro- 
ducing approximately  1  per  cent,  of  the  gas  by  being  burned  in  1,000 
cubic  feet  of  space,  and  five  pounds  will  generate  approximately  5 
per  cent.,  which  is  the  maximum  theoretical  amount  obtainable  by 
burning  sulphur  in  a  confined  space.  This  is  the  amount  usually  used 
when  a  germicidal  action  is  desired. 

The  amount  of  moisture  necessary  to  convert  sulphur  dioxid  into 
sulphurous  acid  is  readily  computed.  It  will  be  found  that  one-fifth  of 
one  pound  of  water  should  be  volatilized  or'  added  for  each  pound  of 
sulphur  burned.  The  water  may  be  added  in  the  form  of  steam  or  in 
the  form  of  a  finely  divided  spray,  or  it  may  be  vaporized  by  the  heat 
generated  by  the  combustion  of  the  sulphur  itself.  The  latter  method- 
is  the  one  that  commends  itself  in  practical  use,  and  is  described  under 
the  "pot  method." 

While  moisture  is  essential  for  the  germicidal  action  of  sulphur 
dioxid,  it  is  not  necessary  in  order  to  kill  insects  and  the  higher  forms 
of  life.  Dry  sulphur  dioxid  is  C|uite  as  efficacious  against  rats,  mice, 
fleas,  flies,  mosquitoes,  bedbugs,  roaches,  etc.,  as  the  moist  gas. 

In  disinfecting  with  sulphur  dioxid  it  is  necessary  to  tightly  seal 
the  compartment.  The  gas  is  disengaged  so  slowly  that  it  may  escape 
through  cracks  and  crevices  almost  as  fast  as  it  is  formed.  In  cold 
weather  the  heating  of  the  room  to  be  disinfected  will  greatly  aid  in  the 
disinfecting  action  of  the  gas. 

There  are  three  well-recognized  methods  of  fumigating  with  sulphur 
dioxid,  viz.,  (1)  the  pot  method,  (2)  liquid  sulphur  dioxid,  (3)  sul- 
phur furnace. 

The  Pot  Method. — The  pot  method  is  at  once  the  easiest,  cheapest, 
and  probably  most  efficient  method  of  using  sulphur  dioxid.  The 
only   materials   required    are  -^  ^^ 

iron  pots  and  some  sulphur,     m  r'^?^-'jfv^^'    ■  m 

The  best  way  to   apply   the      B  mJ^^'^^ii'l'^^W^^^  t 

method  is  by  placing  the  sul-  ^^^^W^^^AjJ \  \  V'"^  ^Lg^^-^f 
phur  in  large,  flat,  iron  pots  ^^^^^H^i^^S^B^^^fe=M^P 
known  as  Dutch  ovens.     Not         '^iigim^iiiM 

more  than  30  pounds  of  sul-        t.      -.r.     r,.      t^      ,>, 

^  .  Fig.  154. — The  Pot  Method  of  Btjkning 

phur  should  be  placed  in  each  Sulphur. 

pot.  The  sulphur  is  prefer- 
ably used  in  the  form  of  flowers  of  sulphur.  If  it  is  in  sticks  or  rolls  it 
should  be  crushed  into  a  powder,  which  may  conveniently  be  done  by 
placing  the  sulphur  in  a  stout  box  and  pounding  the  lumps  with  a  heavy 
timber.  The  pot  holding  the  sulphur  should  be  placed  in  a  tub  of  water, 
as  shown  in  Fig.  154.     The  water  not  only  diminishes  the  danger  from 


1000  CHEMICAL    AGENTS    OF    DISINFECTION 

fire  and  protects  the  floor,  but  by  its  evaporation  furnishes  the  moisture 
necessary  to  hydrate  tlie  sulphur  dioxid,  upon  which  the  disinfecting 
power  of  the  gas  depends.  Thus  the  moisture  is  furnished  automatically 
and  docs  away  with  the  necessity  for  its  introduction  by  means  of  steam 
or  a  spray.  Altliough  the  specific  gravity  of  sulphur  dioxid  is  greater 
than  that  of  air,  when  hot  it  rises,  aided  by  the  upward  current  pro- 
duced by  the  burning  sulphur.  Hence  the  pots  should  not  be  on  the 
floor  or  at  the  bottom  of  the  hold  in  the  case  of  vessels,  lest  the  cold 
gas  settle  and  the  flame,  being  deprived  of  oxygen,  be  extinguished 
before  all  the  sulphur  is  burned.  The  pots  may  therefore  be  placed 
upon  a  table  or  box  or,  in  the  holds  of  ships,  upon  piles  of  ballast 
or  on  the  "  'tween  decks." 

Roberts  and  McDermott^  suggest  that  the  sulphur  be  burned  upon 
pans  arranged  upon  a  rack  as  shown  in  Fig.  155,  instead  of  pots.     The 


FiQ.  155. — Large  Stack  Burner  for  Sulphur,  with  15  of  the  18  Pans  Removed 

TO  Show  Construction. 

advantages  of  this  stack  burner  are  that  a  large  amount  of  sulphur 
may  be  more  quickly  burned  in  less  time  than  is  possible  with  the  pot 
method.  Further,  the  intense  heat  below  each  pan  in  the  stack 
burner  aids  the  complete  and  rapid  burning  of  sulphur  in  the  pans 
above  it.  A  stack  burner  will  burn  sulphur  of  too  poor  a  quality  to 
give  any  satisfaction  in  the  pots.  The  ground  sulphur  is  placed  in 
the  pans,  the  surface  of  the  sulphur  is  moistened  with  alcohol,  and 
ignited.  Each  shelf  should  be  lighted  separately  to  save  time.  The 
upper  pan  or  pans  may  be  filled  with  water  to  hydrate  the  sulphur 
dioxid  necessary  for  its  germicidal  action. 

^Public  Health  Reports,  U.  8.  P.  H.   and  M.   H.  S.,  March  31,   1911,  Vol. 
XXVI,  13,  p.  403. 


GASEOUS    DISINFECTANTS 


1001 


The  sulphur  may  be  lighted  by  means  of  hot  coals  or  a  wood- 
fire,  but  the  most  reliable  way  to  get  it  well  lighted  is  by  alcohol, 
turpentine,  or  kerosene  on  a  pledget  of  waste.  Make  a  little  crater 
of  the  sulphur,  soak  liberally  with  alcohol,  and  ignite.  The  sul- 
phur then  burns  in  the  center,  and  as  it  melts  runs  down  from 
the  sides  and  forms  a  little  lake  at  the  bottom  of  the  crater.  If 
the  sulphur  is  heaped  up  in  a  mound  in  the  pot  the  flame  is  liable 
to  go  out. 

Upon  the  principle  of  not  putting  all  our  eggs  in  one  basket,  it 
is  best  to  have  a  number  of  pots  when  a  large  compartment  is  to  be 
fumigated.  A  pot  should  contain  not  more  than  30  pounds  of  sulphur, 
and  the  pots  should  be  well  distributed  in  various  portions  of  the  place 
to  be  disinfected. 

Use  5  pounds  per  1,000  cubic  feet  where  a  germicidal  action  is 
desired,  and  at  least  2  pounds  per  1,000  cubic  feet  for  insecticidal  pur- 
poses. For  the  destruction  of  bacteria  an  exposure  of  from  6  to  24 
hours  is  necessary,  while  for  the  destruction  of  vermin  from  2  to  12 
hours  is  sufficient,  depending  upon  the  size  and  shape  of  the  compart- 
ment to  be  treated. 

Liquid  Sulphur  Dioxid. — Liquid  sulphur  dioxid,  commonly  known 
as  sulphurous  acid  gas,  while  efficient,  is  about  ten  times  as  expensive 
as  burning  sulphur  by  the  pot  method.  It  has  the  advantage  of  liber- 
ating a  large  volume  of  the  gas  rapidly,  thereby  facilitating  its  dis- 
persion. Further,  the  use  of  liquefied  sulphur  dioxid  has  the  advantage 
of  avoiding  the  danger  of  accidental  fire. 


Sulphur  Dioxide  (si! 


J      S  '!l    ,1  f/     I    'I.    I      '     P   -.     J^tftlHJ 


c  >n   1  ,     U    ,r 


WITH     CftBB 


FiQ.  156. — Liquefied  Sulphur  Dioxid  in  Tin  Can. 


One  pound  of  the  sulphur  will  produce  about  2  pounds  of  sulphur 
dioxid:  S(32)  -f-  02(32)  =  S02(64).  Therefore  2  pounds  of  the  liquid 
sulphur  dioxid  is  necessary  to  produce  the  same  volume  of  sulphur 
dioxid  as  is  generated  from  one  pound  of  .the  burning  sulphur. 

The  method  of  using  the  liquid  sulphur  dioxid  is  very  simple.  If 
the  substance  is  bought  in  small  tins  it  is  only  necessary  to  cut  the 
lead  pipes  in  the  tops  of  the  necessary  number  of  cans  and  invert  the 
latter  in  an  ordinary  washbowl  or  iron  pot,  when  volatilization  rapidly 
occurs.    All  the  cans  must  be  cut  simultaneously  and  the  operator  must 


1002  CHEMICAL    AGENTS    OF    DISINFECTION 

act  quickly  and  be  prepared  immediately  to  leave  the  room  and  shut 
the  door.  If  the  substance  is  contained  in  glass  or  metallic  siphons 
the  necessary  amount  of  liquid  sulphur  dioxid  can  be  projected  from 
the  outside  through  a  pipe  passed  through  the  keyhole  or  other  aperture. 
A  suitable  receptacle  should  be  arranged  on  the  inside  to  catch  the 
drip  and  frozen  mass  which  forms  as  a  result  of  the  expansion.  In 
order  to  obtain  the  maximum  disinfecting  power  with  this  method 
it  is  necessary  to  introduce  moisture.  ^  This  may  be  done  by  placing 
open  pans  of  boiling  water  in  the  room,  by  injecting  steam,  or  by  a  fine 
spray  of  water. 

The  Sulphur  Furnace. — The  sulphur  may  be  burned  in  an  ap- 
paratus of  special  construction  known  as  a  sulphur  furnace,  from  which 
the  resulting  fumes  are  blown  through  a  system  of  pipes  into  the 
room  or  hold  of  a  vessel  to  be  disinfected.  Two  forms  of  sulphur  fur- 
nace are  used :  ( 1 )  the  Kinyoun-Francis  furnace,  and  ( 2 )  the  Clayton 
furnace. 

This  method  requires  expensive  and  cumbersome  machinery  and 
has  little  to  recommend  it  over  the  simpler  pot  method  except  that  a 
large  percentage  of  the  gas  may  be  blown  into  a  given  space.  The 
pot  method  at  best  cannot  produce  an  atmosphere  containing  more  than 
4  per  cent,  of  sulphur  dioxid,  whereas  it  is  theoretically  possible  to 
charge  a  confined  space  with  a  higher  percentage  of  the  gas  by  means 
of  the  furnace.  In  practice  this  is  not  possible  without  burning  a 
great  excess  of  sulphur  and  by  expending  a  very  long  time,  for  the 
reason  that  the  fumes  first  entering  mix  with  the  air  and  as  the  gas 
continues  to  flow  into  the  space  it  displaces  about  an  equal  quantity 
of  this  mixture  of  sulphur  dioxid  and  air,  so  that,  as  a  matter  of  fact, 
in  actual  practice  only  about  21/0  to  6  per  cent,  of  the  gas  is  usually 
obtained  in  the  holds  of  vessels  by  the  sulphur  furnace. 

It  is  advisable  in  using  the  sulphur  furnace  to  arrange  the  pipe 
admitting  the  gas  into  the  room  as  near  the  floor  as  possible.  In  dis- 
infecting the  holds  of  vessels  the  pipe  is  usually  let  down  the  hatch- 
way until  it  is  near  the  bilge.  The  heavy  gas  collects  at  the  bottom 
and  gradually  ascends,  displacing  the  air,  so  that  it  is  important  to 
allow  an  opening  of  some  sort  for  the  exit  of  the  air  near  the  top  of  the 
compartment  that  is  being  disinfected.  This  opening  should  not  be 
closed  until  the  gas  escapes  freely. 

The  Kinyoun-Francis  furnace  consists  of  an  iron  pan  upon  which 
the  sulphur  is  burned.  Under  this  pan  is  a  firebox  with  ashpit  and 
necessary  drafts.  The  firebox  is  designed  to  hold  a  light  fire  of  wood 
or  shavings  and  is  intended  to  heat  the  sulphur  pan  sufficiently  to  ignite 
the  sulphur  when  thrown  upon  it  at  the  beginning  of  the  operation. 
This  part  of  the  apparatus  is  unnecessary,  as  the  sulphur  may  be 
ignited  more  simply  by  means  of  some  alcohol,  turpentine,  or  kero- 


GASEOUS    DISINFECTA^■TS 


1003 


sene  on  waste,  or  a  few  live  coals.     When  once  lighted  there  is   no 
trouble  in  keeping  the  sulphur  burning. 

The  air  enters  at  A.  Eig.  157,  through  a  valve  arranged  to  regulate 
the  amount  of  flow.     It  then  passes  over  the  burning  sulphur  in  the 


OOUBUB     6ULPHUR.  iruRNAce 


Fig.  157. — Section  Through  Sulphur  Furnace. 
direction  shown  hy  the  course  of  the  arrows  to  the  fan.  Fumes  are 
compelled  to  take  a  devious  course  around  the  baffle  plates  and  angle 
irons,  as  shown  in  the  drawing,  in  order  to  insure  complete  combustion 
and  to  arrest  sparks.  Erom  B  the  fumes  are  sucked  to  the  fan,  which 
is  actuated  by  a  steam  engine  or  electric  motor,  and  which  forces  the 
gas  through  the  pipes  to  the  place  to  be  disinfected. 

Eunning  the  fan  at  too  high  a  speed  may  cause  overheating  of  the 
pipes  or  the  carrying  over  of  sparks  of  burning  sulphur.  The  proper 
amount  of  air  should  be  carefully  regulated  so  as  to  obtain  complete 
combustion  and  the  maximum  amount  of  sulphur  dioxid  gas. 

The  pipe  conducting  the  fumes  from  the  sulphur  furnace  to  the 
compartment  to  be  disinfected  gives  a  certain  amount  of  trouble.  It  is 
apt  to  become  clogged  with  sulphur  which  sublimes  in  the  cooler  parts. 
Ordinarily  this  pipe  must  be  from  6  to  8  inches  in  diameter  and  may 
be  made  of  smooth  galvanized  iron  and  the  joints  made  tight  with 
several  layers  of  canvas  saturated  and  coated  with  some  fireproof  paint. 
Eubber  hose  of  this  size  is  very  expensive  and  soon  vulcanizes. 

No  arrangement  is  made  in  this  form  of  apparatus  for  adding  water 
vapor  to  the  sulphur  fumes,  which  is  necessary  to  obtain  germicidal 
action.  As  a  rule  the  holds  of  wooden  vessels,  in  which  sulphur  fumiga- 
tion is  so  much  used,  are  usually  so  damp  that  the  addition  of  more 
moisture  is  not  necessary. 

The  Clayton  furnace  is  a  more  compact  apparatus  than  that  just 
described.     The  sulphur  dioxid  is  passed  through  a  series  of  tubes  sur- 


1004  CHEMICAL    AGENTS    OF    DISINFECTION 

rounded  by  water,  an  arrangement  corresponding  in  all  respects  to 
the  tubular  condenser  of  a  low-pressure  steam  engine.  The  Clayton 
furnace  is  furnished  with  a  Root  blower,  and  has  the  advantage  that 
a  comparatively  large  volume  of  sulphur  dioxid  may  be  pumped  rapidly 
through  pipes  of  small  caliber  without  fear  of  overheating  or  fire.  These 
furnaces  are  being  installed  upon  ships  for  the  purpose  of  fumigation 
at  port  and  during  the  voyage  for  the  destruction  of  rats,  mice,  and 
vermin.    It  is  also  an  efficient  fire  extinguisher, 

A  portable  sulphur  furnace  is  a  useful  apparatus  in  municipal  work, 
particularly  in  the  fumigation  of  sewers,  warehouses,  stables,  barns, 
and  similar  large,  rough  structures  infested  with  vermin.  This  form 
of  furnace  was  used  with  success  in  the  fight  against  rats  in  the 
sewers  of  San  Francisco  in  the  anti-plague  campaign. 

Hydrocyanic  Acid  Gas. — Hydrocyanic  acid  gas  is  a  very  powerful 
insecticide,  but  a  weak  germicide.  It  appears  to  be  effective  against  or- 
ganisms no  hardier  than  those  of  diphtheria  and  typhoid.  On  account 
of  its  extremely  poisonous  nature  it  has  a  very  limited  place  in  practical 
public  health  work  for  the  destruction  of  bacteria.  Hydrocyanic  acid 
gas  is  useful  in  the  treatment  of  stables,  granaries,  outhouses,  com- 
partments of  ships,  sleeping-cars,  day  coaches,  and  similar  isolated  or 
uninhabited  places  for  the  destruction  of  vermin.  For  its  use  as  an 
insecticide  see  page  194. 

Chlorin. — Chlorin  is  a  germicide  of  considerable  but  uncertain 
power.  It  has  little  practical  usefulness  owing  to  its  poisonous  and  de- 
structive action.  Both  in  its  free  state  and  its  watery  solution  it  has 
active  deodorizing  properties.  Moisture  is  necessary  for  the  disinfect- 
ing action  of  chlorin  gas.  At  best  chlorin,  like  all  gases,  is  but  a  sur- 
face disinfectant. 

Chlorin  is  an  extremely  irritating  gas,  and  great  care  must  be 
observed  in  its  employment,  for  the  inhalation  of  very  weak  proportions 
of  the  gas  produces  serious  irritation,  resulting  in  spasm  of  the  larynx, 
bronchitis,  and  even  in  death.  Chlorin  is  heavier  than  air  (sp.  gr.  2.-47) 
and  tends  to  fall.  Therefore  the  vessel  generating  the  gas  should  be 
placed  in  an  elevated  position  in  order  to  obtain  anything  like  effective 
diffusion.  Carpets,  curtains,  and  fabrics  generally  are  injured  by  its 
action,  and  the  element  is  a  very  active  bleaching  agent. 

The  germicidal  action  of  chlorin  depends  upon  its  great  affinity 
for  hydrogen.  So  strong  is  this  affinity  that  it  combines  with  the 
hydrogen  of  water  in  the  presence  of  light,  liberating  the  oxygen  in 
its  nascent  state,  thereby  enabling  the  oxygen  to  exert  its  power  upon 
organic  matter.  The  value  of  chlorin  as  a  deodorant  depends  upon  its 
power  of  decomposing  the  offensive  gases  of  decomposition  such  as  sul- 
phuretted hydrogen  and  volatile  ammoniacal  compounds. 

The  most  convenient  method  of  generating  chlorin  gas  is  by  decom- 


GASEOUS    DISINFECTANTS  1005 

posing  11/2  pounds  of  chlorid.  of  lime  with  6  ounces  of  strong  sulphuric 
acid.  This  produces  sufficient  gas  for  the  disinfection  of  1,000  cubic 
feet  of  air  space,  or  the  gas  may  be  generated  from : 

Common  salt > 8  ounces 

Manganese  dioxid    2       " 

Sulphuric  acid 2       " 

Water    2       " 

The  following  reaction  takes  place : 

2NaCl+Mn02+2H2S04=Na2S0,+MnS0,+2H20+Cl2 

Mix  the  water  and  the  acid  together  and  then  pour  the  mixture  over 
the  salt  and  manganese  dioxid  in  a  glazed  earthenware  basin.  The 
basin  should  rest  on  sand  or  in  water. 

Fisher  and  Proskauer  have  shown  that  in  ordinary  dry  air  5.38 
parts  of  free  chlorin  per  1,000  cubic  feet  of  air  space  appear  to  be 
necessary  to  kill  microorganisms.  If  the  air  is  moist  only  0.3  per  cent, 
by  volume  in  each  1,000  cubic  feet  of  air  is  sufficient,  disinfection  being 
completed  in  5  to  8  hours. 

Free  cMorin  is  much  less  useful  than  sulphur  dioxid,  since  it  is 
more  difficult  to  control,  more  dangerous  to  manipulate,  and  more 
destructive  in  its  effects. 

Oxygen. — The  disinfecting  power  of  oxygen  depends  largely  upon 
the  physical  state  in  which  it  exists.  For  instance,  oxygen  in  the  air 
has  comparatively  feeble  germicidal  properties  when  compared  to  nascent 
oxygen  or  ozone.  The  germicidal  action  of  oxygen  depends  upon  its 
very  active  property  of  combining  chemically  with  the  albuminous 
matter  of  the  cell  j^rotoplasm.  The  oxidizing  properties  of  this  element 
partly  explain  the  purifying  action  of  fresh  air.  While  most  bacteria 
require  the  free  oxygen  of  the  air  for  their  growth  and  multiplication, 
there  is  a  large  class  of  organisms  (the  anaerobes)  to  which  the  oxygen 
of  the  air  acts  like  a  poison  or  strong  antiseptic. 

Ozone. — Ozone  is  an  allotropic  form  of  oxygen  containing  three 
atoms  of  that  element  instead  of  two.  In  sufficient  concentration  it 
is  a  powerful  germicide  and  has  lately  been  found  of  practical  use  in 
the  sterilization  of  water  on  a  large  scale  for  the  use  of  cities  and 
towns.  It  has  also  been  used  for  the  sterilization  of  bandages  and 
other  objects.  There  is  not  sufficient  ozone  in  the  air  normally  to 
exert  any  appreciable  oxidizing  or  disinfecting  properties.  It  requires 
at  least  13  parts  per  million  in  the  atmosphere  to  exert  a  definite  e'ffect 
upon  bacteria;  even  then  the  action  is  not  penetrating.  Such  quantities 
are  harmful  to  man.     (See  page  585.) 


1006  CHEMICAL    AGENTS    OF    DISINFECTION 


LIQUID    DISINFECTANTS 

These  consist  of  substances  either  in  solution  or  suspension.  An 
enormous  number  of  such  disinfectants  have  been  exploited,  but  to  be 
of  practical  value  they  must  not  only  be  strongly  germicidal,  but  must 
also  meet  the  many  exacting  requirements  of  general  practice.  Such  sub- 
stances are  few  in  number. 

Almost  any  chemical  substance  under  one  condition  or  another  has 
the  power  to  retard  the  development  or  destroy  the  activity  of  microbial 
life.  We  need  only  mention  the  well-known  power  of  common  salt 
or  of  sugar,  both  of  which  in  sufficient  concentration  prevent  the  proc- 
esses of  fermentation  and  putrefaction.  In  weaker  dilutionr  these 
same  substances,  on  the  contrary,  favor  growth  of  almost  all  the  known 
bacteria. 

The  undeserved  reputation  of  many  chemical  substances  depends 
more  upon  their  vile  odor  or  judicious  advertising  than  upon  actual 
efficiency.  Only  those  substances  that  have  proven  their  worth  by  scien- 
tific tests  and  shown  themselves  to  be  trustworthy  in  actual  practice  will 
be  discussed. 

There  is  a  complete  analogy  existing  between  a  chemical  reaction 
and  disinfection,  one  reagent  being  represented  by  the  ^disinfectant 
and  the  other  by  the  protoplasm  of  the  bacterium.  Chick  states  that 
the  velocity  of  disinfection  increases  with  the  rise  in  temperature  in 
a  manner  similar  to  that  of  a  chemical  reaction.  In  fact,  the  tempera- 
ture so  greatly  influences  the  disinfecting  power  of  liquids  that  it  is 
strongly  recommended  always  to  use  warm  solutions  in  actual  practice. 
Even  slight  changes  of  temperature  may  make  a  great  difference. 
Feeble  antiseptic  solutions  become  strong  germicides  when  warmed. 
A  good  instance  of  the  effect  of  temperature  is  given  by  Heiden/  who 
found  that  anthrax  spores  which  survived  the  effects  of  a  5  per  cent, 
carbolic  solution  for  36  days  at  room  temperature  were  destroyed  in 
half  an  hour  in  the  same  solution  at  55°  C.  At  75°  C.  it  took  only  3 
minutes  to  kill  them.  A  3  per  cent,  carbolic  acid  solution  killed  the 
same  spores  at  this  temperature  in  15  minutes  and  a  1  per  cent,  solu- 
tion in  from  2  to  21/2  hours. 

It  is  not  enough  in  applying  any  agent  whose  best  working  strength 
is  known  to  use  a  small  volume  of  the  solution  of  that  particular 
strength.  There  must  be  a  sufficient  amount  of  the  substance  used  so 
that  it  shall  be  present  throughout  the  whole  mass  in  the  proportion 
required.  Thus  an  agent  that  is  effective  in  a  2  per  cent,  solution 
cannot  be  used  in  that  strength  to  disinfect  an  equal  volume  of  an 
infected  liquid,  since  the  mixture  would  then  contain  but  1  per  cent. 

'  Centram.  f.  Bakt.,  Bd.  9,  p.  221,  1891.     Archiv  f.  Egy.,  Bd.  15,  1892. 


LIQUID    DISIXFECTAXTS  1007 

Time  is  an  essential  factor  too  frequently  disregarded  in  disinfect- 
ing vrith  liquids  in  suspension  or  solution.  Very  few  chemical  disin- 
fectants act  instantly,  even  in  strong  solutions  and  under  favorable 
conditions.  The  microorganisms  are  so  often  in  clusters  or  are  sur- 
rounded by  mucoid  films  or  imbedded  in  organic  matter  that  no  in- 
considerable time  is  required  for  the  disinfecting  solution  to  penetrate 
to  the  germ.  If  the  microbes  are  dry  it  takes  a  certain  time  to  wet 
them  before  the  chemical  can  act.  This  and  other  factors  must  be 
added  to  the  time  actually  necessary  for  the  substance  to  destroy  the  life 
of  the  germ  after  it  comes  in  direct  contact  with  it. 

The  medium  in  which  the  germs  exist  also  makes  a  great  difference 
so  far  as  the  power  of  liquid  disinfectants  is  concerned.  Behring  found, 
for  example,  that  anthrax  bacilli  suspended  in  water  are  killed  in  a 
few  minutes  with  bichlorid  of  mercury  solution  of  the  strength  of  1  to 
500,000.  In  bouillon  it  requires  a  strength  of  1  to  40,000,  while  in  blood 
serum,  if  the  disinfection  is  to  be  accomplished  in  a  few  minutes,  a 
strength  of  1  to  2,000  is  not  always  sufficient.  Therefore  in  the  presence 
of  organic  matter  or  filth  stronger  solutions  and  longer  exposures  are  re- 
quired. 

As  a  rule  an  emulsion  has  greater  germicidal  power  than  a  solu- 
tion. Thus  soapy  and  resinous  emulsions  of  the  phenols  may  accentuate 
the  germicidal  power  of  these  substances.  Chick  and  Martin^  have 
observed  that  the  particles  of  an  emulsion  or  soapy  preparation  ©f  the 
coal-tar  acids  exhibit  active  Brownian  motion.  The  bacteria  are  con- 
siderably larger  than  the  mean  diameter  of  the  emulsified  particles. 
The  bacteria  may  plainly  be  seen  to  be  bombarded  by  these  particles. 
In  this  way  the  bacteria  are  frequently  brought  into  intimate  contact 
with  the  undiluted  particles  of  pure  coal-tar  acids.  The  maximum 
effect  may  therefore  be  obtained  and  the  death  of  the  bacteria  is  in- 
evitable. Such  a  concentration  is  evidently  impossible  with  substances 
in  solution.  The  coal-tar  acids  in  suspension  act  upon  the  bacteria 
through  physicochemical  absorption,  and  not  through  chemical  com- 
bination. The  bacteria  rapidly  become  surrounded  by  the  disinfectant 
in  a  much  greater  concentration  than  actually  exists  within  the  liquid. 
Other  particulate  matters  present  have  the  power  of  absorption,  and 
their  presence  therefore  interferes  with  the  germicidal  value  of  sub- 
stances in  emulsion.  Thus  the  value  of  phenol  is  barely  impaired  by 
the  presence  of  organic  matter  in  solution,  while  emulsified  disinfec- 
tants are  reduced  to  one-third  or  one-half  their  original  value. 

Germicidal  substances  in  emulsion  have  less  power  of  penetration 
than  substances  in  solution.  The  emulsified  substances  are  deposited 
upon  and  adhere  to  the  surface  of  the  mass.  This  may  readily  be  seen 
by  adding  one  of  the  coal-tar  emulsions  to  a  fecal  mass,  in  which  case 

"■Jour,  of  Eyg.,  Vol.  Ylll,  No.  5,  1908, 


1008  CHEMICAL   AGENTS    OF    DISINFECTION 

a  visible  layer  of  the  coal-tar  creosotes  may  be  seen  to  collect  upon  the 
surface.  These  facts  emphasize  the  great  importance  of  breaking  up 
all  masses  requiring  disinfection. 

Chemical  substances  act  in  a  great  variety  of  ways  to  bring  about 
the  destruction  of  bacteria.  Just  how  the  microbes  are  poisoned  is, 
in  many  instances,  an  unsolved  problem  in  toxicology.  In  particular 
cases  there  appears  to  be  a  chemical  union  between  the  disinfectant 
and  the  protein  of  the  bacteria,  as  appears  to  be  the  case  with  corrosive 
sublimate  or  formaldehyd.  In  some  instances  the  mycoprotein  of  the 
cell  is  coagulated,  as  in  the  case  of  carbolic  acid  and  homologous  sub- 
stances. It  has  been  shown  that  the  higher  the  grade  of  dissociation 
the  greater  is  the  disinfecting  power  of  the  solution.  Thus  in  the  case 
of  the  soluble  metallic  salts,  and  especially  mercury,  it  depends  upon 
whether  in  the  electrolytic  dissociation  the  metal  exists  as  an  independent 
ion  or  whether  it  exists  as  a  complex  ion.  In  the  first  case  the  solution 
has  strong  germicidal  properties;  in  the  second  these  properties  are 
much  weaker.  In  other  liquids,  as,  for  example,  alcohol,  ether,  etc., 
the  metallic  salts  have  very  slight  dissociation  which,  according  to 
Kronig  and  Paul,  explains  the  weaker  disinfecting  power  of  these 
solutions.  The  disinfecting  power  of  metallic  salts  depends,  further- 
more, not  only  upon  the  influence  of  the  metal  ion,  but  also  upon  the 
other  ions  and  upon  the  unassociated  parts  of  the  metallic  salts. 

The  reaction  of  the  solution  and  of  the  medium  to  be  disinfected 
varies  with  the  substance  employed.  Tluis  lime  is  an  alkali,  and  if 
used  to  disinfect  an  acid  substance  enough  must  first  be  added  to 
neutralize  the  medium  and  then  an  additional  amount  of  lime  must  be 
added  necessary  to  accomplish  the  disinfection.  In  the  same  way,  if 
mercuric  chlorid  is  added  to  solutions  containing  sulphids,  caustic 
alkalies,  or  certain  metallic  salts,  sufficient  must  be  added  in  order  to 
first  precipitate  these  substances  and  then  enough  more  added  to  exert 
its  disinfecting  action.  Likewise,  the  greater  the  number  of  germs  to 
be  destroyed  the  greater  the  amount  of  the  disinfectant  required  to  ac- 
complish the  purpose. 

The  choice  of  the  chemical  to  be  used  depends  somewhat  upon  the 
nature  of  the  substance  to  be  disinfected  as  well  as  upon  the  resistance 
of  the  virus.  For  example,  bichlorid  of  mercury  is  inapplicable  to 
the  disinfection  of  albuminous  matter.  Certain  chemicals  have  a  selec- 
tive action  and  appear  to  be  specific  poisons  for  some  microorganisms. 
Taken  altogether,  therefore,  the  choice  of  the  chemical,  its  strength, 
and  time  of  application,  the  temperature  of  the  liquid,  and  its  method 
of  employment  are  all  problems  which  must  be  solved  for  each  particular 
case. 

Methods  of  Using  Chemical  Solutions. — There  are  various  ways  of 
applying  chemical  solutions  for  disinfecting  purposes.     No  method  is 


LIQUID    DISINFECTANTS  1009 

trustworthy  that  does  not  thoroughly  wet  the  ohject  with  the  solution, 
so  that  there  may  be  direct  contact  between  the  substance  in  solution 
and  the  contagious  principle  against  which  the  process  is  directed. 

As  a  rule  this  may  best  be  accomplished  by  immersing  the  infected 
object  in  the  solution.  ^Mien  this  is  not  practicable  the  solution  must 
be  applied  to  the  object.  A  favorite  way  of  applying  disinfecting  solu- 
tions to  surfaces,  such  as  walls,  ceilings,  the  holds  of  ships,  and  other 
rough  structures,  is  by  means  of  a  hose.  The  pressure  is  supplied  either 
by  elevating  the  tank  containing  the  solution  or  by  means  of  a  pres- 
sure jjump.  As  bichlorid  of  mercury  is  practically  the  only  disinfectant 
used  in  this  way,  the  pump  should  be  made  of  iron  and  have  no  copper, 
brass,  or  steel  parts  exposed  to  the  corroding  action  of  the  bichlorid  of 
mercury. 

In  applying  the  disinfecting  solution  to  the  surfaces  of  a  room 
or  the  hold  of  a  ship  the  operator  should  begin  at  one  corner  of  the 
ceiling,  wetting  that  first,  and  then  go  over  every  portion  of  the  walls 
systematically,  from  above  downward.    The  floor  comes  last. 

Solutions  thus  applied  remain  but  a  short  time  in  contact  with 
the  surfaces  to  be  disinfected.  It  is  therefore  an  advantage  to  have  the 
solution  hot  and  strong  and  to  have  sufficient  pressure,  in  order  to  ob- 
tain the  mechanical  cleansing  effect  produced  by  a  vigorous  stream. 

Another  method  of  applying  disinfecting  solutions  to  surfaces  is 
by  means  of  mops,  brooms,  and  the  like. 

The  pulverizer  is  very  popular  in  France  for  the  disinfection  of 
walls  and  other  surfaces  with  solutions  of  bichlorid  of  mercury.  The 
apparatus  for  this  purpose  consists  of  a  metal  cylinder  fitted  with  a 
simple  force  pump  which  compresses  the  air  in  the  reservoir.  The 
solution  does  not  come  in  contact  with  the  pump.  The  current  of  air 
driven  through  one  tube  sucks  the  solution  through  the  other  and 
sprays  it  from  the  nozzle  in  a  nebulous  cloud,  similar  in  principle  to 
the  well-known  hand  atomizers.  It  is  easy  to  demonstrate,  by  using 
a  colored  solution  upon  a  white  wall  or  sheet,  that  a  liquid  sprayed 
in  this  way  does  not  wet  the  entire  surface.  The  method  is  therefore 
an  unscientific  and  unreliable  one  when  used  with  a  non-volatile  chem- 
ical. 

Bichlorid  of  Mercury. — HgCL,  bichlorid  of  mercury  or  mercuric 
chlorid.  commonly  called  corrosive  sublimate,  is  one  of  our  most  valu- 
able and  potent  germicides.  It  destroys  all  forms  of  microbial  life  in 
relatively  weak  solutions.  It  kills  both  germs  and  their  spores.  It  is 
not  a  deodorant. 

The  disadvantages  of  bichlorid  of  mercury  are  that  it  corrodes 
metals,  forms  insoluble  and  inert  compounds  with  albuminous  matter, 
and  is  very  poisonous.  These  disadvantages  place  distinct  limitations 
upon  its  use. 


1010  CHEMICAL   AGENTS    OF   DISINFECTION 

Mercuric  chloric!  (HgCL)  is  a  white,  crystalline  substance  of  heavy 
specific  gravity  (5.43).  It  volatilizes  somewhat  more  readily  than  mer- 
curous  chloric!  (calomel),  even  at  room  temperature.  On  account  of 
this  property  caution  slioulc!  be  observed  to  remove  bichlorid  solutions 
from  living-rooms,  some  instances  of  poisoning  having  been  traced  to 
this  neglect.  It  is  tlierefore  well  to  follow  bichlorid  with  clear  water  and 
a  cleansing  is  always  in  order. 

Bichlorid  of  mercury  will  dissolve  in  16  parts  of  cold  water  and  3 
parts  of  boiling  water.  As  it  is  not  readily  soluble  in  water,  it  is  con- 
venient to  keep  a  saturated  alcoholic  solution  on  hand  and  use  this  to 
nuike  the  watery  solution.  A  25  per  cent,  solution  may  readily  be 
made  in  alcohol,  and  by  the  additioji  of  hydrochloric  acid  or  ammonium 
chlorid  this  solution  keeps  well  without  precipitation.  As  this  method 
would  be  rather  expensive  for  mnking  up  the  large  quantities  re- 
quired in  flushing  the  holds  of  ships  or  other  extensive  surfaces  a  little 
device  pointed  out  by  Geddings  will  be  found  serviceable.  This  con- 
sists in  weighing  out  the  correct  quantity  of  the  bichlorid,  whicli  is 
placed  in  a  canvas  bag,  and  this  is  hung  from  the  faucet  so  that  the 
water  will  run  through  it  into  the  tank  or  receptacle  holding  the  solution. 

The  solution  of  bichlorid  of  mercury  is  facilitated  by  the  presence 
of  hydrochloric  acid  or  a  chlorid  such  as  ammonium  chlorid  or  com- 
mon salt.  Twice  the  weight  of  these  substances  should  be  added  to 
the  quantity  of  bichlorid  used.  If  the  solution  is  to  be  pumped  or 
otherwise  come  in  contact  with  metals  it  is  better  to  use  the  salt  than 
the  acid,  because  the  acid  solution  of  bichlorid  is  very  destructive  to 
the  metal  parts  of  the  pump  and  to  the  couplings  and  nozzle  of  the  hose, 
particularly  if  tliis  is  made  of  copper  or  brass.  Sea-water  contains 
about  4  per  cent,  of  salt,  and  is  well  suited  for  making  bichlorid  solu- 
tions. It  is  extensively  used  at  seaport  quarantine  stations  for  this 
purpose. 

Laplace  first  pointed  out  that  the  addition  of  a  small  amount  of  an 
acid  to  the  solution  of  bichlorid  of  mercury  greatly  increases  its  effi- 
ciency, and  by  lessening  the  formation  of  insoluble  albuminates  also 
increases  its  power  of  penetration.  This  was  later  denied  by  Kronig 
and  Paul,  who  assert  that  the  addition  of  sodium  chlorid  to  a  watery 
solution  of  bichlorid  diminishes  its  power.  They  found  that  potassium 
chlorid  or  hydrochloric  acid  has  the  same  effect. 

The  germicidal  action  of  bichlorid  solution  seems  to  depend  upon 
the  reaction  which  takes  place  between  the  salt  of  mercury  and  the  myco- 
protein  of  the  germ.  Geppert  has  shown  that  in  the  reaction  which  takes 
place  between  the  bichlorid  of  mercury  and  tlie  spores  of  anthrax 
the  vitality  of  the  latter  may  seem  to  be  lost,  but  that  the  bichlorid 
may  be  precipitated  from  its  combination  by  the  action  of  ammonium 
sulphid,  which  restores  the  viability  of  the  spore. 


LIQUID    DISINFECTANTS  1011 

Bichlorid  of  mercury  is  decomposed  by  lead,  tin,  copper,  and  other 
metals,  and  therefore  should  not  be  made  or  kept  in  metal  receptacles. 
Lead  pipes  are  rendered  brittle  and  worthless.  Care  must  therefore 
be  exercised  in  using  this  solution  about  water-closets  and  house 
plumbing. 

Corrosive  sublimate  is  j^^ecipitated  in  alkaline  fluids  containing 
albuminous  substances.  The  precipitate  consists  of  insoluble  and  inert 
compounds;  therefore  corrosive  sublimate  should  not  be  used  for  the 
disinfection  of  media  containing  much  organic  matter,  particularly 
when  the  reaction  is  alkaline.  It  is  totally  inapplicable  to  the  disin- 
fection of  sputum  and  feces,  for  it  forms  a  coagulum  which  prevents 
the  further  penetration  of  the  bichlorid.  It  also  unites  chemically  with 
sulphids  and  the  caustic  alkalies,  so  that  it  should  not  be  employed  as 
a  disinfectant  when  these  substances  are  present  in  any  considerable 
amount. 

To  diminish  the  danger  from  accidents  in  households  and  hospitals 
bichlorid  solutions  should  be  colored  with  permanganate  of  potash  or 
indigo  or  one  of  the  anilin  dyes. 

Bichlorid  of  mercury  is  usualty  used  in  the  proportion  of  1  to  500  or 
1  to  1,000.  A  solution  of  1  to  1,000  is  ample  for  the  destruction  of 
all  the  non-spore-bearing  bacteria,  provided  the  exposure  is  continued  not 
less  than  half  an  hour.  Many  bacterial  cells  are  killed  almost  at  once 
when  brought  into  direct  contact  with  a  solution  of  this  strength,  and 
the  great  majority  perish  within  15  minutes.  The  extra  time  allows 
for  penetration  and  provides  a  factor  of  safety.  Warm  solutions  are 
much  more  potent  than  cold.  For  spores  a  solution  of  1  to  500  is  neces- 
sary and  an  exposure  of  not  less  than  one  hour. 

For  practical  work  the  solution  may  be  made  as  follows: 

Corrosive    sublimate    1  dram     |   1  gram 

Water 1  gallon   |   1  liter 

Mix  and  dissolve. 

This  is  approximately  a  1  to  1,000  solution.  One  ounce  of  this 
solution  contains  very  nearly  half  a  grain  of  corrosive  sublimate. 

Carbolic  Acid. — Carbolic  acid  is  a  very  useful  disinfecting  substance 
with  a  wide  range  of  application.  It  should  not  be  depended  upon  to 
kill  spores.  i\.s  it  does  not  coagulate  albuminous  matter  as  actively 
as  corrosive  sublimate  it  may  be  used  for  the  disinfection  of  soiled 
clothing  and  bedding,  as  well  as  for  excreta  and  sputum. 

Carbolic  acid  is  a  popular  term  for  an  ill-defined  mixture  con- 
sisting largely  of  phenol  and  phenolic  bodies.  Phenol  has  the  chemical 
structure  of  an  alcohol ;  it  is  represented  by  the  formula :  CgHgO^ 
CgHgOH.     It  IS  produced  in  the  dry  distillation  of  coal,  and  is  the  chief 


1012  CHEMICAL    AGENTS    OF    DISINFECTION 

constituent  of  tlie  acid  portion  of  coal-tar  oil.  Pure  phenol  crystallizes 
in  long,  colorless  needles.  Commercial  phenol  forms  a  crystalline  mass, 
which  is  apt  to  turn  reddish  in  time  and  in  contact  with  moist  air 
deliquesces  to  a  brownish  liquid.  Carbolic  acid  has  a  penetrating  odor 
and  a  strong  burning  taste  and  is  a  corrosive  poison. 

The  carbolic  acid  of  commerce  contains  cresols  and  higher  homo- 
logs,  some  of  which  have  a  higher  germicidal  value  than  pure  i)henol 
itself.  The  commercial  prodiict  also  contains  tar  oils  which  are  totally 
lacking  in  bactericidal  properties.  It  should  be  remembered  that  tlie 
crude  carbolic  acid  has  a  higher  germicidal  potency  than  tlie  pure 
phenol. 

Carbolic  acid  dissolves  in  water  with  some  difficulty  and  sliould 
therefore  be  thoroughly  mixed.  At  ordinary  temperatures  phenol  is 
soluble  in  about  15  parts  of  cold  water;  that  is,  a  saturated  solution 
contains  between  6  and  7  per  cent.  Carbolic  acid  or  phenol  is  com- 
monly used  in  solutions  of  2.5  to  5  per  cent.,  which  are  entirely  trust- 
worthy for  destruction  of  all  infectious  processes  due  to  non-spore- 
bearing  organisms.    Warm  solutions  are  much  more  potent  than  cold. 

Carbolic  acid  when  dissolved  in  alcohol  or  ether  loses  in  germi- 
cidal value;  the  addition  of  0.5  per  cent,  of  hydrochloric  acid  aids  its 
activity. 

McClintock  and  Ferry^  have  shown  that  the  large  majority  of  the 
coal-tar  disinfectants  (carbolic  acid,  cresols,  and  the  like)  do  not  destroy 
the  virulence  of  vaccine  virus  in  one-half  per  cent,  solutions  at  five  hours' 
exposure,  while  with  this  strength  and  length  of  time  these  disin- 
fectants would  destroy  practically  all  non-spore-bearing  bacteria.  The 
inference,  therefore,  is  allowable  that  this  class  of  disinfectants  is 
not  safe  to  use  for  such  diseases  as  smallpox  and  the  presumably  pro- 
tozoal diseases  such  as  syphilis,  measles,  scarlet  fever,  etc. 

The  fact  that  carbolic  acid  and  phenol  do  not  actively  coagulate 
albuminous  matter  renders  them  suitable  to  the  disinfection  of  excreta 
and  organic  matters  generally.  They  are  not  destructive  to  fabrics,  colors, 
metals,  or  wood  in  the  strengths  used,  and  therefore  may  be  employed 
for  the  disinfection  of  a  great  variety  of  objects.  Crude  carbolic  acid, 
although  it  has  a  stronger  germicidal  power  than  pure  phenol,  has  the 
disadvantage  of  having  a  more  pungent  and  penetrating  odor  and  leaves 
a  deposit  of  coal-tar  oils  and  other  impurities. 

There  has  been  much  disparagement  of  carbolic  acid  because  labora- 
tory tests  have  clearly  demonstrated  that  it  cannot  be  depended  upon 
to  kill  spores.  This  limits  but  does  not  destroy  its  usefulness,  especially 
as  the  great  majority  of  the  epidemic  diseases  of  man  are  due  to  non- 

^  McClintock,  Chas.  T.,  and  Ferry,  N.  S.:  "The  Kesistance  of  Smallpox 
Vaccine  to  the  Coal  Tar  Disinfectants,"  Jour,  of  the  Am.  Pub.  Health  Assn., 
Vol.  I,  No.  6,  June,  1911,  pp.  418-420. 


LIQUID    DISIIs^FECTANTS  1013 

spore-bearing  bacteria.  The  time  of  exposure  to  a  3  or  5  per  cent, 
solution  should  be  not  less  than  half  an  hour.  Fabrics  are  usually 
immersed  for  one  hour. 

The  Cresols. — By  far  the  majority  of  the  disinfectants  sold  to  the 
public  are  mixtures  of  varying  quantities  of  phenolic  bodies  with  inert 
1  ar  oils  and  an  emulsifying  agent  such  as  soap  or  tar,  and  sometimes 
resin,  gelatin,  or  dextrin.  These  substances  all  possess  a  smell  dis- 
tinctive of  carbolic  acid  and  are  effective  germicides.  The  cresols, 
05114(0113)  OH,  have  the  advantage  over  carbolic  acid  or  pure  phenol 
in  that  they  readily  form  beautiful  emulsions,  have  a  higher  germi- 
cidal value,  and  are  less  poisonous.  It  has  already  been  pointed 
out  that  substances  in  emulsion  are  more  potent  germicides  than  solu- 
tions. 

Ceesol. — Cresol  is  prepared  from  coal-tar  by  collecting  the  distillates 
coming  over  between  140°  0.  and  220°  0.,  and  then  purifying  these 
distillates  by  treatment  with  solution  of  sodium  hydroxid  and  hydro- 
chloric acid.  Oresol  is  a  mixture  of  the  three  isomeric  cresols  obtained 
from  coal-tar  and  freed  from  phenol,  hydrocarbons,  and  water.  It  is 
also  known  as  cresylic  acid  and  trikresol. 

Oreosote. — Oreosote  is  a  highly  refractile  liquid  obtained  from  the 
destructive  distillation  of  wood  or  coke.  Wood-tar  creosote  for  medicinal 
use  is  obtained  from  beachwood;  it  is  a  complex  mixture  of  phenoloid 
bodies,  the  proportions  of  which  differ  according  to  the  modes  of  dis- 
tillation and  purification.  It  contains  phenols,  cresols,  and  higher  homo- 
logs.  Ooal-tar  creosote,  sometimes  called  creosote  oil,  contains  that 
portion  of  the  distillate  from  coal-tar  intermediate  between  crude  naph- 
tha on  the  one  hand  and  pitch  on  the  other.  Coal-tar  creosote  con- 
tains phenols,  cresols,  and  higher  phenoloid  bodies,  also  naphthalene 
and  other  solid  hydrocarbons,  as  well  as  pyridin  and  other  bodies  of 
basic  character.  Oreosotes  vary  in  composition,  and  owe  their  germi- 
cidal properties  to  the  phenol  and  cresols  which  they  contain.  They  are 
seldom  used  as  such,  but  form  bases  of  many  com^mercial  disinfectants 
after  purification  or  the  addition  of  alkalies  or  soaps.  It  is  the  creosote 
from  coal-tar,  and  not  wood-tar,  that  is  used  as  a  germicide  in  public 
health  work. 

Trikresol. — Trikresol  consists  of  a  mixture  of  ortho,  meta,  and 
paracresols.  Matacresol  is  a  liquid;  the  other  two  are  solid  crystalline 
bodies  having  a  low  melting  point.  These  cresols  are  some  of  the  im- 
purities found  in  commercial  carbolic  acid.  The  cresol  group  forms  the 
next  higher  homolog  to  phenol,  one  atom  of  hydrogen  being  replaced 
in  the  latter  by  the  methyl  radical,  OH3.  The  cresols  are  very  insoluble 
in  water.  Their  solution  may  be  facilitated  by  the  use  of  alcohol  or 
glycerin.  Trikresol  is  a  clear  or  pink-colored  syrupy  liquid.  It  is  soluble 
to  the  extent  of  about  2^/2  P^r  cent,  in  water.     It  is  somewhat  less 


1014  CHEMICAL    AGENTS    OF    DISINFECTION 

poisonous  than  carbolic  acid;  its  uses  are  the  same.  It  is  an  effective 
germicide  in  a  1  per  cent,  solution. 

Liquor  Cresolis  Compositus. — Liquor  cresolis  compositus  of  the 
U.  S.  Pharmacopoeia  consists  of  cresol,  500  gm.;  linseed  oil,  350  Fm. ; 
potassium  hydroxid,  80  gm. ;  and  water  sufficient  to  make  1,000  gm. 
This  officinal  mixture  makes  a  clear  solution  in  water.  The  solution  is 
intended  as  a  substitute  for  the  many  commercial  preparations  of  cresol 
on  the  market.  It  has  practically  the  same  uses  as  the  trikresol  of 
commerce. 

Creolin. — Creolin  is  an  emulsion  of  cresols  and  certain  other  prod- 
ucts contained  in  crude  carbolic  acid  with  rosin  soap.  Creolin  forms  a 
milky  emulsion  when  mixed  with  water.  It  is  sometimes  called  creso- 
lin  or  sanatol.  At  least  two  sets  of  preparations  are  on  the  market: 
one  of  German,  the  other  of  English  origin.  It  is  used  in  1  or  2  per 
cent,  solution. 

Lysol. — Lysol  is  a  brown,  oily-looking,  clear  liquid  with  a  creosote- 
like odor.  It  is  similar  to  creolin  except  that  it  has  more  of  the 
cresols  and  less  of  the  other  products.  It  is  made  by  dissolving  the 
fraction  of  tar  oil  which  boils  between  190°  and  200°  C.  in  fat  and 
subsequently  saponifying  by  the  addition  of  alkali  in  the  presence  of 
alcohol.  It  contains  50  per  cent,  of  cresols,  is  miscible  in  water,  form- 
ing a  clear,  saponaceous,  frothy  liquid.  It  is  more  powerful  as  a 
germicide  than  phenol,  and  is  usually  used  in  1  per  cent,  solution. 

SoLVEOL  AND  SoLUTOL. — Solveol  is  a  solution  of  sodium  cresolate 
in  excess  of  cresol.  Solutol  is  a  solution  of  cresol  in  excess  of  sodium 
cresolate. 

There  are  a  vast  number  of  other  commercial  disinfectants  of  similar 
nature  consisting  of  coal-tar  creosotes  in  combination  with  alkalies, 
soaps,  resins,  etc.,  such  as  chloronaphtholeum,  sulphonaphthol,  bacillol, 
paraeresoh  and  other  trade  names. 

Formalin. — Formaldehyd  in  solution  is  known  as  formalin.  This  is 
a  very  valuable  disinfectant  with  a  wide  range  of  usefulness  in  general 
practice.  It  is  superior  to  bichlorid  of  mercury  for  many  purposes, 
especially  as  its  action  is  not  retarded  by  the  presence  of  albuminous 
matter.  Formalin  is  not  injurious  to  most  articles,  and  it  is  not  very 
poisonous.  It  is  a  true  deodorant.  The  more  I  work  with  formaldehyd, 
both  in  solution  and  as  a  gas,  the  more  am  I  impressed  with  its 
trustworthiness. 

Formalin  consists  of  a  40  per  cent,  solution  of  the  gas  formaldehyd 
(HCHO)  dissolved  in  water.  The  liquid  is  a  clear  solution,  giving  off 
an  appreciable  odor  of  the  gas.  It  is  exceedingly  irritating,  but  not 
especially  toxic.  Formalin  solutions  are  rather  unstable.  There  is  a 
constant  loss  by  evaporation  if  the  liquid  is  not  kept  well  corked,  and 
in  cold  weather  the  formaldehyd  polymerizes  and  precipitates  in  one  of 


LIQUID    DISINFECTANTS  1015 

its  polymeric  forms — trioxymethylene.  For  the  description  and  dis- 
cussion of  formaldehyd  see  page  993. 

Hot  formalin  attacks  iron  and  steel,  and  therefore  is  not  suitable. 
It  does  not  attack  copper,  brass,  nickel,  zinc,  and  other  metal  sub- 
stances. It  causes  no  diminution  in  strength  of  textile  fabrics  and  has 
no  bleaching  or  other  deleterious  effects  upon  colors.  Formalin  renders 
leather,  furs,  and  skins  brittle  as  a  result  of  the  union  that  takes 
place  between  the  formaldehyd  and  the  organic  matter  of  these  articles, 
and  they  should  therefore  be  disinfected  by  another  process. 

A  10  per  cent,  solution  of  formalin  in  water  is  about  the  equivalent 
of  a  1  to  500  solution  of  bichlorid  of  mercury,  or  superior  to  a  5  per 
cent,  solution  of  carbolic  acid.  It  must  be  borne  in  mind  that  in  speak- 
ing of  a  solution  of  formalin  a  solution  is  meant  of  the  liquid  con- 
taining 40  per  cent,  formaldehyd;  that  is,  a  1  per  cent,  solution  of 
formalin  would  contain  that  liquid  in  proportion  to  1  to  100,  but 
would  contain  the  substance  formaldehyd  in  the  proportion  of  1  to  250. 

Fecal  masses  are  deodorized  almost  instantly  by  a  small  quantity 
of  formalin,  and  are  disinfected  in  a  short  time  when  mixed  with  an 
equal  volume  of  a  10  per  cent,  solution.  It  is  advisable  to  continue  the 
contact  one  hour  to  insure  complete  action. 

There  is  some  discrepancy  as  to  the  percentage  of  formalin  solution 
necessary  to  accomplish  trustworthy  disinfection  in  general  practice. 
Taking  into  account  the  deterioration  of  the  solution  with  age  and 
allowing  an  excess  as  an  element  of  safety,  it  is  recommended  that  at 
least  a  5  per  cent,  solution  be  used,  but  in  the  presence  of  organic  matter 
10  per  cent,  is  recommended.  It  may  be  used  to  disinfect  urine,  excreta, 
sputum,  and  other  similar  substances. 

Potassium  Permanganate.- — Potassium  permanganate  is  a  germicide 
of  undoubted  value,  but  of  very  limited  application  in  general  practice 
on  account  of  the  readiness  with  which  it  is  reduced  and  rendered 
inert  by  organic  matter.  Despite  its  limitations  it  ranks  high  on  the 
list  of  germicides  for  certain  definite  purposes,  more  particiilarly  in 
surgical  practice.  It  has  been  much  used  in  India  and  other  places  for 
the  purification  of  water. 

Potassium  permanganate  (KaMngOs)  is  a  dark  purple,  crystalline 
substance  with  a  sweet,  astringent  taste.  A  few  crystals  impart  to  a 
large  quantity  of  water  a  rich  purple  tint  which  is  destroyed  by  organic 
matter  and  deoxidizing  agents.  It  is  soluble  in  16  parts  of  cold  and  2 
parts  of  boiling  water.  The  stain  produced  by  potassium  permanganate 
may  be  removed  by  a  solution  of  oxalic  acid,  muriatic  acid,  or  simple 
lemon  juice. 

Potassium  permanganate  readily  gives  up  its  available  oxygen,  and 
it  is  the  free  nascent  oxygen  that  is  the  true  disinfecting  agent.  Stern- 
berg found  a  solution  of  1  to  833  sufficient  to  kill  pus  cocci  in  two  hours. 


1016  CHEMICAL    AGENTS    OF    DISINFECTION 

Koch  found  that  a  5  per  cent,  solution  killed  spores  in  one  day.  Loef- 
fler  found  that  the  bacillus  of  glanders  is  destro^'ed  in  two  minutes 
by  a  1  per  cent,  solution. 

Water  containing  organic  matter  may  be  purified  to  a  certain  extent 
and  rendered  palatable  by  adding,  drop  by  drop,  a  solution  of  per- 
manganate until  the  pink  color  of  the  water  ceases  to  be  destroyed 
after  the  lapse  of  24  hours.  The  clear  liquid  may  then  be  decanted 
and  used.  Permanganate  used  in  this  way  does  not  reach  sufhcient 
concentration  to  be  a  trustworthy  germicide. 

Lime. — Lime  in  certain  of  its  variable  chemical  combinations  is  the 
best  and  cheapest  disinfecting  substance  we  have.  It  is  usually  used 
either  as  lime  or  chlorinated  lime. 

Limey  or  quicklime,  is  a  very  caustic  substance  used  for  the  destruc- 
tion of  organic  matter  as  well  as  germ  life.  On  account  of  its  effi- 
ciency and  cheapness  it  is  a  valuable  addition  to  the  list  of  practical 
disinfectants.  Lime  or  calcium  oxid  (CaO)  is  one  of  the  alkaline 
eartlis.  It  is  not  so  caustic  as  the  alkalies,  having  less  affinity  for 
water.  It  is  obtained  by  calcining  native  calcium  carbonate  (CaCOg), 
such  as  chalk,  limestone,  or  marble,  by  which  the  carbon  dioxid  is 
driven  off  and  the  calcium  oxid  remains  behind.  Lime  as  such  re- 
quires the  addition  of  water  for  germicidal  purposes. 

Slaked  Lime. — Slaked  lime  or  calcium  hydroxid,  Ca(0H)2,  is  pre- 
pared by  adding  one  pint  of  water  to  two  pounds  of  lime.  The  lime 
absorbs  about  half  its  weight  of  water.  The  mass  becomes  heated  and 
the  air  escapes  from  the  pores  of  the  lime  with  a  hissing  noise.  The 
result  is  calcium  hydroxid  or  slaked  lime.  Upon  exposure  to  the  air 
the  slaked  lime  will  absorb  still  more  water  and  also  carbon  dioxid, 
converting  it  into  calcium  carbonate,  which  is  inert  so  far  as  its  dis- 
infecting power  is  concerned.  Freshly  slaked  lime  should  therefore  al- 
ways be  used. 

Whitewash  is  slaked  lime  mixed  with  water.  It  is  commonly  used 
for  the  disinfection,  sweetening,  and  brightening  of  the  walls  of  cel- 
lars, rooms,  barracks,  bams,  stables,  poultry-houses,  and  oiit-l)uildings 
generally.  ^Yhitewash  is  a  very  satisfactory  method  of  destroying  spore- 
free  bacteria  that  may  have  lodged  upon  such  surfaces.  A  mordant 
such  as  glue  is  usually  added  to  whitewash  to  make  it  adhere. 

Milk  of  lime  is  slaked  lime  mixed  with  about  four  times' its  volume 
of  water  to  the  consistency  of  a  thick  cream.  It  is  useful  for  the 
disinfection  of  excreta  and  privy  vaults.  Air-slaked  lime  containing 
the  inert  carbonate  must  not  be  used  in  the  preparation  of  whitewash 
or  milk  of  lime,  freshly  slaked  lime  containing  calcium  hydroxid  be- 
ing necessary  to  accomplish  disinfection.  Calcium  hydrate  is  mostly 
insoluble  and  settles  to  the  bottom ;  the  milk  of  lime  must  therefore 
be  acritated  to  restore  its  homogeneous  character  before  it  is  used.     Milk 


LIQUID    DISINFECTANTS  1017 

of  lime  is  most  powerful  when  freshly  prepared.  It  soon  changes  to 
the  inert  carbonate,  and  therefore  should  not  be  used  if  more  than  a 
few  days  old  unless  carefully  protected  from  contact  with  the  air. 

Almost  all  laboratory  experiments,  while  difEering  somewhat  in 
certain  unimportant  particulars,  confirm  the  conclusions  of  the  early 
investigators  as  to  the  great  practical  value  of  lime  as  a  germicide. 
A  1  per  cent,  watery  solution  of  the  hydroxid  kills  non-spore-bearing 
bacteria  within  a  few  hours.  A  3  per  cent,  solution  kills  typhoid  bacilli 
in  one  hour.  A  20  per  cent,  solution  added  to  equal  parts  of  feces  or 
other  filth  and  mixed  with  them  will  completely  sterilize  them  within 
one  hour. 

Lime  is  particularly  valuable  in  the  disinfection  of  excreta.  The 
lime  in  one  form  or  another  must  be  well  incorporated  with  the  mass 
and  enough  must  always  be  added  in  order  to  make  the  reaction  of  the 
mixture  distinctly  alkaline.  Sternberg  recommends  that  freshly  pre- 
pared milk  of  lime  should  contain  about  one  part  by  weight  of  hydrate 
of  lime  to  eight  parts  of  water.  This  should  be  used  freshly  prepared 
and  added  in  quantity  equal  in  amount  to  the  material  to  be  disin- 
fected. The  mixture  should  be  allowed  to  stand  at  least  two  hours  be- 
fore final  disposal.  Fortunately,  this  valuable  disinfecting  agent  is 
very  cheap,  so  that  it  can  be  used  with  a  liberal  hand  in  excess  of  the 
amount  which  scientific  tests  find  necessary. 

Lime  has  been  used  in  very  early  times  in  connection  with  the  dis- 
posal of  the  dead.  The  method  is  an  admirable  one  for  the  burial  and 
disinfection  of  bodies  dead  from  a  communicable  disease.  The  body 
should  be  placed  in  a  tight  coffin  with  twice  its  weight  of  fresh,  un- 
slaked lime,  without  the  addition  of  water  or  moisture  in  any 
form. 

Chlorinated  Lime  ("Chlorid  of  Lime"). — Chlorinated  lime  was 
used  as  a  disinfectant  and  deodorant  long  before  bacteriology  was  a 
science.  The  early  work  of  Sternberg  demonstrated  that  the  confidence 
placed  in  this  substance  from  an  empiric  standpoint  is  justified  by 
scientific  tests.  Chlorinated  lime  under  certain  circumstances,  in  fact, 
is  one  of  the  most  powerful  germicides  we  possess,  and  has  been  used 
particularly  for  the  disinfection  of  sewage  and  water. 

Chlorinated  lime,  popularly  miscalled  chlorid  of  lime,  is  a  soft, 
white,  friable  substance,  and  is  known  also  as  bleaching  powder.  It 
has  a  peculiar  chemical  composition  and  is  somewhat  unstable.  It  is 
made  by  passing  chlorin  gas  through  lime.  Owing  to  its  affinity  for 
moisture,  which  it  slowly  absorbs  from  the  air,  it  soon  becomes  pasty 
and  loses  some  of  its  chlorin;  the  hypochlorites  are  reduced  to  chlorids, 
which  are  inert  as  germicides.  Freshly  prepared  chlorinated  lime 
should  have  a  very  slight  odor  of  free  chlorin.  A  strong  odor  of  this 
gas  indicates  that  deterioration  of  the  substance  is  taking  place.      It 


1018  CHEMICAL    AGENTS    OF    DISINFECTION 

should  therefore  only  be  used  when  freshly  prepared  and  when  kept 
in  air-tight  receptacles. 

Chlorinated  lime  is  made  by  passing  nascent  chlorin  gas  over  very 
slightly  moist  calcium  hydro.xid.  Concerning  its  exact  chemical  cora- 
jiosition  there  is  some  disagreement.  It  is  represented  by  the  formula 
CaOCl,  or  ClCaOCl  or  Ca(C10)Cl.  According  to  the  U.  S.  Pharma- 
copoeia it  should  contain  not  less  than  35  per  cent,  of  available  chlorin. 
The  British  standard  is  33  per  cent,  and  the  German  25  per 
cent.  Chlorinated  soda  has  almost  the  same  germicidal  value  as 
chlorinated  lime.  Chlorinated  soda  is  sold  only  in  solution,  and  is 
prepared  by  mixing  a  solution  of  chlorinated  lime  and  sodium  car- 
bonate. 

Chlorinated  lime  is  only  partially  soluble  in  water  or  in  alcohol. 
A  solution  in  water  of  0.5  to  1  per  cent,  will  kill  most  bacteria  in  one 
to  five  minutes.  A  5  per  cent,  solution  usually  destroys  spores  within 
an  hour. 

While  the  solution  of  chlorinated  lime  has  an  indefinite  com- 
position it  is  generally  admitted  to  contain  calcium  hypochlorite 
(CaClCaClOo),  which  is  its  active  disinfecting  principle.  It  also  con- 
tains calcium  chlorid  (CaCL),  which  has  a  great  affinity  for  water, 
and  calcium  hydrate  (Ca(0H)2),  which  is  largely  insoluble.  The 
calcium  hypochlorite,  upon  which  the  efficiency  of  the  solution  largely 
depends,  is  readily  broken  up,  even  by  the  carbon  dioxid  found  in  the 
air  and  water,  into  hyperchlorous  acid,  and  this  acid  is  so  unstable  that 
even  in  the  presence  of  light  it  is  decomposed  into  hydrochloric  acid 
and  free  chlorin,  both  of  which  are  active  germicides.  When  bleaching 
powder  is  added  to  water  it  is  the  nascent  oxygen,  and  not  the  chlorin, 
that  is  the  disinfecting  agent.  (See  page  797.)  The  solution  is 
highly  alkaline  and  has  distinct  bleaching  powers.  Its  action  as  a 
deodorant  depends  not  only  upon  its  destructive  influence  upon  organic 
matter  and  its  germicidal  properties,  but  also  upon  its  great  affinity 
for  water,  thus  acting  as  a  disinfectant.  It  also  has  the  power  of 
combining  with  hydrogen  sulphid  and  the  volatile  ammoniacal  com- 
pounds of  decomposition  and  decay. 

Chlorinated  lime  not  only  bleaches  but  is  destructive  to  fabrics.  If 
the  solution  is  employed  for  the  disinfection  of  body  linen  and  wash- 
able clothing  these  articles  must,  after  a  not  too  long  immersion,  be 
thoroughly  washed  in  plenty  of  fresh  water. 

It  should  be  remembered  that  the  hypochlorites  are  decomposed 
and  practically  rendered  inert  by  organic  matter.  They  should  there- 
fore be  used  largely  in  excess.  Thus  a  preparation  containing  10  per 
cent,  of  available  chlorin  has  the  high  carbolic  coefficient  of  21.0,  but 
on  mixing  an  equal  amount  of  this  preparation  with  urine  and  allowing 
the  mixture  to  stand  one  hour  the  coefficient  falls  to   0.8   per  cent. 


LIQUID    DISIXFECTAXTS  1019 

(Klein). ^  Gruber  points  out  that  the  efficiency  of  chlorinated  lime, 
when  used  to  disinfect  cattle  wagons,  is  greatly  increased  by  first  thor- 
oughly washing  away  the  organic  matter. 

Chlorinated  lime  may  be  used  either  as  a  dry  powder  or  in  solution. 
As  a  dry  powder  it  is  very  generally  used  by  strewing  it  into  damp 
corners  of  cellars,  privies,  and  similar  places,  where  it  acts  as  a  de- 
odorant and  desiccant.  The  dry  substance  may  also  be  used  to  disin- 
fect excreta.  For  this  purpose  enough  of  the  chlorinated  lime  must 
be  added  and  well  incorporated  with  the  mass  to  make  a  -1  or  o  per 
cent,  solution. 

In  the  U.  S.  Army  a  -4  per  cent,  strength  of  chlorinated  lime  in 
solution  is  officially  prescribed  for  use  in  the  disinfection  of  the  excreta 
of  the  sick,  it  being  specifically  stated  that  the  chlorinated  lime  so 
used  shall  be  of  good  quality  and  not  have  undergone  decomposition. 
A  solution  known  as  the  "American  standard,"  containing  6  ounces 
of  the  powder  to  the  gallon,  is  largely  used  for  the  disinfection  of 
discharges  and  for  the  scrubbing  of  floors  and  other  surfaces.  In  re- 
cent years  chlorinated  lime  or  chlorinated  soda  has  come  into  special 
prominence  on  account  of  its  use  for  the  disinfection  of  drinking  water. 
A  surprisingly  minute  amount  will  disinfect  a  large  volume  of  water. 
The  amount  required  depends  upon  the  quantity  of  organic  matter 
contained  in  the  water.  A  reasonably  clean  water  may  be  rendered 
practically  sterile  by  the  addition  of  0.1  of  a  part  of  chlorinated  lime 
(estimated  as  available  chlorin)  to  1,000,000  parts  of  water.  For 
waters  containing  organic  matter  as  much  as  1  to  5  parts  per  1,000,000 
may  be  required.     (See  page  797.) 

A  convenient  method  for  using  chlorinated  lime  to  disinfect  drink- 
ing water  is  to  add  1  gram  of  chlorinated  lime  containing  approxi- 
mately 30  per  cent,  of  available  chlorin  to  1  liter  of  water.  This  should 
be  mixed  thoroughly  and  enough  of  the  mixture  added  to  the  water  in 
question  to  make  one  part  of  chlorinated  lime  to  200,000  parts  of 
water.  This  should  be  allowed  to  stand  at  least  20  minutes  after  hav- 
ing been  thoroughly  shaken,  and  the  water  may  then  be  regarded  as 
safe,  so  far  as  typhoid,  cholera,  and  similar  infections  are  concerned. 

Chlorinated  lime  may  also  be  used  to  advantage  to  disinfect  the 
bath  water  in  cases  of  typhoid  fever,  dysentery,  cholera,  or  other  com- 
municable diseases.  It  may  also  be  used  for  the  disinfection  of  springs, 
wells,  cisterns,  tanks,  etc. 

The  Hypoclilorites. — Labakraque's  Solutiox. — Labarraque's  solu- 
tion is  an  aqueous  solution  of  several  chlorin  compounds,  chiefly  sodium 
hypochlorite  (XaClO)  and  sodium  chlorid  (XaCl),  and  should  con- 
tain  at  least   2.6   per  cent,   by  weight    of    available   chlorin   as    deter- 

^FuiJi-G  Health,  Oct.,  1906.  Confirmed  by  Eideal,  Sommerville,  Moore,  and 
others. 


1020  CHEMICAL    AGENTS    OF    DISINFECTION 

iniiKHl  by  titration  with  tliiosulphate.  The  solution  is  clear  and  color- 
less when  pure.  If  prepared  with  an  excess  of  chlorin  it  is  yellowish 
in  color.  It  has  a  feeble  odor  of  chlorin  and  bleaches  indigo,  litmus, 
and  vegetable  dyes.  In  practice  this  solution  diluted  with  water  1  to  4 
is  mainly  used  for  the  disinfection  of  the  person,  but  as  it  is  more  ex- 
pensive and  somewhat  less  efficient  than  chlorinated  lime  it  has  no 
advantages  over  that  substance. 

Antiformin. — Antiformin  is  the  patented  name  of  a  disinfectant 
which  was  introduced  in  1900  by  Victor  Tornell  and  Axel  Sjoo  of 
Stockholm  as  a  cleansing  material  for  fermenting  vats  in  breweries, 
but  it  is  only  since  the  investigations  of  Uhlenhuth  and  Xylander^  in 
1908  that  it  has  come  into  prominence  in  bacteriological  and  sanitary 
work. 

Antiformin  consists  of  equal  parts  of  liquor  sodae  chlorinatse  of  the 
British  Pharmacopoeia  and  a  15  per  cent,  solution  of  caustic  soda.  The 
formula  for  the  liquor  sodae  chlorinatae  is  as  follows: 

Sodium   carbonate    600 

Chlorinated  lime   400 

Distilled   water    4,000 

Dissolve  the  sodium  carbonate  in  1,000  c.  c.  of  the  distilled  water; 
triturate  thoroughly  the  chlorinated  lime  in  the  remainder  of  the 
water;  filter;  mix  the  two  and  filter  again. 

Antiformin  has  a  strong  germicidal  action  in  weak  solutions  (2  to 
5  per  cent.),  killing  ordinary  cocci  and  some  bacilli  rapidly,  five  minutes 
at  most  being  sufficient.  In  this  respect  antiformin  acts  more  rapidly 
and  surely  than  either  of  its  component  parts  used  alone.  It  has,  how- 
ever, very  slight  action  upon  the  tubercle  bacillus,  the  smegma  bacillus, 
and  other  organisms  belonging  to  the  acid-fast  group. 

Antiformin  is  an  almost  colorless  liquid,  with  a  strong  odor  of 
chlorin,  and  is  strongly  alkaline.  It  keeps  fairly  well  without  particular 
precautions  being  taken.  It  has  deep  powers  of  penetration,  owing  to 
its  ability  to  dissolve  and  render  homogeneous  the  various  substances  in 
which  bacteria  are  often  found,  such  as  sputum,  feces,  pus,  urinary  sedi- 
ment, and  even  small  pieces  of  tissue. 

The  germicidal  action  of  antiformin  is  doubtless  due  to  the  ener- 
getic oxidizing  properties  of  the  chlorinated  lime.  The  fact  that  it 
does  not  kill  the  tubercle  bacillus  and  other  acid-fast  organisms  seems 
to  be  due  to  the  biochemical  nature  of  these  bacilli.  The  fatty  or 
waxy  capsule  which  is  present  and  which  gives  them  their  acid-fast 
property  acts  as  an  impervious  coat,  resisting  the  dissolving  action  of 
the  antiformin,  and  so  protects  the  protoplasm  of  the  bacilli  from  its 

^  B.  TcUn.  Wochenschr.,  LXV,  No.  29,  July  20,  1908. 


ACIDS  1021 

germicidal  action.  The  tubercle  bacillus  may  be  isolated  in  pure  culture 
by  exposing  tuberculous  sputum  to  a  20  per  cent,  solution  of  antiformin 
for  24  hours  at  room  temperature  or  4  to  6  hours  at  incubator  tem- 
perature. The  bacilli  may  then  be  thrown  down  by  centrifugalization, 
washed  free  of  alkali,  and  then  planted  upon  solidified  egg  or  other 
suitable  culture  m-edium,  or  injected  into  susceptible  animals. 

While  antiformin  is  therefore  a  very  active  germicide  for  the  ordi- 
nary bacteria  it  cannot  be  depended  upon  for  the  acid-fast  group.^ 

Bromin  and  lodin. — Bromin  and  iodin  have  about  the  same  value 
as  chlorin,  both  in  their  gaseous  state  and  in  solution.  The  tincture 
of  iodin  is  now  much  used  in  surgery  for  the  disinfection  of  the 
skin. 

Ferrous  Sulphate. — Ferrous  sulphate  has  long  been  valued  as  a 
disinfectant  on  account  of  its  power  as  a  deodorant,  and  has  been  used 
extensively,  being  a  comparatively  cheap  substance.  Its  germicidal 
power  has  been  shown  by  laboratory  tests  to  be  rather  feeble,  so  that 
it  cannot  be  depended  upon  as  a  trustworthy  disinfectant. 

Ferrous  sulphate  (FeS04),  commonly  called  green  vitriol,  iron  vit- 
riol, or  copperas,  consists  of  large  bluish-green  crystals  which  slowly 
effervesce  and  oxidize  in  the  air.  It  is  soluble  in  about  twice  its  weight 
of  cold  water,  forming  a  greenish  solution.  It  is  a  much  less  powerful 
germicide  than  the  sulphate  of  copper,  and  is  limited  in  use  to  the  de- 
struction of  odors,  and  even  for  this  purpose  is  not  always  successful.. 

Sulphate  of  Copper. — Sulphate  of  copper  (CuSO^)  is  about  half  as 
strong  as  bichlorid  of  mercury.  It  has  a  peculiar  selective  action  in  that 
it  has  a  remarkable  affinity  for  many  species  of  algge  which  are  killed 
in  the  proportion  of  1  to  1,000,000.  Algae  are  the  most  common  cause 
of  unpleasant  odors  and  tastes  in  drinking  water,  and  sulphate  of  cop- 
per may  therefore  be  used  to  check  or  destroy  their  growth.  (See 
page  800.)  In  these  great  dilutions  sulphate  of  copper  will  not  kill 
the  typhoid  bacillus,  so  that  it  is  not  practical  to  use  it  as  a  disinfectant 
in  water. 

Chlorid  of  Zinc. — Chlorid  of  zinc  (ZnCl)  was  at  one  time  highly 
valued  as  a  disinfectant,  and  is  still  extensively  used  despite  the  fact 
that  it  stands  rather  low  in  the  list  of  germicidal  agents.  It  has  even 
weaker  powers  as  a  disinfectant  than  ferrous  sulphate  and  cannot  be 
recommended  as  trustworthy.     It  has  some  value  as  a  deodorant. 

ACIDS 

Acids  in  sufficient  concentration  are  very  effective  germicides.  An 
amount  of  acid  which  equals  40  c.  c.  of  normal  hydrochloric  acid  per 

*  Paterson,  E.  C. :  "A  Report  on  the  Use  of  '  Antiformin '  for  the  Detection 
of  Tubercle  Bacilli  in  Sputum,  etc.,"  Jour,  of  Med.  Besearch,  Vol.  XXII,  No.  2, 
AprU,  1910,  p.  315. 


1022  CHEMICAL    AGENTS    OF    DISINFECTION 

liter  is  sufficient  to  prevent  the  growth  of  all  varieties  of  bacteria  and 
to  kill  many.  The  variety  of  acid  makes  little  difference.  The  mineral 
acids  are  more  coiTosive  and  also  more  germicidal  than  the  vegetable 
acids.  A  1  to  500  solution  of  sulphuric  acid  kills  typhoid  bacilli  within 
one  hour.  Hydrochloric  acid  is  about  one-third  weaker,  and  acetic 
acid  somewhat  weaker  still.  Citric,  tartaric,  malic,  formic,  and  salicylic 
acids  are  similar  to  acetic  acid.  Boric  acid  destroys  the  less  resistant 
bacteria  in  2  per  cent,  solution  and  inhibits  the  others.     (Park.) 

SOAPS 

Ordinary  soaps  have  but  limited  disinfecting  power.  According  to 
Behring  the  germicidal  power  of  soaps  depends  upon  their  alkalinity, 
but  Serafini  more  correctly  points  out  that  the  free  alkali  present, 
even  in  concentrated  soap  solutions,  is  so  small  in  amount  that  it 
can  exert  no  disinfecting  action  whatever,  and  that  neither  the  alkali 
nor  the  fatty  acid,  nor  the  combination  of  the  two  is  the  effective  agent. 

Unfortunately,  the  disinfecting  power  of  soap  solutions  is  not 
marked  enough  to  make  them  trustworthy  disinfectants  despite  their 
great  value  as  detergents.  The  common  commercial  soaps,  especially 
the  colored  soaps,  are  frequently  of  very  poor  quality,  containing  rosin 
instead  of  fat,  and  are  not  to  be  depended  upon.  The  soft  soaps  should 
also  be  avoided  on  account  of  the  presence  of  all  the  impurities  of  the 
fat  and  alkali  from  which  they  are  made.  There  are  other  conditions 
which  render  the  use  of  soaps  uncertain,  the  chief  of  which  is  the 
hardness  of  the  water. 

The  action  of  soap  solutions  is  much  influenced  by  the  temperature, 
which  is  easy  to  understand  when  we  recall  the  powerful  germicidal 
action  of  hot  water  alone.  It  has  been  shown  that  soap,  even  in  strong 
solution  and  with  prolonged  exposure,  cannot  be  trusted  to  destroy 
the  infection  of  typhoid,  cholera,  or  the  micrococci  of  suppuration. 
Therefore  soaps  alone  cannot  be  depended  upon  for  the  disinfection 
of  objects  and  clothing,  but  in  conjunction  with  certain  compatible 
chemicals,  and  also  with  the  mechanical  cleansing  which  always  ac- 
companies their  application,  soaps  have  a  wide  and  varied  usefulness. 

Soap  solutions  should  always  be  made  with  soft  water.  The  addi- 
tion of  one  of  the  caustic  alkalies,  as  lye,  increases  their  germicidal 
and  detergent  value.  The  solution  should  be  strong,  containing  not 
less  than  10  per  cent,  of  soap,  and  the  water  should  be  as  hot  as  pos- 
sible and  applied  wdth  mops  or  brushes. 

Medicated  soaps  are  for  the  most  part  a  snare  and  delusion  so  far 
as  any  increased  germicidal  action  is  concerned.  In  fact,  the  addition 
of  carbolic  acid,  bichlorid  of  mercury,  and  other  substances  which 
have  the  property  of  combining  chemically  with  the  soap  seems  actually 


SOAPS 


1023 


to  diminish  the  disinfecting  value  of  that  substance.  As  a  rule  a 
very  small  quantity  of  the  disinfecting  substance  is  added  to  the 
soap,  and  when  we  call  to  mind  what  an  exceedingly  small  quantity  of 
soap  is  generally  used  for  the  ordinary  washing  of  the  skin  and  the 
further  dilution  of  this  small  amount  by  the  water  used  it  is  easy  to 
understand  that  medicated  soaps  as  ordinarily  applied  cannot  have 
an  energetic  disinfecting  action. 

An  exception  seems  to  be  the  soap  devised  by  McClintock,  in  which 
a  mercury  salt  exists  unchanged  and  active.  He  found  that  double 
iodid  of  mercury  answers  this  purpose  in  the  proportion  of  0.05  to  2 
per  cent.  A  solution  containing  1  per  cent,  of  the  soap  was  found 
by  him  to  be  fatal  to  pus  cocci,  cholera,  diphtheria,  and  typhoid  bacilli 
in  one  minute.  This  soap  does  not  attack  nickel,  silver,  aluminium, 
steel  instruments,  or  lead  pipes,  and  does  not  coagulate  albumin. 

The  following  is  a  table  of  comparative  antiseptic  values  taken 
from  Park : 

Table  of  Antiseptic  Values 


Alum 

Aluminium  acetate .  . 
Ammonium  chlorid    . 

Boric  acid 

Calcium  chlorid 

Calcium  hypochlorite 

CarboUc  acid 

ChloraL  hydrate 

Cupric  sulphate 

Ferrous  sulphate .... 
Formaldehyd  (40%) . 
Hydrogen  peroxid .  .  . 


222 

6,000 

9 

143 

25 

1,000 

333 

107 

2,000 

200 

10,000 

20,000 


Mercuric  chlorid 

Mercuric  iodid 

Potassium  bromid 

Potassium  iodid 

Potassium  permanganate 

Pure  formaldehyd 

Quinin  sulphate .  .    

Silver  nitrate 

Sodium  borate 

Sodium  chlorid 

Zinc  chlorid 

Zinc  sulphate 


14,300 

40,000 

10 

10 

300 

25,000 

800 

12,500 

14 

6 

500 

20 


CONVENIENT  FORMULJE  FOB  DISINFECTING  SOLUTIONS 
Bichlorid  of  Mercury — Corrosive  Sublimate. 


Bichlorid   of  mercury 1  dram 

Water 1  gallon 


1  gram 
1  liter 


Mix  and  dissolve.  Label  "Poison/"  This  is  approximately  a  1  to 
1,000  solution.  One  ounce  of  this  solution  contains  very  nearly  half  a 
grain  of  corrosive  sublimate.  Useful  for  disinfecting  clothing,  the 
hands,  the  surfaces  of  walls,  floors,  furniture,  etc.  Xot  serviceable  for 
feces  or  material  containing  much  organic  matter. 

Formalin. 


Formalin    13  ounces   I   100  c.  c. 

Water    1  gallon    |       1  liter 


1024  CHEMICAL    AGENTS    OF    DISINFECTION 

Formalin  is  a  watery  solution  containing  40  per  cent,  formaldehyd. 
The  above  solution  contains  approximately  10  per  cent,  of  formalin 
and  is  useful  for  the  disinfection  of  clothing  and  a  great  variety  of 
objects.  As  it  has  no  corrosive  action  it  does  not  bleach  pigments  or 
rot  fabrics.  When  used  to  disinfect  feces  twice  the  above  strength  should 
be  used. 

Milk  of  Lime. — Slake  a  quart  of  freshly  burnt  lime,  in  small  pieces, 
with  three-fourths  of  a  quart  of  water,  or,  more  exactly,  60  parts  of 
water  by  weight  with  100  parts  of  lime.  A  dry  powder  of  slaked  lime 
(calcium  hydroxid)  results.  Prepare  the  milk  of  lime  shortly  before 
it  is  to  be  used  by  mixing  1  quart  of  this  dry  calcium  hydroxid  with  4 
quarts  of  water.  Air-slaked  lime  is  worthless.  Slaked  lime  may  be 
preserved  some  time  if  inclosed  in  an  air-tight  container.  Milk  of  lime 
is  especially  useful  for  the  disinfection  of  feces ;  an  equal  quantity  should 
be  added  to  the  mass  and  thoroughly  mixed. 

Carbolic  Acid. 

Crude  carbolic  acid  (or  phenol) ...     7  ounces  |  50  c.  c. 
Water    1  gallon    |     1  liter 

The  solution  is  facilitated  by  dissolving  in  hot  water.  This  makes 
approximately  a  5  per  cent,  solution.  The  addition  of  from  12  to  14 
ounces  of  common  salt  to  each  gallon  increases  its  germicidal  power, 
especially  when  used  for  the  disinfection  of  excreta.  The  crude  carbolic 
acid  is  more  powerful  than  pure  phenol,  but  can  only  be  used  for  rough 
work,  such  as  floors,  feces,  sputum,  etc.  For  the  disinfection  of  cloth- 
ing phenol  should  be  used  and  the  solution  may  be  mixed  half  and  half 
with  water,  making  approximately  a  21/9  per  cent,  solution. 

Chlorinated  Lime  ("Chlorid  of  Lime"). 

Chlorinated  lime 3  ounces   |   30  grams 

Water    1  gallon    |     1  liter 

Mix.  This  is  about  a  3  per  cent,  solution.  It  is  exceedingly  power- 
ful and  is  useful  for  the  disinfection  of  excreta,  privy  vaults,  cesspools, 
and  many  other  purposes.  It  is  an  active  bleaching  agent  and  destroys 
fabrics  in  this  concentration. 


CHAPTEE  IV 
METHODS    OF    DISINFECTION 

A  few  instances  are  given  upon  the  following  pages  of  the  best 
methods  of  disinfecting  rooms,  excreta,  and  fomites.  The  examples 
selected  have  been  taken  as  types  of  a  class.  In  public  health  work  the 
things  most  frequently  needing  disinfection  are  feces,  sputum,  and 
other  discharges  from  the  body;  bed  and  body  linen,  and  other  fabrics; 
and  bedrooms.  The  disinfection  of  water  and  the  pasteurization  of 
milk  have  already  been  considered.  The  disinfection  of  ships  is  de- 
scribed under  Quarantine. 

Air. — It  is  quite  impossible  to  disinfect  the  air  of  a  room  during  its 
occupancy.  In  fact,  ordinarily  little  heed  need  be  given  to  the  air  itself. 
Any  of  the  known  volatile  substances  in  sufficient  concentration  to  kill 
microorganisms  would  render  the  air  unendurable.  It  is  absurd  to 
place  such  substances  as  carbolic  acid,  formalin,  or  chlorinated  lime 
in  an  open  pan  in  the  sickroom  or  in  the  bathroom  with  the  idea 
that  they  are  serving  a  useful  purpose  in  disinfecting  the  atmosphere  or 
in  preventing  the  spread  of  infection.  Occasionally  a  deodorant,  such 
as  formalin,  may  be  used  with  advantage  about  the  room,  but  where 
proper  cleanliness  and  ventilation  are  observed  such  substances  are 
rarely  called  for. 

It  is  of  first  importance  to  prevent  the  infection  of  the  air  of  the 
room  by  taking  precautions  applicable  to  the  particular  infection  in 
question.  Thorough  ventilation  should  be  maintained,  and  in  this  way 
any  chance  infection  is  soon  lost  by  dilution  or  killed  by  the  sun.  An 
open  fireplace  is  admirable  for  the  ventilation  and  purification  of  the 
air  of  sick  rooms,  for  by  this  method  the  infection  is  not  only  carried 
away,  but  is  destroyed  by  the  heat  of  the  fire  in  exit.  The  hanging  of 
sheets  wet  with  bichlorid  of  mercury  or  some  other  germicidal  solution 
at  the  doorway  serves  no  particular  useful  purpose. 

"When  a  room  has  become  badly  infected,  say  from  a  case  of  pul- 
monary tuberculosis,  and  there  is  danger  of  infection  through  the  dust, 
it  should  be  given  a  preliminary  fumigation  with  formaldehyd.  which 
will  partly  protect  the  operators  who  have  to  take  up  the  carpets  or  re- 
move the  bedding  and  other  articles  to  the  steam  sterilizer. 

1025 


1026  METHODS    OF    DISINFECTIOlSr 

Rooms. — The  disinfection  of  a  living-room  calls  for  all  the  re- 
sources of  the  disinfector's  art.  The  fact  that  it  is  necessary  to  bring 
the  apparatus  and  materials  to  the  room  in  order  to  disinfect  it  and  its 
contents  is  one  of  the  main  difficulties  and  will  often  require  the  in- 
genuity and  always  the  vigilance  of  the  operator. 

The  method  to  be  employed  for  the  disinfection  of  a  room  will  vary 
somewhat  with  the  infection  for  which  the  disinfection  is  done.  In 
routine  work  in  the  treatment  of  rooms  liable  to  be  infected  with  a 
variety  of  bacterial  viruses  formaldehyd  gas  is  the  most  generally  useful 
agent  we  possess.  In  the  case  of  yellow  fever  or  malaria  insecticides  must 
be  selected;  in  the  case  of  plague  our  efforts  must  be  directed  against 
rats,  mice,  fleas,  as  well  as  the  destruction  of  the  plague  bacillus.  In 
cholera  and  typhoid  fever  we  must  pay  particular  attention  to  the  feces, 
urine  and  the  objects  soiled  by  them,  etc. 

Certain  articles  commonly  found  in  living-rooms,  such  as  bedding, 
carpets,  rugs,  cuspidors,  upholstered  furniture,  and  other  objects  liable 
to  become  deeply  infected  must  be  treated  separately  by  some  process 
applicable  to  each  article.  None  of  the  gaseous  disinfectants  can  be 
trusted  to  penetrate  enough  to  render  articles  of  this  class  safe.  In 
case  the  room  is  so  constructed  that  it  is  impracticable  to  disinfect  it 
with  a  gas  the  walls,  floors,  and  all  the  contents  of  the  room  must  be 
disinfected  separately  in  accordance  with  suitable  methods  for  each  case. 

Ordinarily  carpets  and  rugs  should  be  left  in  place  until  a  })re- 
liminary  gaseous  disinfection  is  accomplished.  They  may  then  be  taken 
up  and  removed  for  steam  sterilization,  after  which  they  should  be  gone 
over  with  a  vacuum  cleaner  and  finally  hung  in  the  sun  for  a  day  or  two. 
If  carpets,  rugs,  upholstered  furniture,  or  other  articles  have  become 
badly  contaminated  with  infected  discharges  or  in  other  ways  the  soiled 
areas  should  be  thoroughly  saturated  with  a  strong  solution  of  formalin. 
Bedding,  towels,  curtains,  clothing,  and  other  articles  of  like  nature 
may  be  left  in  the  room  exposed  to  the  action  of  the  gas,  but  should 
afterwards  be  removed  for  boiling,  steaming,  or  immersion  in  one  of  the 
germicidal  solutions,  as  none  of  the  gases  can  be  relied  upon  for  the 
disinfection  of  fabrics.  Articles  removed  from  the  room  for  disinfec- 
tion should  be  placed  in  a  bag  or  wrapped  in  a  sheet  wet  with  bichlorid 
of  mercury.  Eul)bish  that  has  collected  in  the  room  should  be  gathered 
and  burned.    The  cuspidors  and  their  contents  require  special  treatment. 

The  gaseous  disinfectants  cannot  be  depended  upon  where  penetra- 
tion is  required;  therefore  any  article  believed  to  be  deeply  or  badly  in- 
fected should  be  treated  with  another  method. 

After  the  room  has  been  properly  prepared  and  all  has  been  made 
tight,  it  is  filled  with  the  gas  according  to  the  method  selected.  The  room 
should  then  be  sealed  in  such  a  way  that  it  cannot  be  opened  without 
the  knowledge  of  the  disinfector.     After  the  proper  time  has  elapsed 


STABLES  1027 

the  room  should  be  ojDened  by  the  disinfeetor  himself  and  the  operation 
should  not  be  considered  successful  unless  there  is  a  distinct  odor  of 
the  gas  present.  Windows  and  doors  may  then  be  opened  so  as  to  allow 
the  gas  to  blow  away.  Cultures  of  a  test  organism  should  always  be 
exposed  in  order  to  control  the  efficiency  of  the  fumigation  in  each 
case. 

A  room  which  has  been  carefully  treated  as  above  outlined  may  be 
considered  disinfected,  but  it  is  always  advisable  to  follow  the  disinfect- 
ing processes  with  a  very  thorough  mechanical  cleansing  and  a  good 
sunning  and  airing. 

When  a  room  is  to  be  purified  without  the  use  of  one  of  the  gaseous 
disinfectants  a  somewhat  different  procedure  is  followed.  Article  after 
article  is  removed  piecemeal  and  disinfected  by  an  appropriate  method. 
After  the  room  is  emptied  the  walls  and  their  surfaces  are  flushed, 
scrubbed,  or  mopped  with  bichlorid  of  mercury,  1  to  1,000,  or  one  of  the 
alkaline  cresols. 

Stables. — The  disinfection  of  a  stable  requires  a  particularly  thor- 
ough application  of  all  the  resources  at  the  hand  of  the  disinfeetor.  The 
conditions  met  with  in  a  stable  render  its  disinfection  doubly  hard,  not 
only  on  account  of  the  accumulation  of  organic  filth  which  has  worked 
into  the  many  crevices  and  saturated  the  woodwork,  but  on  account  of 
the  high  resistance  of  anthrax  and  tetanus  spores,  for  which  stables  are 
sometimes  disinfected.  In  addition  to  these  diseases  stables  require  dis- 
infection on  account  of  tuberculosis,  glanders,  pleuropneumonia,  and 
various  diseases  of  man  as  well  as  those  of  the  domestic  animals. 

It  is  advisable  to  give  the  stable  a  preliminary  fumigation,  preferably 
with  sulphur,  in  order  to  destroy  surface  infection  and  the  vermin  which 
always  infest  these  places.  The  preliminary  disinfection  is  especially 
important  in  the  case  of  plague  and  glanders,  not  only  to  prevent  the 
spread  of  the  infection,  but  as  a  safeguard  for  the  disinfectors.  Then 
remove  all  small  articles  that  need  disinfection.  The  blankets  should 
be  wrapped  in  moist  bichlorid  sheets  and  boiled,  steamed,  or  burned. 
Buckets,  currycombs,  brushes,  stall  tools,  and  other  equipment  that  has 
been  in  contact  with  the  sick  animals  or  with  infectious  materials 
should  be  mechanically  cleaned  with  a  hot  carbolic  solution  in  which 
they  may  be  allowed  to  soak  over  night.  Metallic  and  wooden  objects  or 
utensils  should  be  given  a  thorough  preliminary  cleansing  with  a  stiff 
brush  and  hot  water  and  soap,  and  then  boiled  or  immersed  in  a  5  per 
cent,  solution  of  carbolic  acid  or  2  per  cent,  solution  of  trikresol  for 
several  hours.  Leather  articles,  as  harness  or  equipment,  should  receive 
a  similar  preliminary  cleansing  and  be  scrubbed  with  either  a  strong 
solution  of  bichlorid  of  mercury  or  carbolic  acid. 

All  hay  and  grain  should  be  removed  from  the  racks  and  mangers 
and  all  bedding  from  the  floors.     After  its  careful  collection  at  some 


1028  METHODS    OF    DISINFECTION 

designated  point  this  refuse  should  be  saturated  with  petroleum  and 
destroyed  by  fire. 

The  stable  nnist  now  be  soaked  with  a  stronj]^  antiseptic  solution 
applied  with  a  hose  or  splashed  on  all  surfaces  by  means  of  mops. 
The  floors,  corners,  and  stalls  must  be  saturated  with  the  solution.  On 
account  of  the  presence  of  so  much  albuminous  matter  carbolic  acid  or 
one  of  its  derivatives  is  preferred  for  this  purpose  to  sublimate  solutions. 
Now  scrape  out  the  debris  from  all  the  cracks  in  the  floors  and  walls; 
collect  it  for  burning.  Then  clean  the  woodwork  with  hot  lye  or  a 
strong  alkaline  soap  solution  and  follow  with  another  general  hosing 
with  the  antiseptic  liquid. 

After  several  days'  exposure  to  air  and  sunshine  the  interior  of 
the  stable  should  receive  a  fresh  coat  of  whitewash,  applied  quickly,  and 
prepared  from  freshly  burnt  lime. 

The  watering  troughs  are  very  apt  to  be  infected,  especially  in 
dealing  with  glanders.  In  all  instances  not  only  the  troughs  and 
watering  buckets  should  be  disinfected,  but  the  water  remaining  in 
them,  for  often  there  is  no  drain  or  sewer,  and  this  water  poured  on 
the  ground  may  be  a  source  of  subsequent  infection.  The  water  may 
first  be  disinfected  by  the  addition  of  a  suitable  amount  of  chlorinated 
lime  or  any  of  the  standard  germicides.  The  troughs  are  then  to  be 
mechanically  cleaned,  thoroughly  removing  all  organic  matter,  and  then 
applying  a  strong  germicidal  solution  to  both  the  inside  and  outside. 
For  metal-linod  troughs  the  use  of  bichlorid  of  mercury  is.  of  course, 
inapplicable,  and  for  such  carbolic  acid,  trikresol,  formalin,  or  potassium 
permanganate  is  recommended.  Most  germicides  are  poisonous,  and 
must  therefore  be  finally  washed  out  of  the  trough  or  buckets  by  flush- 
ing with  fresh  water  and  then  airing  in  the  sunlight  before  they  are 
again  used.  A  strong  carbolic,  formalin,  or  chlorinated  lime  solution 
should  be  poured  down  all  pipes  and  drains. 

Sometimes  the  ground  in  the  immediate  vicinity  of  the  stable  will 
need  attention.  Lime  will  generally  be  found  most  useful  for  this 
purpose.  Carcasses  and  excreta  are  to  be  disinfected  and  disposed  of 
according  to  the  methods  given  under  these  titles.  • 

Railroad  Cars. — Railroad  cars  are  rooms  on  wheels.  The  principles 
of  their  disinfection  present  nothing  novel,  but  the  application  presents 
practical  difficulties. 

Flat  cars  or  open  cars  seldom  need  disinfection,  for,  even  should 
they  become  infected,  the  exposure  to  the  sun  and  water  is  sufficient  to 
render  them  safe  from  the  danger  of  conveying  disease.  They  may 
readily  be  disinfected  whenever  that  may  be  necessary  by  scrubbing  or 
flushing  them  with  carbolic  acid  or  bichlorid  of  mercury  solutions. 

Freight  cars  or  box  cars  seldom  need  disinfection.  They  sometimes 
require  fumigation  on  account  of  mosquitoes,  fleas,  or  rats  and  mice. 


EAILEOAD    CARS  1029 

wliich  such  cars  may  carry.  Freight  cars  are  best  treated  for  this  pur- 
pose with  sulphur  dioxid.  lu  actual  practice  it  will  sometimes  be  found 
useful  to  steam  them  with  steam  from  the  locomotive. 

Cattle  cars  and  cars  used  to  transport  live  stock  need  special  atten- 
tion, particularly  if  anthrax,  tetanus,  glanders,  foot-and-mouth  disease, 
or  tuberculosis  is  the  infection  with  which  they  are  contaminated.  The 
disinfection  of  cars  of  this  type  is  so  much  like  the  disinfection  of  a 
stable  that  it  is  unnecessary  to  repeat  the  description  here.  Cars  of  this 
type,  as  well  as  all  cars,  should  be  kept  scrupulously  and  constantly 
clean. 

Day  Coaches  and  Parlor  Cars. — If  the  disinfection  is  done  as  a 
precautionary  measure  it  is  sufficient  to  fill  the  coach  with  formaldehyd 
gas,  which  should  be  followed  by  a  thorough  mechanical  cleansing. 
The  carpets  and  rugs  and  all  similar  articles,  including  the  upholstered 
seats  and  backrests,  if  removable,  should  be  taken  from  the  car  for 
vacuum  treatment  and  then  exposed  several  hours  to  the  sunshine.  The 
floors  should  be  mopped  or  scrubbed  with  one  of  the  germicidal  solutions 
and  the  spittoons  should  be  well  rinsed  in  a  warm  carbolic  bath  and  the 
contents  disposed  of  in  one  of  the  ways  mentioned  under  the  heading 
Sputum. 

If  the  disinfection  is  done  on  account  of  known  contamination  with 
one  of  the  communicable  diseases  the  car  is  treated  exactly  as  a  room 
would  be  under  like  conditions. 

A  railroad  coach  is  likely  to  harbor  mosquitoes,  flies,  and  other 
insect  pests  that  may  carry  disease;  therefore  precautions  will  have  to 
be  taken  to  keep  these  insects  off  cars  leaving  districts  infected  with 
yellow  fever,  typhus  fever,  malaria,  plague,  etc.,  or  measures  will  have 
to  be  taken  to  destroy  them  after  they  get  on  board.  As  both  these 
requirements  are  difficult,  if  not  impracticable,  it  will  usually  be  found 
best  to  provide  relays  at  a  convenient  point  and  require  the  passengers 
to  change  cars  upon  leaving  an  infected  for  an  infectible  area. 

Sleeping  cars  present  a  greater  difficulty  than  any  other  rolling 
stock.  The  berths  are  apt  to  become  infected  and  the  infective  agent  may 
live  there  a  very  long  time,  especially  as  they  are  kept  closed — almost 
hermetically  sealed,  against  fresh  air  and  sunshine  during  the  daytime. 
Much  of  the  difficulty  encountered  in  the  disinfection  of  the  sleeping  car 
.is  due  to  peculiarities  in  construction,  such  as  the  compact  manner  in 
which  the  bedding  is  stowed  away,  the  heavy  and  unnecessary  carpets 
and  hangings,  the  excessive  molding  and  ornamentation  of  the  older 
type  of  cars,  the  use  of  such  materials  as  plush  for  upholstering,  etc. 
The  wash  basins  and  other  objects  in  the  toilet-rooms  are  liable  to  con- 
tamination with  infected  discharges  from  the  mouth  and  nose.  The 
faucets  should  be  so  arranged  as  to  permit  washing  with  running  water, 
thus  eliminating  danger  from  the  bowl. 
67 


1030  METHODS    OF    DISINFECTION 

Before  attempting  to  disinfect  the  interior  of  a  sleeping  car  or  a 
passenger  coach  with  one  of  the  disinfectants  it  is  important  to  close  the 
sashes  and  all  the  ventilator  openings  for  the  Pintsch  gas  flames.  Much 
gas  will  be  lost  through  the  open  hopper  of  the  water-closet  unless  that  is 
tamponed.  Some  cars  have  a  system  of  ventilating  ducts  of  fresh  air 
entering  under  the  seat  or  somewhere  near  the  bottom  of  the  car.  This 
must  be  closed.  Formaldehyd  gas  and  hydrocyanic  acid  gas  are  practi- 
cally the  only  gases  which  may  be  used  for  the  treatment  of  the  sleeping 
car.  As  these  gases  lack  the  power  of  penetration,  all  the  berths  must  be 
opened  and  all  the  bedding  and  other  fabrics  should  be  removed  for 
steaming  or  other  treatment.  Hydrocyanic  acid  is  especially  serviceable 
for  the  destruction  of  bedbugs  and  vermin  which  frequently  infest  sleep- 
ing cars. 

After  the  bedding,  hangings,  carpets,  and  other  fabrics  have  been 
removed  from  the  car  the  toilet-room  should  be  given  special  attention. 
The  drinking  glasses,  the  wash  basins  and  slabs  of  the  washstands,  the 
brushes  and  combs,  the  seat  of  the  water-closet,  and  other  objects  liable 
to  infection  should  be  washed  or  immersed  in  one  of  the  standard  germi- 
cidal solutions. 

Feces. — The  disinfection  of  feces  is  most  important  because  these 
discharges  are  most  dangerous  and  at  the  same  time  most  diilficult  to 
render  safe.  Fecal  discharges  may  be  disinfected  with  carbolic  acid, 
cresols,  lime,  chlorinated  lime,  or  formalin.  In  hospitals  the  infected 
discharges  are  sometimes  boiled  in  an  appropriate  vessel  with  the  addi- 
tion of  a  deodorizing  substance,  as  potassium  permanganate. 

From  patients  the  discharges  should  be  received  in  a  glass  or  im- 
pervious vessel  containing  some  of  the  germicidal  sul)stance,  more  of 
which  is  added  afterwards,  and  the  mass  thoroughly  mixed.  The  mix- 
ture should  stand  at  least  one  hour  before  the  contents  are  disposed  of, 
'and  the  vessel  given  a  thorough  cleansing  and  disinfection  before  it  is 
again  used.  At  least  an  equal  quantity  of  the  germicidal  solution  should 
be  used  to  the  mass  disinfected  and  enough  should  always  be  added  to 
entirely  submerge  the  mass.  Excreta  must  always  be  protected  from 
flies  and  other  insects,  even  while  undergoing  disinfection. 

Milk  of  Lime. — Use  freshly  prepared  milk  of  lime  containing  1  part 
by  weight  of  the  freshly  slaked  lime  to  4  parts  of  water.  Add  at  least  an 
equal  quantity  to  the  amount  of  material  to  be  disinfected  and  allow  the 
mixture  to  stand  no  less  than  two  hours  before  final  disposal.  The 
perfunctory  sprinkling  of  fecal  matter  with  lime  or  milk  of  lime,  as  is 
often  done,  is  not  effective.  Lime  should  not  be  thrown  into  the 
hoppers  of  water-closets  for  the  disinfection  of  dejecta,  for  otherwise 
a  thick  mass  will  accumulate  and  obstruct  the  pipes.  In  disinfecting 
excreta  with  lime  the  reaction  of  the  resulting  mixture  must  be  alkaline 
else  the  object  will  not  be  attained. 


SPUTUM  1031 

Lime  or  milk  of  lime  is  very  useful  for  the  disinfection  of  privies^, 
or  trenches  in  camp,  or  in  country  practice.  For  its  use  under  these 
circumstances  the  amount  required  may  be  arrived  at  as  follows :  The 
amount  of  fecal  matter  per  person  is  reckoned  at  400  grams  a  day.  If 
the  urine  is  also  to  be  disinfected  this  may  be  counted  as  1^500  to  3,000 
c.  c.  per  person  daily.  For  the  disinfection  of  the  solid  excrement  alone 
5  grams  of  lime,  or  40  c.  c.  of  the  milk  of  lime  (1  to  8),  must  be 
reckoned  for  each  person  per  day.  If  the  urine  is  included  it  will  take 
four  to  five  times  as  much.  The  mixture  must  have  an  alkaline  reaction. 
Attention  is  again  called  to  the  fact  that  air  slaked  lime  is  inert. 

Chlorinated  Lime. — This  is  one  of  the  most  useful  and  potent 
germicidal  substances  for  the  disinfection  of  feces.  L'se  at  least  a  3 
per  cent,  solution  and  an  amount  equal  to  the  mass  to  be  disinfected. 
Thoroughly  mix  and  allow  to  stand  at  least  2  hours.  Chlorinated  lime 
combined  with  air  is  rendered  inert  by  organic  matter;  therefore  an 
excess  should  always  be  used. 

Formalin. — A  10  per  cent,  solution  of  formalin  may  be  depended 
upon  to  disinfect  feces  if  thoroughly  incorporated  with  the  mass  and 
allowed  to  stand  at  least  one  hour.  As  a  deodorant  it  acts  almost  in- 
stantly. 

Carbolic  Acid. — A  5  per  cent,  solution  of  crude  carbolic  acid  added 
to  an  equal  bulk  of  excreta  may  be  depended  upon  to  disinfect  in  one  to 
two  hours,  provided  the  germicide  is  thoroughly  incorporated  through- 
out the  mass. 

The  cresols  and  the  alkaline  coal-tar  creosotes  are  valuable  agents  for 
the  disinfection  of  fecal  matter  in  small  amounts  on  account  of  their 
energetic  action  and  because  their  efficiency  is  not  greatly  impaired  by 
the  presence  of  albuminous  matter.  As  a  rule  substances  in  emulsion 
lack  the  power  of  penetration,  and  if  used  must  be  very  thoroughly" 
mixed  and  incorporated  with  the  mass. 

Dry  earth  promotes  the  disinfection  of  excreta,  thus  delaying  putre- 
factive changes  while  absorbing  the  odors.  It  has  no  inherent  germicidal 
qualities.  Corrosive  sublimate  is  unfit  for  the  disinfection  of  feces  and 
sputum.  The  discharges  from  the  mouth  and  nose,  not  alone  of  the 
sick,  but  of  well  persons,  are  often  laden  with  infection.  This  is  one. of 
the  frequent  means  by  which  disease  is  transferred.  The  proper  disposal 
of  sputum  and  its  efficient  disinfection  are  therefore  an  important  public 
health  measure  to  check  the  spread  of  tuberculosis,  diphtheria,  scarlet 
fever,  measles,  whooping-cough,  infiuenza,  tonsillitis,  common  colds, 
pneumonia,  the  pneumonic  form  of  plague,  etc.  It  is  a  good  rule  to 
require  the  discharges  from  the  mouth  and  nose  of  all  hospital  patients 
to  be  received  upon  small  pieces  of  gauze  or  in  individual  cups  which 
may  subsequently  be  burned. 

Sputum. — The  most  trustworthy  chemical  disinfectants  for  sputum 


1032  METHODS    OF   DISINFECTION 

are  carbolic  acid,  5  per  cent;  formalin,  10  per  cent,  or  stronger;  chlor- 
inated lime,  3  per  cent. 

Sputum  should  be  kept  well  covered  in  suit{il)le  receptacles  until  it 
is  disposed  of.  Simply  keeping  water  in  the  bedside  cups  or  in  cuspidors 
will  prevent  whatever  slight  danger  exists  in  the  dissemination  of  in- 
fection from  such  sources.  Antiseptic  solutions  may  be  used  for  this 
purpose,  but  are  not  necessary. 

The  disinfection  of  the  large  amounts  of  sputum  such  as  that  col- 
lected in  hospitals,  public  buildings,  and  other  places  is  a  difficult  and 
disagreeable  task.  On  account  of  its  dense  consistency  it  prevents  the 
penetration  of  chemical  solutions.  A  very  good  apparatus  for  the  disin- 
fection and  disposal  of  sputum  in  hospitals,  sanatoria,  etc.,  consists  of 
an  autoclave  in  which  the  material  is  steamed  under  pressure  and  at 
a  temperature  of  120°  C;  after  the  completion  of  the  process  the  disin- 
fected mass  is  washed  through  the  drain  into  the  sewer  by  water  entering 
the  autoclave.  The  entire  operation  can  thus  be  conducted  under  cover. 
Dr.  Wm.  J.  Manning^  describes  an  ingenious  and  efficient  method  of 
handling  spittoons  and  disposing  of  the  sputum  at  the  Government  Print- 
ing Office  in  Washington.  The  cuspidors  are  self-draining.  They  are 
collected  and  handled  by  devices  so  that  the  attendants  do  not  have  to 
handle  them  directly. 

Bed  and  Body  Linen. — Fabrics,  such  as  towels,  napkins,  handker- 
chiefs, sheets,  pillowslips,  and  similar  articles,  should  always  be  disin- 
fected after  contact  with  any  of  the  communicable  diseases,  for  they  are 
very^  apt  to  become  infected.  They  may  be  steamed  or  boiled  or  im- 
mersed in  a  germicidal  solution  such  as  carbolic  acid,  5  per  cent. ; 
formalin,  10  per  cent. ;  or  bichlorid  of  mercury,  1  to  1,000. 

Special  care  is  necessary  in  washing  or  disinfecting  towels,  sheets, 
underwear,  and  other  fabrics  soiled  with  such  discharges  as  pus,  blood, 
or  excreta.  If  they  are  heated  or  boiled  without  special  precautions  they 
will  become  indelibly  stained  by  the  coagulation  of  the  albuminous  mat- 
ter which  becomes  fixed  in  the  fiber. 

Soiled  wash  may  be  treated  as  follows :  It  is  wrapped  in  a  sheet  wet 
with  sublimate  solution,  and  this  placed  in  a  sack  likewise  moistened 
with  a  germicidal  liquid.  The  sack  is  placed  unopened  in  a  solution 
containing  3  per  cent,  of  soft  soap  and  heated  to  50°  C.  for  three  hours 
and  left  in  the  same  solution  forty-eight  hours  after  it  cools.  If  not 
soiled  with  albuminous  matter  the  wash  may  be  immersed  in  a  solution 
of  bichlorid  of  mercury  1  to  1.000.  with  the  addition  of  common  salt. 
After  this  preliminary  disinfection  the  articles  are  boiled  half  an  hour 
in  a  water  containing : 

•J.  A.  M.  A.,  Sept.  11,  1909,  Vol.  LIT,  pp.  829-832. 


BOOKS  1033 

Petroleum 10  grams 

Soft  soap   250       " 

Water   30  liters 

Books. — With  the  exceiDtion  of  their  external  surface,  books  cannot 
be  disinfected  in  the  bookcase  or  on  the  shelves  of  houses  and  libraries. 
However,  if  the  books  have  not  been  handled  or  exjDosed  to  infection  in 
any  way  except  by  their  presence  in  the  sickroom  there  is  no  reason  for 
considering  any  part  of  the  book,  except  the  exposed  surface,  as  infected. 
Such  books  may  be  disinfected  by  exposing  them  to  formaldehyd  gas 
without  first  disturbing  them  in  any  way. 

Books  which  have  been  handled  by  the  patient  or  which  have  been 
otherwise  exposed  to  infection  require  particular  care  in  their  disinfec- 
tion on  account  of  the  diflBculty  of  penetrating  between  the  leaves.  Books 
used  in  public  libraries  are  often  regarded  with  suspicion,  and  many 
librarians  require  that  they  should  be  sunned,  aired,  or  disinfected  be- 
fore they  are  again  issued.  The  danger  from  this  source  has  doubtless 
been  exaggerated.  Books,  however,  which  have  been  handled  by  persons 
suffering  with  one  of  the  readily  communicable  diseases  should  always 
be  disinfected  before  they  are  again  used. 

Books  may  be  disinfected  in  a  specially  constructed  chamber  by  means 
of  heat  and  formaldehyd  gas.  They  must  be  arranged  to  stand  as  widely 
open  as  possible  upon  perforated  wire  trays.  Under  these  conditions  the 
exposure  should  be  continued  twelve  hours  with  high  percentages  of  for- 
maldehyd and  a  temperature  of  80°  C,  a  partial  vacuum  having  first 
been  introduced.  The  binding,  illustrations,  and  print  of  books  are  not 
injured  by  this  process. 

When  only  a  few  books  are  to  be  treated  in  the  absence  of  a  special 
apparatus  they  may  be  disinfected  by  placing  2  or  3  drops  of  a  40  per 
cent,  formalin  solution  on  every  second  page,  taking  care  to  distribute 
the  drops  well.  The  book  is  then  laid  in  a  close  box  or  drawer  in  which 
more  formalin  has  been  sprinkled,  and  left  in  a  warm  place  for  not 
less  than  twenty-four  hours. 

Pamphlets  and  unbound  volumes  may  be  steamed  without  serious 
harm.  Steam  is  not  applicable  to  the  disinfection  of  bound  books  on 
account  of  the  glue  and  leather. 

Beebe^  recommends  dipping  the  books  in  a  solution  of  carbolic  acid 
and  gasoline.  After  immersion  the  books  should  be  placed  before  an 
electric  fan,  which  rapidly  drives  off  the  gasoline. 

Nice^  recommends  the  use  of  moist,  hot  air  at  80°  C.  and  30  or 
40  per  cent,  humidity  for  thirty-two  hours  for  the  disinfection  of  books. 
This  is  said  to  destroy  all  non-spore-bearing  bacteria  in  closed  books, 

'^  Jour.  Am.  Public  Health  Assn.,  Vol.  I,  No.  1,  p.  54,  Jan.,  1911. 
V.  A.  M.  A.,  April  20,  1912,  Vol.  LVIII,  No.  16,  p.  1201. 


1034  METHODS    OF    DISINFECTION 

even  tubercle  bacilli  in  thick  layers,  without  injuring  the  most  delicate 
bindinirs. 

Cadavers. — Dead  bodies  may  be  the  cause  of  the  spreading  of  some 
of  the  communicable  diseases.  The  body  without  previous  washing 
should  be  wrapped  in  a  sheet  wet  wnth  a  strong  germicidal  solution,  such 
as  bichlorid  of  mercury,  1  to  500 ;  carbolic  acid,  5  per  cent.,  or  trikresol, 
1  per  cent.,  until  it  is  disposed  of.  Should  it  be  desirable  to  wash  the 
body  it  should  be  done  with  formalin  (10  per  cent.)  or  Labarraque's 
solution,  or  one  of  the  germicidal  solutions  above  mentioned. 

From  a  sanitary  standpoint  bodies  dead  of  one  of  the  communicable 
diseases  are  best  disposed  of  by  burning.  Wlien  cremation  is  not 
practicable  the  body  may  be  surrounded  by  twice  its  weight  of  freshly 
burnt  lime  in  an  hermetically  sealed  coffin  and  buried  at  least  6  feet 
underground.  There  is  much  less  danger  from  the  spread  of  disease 
from  bodies  buried  in  the  ordinary  way  than  is  commonly  supposed. 

Embalming  with  strong  solutions  of  formalin  and  arsenic  that  are 
commonly  used  for  this  purpose  is  effective  in  destroying  all  but  the  sur- 
face infection. 

The  disposal  of  bodies  dead  of  anthrax  is  an  important  and  difficult 
matter  and  has  been  discussed  on  page  285. 

Thermometers. — A  thermometer  may  be  the  source  of  conveying  dis- 
ease from  one  person  to  another,  and  it  behooves  the  physician  to  exercise 
special  care  concerning  its  cleanliness  and  disinfection.  The  best  prac- 
tice is  to  keep  pure  formalin  in  the  thermometer  case  in  which  the  in- 
strument is  kept  constantly  bathed. 

Wells  and  Cisterns. — The  disinfection  of  a  well  may  be  accomplished 
by  the  use  of  freshly  burnt  lime.  About  half  a  barrel  is  thrown  into  the 
well,  stirred  up  with  the  water,  and  the  walls  are  scrubbed  down  with 
the  resulting  milk  of  lime.  The  well  is  then  pumped  out,  cleaned, 
allowed  to  refill,  and  a  second  supply  of  lime  added,  after  which  the  well 
is  allowed  to  stand  twenty-four  hours.  After  a  thorough  stirring  the  so- 
lution is  then  pumped  out  and  the  well  is  allowed  to  refill  and  is  re- 
emptied  until  the  water  is  practically  free  from  lime.  Instead  of  lime 
chlorinated  lime  may  be  used  for  this  purpose,  sufficient  being  added  to 
make  approximately  a  1  per  cent,  solution. 


INDEX 


Abattoir,   543 

Abba,  674 

Abortion,   contagious,   513 

Abortive  eases  of  poliomyelitis,   277 

Absolute   humidity,   606 

Absorption,   soil,   674 

Acapnia,  600 

Acarines,   261 

Accelerated   reaction  in  vaccinia,   15 

Accidents,  to  eyes,  61 

industrial,  914 

relative  to  fatigue,  916 

preventable,  920 
Acetoarsenite  of  copper,  197 
Acharde,  552 
Achorion  schonleinii,  962 
Acid  waters,  732 
Acids,   germicidal,   1021 

mineral,  in  air,  587 
Acidosis,  498 
Acquired  immunity,  343 
Actinomycosis,   550 
Active  immunity,  343 
Acute  carrier,   315 
Adenoids,    956 
Adulteration,   of  food,  465 

of  milk,   509 
Aedes  calopus,  212 
"Aerial"  conveyance  of  yellow 

fever,   217 
Aerogenic  infection,  129 
Agaricus  campester,  573 
Agglutination,   400 

in  cholera,   104 

in  glanders,   282 

in  melitensis,   291 
Agglutinins,  400 
Agramonte,  181,  213,  221 
Air,  582 

amount  of,  required,  654 

bacteria  in,  630 


Air,  GomiDosition  of,  582 

cun-ents  in,  603 

disinfection  of.  1025 

dust   in,    625 

fresh,   641 

humidity  of,   605 

infection  and,  632 

movements  of,   602 

physical   changes  in,   647 

poisonous  gases  in,  635 

pressure   of,   598 

sewer  gas  in,   638 

in  soil,  674 

temperature  of,  603 

vitiated,    642 

by  respiration.   653 
Air  ducts,   659 
Air-borne   diseases,   633 
Air-borne   measles,    157 
Air-lock,    601 
Aitken,   629 
Albinism,  hereditary  transmission  of, 

448 
Albuminoid    ammonia,    739 
Alcohol,   58,    355 

immunity   and,    354 

insanity  and,  301 

pneumonia  and,  170 

sex  hygiene  and,  68 
Alcoholic  fermentation  of  milk,   508 
Alcoholism,    hereditary    transmission 

of,   453 
Alexin,  359 

Algae,  effect  of  copper  sulphate 
upon,  in  water,  800 

in  water,  723 
Allergie,  404 
Allowable    limits    of    impurities    in 

water,  764 
Alsberg,  580 

Altitude,   pressure  of   air   and,  599 
1035 


1036 


INDEX 


Alum,  as  coagulant,  789 

in  water,  799 
Aluminium   sulphate  in   water,   799 
Amanitas,   572 

Amblyomma  americanus,  265 
Amebic  dysentery,  111 
Amitosis,  434 
Ammonia,  in  air,  586 

in  water,  736 
Ammoniacal  vapors  in  air,  638 
Amoss,  278,  410,  646 
Amount  of  infection  in  tuberculosis 

136 
Amylase,   501 
Anabsena,  726 
Anabolism,    676 
Anaphylaxis,   403 

chronic,   405 

local,   406 

tuberculosis  and,   136 
Anchylostoma  duodenale,  115 
Anchylostomiasis.       See     Hookworm 

disease 
Anderson,    70,    133,    136,    152,    154, 
156,   264,  270,  277,  279,  366, 
368,   375,  410, 
Anderson  process,  800 
Andre  jew,  407 
Andrews,   914 
Anemometers,   603 
Angelici,  648 
Anilin  dyes,  466 
Animal  antitoxins,  367 
Animal  parasites,  in  soil,  689 

in  water,  837 
Animals,   lower,   diseases  from,  313 
Ankylostoma   duodenalis,   230 
Annette,  488 
Anopheles,  207,  208 
Anopheles  albipes.  208 
Anopheles  argyrotarsus,  208 
Anopheles  costalis,  208 
Anopheles  maeulipennis,  208 
Anopheles  nigeiTinus,  223 
Anopheles  punctipenis,  209 
Anopheles    quadrimaeulatus.   208 
Anopheles  sinensis,  208 
Ante-mortem  inspection,  548 


Anterior  poliomyelitis,  275 
Anthracosis,  627 
Anthrax,  285,  943 

flies  and,  224 

meat  and,  550 

soil  and,  686 
Antifonnin,  138,   1020 
Antiseptics,  966 
Antitoxic  immunity,  360 
Antitoxin,  358,  365 

botulismus,   560 

diphtheria,  149,  151 

preparation  of,  369 
Aphthous  fever,  286 
Appert,   481 

Apples,   evaporated,   478 
Aqua  chlorini  in  ophthalmia 

neonatoinim,   64 
Aquaphones,    696 
Aqueous  vapor,   605 
Aragao,  236 

Arctomys-bobac,  241,  253 
Argas   persicus,   267 
Argon,  585 
Argyrol,  64 
Arms,  147,  282 
Aniold  steam  sterilizer,  983 
Arrhenius,   371 
Arsenate  of  lead,  198 
Arsenic,  197,  250,  490 

industrial  hygiene  and,  934 

in  wall  paper,  furs,  etc.,  934 
Arsenical   dip,   262 
Arsenite  of  copper,  197 
Arsenite   of  lead,    198 
Arsenite  of  lime,  199 
Artesian  well,   712 
Arthus'  phenomenon,  406 
Artificial    ventilation,   665 
Ascaris  lumbricoides,  688,  837 
Ascoli,    398 
Asepsis,   967 
Ashbum,  221 
Ashford,  117 

Ashland   typhoid   epidemic,  829 
Asiatic   cholera,   101 
Asitia,  463 
Aspergillus  fumigatus,  578 


INDEX 


1037 


Aspiration,   661 

Aspirators,  632 

Association    for    Labor    Legislation, 
914 

Asterionella,   726 

Asthma  and  antitoxin,   153 

Asthmatics,  serum  therapy  for,  411 

Atavism,   432 

Ataxia,  hereditary.     See  Friedreich's 
disease 

Atmospheric  pressure,  598 

Atoxyl,  use  of,  in  sleeping  sickness, 
234 

Atreptie  theory,  539 

Attitude    toward    venereal    prophy- 
laxis, 55 

Atwater,  461 

Authority  in  epidemic  campaign,  319 

Autoclave,  983 

Auto-vaccination,  19 

Auzinger,    535 

Available  chlorin,  797 

Avian  tubercle  bacillus,  124 

Azobaeter,  679 

Babeock,  577 
Babcock   method,  528 
Babes,  43 

Babesia  bigemina,   263 
Bacillai-y  dysenteiy,  111 
Bacilli,  on  blankets,  92 

in  blood,    81 

in  feces,  81 

in  ice,  88 

in  milk,  89 

in  milk  products,  90 

in  nature,   84 

in  urine,  81 

on  vegetables,  91 

in  water,   61,  86,  87 
Baeilluria,  83 
Bacillus : 

B.  abortus,    513 

B.  aeidi   laetici,   507 

B.  aerogenes  capsulatus,   836 

B.  anthracis,  230,  943 

B.  botulinus,  558 

B.  bulgaricus,  507 


Bacillus : 

B.  of   cholera,   103 

B.  cholera    suis,    553 

B.  coli,    759 
in  water,  759 

B.  coli  communis,   559 

B.  eyanogenes,  508 

B.  denitiificans,   679 

B.  diphtheriae,  69 

B.  dysenteriEB,  111 

B.  enteritidis,  253,  552 

B.  lactis  aeidi,  507 

B.  lactis  viseosis,  508 

B.  leprae,  292 

B.  mallei,  281.     See  also   Glan- 
ders 

B.  maydis,  578 

B.  mesenterieus,  836 

B.  paracolon,   553 

B.  paratyphoid,  253 

B.  paratyphosus,  552,  555 
in  flies,  229 

B.  pestis,    69,   255 

B.  proteus,    761 

B.  proteus  vulgaris,  559 

B.  pseudotuberculosis,    553 

B.  psittacosis,  553 

B.  pyocyaneus,  148,   230,  836 

B.  radicieola,    585,   679 

B.  solaniferum,  573 

B.  subtilis,    69 

B.  tuberculosis,  human,  123 
bo^dne,  123 

B.  typhi  murium,  253 

B.  typhosus,    230,    555,    686 
Bacillus   carriers,   348.     See   also 
Carriers 

acute,   349 

in   cholera,   107 

chronic,  349 

in  diphtheria,  146 

in  dj'sentery,   112 

in  pneumonia,  171 

temporary,   349 

in  typhoid,   83 
Bacot,  229 
Bacteria,  in  air,  630 

in  dust,   628 


1038 


INDEX 


Bacteria,  flies  and,  228 

in  milk,  509 
kinds  of,  524 
number  of,  523 

in  sewer  gas,  639 

in  soil,    681 

in  vaccine  virus,  6 

in  water,  kinds  of,  758 
number  of,  755 
Bacterial  rat  viruses,  253 
Bacterial  vaccine,  345 
Baeteriologic    examination    of    milk, 
523 

of  water,  754 
Bacteriolysins,  388 
Bainbridge,  553 
Bait,  poison,  for  rats,  250 
Balardini,   578 
Balast,   332 
Bandi,   256 
Banks,  239 

Barbiero  fever,  187,   236 
Barium   carbonate,   250 
Barometers,  601 
Barreto,   213 
Barros,   213 
Bartel,  133 
Bateson,  427 
Beaumes'  law,  447 
Becker,  492 

Bed  linen,  disinfection  of,  1032 
Bedbugs,  272 
Beebe,   148,   1033 
Beef  extracts,  539 
Beef  juice,  540 
Beef  tapewoiTn,  563 
Behring,  132,  134,  154,  365 
Bellei  test,  536 
Bendick,  108 
Bendig,   54 
Bends,    601 

Benzoate  of  soda,  486 
Benzoic   acid,   486 
Bergenholtz,  275 
Bergey,   645 
Bergmann,   470 
Beri-beri,  574 
Berkefeld  filters,  793 


Bernard,   Claude,  643 

Berry,   193 

Bert,  585,  600,  643 

Besredka,   98 

Betanaphthol,  118 

Beu,    645 

Beyer,   213 

Bezzola,    303 

Bichlorid  of  mercui-y,  1009 

use  of,  in  ophthalmia  neonatorum, 
64 
Biei-'s  method,  348 
Bignami,   208 

Bilibid  prison,  hookwonn  in,  121 
Biliousness,  463 
Bill  of  health,  327 
Billings,    645 

Bimetallic   thermometer,   604 
Binot,    631 

Biological    products,    licensed    estab- 
lishments for,  382 
Biological   transmission,   181 
Biometi-y,    436 
Bircher,  809 
Birdseye,  265 

Births,  registration  of,  879 
Bisulphid   of  carbon,   195 
Bisulphite,   490 
Bites  of  animals,  38 

rat  bites,  246 
Bitter  milk,  508 
Bitzke,  122 
Black,  180 

Black  Hole  of  Calcutta,  642 
Blackboard,   952 
Blanchard,  147,  295 
Bleached  flour,  467,  485 
Bleaching  powder,  1017 

in  water,  797 
Blindness,  preventable,   60 
Bliss,  488 
Blood,  in  immunity,  341 

typhoid   bacilli   in,   81 
Blood  cultures  in  typhoid,  80 
Blood  relationship,  398 
Blood  supply,   348 
Blood  tests,   399 
Blowers,    665 


INDEX 


1039 


"Bob   veal,"   567 

Body  heat,  614 

Bogliolo,  Father,  297 

Boiled  milk,  522 

Boiled    water,    780 

Boiling,   493,    981 

Bolduan,  153,  414 

Bollinger,    568 

Bolton,    69,    375 

Books,   disinfection   of,   1033 

Boophilus  bovis,  263 

Borax,   487 

Bordeanx   mixture,    199 

Bordet,   390 

Bordet-Gengou   phenomenon,    394 

Boric  acid,  487 

in  ophthalmia  neonatorum,  64 
Boston  school  desk,  952 
Bothriocephalus  latus,   563 
Botulismus,   558 
Bovine  tubercle  bacilli,  123 

in  milk,  127,  513 
Bovine   tuberculosis,    in   man,   124 

prevention  of,  142 
Bovine  vaccine  virus,  4 
Bowditch,   617,  949 
Boxwood    dust,    941 
Boycott,  615 

Boylston,  Dr.  Zabdiel,  24 
Brachydaetylism,     hereditary     trans- 
mission of,  451 
Bramwell-Deaue  sterilizer,  984 
Brandeis,  918 
Breath,  expired,  644 
Breaudat,  575 

Breeding  places  of  mosquitoes,  202 
Breeding  rats,  243 
Bretonneau,  153 
Breweries,  CO2  in,  644 
Bridge,  796 
Brieger,   374,   470 
Brill's  disease,  270 
Brinckerhoff,  21,  28,  293,  296 
Brion,   552 

British  PlagTie  Commission,  241 
Broad  irrigation,   856 
Broad  Street  case,  105 


Broad   Street  outbreak  of  cholera, 

815 
Broeck,  295 
Broiling,   492 
Bromin,    1021 
Brown-Sequard,   644 
Bruce,  234,  236,  288 
Bruck,   90 
Brues,  277,  279 
Bruns,  71 
Bryant,   461 
Bubonic  plague,  254 
Buchanan,    143 
Buchner,    359,    389 
Buckwheat  poisoning,  579 
Budd,   620 
Buhach,   192 
Building   materials,   permeability  of, 

662 
Buildings,  rat  proof,  249 
Bujwid,  43 

Burdon-Sanderson,   474 
Burning,    980 

Butchers,  bovine  tuberculosis  in,  128 
Butler  typhoid  epidemic,  832 
Butter  fat,  498 

standards  of,  498,  499 
Beyerinck,  679 
Byssinosis,  627 

Cabot,   41 

Cadaverin,  472 

Cadavers,  disposal  of,  1034 

Cadman,    615 

Caisson  disease,  600 

Calculi  due  to  water,  807 

Calmette,  132 

Calomel  ointment,  use  of,  in 

syphilis,  53 
Calorie,   460,    666 
Camphophenique,    193 
Camphor,  spirits  of,  206 
Can  ice,  839 
Cancer,    hereditary   transmission    of, 

448 
Candling,  569 
Canning,  481 
Cannon,  463 


1040 


INDEX 


Cannus,  359 
Carbolic  acid,  1011 

in   ophthalmia  neonatorum,   64 

in   smallpox,   29,  36 
Carbolic  coefficient,  973 
Carbon   bisulphid,   195 

in  air,  638 
Carbon  cycle,  680 
Carbon  dioxid,  587 

increase  of,   643 

as  an  index  of  \-itiation,  588 

method  for  determining,  590 
Carbon   monoxid,  635 

destruction   of  rats  with,  252 

poisoning  by,  936 
Carbon  tetrachlorid,  196 
Carburetted  hydrogen   in   air,   638 
Carcass,  disposal  of,  286 
Cargo,  332 
Carini,  20,  37 
Camelley,  589,  639 
Carpenter,  221 
Carrasquillo,   295 
CaiTiei-s,  315 

of  meningococcus,   178 
Carroll,   181,  213 
CaiTot  juice,  467 
Carter,  172,  218,  219,  266 
Casein,   495 
Castellans,  233,  236 
Castle,  415,  432 
Castration,   56 
Catabolism,   676 
Catalase,    501 
Catalase  test,  535 
Cataract,  hereditary  transmission  of, 

451 
Catch  basins,  848 
Catchment   areas,  720 
Cather,  59 
CatUn,  148 
Cats,  bites  by,  38 

whooping-cough  in,   166 
Cattani,  43,   228 
Cattle  immunized  with  tubercle 

bacilli,  137 
Causes    of    death,    classification'   of, 
905 


Cauterization  of  wounds,  rabies  and, 

39 
Cavendish,  692 
Cell,   in   heredity,   434 
CelU,  208,  836 

Cellular  theory,  immunity  and,  387 
Centrifugal  cream,  497 
Ceratophyllus  acutus,  239,  254 
Ceratophyllus  faseiatus,  239,  240 
Cerebrospinal  fever,  176 
Certificate  of  death,  standard,  883 
Certified  milk,  504 
Cesspools,  866 
Chalicosis,    627 
Chance,  law  of,  437 
Chancre,  50 
Chancroid,  49,   54 

Channels,    of    entrance   and   exit   in 
typhoid,   80 

of  infection,  314,  316 
Chapin,  93,  145,   157,  158,  634 
Chaussat,   236 
Chauveau,  131,  339 
Cheese,  typhoid  bacilli  in,   90 
Chemical  analysis  of  milk,  527 
Chemical    methods    of    puiifying 

water,  794 
Chemical  precipitation  in  sewage, 

854 
Chemical   preservatives,   483 

of  milk,  509 
Chemical  results,  expression  of,  751 
Chemical  standards  of  milk,  499 
Chemotaxis,  384 
Chicago,  705 

drainage  canal  in,  719 

typhoid  epidemic  in,  834 
Chickenpox,    280 
Children,  work  by,  917 
Chipped  beef,  478 
Chiswell,  Sarah,  24 
Chittenden,  486,  487 
Chlorid  of  Ume,  797,  1017 
Chlorinated  lime,  1017 

as  bleaching  powder,  797 

hookworms  and,  119 

in  water,  797 


INDEX 


1041 


Chlorin,  1004 

in   water,  744 
Chloroform,  hookworms  and,  118 
Chlorophyceae,  754 
Chlorops  leprae,  295 
Chlorops  vomitoria,  295 
Cholera,   Broad   Street    outbreak   of, 
815 

cause  and  contributing  causes  of, 
102 

diagnosis    of,    103 

flies  and,  228 

Hamburg  epidemic  of,  819 

immunity  and  prophylactic  inocu- 
lations in,  108 

modes  of  transmission  of,  104 

prophylaxis  against,  110 

quarantine  in,  109,  323 

soil  and,  687 
Cholera  morbus,  101 
Cholera  nostras,  101 
Cholera  vibrio  in  water,  761 
Cholin,  472 
Chorea,  963 

Huntington's,  hereditary  trans- 
mission of,  454 
Chowning,   265 
Christophers,  274 
Chromosomes,  434 
Chronic  carrier,  315 
Chrysops,  224 
Cimex  lectularius,  272 
Circumcision,  60 
Cisterns,  701 

disinfection  of,  1034 

mosquitoes  in,  204 
Citellus  beecheyi,  241,  254 
Citronella,  206 
Cladothrix  odorifera,  681 
Claims  for  vaccination,  17 
Clams,  565 
Clark,  798 
Class,  439 
Classification,  of  causes  of  death,  905 

of  milk,  504 

of  soils,  671 

of  water,  692 
Claviceps  purpurea,  571 


Clay  in  soil,  671 
Clayton  furnace,  1003 
Cleanliness,  185,  684,  968 

and  hookworms,  120 

of  schools,  956 
Clegg,  293 

Cloak  room  in  schools,  956 
Clostridium  pasteurianus,  679 
Coag-ulant,  789 
Coal  gas,  636 
Coal  mining,  941 
Coal  oil,  196 

for  mosquitoes,   203 
Coal  tar  disinfectants,  1012 
Coal  tar  dyes,   467 
Cobbett,  132 
Coeeulus  indicus,  269 
Cochin-China  diarrhea,  116 
Coefficient,  of  insecticides,  189 

of  variability,  439 
Cohen,  623 

Cohen  and  Appleyard  method,  595 
Cohnheim,  600 
Coit,  504 

Cold,  production  of,  668 
Cold  damp  air,  616 
Cold  foods,  474 
Cold  storage,  475,  476 
Colds,  173 
Collateral    benefits    in    hookworm 

campaign,   121 
Collection  of  garbage,  873 
Colles'  law,  447 

Colon    bacillus,    presumptive    tests 
for,  759 

in  typhoid  group,   553 

in  water,   759 
Colon-typhoid  group,  553 
Color,  of  walls  in  schoolroom,  948 

of  water,   728,   729 
Color-blindness,  hereditary  transmis- 
sion of,  449 

tests  for,   960 
Colored  milk,  508 
Coloring,  of  food,  467 

of  milk,  509 
Comma  bacillus,  102 
Commission,  milk,  505 


1043 


INDEX 


Common  colds,  173 
Communicable  disease,  317 
Compensation,  workmen's,  920 
Complement,  359 

fixation   of,   394 

in  diagnosis  of  glanders,  283 
Complemental  air,  654 
Complications   of  vaccination,  19 
Composition,  of  meats,  538 

of  milk,  495 

of  soil,  672 
Compulsory  vaccination,  22 

death  rates  compai-ed  in,  23 

in  Geraiany,  33 
Condemned  room  in  abattoir,  544 
Condensation  of  water,  777 
Condiments,   486 
Conduction,   666 
Congenital  transmission,  445 
Conn,    91 

Conorhinus  megistus,   187,  236 
Conradi,   94 

Consanguineous  marriage,  444 
Conscience  clause,  23 
Contact,  infection  by,  314 

in  cholera,  106 

in  tuberculosis,  134,  135 

in  typhoid,   92 
Contact  beds,  857 
Contagious    abortion,   513 
Contagious  disease,  317 
Continence,   57 
Control  of  outbreaks,  149.    See  also 

Institutions. 
Convalescents,    release    of,    in    diph- 
theria, 150 

in   typhoid,   100 
Convection,  666 
Cooking,   491 

pots  and  pans  used  in,  492 
Cooling  of  rooms,  668 
Cooper-Hewitt  lamp,  802 
Cooperative  sanitation,  863 
Copper  sulphate,   1021 

in  food,  467 

in  water,  800 
Copperas,  1021 
Corn,  pellagra  and,  579 


Cornet,  129,  130 

Cornutin,   572 

Corrected  death  rates,  901 

CoiTcns,  429 

CoiTodor,   295 

Corrosive  sublimate,  1009.     See  also 

Bichlorid  of  mercury 
Cost  of  disease: 

blindness,  63 

defectives,  418,  420 

industrial  accidents,  914 

typhoid,  75 
Councilman,  21 

Course   of   vaccine  eruption,   11 
Cowls,  661 
Cowpox,   1,   23 

clinical  course  of,  3 

smallpox  and,  unity  of,  21 
Cow's  milk  and  woman's  milk,  503 
Craig,  221 
Cream  containing    typhoid    bacillus, 

90 
Cream  line,  498 
Crede's  method,   63 
Creel,  91 

Crenothrix  kuehniana,  749 
Creolin,  1014 
Creosote,    1013 
Cresols,  1013 
Cretinism,  808 
Croupous     pneumonia.     See     Lobar 

pneumonia 
Crowd  poisoning,  602 
Crude  death  rate,  903 
Cruz,  218 

Ctenocephalus   felis,  239 
Culex  fasciatus,  212 
Culex  fatigans,  221,  223 
Culex  pipiens,   221 

malta  fever  transmitted  by,  289 
Culex  pungens,  295 
Currents,  air,  602 
Currie,  253,  293,  294 
Curtain  window,  954 
Curve,  nonnal  frequency,  437 
Cutting,  581 
CyanophyceaB,  754 
Cyclops  quadricornis,  837 


INDEX 


1043 


Cystieereus  bovis,  563 
Cystieercus  cellulosaB,   248,  562 
Cytase,  359 
Cytolysins,  389 
Cyton^hyetes  variolse,  21 
Cytotoxins,    393 
Czerny,   498 

Dairy  faiTas,  typhoid  on,   76 

Daltonism,     hereditary     transmission 
of.     See   Color-blindness. 

Damien,   Father,    297 

Damp  cold  air,  616 

Dangers  of  vaccination,  19 

Daniels,  208 

Danysz  vinas,  253 

D'Arsonval,  644 

Darwin,  422 

Danvin's  theory,  425 

Davies,  694 

Day,  148 

Deaf-mutism,     hereditary     transmis- 
sion of,  448 

Dean,  146,  153 

Death,    classification    of    causes    of, 
905 

Death  certificate,  standard,  883 

Death  rates,  crude,  901,  903 

Deaths,   registration  of,  879 

De   Chaumont,   589,    619 

Decomposed  foods,  468 

Decomposition  of  milk,   506 

De  Crocq,  942 

Defective   school   children,   964 

Defectives,  455 

propagation   of,   416 
statistics   of,   418 

Defects,  443 

Definitive  host,  181 

Defoe,    335 

De  Frise,   796 

Degenerate  families,  419 

Degeneration,  stigmata  of,  416 

Degrees  of  hardness,   734 

Dehaan,  575 

Delepine,   513 

Delinquents,   455 

Dembo,   547 


Demography,   888 

Dengue,   220 

Denitiification,  679 

De  Nobele,  552 

Deodorant,    967 

Deodorizers,    955 

Depressed  vitality,   351 

Dermacentor   marginatus,   265 

Dermaeentor  occidentalis,   265 

Dennaeentor  variabilis,  265 

Dermacentor  venustus,   265 

De  Sandro,  353 

Desiccation  of  food,  477 

Desk,  school,  949 

Desmon,   359 

Desquamation  in  scarlet  fever,  161 

Detention,    period    of,    in    maritime 
quarantine,   322 

Determiner  in  heredity,  429,  431 

Deviation  of  complement,  395,  439 

De  Vries,  426,  427,  429 

Dew  point,  determination  of,  606, 
612 

Dewing  apparatus,  596 

Deycke,    297 

Diabetes   mellitus,    hereditary   trans- 
mission of,  452 

Diagnosis,  of  cholera,  103 
of  rabies,   48 
of  tuberculosis,  141,  142 
of  typhoid,  80 

Diaphanometers,    731 

Diarrhea,   infantile,  114 

polluted  water  a  cause  of,  835 

Diastase,   501 

Diatoms,   723,   726 

Diathesis,  445 

Dibothriocephalus  latus,   565 

Diet,    influence    of,    upon    intestinal 
flora,  507 

Diets,  unbalanced,  464 

Dieudonne's  method,  104 

Differential    capacity,    654 

Differential    diag-nosis   betweeen 
smallpox    and   chiekenpox, 
17,  280 

Digestion   tanks,   853 


1044 


INDEX 


Dilution,  disposal  of  sewage  by,  848 

by  water,  779 
Dinobryon,  754 
Diodon,  564 
Dip,  arsenical,  262 
Dipbtheria,   143 

bacillus  carriers  of,  146 

of  conjunctiva,   64 

immunity   from,    149 

due  to  infected  milk,  514 

milk-borne,  146 

post-dipbtheritic    paralysis   follow- 
ing, 151 

predisposing  causes  to,  149 

pi'evalence  of,  143 

prevention   of,   149 

resistance  to,  149 

transmission  of,  144 
Diphtberia    antitoxin    as    a    propby- 

lactic,  149,  151 
Diphtberia    bacilli,    from    cows,    146 

in  milk,  146 
Dipbtberitic   paralysis,  151 
Diplococcus,    in    conjunctivitis,    64 

in  meningitis,   176 
Dipping  ticks,  262 
Dips,  sulpbur,  191 
Diptera,    223 
Dipylidium  caninum,  240 
Direct  system   of  beating,   668 
Direct-indirect    system    of    beating, 

668 
Dirt,  683 
Dirt  test,  509 
Dirty  milk,  509 
Discontinuous   evolution,   427 
Disease,    bereditaiy   transmission   of, 
442 

sex-limited,  442 
Diseases,    of    occupation,    911.      See 
also  Industrial  Hygiene 

spread  by  milk,  512 
Disinfecting  chamber,  steam,  984 
Disinfecting  solutions,   formulae  for, 

1023 
Disinfection,   966 

of  air,   1025 

of  books,   1033 


Disinfection,   carbolic,   coefficient   in, 
973 

cleanliness   and,   968 

control  of,  969 

definitions  of,   966 

in  diphtheria,  151 

of  feces,   1030 

gaseous,  992 

liquid,    1006 

methods  of,  1025 

nature's  agencies  of,  967 

physical  agents  of,  979 

of  railroad   cars,   1028 

of  rooms,  1026 

of  sewage,  859 

of  ships,   329 

in  smallpox,  33 

of  stables,   1027 

standardization  of,  971 

symbiosis  and,  968 

tenninal,    970 

in  tuberculosis,  141 

in  typhoid,  98 
Disinfeetor,  969 
Disposal   of  refuse,  870 
Disposition,  tuberculous,  transmitted, 

137 
Distilled   water,    780 
Distribution    of    bookwonn    disease, 

114 
District   sewers,   845 
Divers'  palsy,  600,  601 
Diving  bell,  600 
Doane,  488 

Doane-Buekley  method,  526 
Doen-,  237,  405 
Dogs,  bites  of,  38 

whooping-cough  in,  166 
Domesticated  animals,  diseases  from, 

333 
Dominance  in   heredity,   428 
Donovan,  274 
Dorange,  841 
Dorr,  111 

Double  water  supplies,  697 
Dourine,  236 

Dracunculus    medinensis,    837 
Drafts,  175 


INDEX 


1045 


Drainage,  and  malaria,  210 

and  mosquitoes,   203 
Drainage  canal,  705 
Draschfeld,   96 
Dried  antitoxin,  370 
Dried  eggs,  478 
Dried  fruit,  477 
Dried  meat,  477 
Dried  milk,  479 
Drigalski,  112 
Droplet     infection     in     tuberculosis, 

131 
Drugs,  lowered  resistance  due  to  use 
of,   354 

in  milk,  503 
Dry  climates,   608 

Dry  earth,  disinfection  of  feces  pro- 
moted by,  1031 
Dry  earth  system,  844 
Dry  heat,  980 
Dry  heated    air,    666 
Dry  paints,    5 
Dry-wall  sterilizer,  980 
Dry  warm  air,  617 

effects  of,  666 
Drying  of  food,  477 

of  sjDutum,  130 
Dryness,    effect    of,    on    hookworms, 

118 
Ducts,  air,   659 

ventilating,  661 
Dugdale,   420 
Dunbar,   247 
Dupony's  method,  535 
Durgin,  957 
Durham,  552 
Dust,  625 

and  disease,   627 

tubercle  bacilli  in,  130 

typhoid  and,  92 
Dusty  trades,   938 
Dutton,  233,  236,  267 
Duval,  293 
Dyer,  298 
Dyes,  food,  466 
Dysentery,   amebic.   111 

bacillary.  111 

immunity  to,  113 


Dysenteiy,  in  infants,  113 
prophylaxis  against,   113 
transmission  of,  112 
water-borne,   834 

Ears,   school  children's,   961 

Earth,  dry,  disinfection  of  feces  pro- 

•      moted  by,  1031 
Earthenware,   926 
Ecdysis,  116 

Economic  factors  in  insanity,  306 
Economic  importance  of  rats,  248 
Ectoparasites,  183 
Eczema  contagiosa,  286 
Edgar,  64,   65 
Edsall,  924,  942 
Education,  of  defectives,  416 

in  epidemic    campaigns,    321 

in  insanity,    311 

in  prophylaxis  against  hookworm, 
120 

in  tuberculosis,  140 

in  venereal  prophylaxis,  55 
Edwards   family,   422 
Effective  size  of  sand,  784 
Efficiency  of  ventilation,  656 
Eggs,    568 

dried,    478 

idiosyncrasy  to,  cure  of,  570 
Ehrenberg,  626 
Ehrlich,  154,  212,  339,  359,  374,  474 

side  chain  theory  of,  355 
Electric  heating,  668 
Electrical    methods   of   water  purifi- 
cation, 802 
Electricity,   621 

germicidal  action  of,  980 
Ellison's  bricks,   663 
Elmassian,   236 
Elser,  177 
Elster,   622 

Emergency   slaughter,    546 
Emery,  348,  385 
Emmerich,  103,  148 
Empusa  musc«,  225 
Emulsions,  germicidal,  1007 
Endemic,  definition  of  term,  317 
Endemic  diseases,  types  of,  182 


1046 


INDEX 


Endemic  foci,  plague,  257 
Endoparasites,    183 
Endo's  medium  for  diagnosis  of  ty- 
phoid, 81 
Endotoxins,  372,  412 
Enemies  of  rats,  250 
English  filtei-s,  781 
English     Tuberculosis     Commission, 

125 
Entameba  histolytica,   111,  835 
Enteritis,    550 

Enteritis  anaphylactica,   405 
Entomology,  183 
Entomophthoreae,  232 
En\dronment  vs.   heredity,  440 
EnzjTues,  milk,  500 

tests  for,  535 
Epidemic,  317 

control  of  diphtheria,  150 

due  to  contact  infection,  93 

of  insect-borne  diseases,  183 

management  of  plague,  257 

milk-borne,  516 
Epidemic  campaign,  319 
Epidemiology,  of  smallpox.  27 

of  water-borne  typhoid,  87 
Epilepsy,  hereditary  transmission  of, 

453,    963 
Epithelioma  of  fowls,  224 
Epizootic  catarrh,  286 
Erclentz,   602 
Ergotism,  571 
Ermengen,   558 
Esten,  228 

Estivo-autumnal  fever,  207 
Etiology  of  tetanus,  66 
Eucalyptus  oil,  118,  271 
Eugenics,  415,  423 
Evans,  172,  236,  486 
Evaporation  of  food,  477 

of  pei-spiration,   614 

of  water,  777 
Ewald,  809 

Examination,     bacteriological,     of 
water,  754 

microscopic,  of  water,  753 
Examples    of    water    analysis,    765 
Excesses,  354 


Exhaustion  theory,  339 

Expansion  of  air,  604 

Expired  air,  583 

Expired  breath,  poisons  in,  644 

Exposure  to  wet  and  cold,  351 

Expression  of  chemical  results,  751 

Extermination  of  insects,  184 

External   ventilation,  661 

Extrinsic   period   of  incubation,   212 

Eyes,  school  children's,  959 

Eykman,  575 

Fabrics,  disinfection  of,  1032 

Factor  of  safety  in  tuberculosis,  135 

Factory  inspection,  919 

Falcioni,    71 

Falkao,  296 

Families,   degenerate,  419 

Family,  Zero,  420 

Family  disease,  tuberculosis,  135 

Famine  a  cause  of  pestilence,  353, 

463 
Famine  fever,  266 
Farcy,   281 
Farr's  law,  168 
Fasting,  463 

Fat  globules,  size  of,  in  milk,  497 
Fatigue,  353,   916 

in  school  children,  946 
Fats,  breaking  up  of,  680 

decomposition  of,  472 

digestive  troubles  due  to,  in  in- 
fants,   498 

in  milk,  497 

determination   of,  528 
Faust,  471 
Favis,  962 
Fear,  321 
Feces,  disinfection  of,  1030 

typhoid  bacilli  in,  81 
Feeding,    sensitization    by,    408 
Fehling's  solution,   531 
Ferenbaugh,  288 
Ferment  antitoxins,  368 
Fermentation,  469 
Ferments,  milk,  500 
FeiTau,  42,  43,  108 
Ferrous  sulphate.   1021 


INDEX 


1047 


Fertility  and  industrial  occupations, 

919 
Filaria  banerofti,  222 
Filaria  diuma,   222 
Filaria  loa,  222 
Filaria  noeturna,  222 
Filaria  perstans,  222 
Filariasis,   222 
File  cutting,  927 

Filial  regression,  Galton's  law,  433 
Filter  galleries,  710 
Filters,  781 

household,  792 

mechanical,  788 

percolating,  858 

slow  sand,  781 

sprinkling,  858 

trickling,   858 
Filth  disease,  684 
Filtration,  intermittent  sand,  856 
Finlay,  181,  221 
Fire  places,  666 
Fireless  cookers,  492 
Firth,    97 
Fisch,  375 
Fischer,  553,  556 
Fish,   564 

goiter  in,  809 

leprosy  not  due  to  eating,  294 

mosquitoes  destroyed  by,  203 

poisoning  by,  564 
Fish  tapewonn,   565 
Fish  tuberculosis,    124 
Fishy  odor  in  water,  726 
Fitz  method,  595 
Fixation  of  complement,  394 
Fixative,   359 
Fixed  virus,  41 
Fleas,  237 

pulieides  and,  240 

relation  of  plague  to,  240 

typhus  fever  and,  240 
Flexner,  111,  177,  275 
FKes,  223 

anthrax  and,  224 

bacteria  and,  228 

cholera  and,  107,  228 

formalin  for  destruction  of,  232 


Flies,  Hodge  trap  for,  231 

horse  sickness  (Pferdesterbe)   and, 
224 

leprosy  and,  295 

as    mechanical    carriers    of    infec- 
tion,   226 

relapsing  fever  and,  224 

suppression  of,  230 

tuberculosis   and,  134 

typhoid  fever  and,  91,  229 
Floor  space,   659 

per  pupil,   948 
Flour,  bleached,  467,  485 
Flow  of  streams,  704 
Flowers  of  sulphur,  191 
Flugge,  131,  177,  179,  602,  649 
Fluorescin,    719 
Fluorids,  489 
Fluoroscope,  719 
Flushing  of  sewers,  848 
Fly,  tsetse,  233 
Foci,  endemic,  in  plague,  257 
Fog,  625 
Fomites,  183 

typhoid  transmitted  by,  92 
Food,  fresh  air  and,  461 

immunity  and,  353 

insufficient,   353 
Foods,  458 

adulteration  of,   465 

amount  of,  462 

animal,  494 

beri-beri  and,   574 

"Bob"   veal,   567 

botulism  and,  558 

classification    of,   461 

decomposed,  468 

eggs,   568 

ergotism  and,  571 

fish,  564 

lathyrism   and,    572 

meat,  494 

milk,  538 

mushroom  poisoning  and,  573 

paratyphoid  fever  and,  55 

pellagra  and,  577 

plant,   571 

potato  poisoning  and,  573 


1048 


INDEX 


Foods,   preparation   of,  491 

preservation  of,  473 

shellflsh,  565 
uses  of,   460 
Foot-and-mouth  disease,  286,  516 

and  vaccine  virus,  20 
Foot  pound,  460 
Fore  milk,    497 

Foreign  inspection  service,  109,  333 
Forests,  rainfall  and,  700 

water  supply  and,  700 
Formaldehyde,      food      preservative, 
488 

insecticide,  191 
Formaldehyde  gas,  993 
Formalin,  993,  1014 

for  destruction  of  flies,  191,  232 
Formalin-lime   method,   997 
Formalin  permanganate  method,  996 
Formula  for  bait  for  rats,  251 

of  De  Chaumont,  655 
Formulae  for  arsenical  dip,   262 

for  disinfecting  solution,  1023 
Fornell,  1020 
Foster,  154,  488,  584 
I'owls,  epithelioma  of,  224 
Fraenkel,  132,  166 
Fragilatis  ossium,  932 
Francione,  409 
Francis,  193,  213 
Frankland,   639 
Franklin  stoves,  667 
Franz,  237 
Frapolli,  578 
Fraser,  575 
Free  anmionia,  736 
Freeman's   pasteurizer,  520 
Freezing,  474 

effect  of,  on  hookworms,  118 

machines  for,  669 
Freibank,  482 
Freibank  system,  545 
Frequency,  normal  curve  of,  437 
Fresh  air,   641 

food  and,  461 

in  schools,  947 
Friedberger,  153 
Friedemann,   398 


Friedreich's  disease,  455 
Frisch,   474 
Fritted  glaze,  926 
Froesch,  287 
Frost,  277,  279,  402 
Fruits,  dried,  478 

typhoid  and,  91 
Frying,  493 
Fuel  value,  460 
Fugo-pyrismus,  579 
Fugu,  564 
Fumigation,  for  destruction  of  rats, 

252.     See  also   Insecticides. 
Fungi  plant,  destruction  of,  198 
Fungicides,  198 
Furnaces,  hot-air,   667 

effect  of,  666 
Furs,  arsenic  in,  934 
Furst,  178 

Gaertner,  253 
Gage,  797,  798 
Galactase,   500 
Galactose,  507 
Gall  sickness,  236 
Galleries,  filter,  710 
Galli-Valerio,   230 
Galliotti,   256 
Gallon,  grains  per,  752 
Galton,   422,   423 

law  of  filial  regression,  433 
Garbage,   873 
Gardner,   118 
Gartner,  552 
Gas,   illuminating,   636 
Gas  heaters,  667 
Gas  pipes,  638 
Gaseous  disinfectants,  992 
Gases,  poisonous,  in  air,  635 
Gasoline,  118 
Gastritis,  550 
Gastrotoxin,  393 
Gay,  414 
General   debility,   351 

immunity  and,  347 

paresis  and,  300 
Generalized   vaccination,    19 
Gengou,  394 


INDEX 


1049 


Gentry,    288 

Geodesy,   671 

Gerber,  296 

Gerhard,   796 

German  Plague  Commission,  256 

German     Tuberculosis     Commission, 
125 

Germicidal  property  of  milk,  511 

Germicides,  967 

Ghon,  129 

Gibson's  method,  370 

Gillette,    409 

Glaisher's  hygrometric  tables,  606 

Glanders,  281 
bacillus  of,  isolation  of,   281,  283 

Glaze,   926 

Gley,  359 

Glossina  palpalis,  233 

Gluttony,  463 

Glycerinated  vaccine  virus,  5 

GlycocoU,  486 

Gnats,  235 

Goats,  Malta  fever  and,  289 

Goddard,  421 

Goiter,  807 

Goldberger,  154,  156,  194,  213,  264, 

270 
Goldmark,  918 
Gonorrhea,   49,  53 

and  eyes  of  new-bom,  61 
Goodhue,  295 
Gorgas,  218 

Gosio's  reaction  for  corn,  580 
Gotchlich,  104 

Gout,  hereditary  transmission  of,  451 
Government  control  of  vaccine  virus, 

21 
Graham,  221 

Graham-Smith,  146,  153,  230 
Grancher,   157,  634 
Grassi,  181,  208 

Grave-yards,  bacteria  of  soil  in,  682 
Gravity  circulation,  661 
Gravity  cream,  497 
Gray,  577 
Great  Lakes,  705 
Green  vaccine  virus,  6 
Green   vitriol,   1021 


Grieber,  178 

Grit  chambers,  sewage,  852 

Ground   itch,   117 

Ground  water,   675,  708 

Grove,  492 

Gruber,  390,  1019 

Gruber  reaction,  400 

Guaiac  test,  536 

Guernsey  cows,  fat  in  milk  of,  497 

Guinea  worm,  837 

Guiteras,  213,  221 

Gumma,  51 

Gunn,   115 

Gunning  modification,  532 

Gutierrez,   117 

Haab,  64 

Hsematobia,  224 

Hsematopinus  spinulosus,  236 

Hafekine,   108 

Haffliine's  prophylactic,  256 

Hair  hygrometer,  612 

Haldane,  645 

Haldane's  apparatus,  CO2,  591 

Haldane's  method,  591 

Halteridum,  208 

Hamburg,  cholera  epidemic  in,  819 

Hamilton,  91,  188,  227,  914 

Hammond,  644 

Hamonic,  52 

Hansen,  292 

Haptophore,   357 

Hardness,    733 

Harrington,   490,   659,   671 

Harris,   45 

Hartsock,  95 

Harwitz,    275 

Hazen,  695 

theorem  of,  804 
Heat,  action  of,  on  food,  491 

efPects  of,  942 

on  milk,  522 

man's  adaptation  to,  604 

stagnation  of,  602,  613 

transfer  of,  614 
Heat  regulating  mechanism,   613 
Heated  milk,  tests  for,  535 
Heaters,  hot  water,  636 


1050 


INDEX 


Heating,   665 

Heiser,  258,  298,  575 

Hektoen,  154,  156 

Heller,  132 

Hematocytozoa,   207 

Hemolysins,  389 

Hemolysis,  392 

Hemolytic   system,  283 

Hemophilia,   hereditary   transmission 

of,  450 
Henrijean,  71 
Henshaw,  265 
Hepatotoxin,  393 
Herdman,  566 
Hereditai-y  ataxia.     See  Friedreich's 

disease. 
Hereditaiy  transmission,  of  albinism, 
448 

of  alcoholism,    453 

of  braehydactylism,  451 

of  cancer,   448 

of  cataract,  451 

of  color-blindness,   or   Daltonism, 
449 

of  deaf-mutism,  448 

of  diabetes  mellitus,  452 

of  disease,  442 

of  epilepsy,  453 

of  Friedreich's  disease,  455 

of  gout,  451 

of  hemophilia,  450 

of  Huntington's  chorea,  454 

in  insects,  262 

through  insects,  182 

of  leprosy,  448 

of  myopia,   451 

of  orthostatic    albuminuria,   453 

of  polydactylism,  451 

of  retinitis  pigmentosa,  451 

of  spirillum,  267 

of  syphilis,  446 

of  a  tendency,  445 

of  tuberculosis,   137,  446 
Heredity,  415 

cell   in,  434 

dominance  in,  428 

vs.  environment,  440 

Galton's  law  of  filial  regression  in, 
433 


Heredity,  insanity  and,  304 
Mendel's  law  of,  428 
normal  frequency  curve  of,  437 
principles  of,  425 
segregation  and,  428 
unit  characters  and,  428 
variation  in,  425 
Weismann's  %dews  on,  427 
Hermans,  644 
Herter,    486 
Hertz,  476 
Heubner,  498 
Heusinger  desk,  951 
Hewlett,  148 
Hexamethylenamin,  80 
Heymann,   602 

Hides,  disinfection  of,  286,  944 
Hill,  586,  602,  648 
Hinckes-Bird  ventilator,  664 
Hinds,  196 
Hippelates,   227 
Hippobosca  rufipes,  236 
Hirsch,  271 

Historical  note  on  diphtheria,  153 
Hodge  fly  trap,  231 
Hoffman,  486 
Hog  cholera  and  meat,  550 
Hogs,  tuberculosis  in,  549 
Holeomb,   59 
Hollmann,  296 
Holman,  293 

Holstein  cows,  fat  in  milk  of,  497 
Holt,  54 

Homalomjaa  canicularis,  228 
Homogenized  milk,  498 
Hookworm  disease,  114 
cleanliness  and,   120 
collateral  benefits  in  campaign 

against,  121 
distribution  of,  114 
education  in,  120 
eradication  of  infection  of,  in 

man,  119 
immunity  in,  118 
parasite  in,  116 

personal  prophylaxis  against,  120 
prevention  of,  119 


INDEX 


1051 


Hookworm  disease,  resistance  to,  118 
soil  pollution  and,  119 
transmission  of,  115 
varieties  of,  115 
Hoplopsyllus  anomalus,  241 
Horner,   166,   449 
Hon'icks,  639 
Horrocks,   290 
Horse  flesh,  test  for,  400 
Horse   sickness    (Pferdesterbe),   flies 

and,  224 
Hospitals  for  insane,  308 
Hot-air  furnaces,  667 
Hot-air  sterilizer,  980 
Hot  water  heaters,  636 
Hot  water   pipes,   668 
Hours  of  woi'k,  916 
House  disease,  tuberculosis  a,  135 
House  flea,  239 

House  fly.     See  Musca  domestica. 
House  sewers,  845 
Household  filters,  792 
Housing       conditions,       tuberculosis 

and,   142 
Houston,   681 
Howard,  224,  227 
Hoyges,  43 
Hubbard,   227 
Hiibener,  554 
Huggard,  608 

Himian  tubercle  bacilli,  123 
Human  vaccine  virus,  4 
Humidity,  605 

and    temperature,    relation    of,    to 

health,  613 
Humoral  theory  of  immunity,  387 
Humus,  671 
Hunger,  463 
Hunt,  472 
Hunter,  389 
Huntington's       chorea,       hereditary 

transmission  of,  454 
Huntoon,  177 
Hutchins,    88,   841 
Hutchinson,    294 
Hydrochloric   acid  in   air,   638 
Hydrocyanic  acid  in  food,  485 


Hydrocyanic  acid  gas,  1004 

as  insecticide,  194 
Hydrogen   perosid,  490 

in  air,  586 
Hydrogen  sulphid,  in  air,  638 

poisoning  by,  937 
Hydrophobia.     See  Rabies. 
Hygiene,  337 

industrial.     See  Industrial  hygiene 

of  sex,  54,  58 
Hygiene  laboratory  scheme  for  Pas- 
teur treatment,  44 
Hygrometers,    610 
Hygrometric  tables,  606 
Hymenolepis  diminuta,  248 
Hypersusceptibility,   403 
Hypochlorites,  1019 


Ice,   837 

disease   due  to,  840 

manufactured,   839 

natural,  838 

properties   of,    840 

typhoid  fever  and,  88 
Ice-box,  475 

Ice-cream,  typhoid  and,  90 
Ichthyotoxismus,    564 
Idiosyncrasies,   413 

to  eggs,  570 
Illuminating  gas,  636 

in  soil,  674 
Illumination,  measure  of,  621 
Imbecility,  455 
Imhoff  tank,  853 
Immediate  reaction  in  vaccinia,  17 
ImmigTation,  hookworms  and,  121 

insanity  and,  307 
Immune  body,  359 
Immunitas  non  sterilans,  348 
Immunity,   337 

acquired,    343 

agglutinins,  400 

anaphylaxis  and,  403 

to  anthrax,  285 

antitoxins  and,  365 

to  cholera,  102 

to   diphtheria,  149 


1052 


INDEX 


Inmuinity  to  dysentery,  113 

endotoxins  and,  372 

to  hookworm,  118 

induced,  to  egg,  570 

to  influenza,    172 

inheritance  and,  440 

latency  and,  350 

to  lei^rosy,   293 

local  and  general,  347 

lowered  resistance  and,  357 

lysins    and,    388 

to  malaria,   209 

to  measles,  155 

mechanism  and  theories  of,  338 

mixed,  343 

natural,  341 

opsonins  and,  388 

to  paratyphoid,  556 

to  phagocytosis,  384 

to  plague,  255 

to  pneumonia,  170 

to  i^oliomyelitis,  277 

precipitins  and,  396 

to  rabies,  46 

to  scarlet  fever,  163 

side  chain  theoiy  of,  355 

to  smallpox,  14 

specificity  and,  346 

to  syphilis,   51 

toxines  and,  360 

to  tuberculosis,  135 

to  whooping-cough,  166 

to  yeUow  fever,  213 
Immimization    with    tubercle    bacilli, 

137 
Impetigo,  963 
Impetigo      contagiosa      complicating 

vaccination,  19 
Impounding  reservoii-s,  705 
Inabo,  166 
Inanition,  463 
Inbreeding,  444 
Incinerating  plants,   872 
Incision,   vaccination  by,   9 
Incubation  period  of  cholera,  102 

of  tetanus,  70 
Index,  of  mortality,  902 

of  xitiation,  COj  and,  588 


Indian    corn,    579 
Indian  Plague  Commission,  241 
Indices  of  successful  vaccination,  11 
Indirect  infection,  315 
Industrial    hygiene    and    diseases    of 
occupation,  911,   921 

arsenic  and,  934 

carbon   monoxid  and,   936 

children  and,  917 

dusty  trades   and,   938 

factory  inspection  and,  919 

fatigue  and,   916 

file  cutting  and,  927 

fimdameutal  considerations  in  pre- 
vention, 915 

heat,  effects  of,  and,  942 

hours  of  work  and,  916 

hydrogen  sulphid  and,  937 

lead  and,  922 

mercury  and,  935 

mining  and,  941 

parasites  and,  943 

phosphorus  and,  930 

pottery  and  earthenware  and,  926 

preventable  accidents  and,  920 

sedentary  occupations  and,  921 

textile  industries  and,  939 

women  and,  918 

wood  dust  and,  941 
Industrial  insurance,  142 
Infant  mortalitj^,  919 
Infantile   paralysis,   275 
Infants,  dysentery  in,  113 
Infected  water,  692,  717 
Infection  in  air,  632 

carried  by  flies,  226 

sources  of,  313 
Infectious,  definition  of,  317 
Infectious  diseases,  insanity  and,  299 
Influenza,  172 
Ingestion    infection    in    tuberculosis, 

131 
Inheritance,  immunity  and,  440 
Injuries  to  head,  insanity  and,  304 
Inlets,   659 
Inoculation,  23 

Chinese  method  of,  27 

typhoid,  94 


INDEX 


1053 


Inorganic    matter    in    water,    signifi- 
cance of,  807 
Insane,  hospitals  for,  308 
Insanity,   298,  455 

heredity  and,  304 

increase  of,  419 

infectious  diseases  and,  299 
Insects,    hereditary    transmission    in, 

262 
Insect-borne  diseases,  181 

bedbugs  and,   272 

dengue,  220 

filariasis,  222 

fleas  and,  237 

flies  and,  223 

fungicides  and,  198 

general  considerations  in,  181 

insecticides  and,   187 

kala-azar,  274 

leprosy,  295 

lice  and,  268 

malaria,   207 

mosquitoes  and,  200 

pappataci  fever,  237 

plague,  254 

rats  and  fleas  and,  240 

poliomyelitis,   278 

relapsing  fever,   266 

relative  efficiency  and,  188 

Rocky     Mountain     spotted     fever, 
263 

rodents  and,   242 

sleeping  sickness,  232 

South  African  tick  fever,  267 

Texas  fever,  263 

ticks  and,  261 

trypanosomiasis,  236 

typhus  fever,  269 

yellow  fever,  212 
Insecticides,  187 

relative  efficiency  of,  188 
Inspected  milk,  505 
Inspection,   ante-mortem,   548 

meat,   542 

milk,    518 

post-mortem,   548 
Inspection  laws,  meat,  517 
Inspection  service,  foreign,  333 


Inspector,  meat,  545 

medical,  958 
Institutions,  control  of  outbreaks  of 

diphtheria  in,  149 
Insurance,  industrial,  142 

against  syphilis,  52 
Intercepting  sewers,  846 
Intermediate  host,  181 
Intermittent  sand  filtration,  856 
Interpretation     of     water     analysis, 

763 
Interstate  pollution  of  streams,  719 
Interstate  quarantine,  333 
Intestinal  flora,  507 
lodin,  1021 
Iron,  in  water,  749 

purification  of,  800 
Iron  pipes,  750 
Irrigation,  subsurface,  855 

broad,  856 
Isochlors,  744 
Isohemolysins,  396 
Isolation,   334 

in  diphtheria,  150 

in  measles,  158 

in  smallpox,  33 
Itchmite,  191 

Ithaca  typhoid  epidemic,  831 
Ixodiasis,  261 
IxodidsB,  261 

Jackson,  177 

Jacoby,  572 

Jahn,  166 

Jeanselme,   296 

Jellies,  480 

Jenner,  339 

Jerked   beef,   478 

Jersey  cows,  fat  in  milk  of,  497 

Jesty,  1 

Joly,   295 

Jones,   45 

Jordan,  405,  406,  410 

Jorger,   420 

Joseph,  Father,  295 

Joshua  Nicholson,  S.S.,  290 

Jost,  304 


1054 


INDEX 


Joule,   668 
Jukes  family.  420 

Kakke,  574 
Kala-azar,  237,  274 
Kalbnmner,  192 
Kallikak  family,  421 
Kayser,  84 
Keens,  942 
Kefir,  508 
Keller,  498 
Kempner,  559 
Kendall,  507 
Kennedy,  289 
Kenotoxin,  646 
Kerosene,  196 

emulsion  of,  199 
Kerr,   62 

Kilborne,  262,  263 
Kinderblattem,  25 
Kinds  of  bacteria  in  water,  758 
King,  117,  208,  264 
Kinyoun-Francis  chamber,  988 
Ivinyoun-Francis  furnace,  1002 
Kister,  247 

Kitasato,  66,  71,  154,  374 
Kitashima,   365 
Kjeldahl  method,  532 
Klein,  92,  566,  1019 
Kleine,  234 
Klimenco,  166 
Kling,  278 
Knorr,  365 
Kober,   730 
Kobert,  572 
Koch,   94,   124,   129,   208,   211,   266, 

755 
Koch  steamer,  983 
Kocher,  809 

KoUe,  94,  96,  104,  256,  390 
Koniscope,  629 
KorsakoVs  disease,  302 
Kraepelin,  304 
Kraus,  111,  397 
Kronecker,   600 
Kronig,  1008 
Krumwiede,   125,  127 
Kuhn,  285 


Kumyss,   508 
Kurth,   160 

Laban-aque's  solution,  1019 
Laboratories,  Board  of  Health,  151 
Lactalbiunin,  497 
Lactic   acid  fermentation,  506 
Lactodensimeter,  534 
Lactoglobulin,  497 
Laetokinase,  501 
Lactose,  499 

decomposition  of,  507 
Lakes,  704 

Lamblia  duodenalis,  248 
Lansteiner,  160,  275,  277 
Lar^•icide  used  at   Panama,  206 
Latency,  350 
Latent  heat,  840 
Lateral  sewers,  845 
LathiiTism,   572 
Laurans,  296 

Lausen,  typhoid  epidemic,  823 
Lavender,  577 
Laveran,  207,  208,  836 
Lavoisier,  583 
Law,  model  registration,  879 

of   probability,    437 
Lawrence  and  Lowell  typhoid  epi- 
demic, 832 
Laws,  compulsory  vaccination,  22 

meat  inspection,  547 
Lazear,  181,  213 
Leaching  cesspools,  866 
Lead,   in   food,  485 

manufacture  of,  924 

in   occupations,   922 

poisoning  by,  prevention  of,  928 
symptoms  of,  924 

in  water,  751,  810 
Lead  oxid,  924 
Lead  service  pipes,   810 
Leal,  719 
Leblanc,  39,  512 
Lecithin,   472 
Ledbetter,  59 
Lederer,  805 
Ledingham,   274 
Leffmann,  780 


IXDEX 


1055 


Legge,  924 

Legislation      conceiTiing     defectives, 

416 
Lehmaiin,  644,  645 
Leidy,  226,  474 
Leiner,  277 

Leishruan,  94,  96,  267,  274 
Leutz,  556 
Leprolin,  297 
Leprosaria,  297 
Leprosy,  292 

hereditary  transmission   of,  448 

quarantine  in,  326 

rats  and,  248,  293 
Leucocytes  in  milk,  503 
Leukoeidin,  393 
Leukomaines,   469 
Levaditi,  160,  277 
Levy,  71,  84,  154 
Lewin,  932 
Lewis,   236,   275 
Lice,  268,  962 
Lieeaga,  218 

Licensed  establishments,  382 
Liebreieh,  487 

Life  insurance  and  syphilis,  52 
Light,  620 

measure  of,  621 
Lighting  schoolrooms,  £53 
Lime,  1016 

chlorinated,   in  water,  797 
Lime  water,  standard,  591 
Limestone  formation,   715 

ground  water  in,  711 
Linen,  disinfection  of,  1032 
Lipase,  501 

Liquid  sulphur  dioxid,  1001 
Liquor  cresolis  compositus,  1014 
Lister,  633 
Litharge,   924 
Lithium,    to   detect   water   pollution, 

•  719 
Little,  576 
Loam,  671 

Lobar   pneumonia,   168 
Lobeck  tube,  535 
Lobenhoffer,   809 
Local  immunity,   347 


Local     reactions    in    Pasteur    treat- 
ment, 45 
Loeffler,  153,  253,  287 
Loemopsylla    cheopis,    239,    240 
Lombroso,  416,  471,  578 
London  purple,  198 
Londonderiy,   S.   S.,   643 
Long,   486 
Loos,  117 
Lord,  173 
Lorenz,  148 
Lorenz  apparatus,  509 
Low,  208,  223,  274 
Lowe,  188 

Lower  animals,   diseases  from,    313 
Lowered  resistance,   351 
Lubai-sch,  389 
Liibberd,  645 
Lucas,  278 
Lustig,  256 
Luxfer  prisms,  953 
Lymph,  vaccine,  5,  7 
Lymphoid  stage  in  tuberculosis,  133 
Lysins,   388 
Lysol,  1014 

MacFarland,  20 
MacFayden,  289,  474,  837 
Macfie,   621,   627 
Maeroc5d:ase,  387 
Macrogametocytes,  209 
Madsen,   371 
Maggots,   225 
Maize,  579 
Mai  de  Caderas,  236 
Malaria,   207 

immunity  from,  209 

mosquito    and,    208  . 

personal  prophylaxis  against,  210 

prevention  of,  210 

quinine  prophylaxis  against,  211 

relation  of,  to  water,  207 

transmission   of,   207 

and  yellow  fever,  prevention  of, 
contrasted,  220 
Malarial   mosquito,   208 
Malignant  edema,  686 
Malignant  pustule,  285 


105G 


INDEX 


Mallein  test,  282 

Mallory,  153,  160,  166 

Mallory  method  for  uegri  bodies,  48 

Malta  fever,  288,  516 

Mammitis,  550 

Management,  of  case  of  typhoid,  98 
of  ejiidemic   campaign,   319 
of  i)lagiie   campaign,  257 

Maneuver  division,  U.  S.  A.,  treated 
with  typhoid  vaccines,  97 

Mankato  typhoid  epidemic,  831 

Manneberg,  208 

Manning,  669 

Manson,  181,  208,  222,  267,  274 

Manteufe,  267 

Manufactured  ice,  839 

Marchand,  274 

Marchoux,   213 

Margaropus  annulatus,  263 

Marie,  41,  367 

Maritime   quarantine,  322 

Marker,  662 

Market  milk,   505 

Marlatt,  197,  272 

Marimer,  796 

Marmot,  253 

Marriage,  consanguineous,  444 

Martin,    256 

Marx,   42 

Marzari,  578 

Mason,  228 

Massicot,   924 

Matches,  930 

Maternal    transmission    of    anaphy- 
laxis, 408 

Maximum  temperature,  605 

Mayow,  583 

Mayr,  156 

McClintie,  266 

McClintock,   29,   188,   1012 

McCollum,  208 

McCoy,  241,  246,  247,  253 

McCullom,    161 

McLoughlin,   107,   805 

McNeal,   233 

McRae,  228 

Me  Vail,  159 

Meader,  83 


Mean,  438 
Measles,  154 

immunity  to,   155 

prevention  of,  158 

resistance   to,   156 

transmission  of,  156 
Measly  tapeworm,  562 
Meat,   538 

composition   of,   538 

dried,  477 

inspection    of,    542 

inspection  laws  regarding,  547 

inspector  of,  545 

nutritive  value  of,  539 

poisoning  by,   552 

preservatives   of,  541 

reaction  of,  539 

sources  of,  540 

spoiled,   540 

structure  of,  538 

test   for,   400 
Meat  inspection  laws,  547 
Meat  inspector,    545 
Meat  poisoning,    552 
Mechanical     earners     of     infection, 

226 
Mechanical   filters,  788 
Mechanical   transmission,  181 
Mechanical  ventilation,  665 
Mechanism,  heat  regulating,  613 

of  immunity,  338 
Median,    438 

Medical   inspection   of   schools,   956 
Medical  inspectors,  958 
Medical    Milk    Commission,   505 
Medical   prophylaxis   against    ven- 
ereal diseases,  58 
Melier,  218 
Mendel,  429 
Mendel's  law,  428 
Meningitis,   cerebrospinal,   176 
Meningococcus,    176 

carriers  of,  178 
Mental  diseases,  298 
Mental  hygiene,  310 
Mercurial   thermometer,   604 
Mercuric    chlorid,    1009.      See    also 
Bichlorid  of  mercury 


INDEX 


1057 


Mercury,  industrial  poisoning  by,  935 
Merkel,  645 

Metabolism,  protein,  411 
Metehnikofe,  52,  98,  359,  365,  384 
Methods,   of  complement   fixation  in 
glanders,  284 

of  isolating  cholera,  104,  107,  108 

of  isolating  typhoid,  81 

of  slaughter,   546 
Metritis,    550 
Metz,  193 
Meyer,   178,    376 
Miasmatic,  317 
Mice,  242 

Micrococcus   freudenreiehii,   508 
Micrococcus  melitensis,  288 
Microcytase,   387 
Mierogametocytes,    209 
Microscopic    examination,    of    milk, 
525 

of  water,  753 
Migration  of  rats,  244 
Milchner,  376 
Milk,  494 

adulterations   of,   509 

bacteria  in,  509 

bacteriologic  examination  of,  523 

character   of   epidemics   borne   by, 
516 

chemical  analysis  of,  527 

classification  of,  504 

composition   of,   495 

cow's,  and  woman's,  503 

decomposition  of,  506 

dirt  test  for,  509 

diseases  spread  by,  512 

dried,  479 

effects  of  heat   upon,  522 

excretion  of  drugs  in,  503 

ferments  in,   500 

germicidal  property   of,   511 

inspection  of,  518 

leucocytes  in,  502 

of  lime,  1016 

pasteurization  of,  518 

standards  of,  499 
Milk  products,  517 
Milk  sickness,  515 


Milk  standards,    499 
Milk  sugar,   499 

determination  of,  531 
Milk-borne  diseases,  512 

cholera,   106 

diphtheria,   146 

scarlet  fever,  162 

tuberculosis,   127 

typhoid,  75,  89,  90 
Milk-borne   epidemics,    516 
Mills,   248 

Mills-Reincke  phenomenon,   804 
Mim's   eulicide,    193 
Minchim,  234 
Mine   water,   732 
Mineral  acids  in  air,  587 
Miner's    anemia.      See   Hookworm 

disease. 
Minimum  temperature,  605 
Mining,   941 
Miquel,  630,  639,  702 
Misbranding,   407 
Missed   cases,   316 
Mita,  153 
Mitchell,  645 
Mites,  191,  261 
Mitosis,  434 
Mitzmain,  240,  241 
Mixed  immunity,  343 
Miyake,  246 
Moczutkowski,  266 
Mode,  438 

Mode  of  transmission,  of  diphtheria, 
144 

of  foot-and-mouth  disease,  287 

of  hookworm  disease,  115 

of  influenza,  172 

of  leprosy,  294 

of  Malta  fever,  288 

of  measles,  156 

of  pneumonia,  169 

of  poliomyelitis,  277 

of  scarlet  fever,  160 

of  smallpox,  27 

of  tuberculosir,  129 

of  typhoid,  SQ 

of  whooping-cough,  166 

of  yellow  fever,  217 


1058 


INDEX 


Model  registration  law,  879 

Modes  of  transference,  314 

Modified  smallpox,  23 

Mohler,  20,  514 

Moist  ■warm  air,  616 

Moisture,  soil,  675 

Moizard,   157,   034 

Monospora,  386 

Monsoons,   603 

Montagu,  Lady  Mary  "Wortley,  24 

Moore,  296 

Morax,  376 

Mosca    brava,    236.      See    also    Sto- 

moxj's  ealeitrans 
Moser,   165 
Mosquitoes,  200 

breeding  places  of,  202 

desti-uction    of,    202 

life  history  and  habits  of,  200 

screening    as     protection     against, 
205 

suppression  of,  210 

transmission  by,  of  malaria,  207 
of  leprosy,  295 
of  Malta   fever,   289 
of  yellow  fever,  213 
Mosso,  600 

Mountain    sickness,   599 
Mouse,  243 
Mouth  breathing,  961 
Movements  of  air,  602 
Muck,   673 
Mucor  mecedo,  934 
Muddiness  of  water,  729.     See   also 

Turbidity 
Miiller,  45 
Miunps,  168 
Miinch,  266 
Murchison,  684 
Muridae,  242 
Mus,  242 

Mtis  alexandrinus,  243 
Mus  musculus,  243 
Mus  nor\'egicus,  243 
Mus  rattus,  243 
Musca  domestica,  295 
life  historj'  of,  224 
Musca  leprae,   295 


Muscarin,  573 

Muscle,   in    anaphylaxis,   406 

Musgrave,  835 

Mushroom   poisoning,   572 

Mussel  poisoning,  567 

Mussels,  565 

typhoid  bacilli  in,  91 
Mutation,  426 
Muzzling  dogs  as  protection  against 

rabies,   39 
Myopia,   hereditary  transmission  of, 
451 

posture  and,  953 

in  school  children,  960 
Mj^tilus  edulis,  567 

Naegeli,   122,   639 

Nagana,   236 

Nankivell,  148 

Nastin,   297 

National  quarantine,   333 

Natural  ice,   838 

Natural   immimity,   341 

Natural  ventilation,   661 

Nature's  method  of  purifjdng  water 

776 
Necator  americanus,  115 
Negative  phase,  345 

in  typhoid,   96 
Neisser,   396,  400 

Neisser-Wechsberg  phenomenon,  395 
Neech,  161 
Negii  bodies,  48 
Negroes,  hookworm  among,  118 
Nephrotoxin,   393 
Nessler  tubes,  736 
Nesslei-'s  reagent,  737 
Neuman,   133 
Neumann,    213 
Neurasthenia,  964 
Neuronites  hydrophobiae,  48 
Neurotoxin,  393 
Neustaedter,  279 

New  Haven  tj'phoid  epidemic,  829 
Newsholme,  143,  153 
Niagara's  typhoid  rate,  777 
Nice,  1033 
Nicolle.  52,  240,  270 


INDEX 


1059 


Nitrates  in  water,  742 

Nitric  acid  for  dog  bites,  41 

Nitrites  in  water,  741 

Nitrobaeter,  679 

Nitrogen  in  air,  585 

Nitrogen  as  ammonias,  nitrates,  etc., 

736 
Nitrogen  cycle,  676 
Nitrogen  peroxid  in  flour,  467 
Nitrosobacteria,  678 
Nitrosoeoccus,  678 
Nitrosomonas,  678 
Nits,  962 
Nocard,  38 

Non-potable   water,    692 
Normal  chlorin  in  water,  744 
Normal  frequency  curve,  437 
Normal  typhoid,  79 
Nose   and    throat,    school    children's, 

961 
Nosebleed,  961 

Notification  of  tuberculosis,  140 
Nott,  208 

Novy,  233,  267,  488 
Nuisances,  sewage  works  as,  862 

trade  wastes  as,  863 
Number  of  incisions  in  vaccination, 

10 
Nuttall,  153,  242,  295 
Nutritive  value  of  meat,  539 

Obermeier,  266 

Occupational    diseases.       See   Indus- 
trial hygiene 
Odors,  619 

in  water,  723 
CEnothera  lamarckiana,  427 
Offelman,  228 

Ogdensburg,  typhoid  in  ice  at,  88 
Oliver,  627 
Open  fires,   666 
Open-air  schools,  947 
Ophthalmia  neonatorum,  61 

prevalence  of,  62 

prevention  of,  63 

legislation   regarding,   65 
Opsonic  index,  388 
Opsonins,   388 


Organic  impurities  in  water,  806 
Organic    matter,   in   expired    breath, 
646 

in  water,   736 

significance  of,  806 
Organization  of  epidemic  campaign, 

320 
Ornithodoros  moubata,  266 
Ornithodoros  savignyi,  268 
Orthostatic    albuminuria,    hereditary 

transmission  of,  453 
Osborne,  408 
Osgood,  278 
Ostertag,  568 
Otto,  213,  796 
Outbreaks  of  diphtheria,  control  of, 

in  institutions,  149 
Outlets,   659 
Over-heated  air,  666 
Owen,  561 

Oxid  of  iron  in  food,  467 
Oxygen,  absorbed,  746 

in  air,  584 

consumed,   746 

diminution  of,   643 

dissolved,  748 

as  a  germicide,  1005 

method  of  determining,  584 

required,  746 

in  water,  746 
Oxyuris  vermicularis,  837 
Oysters,   565 

fattening,   566 

floating,  566 

laying  out,  566 

and  typhoid,  91 
Ozone,  585,  1005 

in  water,  794 
Ozonizer,  795 

Packard,  224 

Page,   148 

Paltauf,   39 

Panama,  larvicide  used  at,  206 

Pandemic,  317 

Pangonia,  183 

Panpoukis,  45 

Pans,   cooking,  492 


1060 


INDEX 


Panum,   470 

Pappataei  fever,  237 

Parafonn,    993 

Paralysis,  Pasteur  treatment  for,  45 

post-diphtheritic,   151 
Parasites,  animal,  in  watei",  837 

in   diseases  of  occupation,  943 

in  rats,  248 
Paratyphoid  fever,  553,  555 
Paresis,  300 
Paris  green,  197 
Park,   71,   125,    147,   153,   177,   797, 

1023 
Parker,  213 
Parkes,   658 
Parks,  661 
Parthenogenesis,  435 
Passive  immunity,  343 
Pasteur,  41,  285,  339,  631 
Pasteur  institutes,   43 
Pasteur   prophylaxis    against   rabies, 

39 
Pasteur   treatment    for   rabies,    care 
during,  45 

complications  in,  45 

contraindications  to,  46 

results  of,  46 

when  to  give,  47 
Pasteur-Chamberland  filters,  793 
Pasteurization,   518 
Patton,  263 
Paul,  602,  647 
Pearson,  436 
Peat,  673 
Pediculi,  268,   295 
Pediculus  capitis,  268,  962 
Pediculus  corporis,   208 
Pediculus  humanus,  268 
Pediculus  pubis,    268 
Pediculus  vestimenti,  268 
Pellagi'a,  557 

insanity  and,  301 
Penieillium  brevieaule,  934 
Pennyroyal,  206 
Percolating  filters,  858 
Perflation,   661 
Pericarditis,  550 
Peridiuium,  754 


Period    of   incubation,    intrinsic    and 

extrinsic,   212 
Period     of    isolation     in     whooping- 
cough,  167 
Permanent  hardness,  734 
Permanganate  formalin  method,  996 
Permanganate    of    potash    in    water, 

798 
Permeability  of  soil,  673 
Peroxidases,  501 
Persian  insect  powder,  192 
Personal  hygiene,  sex,  58 
Personal    prophylaxis,    against    cere- 
brospinal fever,  179 

against  cholera,  110 

against  diphtheria,  151 

against  dysenteiy,   113 

against  hookworms,    120 

against  malaria,  210 

against  plague,  260 

against  tubei'culosis,   135,   139 

against  typhoid,  100 
Perspiration,  614 
Pestis  minor,  259 
Petit  mal,  963 
Petri,  method  of,   632 
Petroleum,   196 
Petrusehky,  83,  148 
Pettenkofer,  92,  103,  589,  619 
Petterson-Palmquist  method,  593 
Pettersson,  278 

Pfeiffer,  94,  96,  107,  172,  390 
Pfeiffer's  phenomenon,  389 
Phagocytosis,   384 
Phenol,  1011 
Phenol  camphor,    193 
Phenol  coefficient,  977 
Phenolsulphonic  acid  method,  742 
Phlebitis,  550 

Phlebotomus  duboscqi,   235 
Phlebotomus   pappatasii,   221,   237 
Phosphorus,  250,  930 

in  rice,  575 
Phossy  jaw,  931 
Photodynamie  theory,  579 
Phthirius   pubis,   268 
Phthisiophobia,  140 
Physical  changes  in  air,  647 


INDEX 


1061 


Pickling,  479 

Pietet,  474 

Pig-pen  odor  in  water,  726 

Pin  worm,  837 

Pintsch  gas,  rats,  252 

Pipes,  lead  service,  810 

Piroplasma,   263 

Pirquet,  von.     See  von  Pirquet 

Pitometers,    696 

Pittsburgh    and    Allegheny   typhoid 

epidemic,  833 
Place  diseases,  183 
Plague,  254 

bubonic,  254 

endemic  foci  of,  257 

epidemics      of,     management     of 
257 

immunity  to,  255 

pneumonic,   254 

prevention  of,  260 

quarantine  in,  259,   324 

in  rats,  246 

acute  and   chronic,    246 
diagnosis  of,  24 

relation  of,  to  rats  and  fleas,  240 

in  squirrels,  254 
Plant  antitoxins,  368 
Plant  foods,   571 
Plasmodium  malarite,   207 
Plasmodium  falciparum,   207 
Plasmodium  vivax,  207 
Plate  ice,  839 

Platinum  cobalt  standard,   729 
Platinum  wire  method,  731 
Playgrounds,  947 
Plehn,  24,  211 
Plenum  system,  665 
Plett,  1 

Plumbo-solvent   action,   811 
Plumert,    296 

Plymouth  typhoid  epidemic,  827 
Pneumococcus,  168,  169 
Pneumonia.     See  Lobar  pneumonia 
Pneumonic   plague,   254 
Pneumonokoniosis,  627 
Poellmann,  421 

Point  of  election  in  vaccination,  9 
Poisonous  gases  in  air,  635 
69 


Poisons,  for  destruction  of  rats,  250 

endogenous     and     exogenous,     in- 
sanity and,  303 

insanity  and,  301 
Polariscope  method,  531 
Poliomyelitis,   275 
Pollack,  54 
Polluted  water,  692 
Pollution,     interstate,      of     streams, 
719 

of  streams,  848 

of  soil,  682 

of  water,  717 

simple   tests  for,   718 
Polyarthritis,  550 

Polydactylism,    hereditary    transmis- 
sion of,  451 
Ponder,  286 
Ponds,  704 
Poor,  41 
Popper,    275 
Population,  888 

methods  of  estimating,  893 
Pore  volimae,  673 
Pork  tapeworm,  562 
Porosity,    673 
Porto    Rican    Anemia    Commission, 

120 
Post-diphtheritic   paralysis,   151 
Post-mortem  inspection,  548 
Posture,   952 
Pot  method,  999 
Potable  water,   692 
Potassium  nitrate,   489 
Potassium   permanganate,   489,   1015 
Potato  poisoning,  573 
Pothier,  213 
Pots,  cooking,  492 
Potter's  asthma,  927 
Potter's  rot,  627,  927 
Pottery,  926 
Poultry,  drawn,  476 
Powdered  meats,  478 
Prasek,    160 
Precipitation,  chemical,   of  sewage, 

854 
Precipitin  blood  test,  400 
Precipitins,  396 


1062 


INDEX 


Predisposing  causes   of  diphthei-ia, 

149 
Predisposition  to  pneumonia,  170 
Pregnancy  and  work,  918 
Preparation,  of  food,  491 

of  room  for  fumigation,  187 
Preparative,  359 
Prescott-Breed  method,  526 
Presen-atives,  chemical,  483 

meat,   541 
Preserves,  480 
Pressure,  air,  598 
Prevalence,  of  rats,  243 

of  typhoid,   75 

of  smallpox,  25 
Preventable  accidents,   920 
Preventable  blindness,    60 
Prevention,    of    bovine    tuberculosis, 
142 

of  cerebrospinal  fever,   179 

of  cholera,  110 

of  common  colds,  175 

of  diphtheria,  149 

of  glanders,   284 

of  hookworm  disease,  119 

of  insanity,  308 

of  leprosy,  296 

of  malaria,    210 

of  malaria  and  yellow  fever  con- 
trasted, 220 

of  Malta  fever,  291 

of  measles,  158 

of  mental  diseases,   298 

of  pellagra,   580 

of  plague,  260 

of  pneumonia,   170 

of  poliomyelitis,  279 

of  sleeping  sickness,  234 

of  tuberculosis,  138 

of  whooping-cough,  167 

of  yellow  fever,  218 
Preventive  inoculations  for  typhoid, 

94 
Preventoria,  142 
Price.  148,  197,  488 
Pi-iestley,  583 
Primrose,   427 
Privies,  866 


Pri\-ies,  in  the  South,  119 
Pro-agglutiuoid   zone,    291,    401 
Probabilities,  law  of,  437 
Products,  milk,  517 
Proescher,   42,   43 
Profeta's  law,  447 
Propagation,  of  defectives,  416 

of  vaccine  virus,  7 
Prophylactic  inoculations,  108 
Prophylaxis  of  pneumonia,  173 

of  scarlet   fever,   163 

of  tetanus,   72 
Prosodemic,  317 
Prosodemie  typhoid,  80 
Prostatolysin,  393 
Prostitution,  58 
Protargol,   64 
Protein  metabolism,  411 
Proteins,  bacterial,  411 

in  milk,  495,  532 
Pseudomonas  protea,  402,  761 
Psychical  causes  of  insanity,   306 
Psychrometei's,   610 
Ptomaiu  poisoning,  469 
Public  health  day  in  schools,  120 
Pulex,  239 
Pulex  in-itans,  239 
Pules  seiTaticeps,  239 
Pulieides,  239,  240 
Pulp,   vaccine,  5 
Pumpelly,  639 
Puncture,   vaccination  by,   9 
Purification  of  water,  776 
Puscariu,  43 
Putrefaction,  469 
Putrescin,  472 
Putrid  milk,  507 
Pyemic  conditions  in  meat,  550 
Pyocyanase,  148 
Pyrethrum,    192 
Pyrolignic   acid,  481 
Pyrosoma  bigeminum,  263 
Pjrthogenic  theory,   684 

Quantitative  viev^,  436 
Quarantine,  321 

bill  of  health  and,  327 

in  cholera,  109,  323 


INDEX 


1063 


Quarantine,     disinfection     of     ships 
.    in,  329 

equipment  for,  328 

interstate,  333 

in  leprosy,  297,  326 

maritime,   322 

national  vs.  state,  333 

in  plague,  259,  324 

procedures  in,   326 

qualifications   for   quarantine    offi- 
cer,  328 

in  rabies,  39 

in  smallpox,   324 

in  typhus  fever,   326 

in  yellow  fever,  325 
Quartan  fever,  207 
Quartile,  439 

Quevenne   laetodensimeter,   534 
Quick  lime,  1016 
Quinine  prophylaxis  against  malaria, 

211 
Quinine    solution   in   hookworm   dis- 
ease, 119 

Rabies,  36 

diagnosis  of,  48 

entrance  and  exit  of  virus  in,  38 

immunity  to,  46 

Pasteur  treatment  of,  41 

period   of   inoculation  in,   38 

prophylaxis  against,   39 

relative  danger  of  bites  and,  38 

viability  of  virus  in,  39 
Radiation,   666 
Radioactivity,  622 

Railroad  ears,   disinfection   of,    1028 
Rain  water,  698 
Rainfall,  amount  of,  699 
Ramsey,  585 
Rankine,   694 
Ransom,   376 
Rat-bite  disease,  246 
Ratproof  building,  249 
Rate   of  filtration,  785 
Rats,  242 

bites  by,  246 

blacK,  243 

breeding,  243 


Rats,  brown,  243 

domestic  animals  and,  251 

economic  importance  of,  248 

Egyptian,  243 

English,  243 

food  of,  245 

fumigation  for  destruction  of,  252 

habits   of,   245 

house,   243 

keeping  food  from,  249 

leprosy  and,  248,  293 

migration  of,  244 

natural  enemies  of,  250 

in  Norway,  243 

other  parasites   and,   248 

plague  and,  240,  246 

prevalence   of,   243 

poisons  for  destruction  of,  250 

on  roof,  243 

shooting,  251 

suppression  of,  249 

traps  for,  250 

trichinosis   and,   248 

typhoid  and,   248 

on  vessels,  245 
Raubitsehek,   579 
Rauer,   645 
Rauschkiuder,   303 
Ravenel,  132,  148 
Raybaud,  242 
Rayleigh,  585 

Rays,  ultra-violet,  in  water,  801 
Reaction,  accelerated  in  vaccinia,  15 

immediate  in   vaccinia,  17 

of  milk,  533 

to  typhoid  vaccines,  95 

of  water,   731 
Receptor,    356 
Recess,  953 
Red  blood  cells,  influence  of  altitude 

upon,   598 
Red  corpuscles,  598 
Red  lead,  924 
Reductases,   501 

test  for,  535 
Reduction  plants,  872 
Reed,  92,  181,  213,  227 
Referee   Board,   486 


1064 


INDEX 


Refraction,  errors  of,  in  school  chil- 
dren. 960 
Refractonieter,    533 
Refrigeration  temperatures,  475 
Refrigerators,    475 
Refuse  disposal,  870 
Registering  thermometer,   605 
Registration,    of    tuberculosis,    140 

of  venereal  diseases,  57 
Registration  area  in  U.  S.,  876 
Registration  law,  model,  879 
Regnault's  apparatus,   612 
Regulating  mechanism  for  heat,  613 
Relapse,  348 
Relapsing  fever,  266 

flies  and.   224 
Relation   of  humiditj'   and   tempera- 
ture to  health,  613 
Relative  humidity,  606 
Remlinger,    45 
Remsen,  486 
Renovating,  coni,  5S0 
Reserve  air,  653 
Reservoirs,    705 
Residual  air,  653 

typhoid  and,  79 
Resin-lime    mixture,    199 
Resistance  of  the  virus,  338 

of  anthrax,  2S5 

of  diphtheria,   149 

of  dysentery-,  113 

of  hookworm,  118 

of  Malta  fever,  291 

of  measles,  156 

of  pneumonia,  169 

of  poliomyelitis,  277 

of  smallpox,  28 

of  tetanus,  70 

of  tuberculosis,  169 

of  typhoid,  83 
Respiration,    vitiated    air   and,    653 
Respiratoi^'  capacity,  654 
Results,  chemical,  expression  of,  751 
Retaining  room  in  abattoir,  544 
Retention  theory',  339 
Retinitis    pigmentosa,   hereditary 

transmission  of,  451 
Retrovaccination,   7 


Rettger's  method,   632 

Return      cases      in      scarlet     fever, 

161 
Reudiger,  86 
Revaeeination,   14,  15 

in   Germany,  33 
Reversion,  432 
Rice  and  beri-beri,  574 
Richardson,  94,  278,  643 
Richet,  403 
Ricketts,  264,  270 
Rideal-Walker  method,  973 
Rigor  mortis,   539 
Rimpler,   64 

Ringelmann's  chart,  624 
Ringwonn,   962 
Ripe  vaccine  virus,  6 
Risers  in  school  stairs,  948 
Rivers,  450,   702 
Roasting,  492 
Roberts,   1000 

Rocky  Mountain  spotted  fever,  263 
Rodents,    242 
Rodrigues,  213 
Rogei-s,    274 
Rooms,  cooling  of,  668 
disinfection   of,  1026 
preparation  of,  for  disinfection, 

992 
for  fumigation,  187 
size  and  shape  of,  657 
Ropey  milk,  507 
Rosenau,  20,  70,  133,  136,  138,  152, 

213,   253,   277,  278,   279,   292, 

368,   375,   380,   410.   646 
Ross,  181,  207,  208,  213,  836 
Rost,  297 
Rotch,  503 
Rots,   569 
Rouget,    236 
Roughing  filters,  793 
Rous,  38,  52 
Rowan,  73 

Rubner,  460,  614,  616 
Riihm,  534,  536 
Rural   problem   of   sewage   disposal, 

864 
Russ,  237 


INDEX 


1065 


Russell,   94,   97 

Rye  Beach  epidemic,  841 

Saccharin,  466 

Sachs,  359,  400 

Safety  match,   930 

Salicylic  acid,  489 

Salimbeni,  213 

Saliva,  spread  of,  145 

Salmon,  298 

Salting,  479 

Saltpeter,  489 

Salvarsan,    59 

Sambon,   208 

Samplers,  591 

Sanatoria,  treatment  of  tuberculosis 

in,  139 
Sand  filtration,  intermittent,   856 
Sandwith,   118 

Sanitary  analysis  of  water,  722 
Sanitary     inspection,    value     of,     in 

cholera,  109 
Sanitation,   337 
Sarcolactic  acid,  539 
Sarcoptes  scabiei,  191,  295 
Sarcosporidia,  542 
Sausage  poisoning,  558 
Scabies,  962 
Scales  in  measles,  157 
Scarification,    vaccination    by,    9 
Scarlet  fever,  160 

immunity  to,  163 

milk-borne,  162,  514 

modes  of  transmission  of,  160 

prophylaxis  against,  163 

specific  prophylaxis   against,   164 
Schardinger  test,  536 
Schaudinn,   208 
Scheele,  275,  583 
Scheele's  green,  197 
Scheurer,  177 
Schick,  408 
Sehiotz,  148 
Sehittenhelm,  405 
Schlenker,  488 
Schmidt,   64 

Schmidt-Miller  test,  535 
Schmiederberg,  470 


Schmutzdecke,  781 
Schneider,  236,  637 
Scholley,  147 
Schonbein,  585 
School  building  947 
Schoolroom,  948 

color  of  walls  in,  948 
Schools,   945 

cleanliness  of,  956 

cloak  rooms   in,  955 

closing  of,  for  communicable  dis- 
ease, 959 
for  measles,  159 

communicable  diseases  in,  959 

furniture  in,  949 

hookworm  infection  in,  119 

lighting  of,  953 

medical   inspection   of,   956 

posture  of  children  in,  951 

public  health  day   and,   120 

ventilation  and  heating  in,  954 

water  closets  and  urinals  in,  955 
SchottmuUer,  552,  555 
Schroeder,   513 
Schuberg,  285 
Schubert,  283 
Schutz,   283,  405,  406,  410 
Selerotium,  572 
Scott,  148 
Screening,   205 

of  sewage,  852 

of  water,  793 
Scrubbing  filters,  793 
Scurvy,  464 
Scutigera,  232 

Sea  water,  hookworm  in,  119 
Seat,  adjustment  of,  in  schools,  949 
Sedentary   occupations,    921 
Sedgmck,  25,  93,  318,  620,  637,  670, 

698,  805,  837 
Sedgwick-Rafter  method,  754 
Sedimentation,   779 

of  sewage,   852 

of  water,   794 
Seed  vaccine  virus,  7 
Segregation,  of  defectives,  416 

heredity  and,  428 

Mendelism  and,  428 


1066 


INDEX 


Segregation,  in   leprosy,   297 

in  tuberculosis,  139 

in  venereal   diseases,  59 
Self-purification  of  streams,  777 
Selmi,   470 
Seni,  578 
Sensitizer,  359 
Sepsin,  471 

Septic  conditions  in  meat,  550 
Septic  sore  throat,  milk  and,  514 
Septic  tanks,  853 
Septicemic  plague,  254 
Serum  anaphylaxis,  404 

antistreptococcus  and,  165 

disease  and,  152 

sickness  and,  152,  408 
Service,  foreign  inspection,  333 
Sesquisulphid  of  phosphorus,  932 
Settling  tanks  for  sewage,  853 
Seven-day  fever,  266 
SeAvage,  composition  of,  846 

disinfection  of,  859 

disposal  of,  843,  848 

dry-earth  system   of,  844 
water  carriage  system  of,  844 

quantity  of,  846 

relative      efficiency      of      different 
treatments  of,  860 

rural  problems  of,  864 

stream   pollution  by,  848 

streptococci  in,  761 

treatment  of,  851 
Sewage  streptococci,  761 
Sewage      works,      management      of, 

860 
Sewage  systems,  845 
Sewer  gas,   638 
Sewers,   845 

kinds  of,  845 

ventilation   of,   640 

ventilation   and  flushing  of,  848 
Sex-limited   disease,  442 

inheritance  and,  443 
Shakespeare,  92,  227 
Shallow  well,  712 
Shaw,  290,  623 
Shellfish,    656 

typhoid    and,   91 


Shennan,  131 
Sheppard,  278 
Sheringham  valve,  663 
Sheroux,   296 
Shiga,  111,  256 
Ships,   disinfection   of,   329 
Shock,   anaphylactic,   152,  410 
Shooting  rats,  251 
Shuberg,   267 
Shuttles,    941 
Shuttleworth,  756 
Side  chain  theoiy,  355 
Siderosis,    627 

Siemens-Halske  method,  796 
Silica  standard,   731 
Silicosis,  627 

Silver  acetate  in   ophthalmia  neona- 
torum,  64 
Silver  catarrh,  64 
Silver  nitrate,    Crede's   method   of 

using,  63 
Simond,  213,  '241 
Simonds,  228 
Simulium,  235 
Single  standard,  57 
Size  of  fat  globules  in  milk,  497 
Skimming  milk,  509 
Slack,   147 
Slaked  lime,  1016 
Slaughter,  emergency,  546 

methods  of,  546 
Slaughter  house,   543 
Sleeping  sickness,  232,  236 

prevention  of,  234 

tsetse  fly  and,  233 
Slimy   milk,   507 
Sling  psychrometer,  610 
Slow  sand  filters,  781 
Sewage  disposal,  854 
Smallpox,   1 

and  cowpox,  unity  of,   21 

desquamation  in,   36 

disinfection  in,   33 

epidemiology  of,  27 

hospitals  for,   33 

isolation  in,  33 

modes  of  infection  by,  27 

mortality  in,   27,  29 


INDEX 


1067 


Smallpox,   prevalence  of,   25 

quarantine  in,   324 
release  from,  36 

resistance  of  wus  of,  28 

in    vaccinated    and    unvaccinated, 
29 
Smirnoff,  165 
Smith,   580 

Smith,   Argus,   587,  622 
Smith,  Claude,    117 
Smith,  R.   M.,   165 
Smith,  Theobald,  71,  181,  262,  263, 

400 
Smoke,  622 
Smoking,    481 
Snow,  Dr.,  816 
Soaps,  germicidal,  1022 
Sodium  bicarbonate,   490 
Sodium  fluorid,  489 
Sodium  nitrate,  489 
Softening  of  the  brain,  300 
Soil,   670 

air  in,  674 

bacteria  in,  681 

carbon   cycle  and,   680 

classification  of,   671 

cleanliness  and,  684 

composition  of,   672 

dirt  and,  683 

diseases  associated  with,  684 

influence  of,  upon  health,  684 

nitrogen  cycle  and,  676 

pollution  of,  682 

hookworm  disease  and,  119 

relation  of,  to  disease,  681 

surface  configiiration   of,   671 

temperature   of,   673 

typhoid  and,  92 

water  in,   675 
Solanin,  573 

Solids,  milk  standards  and,  499 
Solutol,   1014 
Solveol,   1014 
Sommer,  295 
Sonden,  591 
Sophian,  180 

Sore  throat  due  to  milk,  514 
Sour  milk,  506 


Sources  of  infection,  313 

of  meat,  540 
South  African  tick  fever,  267 
Soxhlett  method,  529 
Space,  for  puj^il,  948 
Special  schools,  947 
Specific   death  rates,  901 
Specific  gravity  of  milk,  534 
Specific   nature   of  insect-borne   dis- 
eases, 182 
Specific   prophylaxis   against   scarlet 

fever,  164 
Specificity,  346 

anajohj^laxis  and,  406 
Spermotoxin,   393 
Sphacelinic   acid,    572 
Spices,  486 
Spieler,   133 

Spirillum  obeiTQeieri,  266,  267 
Spirochseta  duttoni,  267 
Spii'ocheeta  pallida,  50 
Splenetic  fever,  263 
Spoiled  corn,  580 
Spoiled  meat,  540 
Spooner,  97 
Sporozoites,   209 
"Sports,"  427 
Spots,  569 
Spotted     fever.     Rocky     Mountain, 

263 
Spraying  method,  997 

destruction  of  ticks  by,  262 
Springs,  716 
Sprinkling  filters,  858 
Sputum,   disinfection   of,  1031 

disposal   of,   in  tuberculosis,   141 
SquiiTel  flea,  241 
Squirrels,  242,   253 
Stable  fly,  279 
Stables,   disinfection  of,  1027 
Stage  of  river,  704 
Stag-nation  of  water,  706 
Stairs  in  schools,  948 
Standard,  of  butter  fat,  498 

of  population,  902 
Standard  ammonium  chlorid  solu- 
tion,  737 
Standard  certificate  of   death,   883 


1068 


INDEX 


Standard  methods  in  water  analysis, 
722 

Standard  lime  water,  591 

Standards  of  milk,  499 
of  ventilation,   656 

Standardization,   of  diphtheria   anti- 
toxin, 378 
of  disinfectants,  971 
of  tetanus  antitoxin,  380 

Staphylococcus  for  diphtheria  car- 
riers, 148 

Starvation,  463 

State  quarantine,  333 

Stationary  air,  653 

Statistical  methods,  436,  439 

Statistics,  436 

Steam,  982 

Steam  chamber,  984 

Steam  pipes,  668 

Steam  vacuum  method,  590 

Steel  grinder's  phthisis,  627 

Stegomyia  calopus,  212,  215 

Stegomyia  fasciatus,  212 

Stenocephalus  canis,  239 

Stei-ility.  gonorrhea  and,  53 

Sterilization,    966 

Sterilizer,   drj'   wall,   980 

Stem,  398 

Sternberg,  1017 

Stevens'  drawer,  664 

Stevenson,  64 

Stewart-Slack  method,  525 

Stewing,  493 

Sticker,  296 

Sticky  fly  paper,  193 

Stigmata    of    degeneration,    416 

Stiles,  115,  118,  119,  688 

Still.  131 

Stimson,  254 

Stitt.  212,  222 

St.  Lawrence    State    Hospital,    841 

Stomoxys   calcitrans,    224.   226,   279, 
285 

Stone-mason's  phthisis,  627 

Storage  cisterns,  701 

Storage  of  water,  779,   793 

Storch  test,  536 

Storm  sewers,  845 


Stoves,  667 

Straus  home  pasteurizer,  521 

Strauss,  278,  282 

Strauss  reaction,   282 

Streams,  flow  of,  704 

interstate  pollution  of,  719 

pollution  of,  848 

self-purification  of,  777 
Street  virus,  41 

Streptococci  in  scarlet   fever,   160 
Streptococci  in  sewage,  761 
Streptococcus  conglomeratus,  160 
Streptococcus  equinus  fecalis,  229 
Streptococcus  laetis,  507 
Streptococcus  mucosus,  177 
Streptococcus  scarlatinae,  160 
Streptococcus  vaccines  for  scarlet 

fever,   164 
Stripping  resers'oir,  707 
"Strippings"  in  milk,  497 
Strong,   256,  576 
Strongj'loides  stercoralis,   116 
Structure  of  meats,  538 
Strychnin,  250 
Stiller,  924 

St.  Yitus's  dance,  963 
StjTiis,   796 
Sub-soil  drainage,  676 
Substitution,   468 
Sub-surface  irrigation,  855 
Sudden   death,  in  anaphylaxis,   409 

antitoxin   and,    152 
Sugai,  293 
Sulphate  of  aluminium,  789 

in  water,  799 
Sulphate  of  copper.  1021 
Sulphate  of  ii'on,  1021 
Sulphites,  490 
Sulphur  dioxid,   997 

in  air,   638 

for  destruction   of  rats,   252 

in  foods,  490 

as  insecticide,  190 

liquid.  1001 
Sulphur  dips,  191 
Sulphur  furnace.  1002 
Sulphur  insecticides,   190 
Sulphur  ointment,  191 


INDEX 


1069 


Sulphurous  acid,  490 
Sunlight,  979 

and  water,  779 
Supplemental  air,  653 
Suppression,  of  bedbugs,  273 

of  institutional   diphtheria,    149 

of  rats,   249 

of  vermin,  185 
Surface  waters,  702 

analysis  of,  775 
Surgery  for  defectives,  417 
Surra,  236 

Sur\ival  of  the  fittest,  425 
Susceptibility  to   diphtheria,  149 
Sutton,   221 

Swine  plague,  meat  and,  550 
Swithinbank,   514 
Symbiosis,   968 
Symmers,  132 

Sjrmptomatie  dysentery.  111 
Syncytiolysin,  393 
Synura,  754 
Syphilis,  50 

economic    aspects    of,   50 

hereditaiy  transmission  of,  446 

immunity  to,   51 

insanity  and,  300 

medical  prophylaxis  against,  58 

modes  of  transmission  of,  51 

relation  of,  to  life  insiirance,  52 
Syrups,  480 

Tabanus,  224 

Tabanus  tropicus,  236 

Tabardillo,  270 

Tenia  sagiriata,  563 

Tenia  solium,  562 

Tenia  medioeancellata,  563 

Takaki,  574 

Tank-room  in  abattoir,  544 

Tanking,  545 

Tanks   and   mosquitoes,   204 

settling,  septic,  etc.,  853 
Tapewoi-m,  beef,  563 

fish,  565 

pork,  562 
Tapeworm  cysts,  550 
Taste  of  water,  723 


Taussig,  237 

Taute,  234 

Taylor,  486 

Teakwood  dust,  941 

Technique.    See  Method 

Teeth,  school  children's,  961 

Teleky,  924 

Temperature,    adaptation    to,    604 

of  air,  603 

food  preservation  and,  475 

of  refrigerator,  475 

relation   of,  to  health,  613 

of  soil,   673,  674 
Temporary  carrier,  315 
Temporary  hardness,  734 
Tendency,  to  disease,  transmission 
of,  408 
hereditaiy,  445 

to    tuberculosis,   transmitted,    137 
Terminal   disinfection,    970 

in  measles,   159 

in  scarlet  fever,  163 
Terni,  256 
Tertian  fever,   207 
Terzi,  208 
Tests,  for  blood,  399 

for  water  pollution,  718 
Tetanolysin,   373 
Tetanospasmin,  373 
Tetanus,   66 

etiology  of,  66 

incubation  period  of,  70 

prophylaxis    against,    72 

resistance   to,  70 

standardization   of,   378 

soil  and,   685 

vaccination  and,  19 

in    vaccine    and    biological    prod- 
ucts,  69 
Tetanus  antitoxin,   72,   377 
Tetanus  dolorosus,  376 
Tetanus  toxine,   373 
Tetanus  trismus  neonatorum,   68 
Tetrodon,   564 
Texas  fever,  263 
Textile  industries,  939 
TheUer,    236 
Theories  of  immimity,   338 


1070 


INDEX 


Thermal  circulation,  6G1 

unit  of,  666 
Thermal   death    point    of   B,    tuber- 
culosis, 138 

of  milk  enzymes,  502 
Thermometers,  604 

automatic,   989 

disinfection  of,  103-i 

wet  bulb,  615 
Thickening  agents  in  milk,  509 
Thompson,  241 
Thorpe,   926 
Thro,  279 
Thrushfield,  144 
Thymol,  hookworms  and,   119 
Thyroid  glands  in  fish,  809 
Tick       fever.       South       African. 

267 
Ticks,    261 
Tidal  air,  653 
Tindal,   796 
Tizzoni,  43,  228 
Tobacco  smoke,  192 
Tobin's  tube,  663 
Todd,  111,  146,  233,  237,  267 
Tolerance,    338 
Tonnage,  331 
Tonsilitis  and  milk,  514 
Torrey,  229 
Total  solids,  in  milk,  499,  527 

in  water,  732 
Toxicogenic,  559 
Toxin,  357 
Toxines,   360 

botulismus,    559 

dysentery,  111 

tetanus,  373 
Toxoid,   357 
Toxophore,  357 
Trachoma,   60 
Trade  A\'inds,   603 
Trade  wastes  as  nuisances,  863 
Trades,  dusty,  938 

Transference.     See    Mode    of   trans- 
mission 
Transmission,    congenital,    445 

hereditary,  of  disease,  442 

in  insects,  262 


Transmission  of  tendency,  445 

See  also  Mode  of  transmission 
Traps,   rat,  250 
Trask,  146 

Treads  in  school  stairs,  948 
Treatment,    of    hookworm    disease,   - 
119 

for  lice,  269 
Treponema  pallidum,  50 
Trichina  spiralis,  347,  560 
Trichinella  spiralis,  248,  560 
Trichinosis,    560 

rats  and,  248 
Trichiuris  trichiura,  688,  837 
Trickling  filters,  858 
Tricresol,   1013 
Triller,  578 
Trioxymethylene,    993 
Trismus   neonatorum,   68 
Tropical   malaria,   207 
Troussart,  242 
Trudeau,   137 
Tnink  sewers,  845 
T  r  y  13  a  n  o  s  o  m  a     gambiense,    233, 

248 
Tiypanosoma  gnassei,  233 
Tryi^anosoma  lewisi,   233 
Tiypanosomes,  236 
Tsehemiak,  429 
Tsetse  fly,  233 

extermination    of,   234 
Tsistowitch,   397 
Tubercle   bacilli,   avian,   124 

bovine,    123 

in  dn'  sjDutum,  130 

human,   123 

in  milk,  513 

in  water,  138 
Tubercles  in  iron  pipes,  750 
Tuberculin,   136 

bo\Tne  and   human,  124 

reaction  of  eye  to,  412 
Tuberculosis,    122 

aerogenic  infection  in,  129 

anaphylaxis  and,  412 

bovine,  in  man,  124 
prevention  of,  142 

contact  infection  in,  134 


IXDEX 


1071 


Tuberculosis,       difference       between 
human   and   bovine,   123 
disinfection  in,  141 
disposal  of  sputum  in,  141 
droplet   infection   in,   131 
early   diagnosis   of,   141 
education  and,  140 
flies  and,  134 

hereditary  transmission  of,  446 
housing  conditions  and.  142 
immunity  to,   135 
industrial  insurance   and,  142 
ingestion   and,   131 
insanity  and,  301 
meat   and,  549 
milk  and,   513 
modes  of  infection  in,  129 
notification  regarding,   141 
of  fish,  124 

personal  prophylaxis  against,  139 
prevention  of,  138 
resistance  of  virus  of,  137 
segTegation  and,  139 
soil   and,   687 
water  and,  134 
Tunnicliff,  488 
Turbidimeters,    731 
Turbidity,  729 
Turnover  of  water,   706 
Tyler,  577 
Tyndall,   631 
Type,  size  of,  960 
Typhoid,   a  contagious  disease,   94 
on  daily  farm,  76 
death-rates   from,    75-79 
diagnosis  of,  80 
epidemic  of,  at  Ashland,  829 
at  Butler,   832 
at  Chicago,  834 
at  Ithaca,   831 
at  Lausen,  823 
at  Lawrence  and  Lowell,  832 
at  Mankato,  831 
at  New  Haven,  829 
at  Pittsburg  and  Allegheny,  833 
at  Plymouth,  827 
flies  and,  227 


Typhoid,  in  hospitals,  93 

inoculations  against,  94 

insanity   and,   299 

management  of  case  to  prevent 
spread  of,   98 

maneuver  division  and,  97 

milk  and,  514 

modes  of  spread  of,  86 

in  oysters,  566 

personal  prophylaxis  against,   100 

prevalence  of,  75 

rats  and,  248 

residual  or  normal,  79 

resistance  of  \T.rus  of,  83 

soil  and,  686 

in    Spanish-American  War,   93 

summaiy  of  subject  of,  100 

water,  influence  of,  upon,  822 

water-borne,  823 
Typhoid  bacillus,   carriers  of,   83 

channels  of   entrance  and  exit  of, 
80 
Typhoid  vaccines,    94 
Typhoid-colon  gToup,  553 
Typhus  fever,  269 

fleas  and,   240 

quarantine  in,  326 
Tyrotoxicon,  471 
Tyzzer,  21,  28,  280 

Uhlenhuth,  399,  407,  1020 
Ultra-violet  rays,  801,  979 
Uncinariasis.      See    Hookworm    dis- 
ease 
Underdraining,  malaria  and,  210 
Underdrains,  845 
LTngTaded  schools,  947 
UnifoiTQity  coefficient,  784 
Unit  character,  428 
Urinary  calculi,  water  and,  807 
Urine,  typhoid  bacilli  in,  81 
Uroglena,  726,  754 
Urotropin,  80,  100 

Vaccination    (vaccinia),    anaphylaxis- 

and.   413 
auto-,  19 


1072 


IXDEX 


Vaccination  (vaccinia),  claims  for.  17 

compulsory,  22 

course   of  eruption  in,   11 

dangers   and   complications  of,    19 

definition  of.  3 

of  exposed  pei-sons,  17 

and  foot-and-mouth  disease,  20 

general  symptoms  of,  11 

generalized,  19 

in    Germany,  33 

immimity  and,  14 

impetigo  contagiosa   and.   19 

incision  for,  8 

indices  of  successful  take  in,  11 

methods  of,  8 

number  of  incisions  in,  10 

the  operation  of,  10 

during  period  of  incubation  of 
smallpox,  18 

point   of  election  in,  9 

puncture  in,  8 

scarification  in,  8 

tetanus  and,  19,  73 
Vaccine  virus,  1 

bacteria   in,   6 

bovine,    -i 

definition  of,  3,  344 

drj',  4 

forms  of,  4 

fresh,   4 

green,   6 

gh-cerinated,    4 

government  control  of,  21 

human  and  bovine,  4 

propagation   of,   7 

ripe,  6 

seed,   7 

vaccine  lymph,  5 

vaccine  pulp,   5 
Vaccines,  bacterial,  definition  of,  344 

immunity  from,   345 

meningococcus    and,    180 

plague  and,  256 

streptococcus   and,   164 

typhoid  and,  95 
Vacuiun  system,  665 
Vaillard,  71 
Valentin.  643 


Vallee,   132 

Van  Beneden,  435 

Van   Gehuchten,  49 

Vapor  tension,   606 

Variate,  439 

Variation  and  heredity,  425 

Variola,  1 

Variola   inoculata,   23 

Variola  vera,  23 

Varioloid,   17 

Vasectomy,  417 

Vaughan,  92,  153,  227.  471,  488 

Veenboer.  488 

Vegetables,  and  tj-phoid,  91 

and  hookwonn,  120 
Venereal  diseases.  49 
Venereal  prophylaxis,  54 
Ventilating  ducts,  661 
Ventilation,  651 

of  sewers.  640,  848 

standards  of,   656 
Vessels,  rats  on,  245 
Viability   of  rabies,   39 
Vibrio  choler^e,  102 
Vibrione   septique,   686 
Vienna  water  supply,  goiter  and, 

808 
Vieusseux.  177 
Vincent,   71 

Virulence  of  diphtheria  bacilli,  147 
Virus,  dauysz.  253 

definition  of,  344 

fixed,   41 

in  rabies,  42 

rat,  253 

resistance  of,  41.     See  also  Resist- 
ance of  vims 

street,  41.     See  also  Vaccine  virus, 
and  Vaccines,  bacterial 
Vital  capacity.  654 
Vital  rates,  888 
Vital  statistics,  874 
Vitiated  air,  354,  641 

index  of.  58.8 

by    respiration,   653 
Voltmann,  178 
Volvarias,   572 
vonPirquet,  122,  404,  408 


INDEX 


1073 


von  Pirquet  reactions,  17 
Vosmaer,   796 
Vulcanstein,  132 

Wade,   147 

Walker,    242 

Wall  paper,   arsenic  in,  934 

Walls,  color  of,  schools,  948 

Ward,   308 

Warm  dry  air,  617,  666 

effect  of,  666 
Warm  moist  air,  616 
Warren,  177,  208 
Wassermann,  399 
Wassermann  reaction,  394 
Water,    691 

ammonias  in,   736 

amount  of,  used  and  wasted,  694 

analysis  of,  722 

bacteria  in,  754 

boiled,  780 

chemical    results    of    analysis    of, 
expression  of,  757 

chlorin  in,  744 

chlorinated   lime   in,   797 

classification  of,  692 

color  of,  728 

composition  of,  692 

distilled,   780 

double  supplies  of,   697 

filtration  of,  and  filters  for,  781 

ground,  708 

hardness   of,   733 

infection  of,  717 

iron  in,  749 

lead  in,   751 

microscopic  examination  of,  753 

in  milk,  532 

nitrates  in,  742 

nitrites   in,    741 

odors  of,  723 

organic  matter  in,  736 

oxygen  in,   746 

ozone  in,  794 

pollution  of,  717 

simple    tests    for,    718 

properties  of,   692 

purification  of,   776 


rain,  698 

reaction  of,  731 

relation  of,  to  disease,  803 

sanitary   analysis   of,   722 

interpretation  of  notes   on,   763 
standard  methods  in,  722 

sedimentation  of,  794 

soil,  675 

sources  of,  698 

streams,  interstate  pollution  of, 
719 

storage  of,  793 

surface,  702 

tastes   in,   723 

total  solids  in,  732 

tubercle   bacilli  in,   139 

turbidity  of,  729 

uses  of,  in  body,  693 
Water  analyses,  examples  of,  762 

interpretation  of,  763 
Water-borne  cholera,  105 
Water-borne  hookworms,   120 
Water-borne  tuberculosis,   134 
Water-borne   typhoid,  86 

epidemics  of,  823 
Water  capacity,  673 
Water  carriage  system,  844 
Water  closets  in  schools,  955 
Water  gas,   636 
Water  pollution,   717 
Water  purification   by   chemical 

methods,  794 
Water-retaining  capacity,  673 
Water  siphon  method,  590 
Water  supplies,  double,  697 
Water  vapor,  605 
Wateiing  milk,  509 
Waterhouse,   3 
Webb,   137 
Weber,   127 
Wechsberg,   395 
Wedgewood,  422 
Weichardt,  405,   646 
Weichselbaum,  133,  176,  177 
Weismann,   416 

Weismann's  riews  on  heredity,  427 
Weisner,    277 
Welch,   360 


1074: 


INDEX 


Welch,  Thomas,  177 
Wells,  712 

construction   of,  713 

disinfection  of,  1034 
Werner,   29G 

Werner-Schmidt  method,  529 
Wernstedt,   278 
Westphal  balance,  535 
Wet  and  cold,  351 
AVet  bulb  thermometer,  615 
Weyl,  374 
Wheeler,  88 
Wherry,    253,    295 
Whipworm,  837 
Whipple,  86,  753 
White,   218 
White  lead,  925 
Whitewash,    1016 
Whitla,  132 
Whooping-cough,  166 
Wiekman,  275,  278 
Widal,  390 
Widal   reaction,  400 
Wilder,   270 
Wiley,  474,  483 
Wilkinson   test,   536 
Williams,    64,    137 
Willson,  20 
Wilson,   265,   428,  435 
Window  ventilator,  663 
AVindows  in  schoolrooms,  954 
Winkler,  748 
WinogTadski,   678 
Winship,  422 
AA'inslow,   640 
AVolbach,  237 
AYolf  bites,  38 
Wolpert  method,  595 
Woman's  milk  and  cow's  milk,  503 
Women,  work  of,  918 


Wood,   577 

Wood   alcohol,    61 

Wood  dust,   941 

AYood  lice,  261 

Woodward,  128,  131 

Wool  sorters'  disease,  285,  943 

Workmen's   compensation,  920 

Wound  infections  in  vaccination,  19 

Wounds,  tetanus,  67 

treatment  of,  72 

treatment  of,  in  rabies,  39,  40 
Wright,  94,  96 
Writei-s'  cramp,  916 

X  Y  Z  theory  of  Pettenkofer,  103 

Y^ellow  fever,  212 

aerial  conveyance   of,   217 

historical  note  on,  219 

immunity  to,  213 

and   malaria,    prevention    of,    con- 
trasted, 220 

mosquito  and,  213 

prevention   of,   218 

quarantine  in,  325 

water  and,  837 
Yemelyanoff,   165 
Yersin,   242 
Yersin   serum,   257 
Y'oung,   941 

Zammit,  290 
Ziemann,  211 
Zienka,  399 
Zinc  chlorid,   1021 

Zinc  sulphate  for  treatment  of  con- 
junctivitis, 64 
Zweifel,  64 
Zwischkorper,  359 


(1) 


DATE  DUE 


DEMCO  38-296 


COLUMBIA  UNIVERSITY  LIBRARIES 


0041068807 


